AP Biology Exam Review Information

Transcription

1 AP Bilgy Exam Review Infrmatin The AP Bilgy Exam puts yur knwledge and understanding f mdern bilgy t the test -- and gives yu the chance t earn cllege credit befre yu're dne with high schl. The AP Bilgy Exam cnsists f tw sectins: multiple chice and free respnse. Bth sectins include questins that assess students understanding f the big ideas, enduring understandings, and essential knwledge and the ways in which this understanding can be applied thrugh the science practices. These may include questins n the fllwing: the use f mdeling t explain bilgical principles; the use f mathematical prcesses t explain cncepts; the making f predictins and the justificatin f phenmena; the implementatin f experimental design; and the manipulatin and interpretatin f data. The exam is 3 hurs lng and includes bth a 90- minute multiple chice sectin and a 90-minute free-respnse sectin that begins with a mandatry 10-minute reading perid. The multiple-chice sectin accunts fr half f the student s exam grade, and the free-respnse sectin accunts fr the ther half. THE FOUR BIG IDEAS OF AP BIOLOGY: The key cncepts and related cntent that define the AP Bilgy Exam are rganized arund a few underlying principles called the big ideas, which encmpass the cre scientific principles, theries and prcesses gverning living rganisms and bilgical systems. BIG IDEA 1: The prcess f evlutin drives the diversity and unity f life. Evlutin ccupies a central psitin in the discipline f bilgy. BIG IDEA 2: Bilgical systems utilize free energy and mlecular building blcks t grw, t reprduce and t maintain dynamic hmestasis. Different rganisms emply varius strategies t capture, use, and stre free energy and exchange matter with the envirnment. BIG IDEA 3: Living systems stre, retrieve, transmit and respnd t infrmatin essential t life prcesses. Genetic infrmatin prvides fr cntinuity f life, and this infrmatin is passed frm parent t ffspring. Randm changes in infrmatin allw fr evlutin, with natural selectin acting upn phentypes. BIG IDEA 4: Bilgical systems interact, and these systems and their interactins pssess cmplex prperties. All bilgical systems are cmpsed f parts that interact with ne anther and the envirnment, and these interactins result in characteristics nt fund in the individual parts alne. Sectin I, Part A, cnsists f 63 multiple-chice questins that represent the knwledge and science practices utlined in the AP Bilgy Curriculum Framewrk that students shuld understand and be able t apply. Part B includes 6 grid-in questins that require the integratin f science and mathematical skills. Fr the grid-in respnses, students will need t calculate the crrect answer fr each questin and enter it in a grid in the grid-in sectin n their answer sheet, as shwn belw. In Sectin II, students shuld use the mandatry 10 minute reading perid t read and review the questins and begin planning their respnses. This sectin cntains tw types f free-respnse questins (shrt and lng), and the student will have a ttal f 80 minutes t cmplete all f the questins. Due t the increased emphasis n quantitative skills and applicatin f mathematical methds in the questins n bth sectins, students will be allwed t use simple fur-functin calculatrs (with square rt) n the entire exam. Students will als be supplied with a frmula list as part f their testing materials. A student s ttal scre n the multiple-chice sectin is based n the number f questins answered crrectly. Pints are nt deducted fr incrrect answers r unanswered questins.

2 Exam Review Sessins Review sessins fr the AP Bilgy Exam will ccur in rm 301 n Tuesdays befre and after schl beginning n March 24 th. During the week prir t the exam, we will have mrning review sessins as well. Althugh these review sessins are nt required, it is highly recmmended that yu attend as many as pssible. During these sessins, students will be given the pprtunity t ask questins cncerning the material that is cvered in the AP Bilgy Exam Review Packet, as well as the material cvered this semester. We will als be discussing the frmat f the exam and reviewing sme vides abut the science practices that students will be expected t be able t demnstrate n the exam. Review Sessin Schedule Date Time(s) Tpics Tuesday, March 24 th Orientatin - 3:15 pm 4:15 pm Review Manuals Tuesday, March 31 st 7:00 am 7:30 am Big Idea #1 3:15 pm 4:15 pm Tuesday, April 7 th 7:00 am 7:30 am Big Idea #2 3:15 pm 4:15 pm Tuesday, April 14 th 7:00 am 7:30 am Big Idea #3 3:15 pm 4:15 pm Tuesday, April 21 st 7:00 am 7:30 am Big Idea #4 3:15 pm 4:15 pm Tuesday, April 28 th 7:00 am 7:30 am 3:15 pm 4:15 pm Mathematics in AP Bilgy Mnday, May 4 th 7:00 am 7:30 am Student Chice Tuesday, May 5 th 7:00 am 7:30 am 3:15 pm 4:15 pm am: Student Chice pm: Practice Exams Wednesday, May 6 th 7:00 am 7:30 am Student Chice Thursday, May 7 th 7:00 am 7:30 am Student Chice Friday, May 8 th 7:00 am 7:30 am Student Chice

3 AP Bilgy Exam Review Packet AP Bilgy Free Respnse Writing Tips General Tips: One r mre f the questins will likely be AP Lab-based. (See Tips fr AP Lab Questins belw.) Yu must write in paragraph frm! There is rm n the test fr yu t create an utline t guide yur answer, but utlines are nt graded. That being said, perfect essay writing is nt expected. There are n deductins fr grammar r spelling mishaps (prvided the spelling is clse enugh t determine the wrd yu are trying t write). Diagrams are helpful. Hwever, if yu draw a diagram, be sure t refer t it in yur answer. Yu will nt earn pints fr diagrams that stand by themselves. Pints are nt deducted frm yur scre if yu give an incrrect statement. Yu just d nt receive pints fr incrrect statements. Hwever, yu must be careful nt t cntradict yurself. If yu state smething crrectly but then later state the ppsite, yu will nt earn the pint. Tips fr AP Lab Questins: AP Lab Questins will ften present an experiment setup very similar t ne f the AP Labs yu perfrmed. Review each f the labs thrughly befre the exam. Remember t always reference an experimental cntrl. Using an experimental cntrl in an experiment invlves setting up cntrl grups that have nt been affected by the experimental (independent) variable. Cntrls are used s that an experimenter can cmpare the grup that has changed t the grup that stayed the same. In ther wrds, cntrl grups are nt expsed t a chemical r treatment being investigated s that it can be cmpared with experimental grups that are expsed t the chemical r treatment Cntrl grups are useful t derive baseline measures r bservatins used fr evaluating the effects f an experimental (independent) variable. In EVERY AP Lab Questin, yu shuld discuss the fllwing infrmatin, even if the questin des nt specifically ask fr it: (remember, yu are never deducted fr t much infrmatin, but keep it relevant): State the testable hypthesis and identify it as such. State the cntrl grup. State the independent (experimental) and dependent (measured) variable(s). (Example: If yu decide t measure the prduct f an enzymatic reactin at different times, then time is the independent variable and prduct cncentratin is the dependent variable.) Identify ther variables being held cnstant. (Example: amunt f time, stirring, temperature, etc.) State hw and when data will be cllected r bservatins made. (Example: measure mass after 3 minutes) State what calculatin will be used. (Example: average 3 values fr mass, write ut frmulas used) State hw yu will be cnfident in yur results. (Example: repeat trials, using a large sample size, etc.) State hw yu will share yur results. (Example: tables, graphs, drawings, etc.) State what yu expect t happen and why. We will d practice AP Test Lab questins s that all f this will seem a breeze! Nevertheless, it is a gd idea t practice n yur wn with an AP Bilgy Exam practice bk t prepare. Students wh pass with an 80% r better n the multiple chice sectin f the test and earn 50% r better f the pints n their free respnses, usually earn 5s n the exam. An verall scre f 50% cmbined (multiple chice and free respnse) usually earns a scre f 3 r abve.

4 DOS and DON TS n Exam Day DO THIS n Exam Day: DO use yur ten minute reading time advantageusly. Carefully read all f free respnse questins and map ut yur answers. These maps will NOT be graded, but yu can use them t write yur respnses. Read the prmpt thrughly, then read the prmpt again, then read the prmpt, then read the prmpt again, then read the prmpt, then Jt dwn the big ideas. Make sure yu clearly understand what yu are being asked t d. Use this time t create a mindmap r bullet pints f the main terms yu want t elabrate n. Outline yur answer t rganize yur thughts. Remain fcused and n task. DO underline the imprtant terms in the questin such as OR and CHOOSE 2 and the pwer verbs such as DESCRIBE, IDENTIFY, LABEL, CONSTRUCT, DESIGN, r EXPLAIN. DO use the 80 minutes t write thrugh respnses t all f the free respnse questins. DO stay fcused n what the prmpt is requiring yu t d it is all in the frmat f the questin and hw it is wrded. Pay particular attentin t wrds like these: Discuss: give reasning pr and cn; analyze carefully Analyze: summarize in detail with a selected fcus Explain: clarify and interpret; give reasns fr differences, analyze causes Cmpare/cntrast: emphasize similarities and differences Relate: shw hw ideas r cncepts are cnnected t each ther DO use the utline, mindmap r bullet pints that yu develped during the 10 minute reading time. DO write as legibly as pssible, using black ink. If the persn scring yur answers cannt read what yu have written, then yu will nt earn any pints. DO answer in the frmat f the questin s that yu d nt slw the reader dwn. Use the frmat f the free respnse t write yur answer s that the reader has an easy time finding yur respnses t each sectin f each questin. Organize the free respnse questins using the frmat f the questin write 1a then respnd t 1a; write 1b then respnd t 1b, etc It is best nt t skip arund when respnding t sub-questins in ne questin. DO apply the language f science, shw depth, elabratin, and give examples. Pull, tie, link and lp tgether yur ideas shw hw ideas cnnect. Use a scientific term and then explain what it means. Write fr clarity, accuracy, thrughness, and breadth (nt just factual regurgitatin). DO use graphs r diagrams when it will enhance yur respnse. Hwever, unless the prmpt specifically asks fr drawings/graphs, every thught yu cnvey shuld als be put in writing. DO clearly mark yur answer sheet with the free respnse questin yu are answering. The free respnse questins d nt have t be answered in any particular rder, as lng as they are clearly marked. Write freely n the respnse sheet use several sheets as needed. Usually the lnger the answer t the questin the mre pints yu will earn! Write! Write! Write! DO answer ALL subunits f a questin thrughly t ensure yu will gain maximum pints fr yur respnse. DO label all graphs crrectly. Include a graph title. Include a key identifying lines and data pints. Label axes (including units). DO use the time at the end t re-read respnses underlining key cncepts, checking fr clarity, accuracy and thrughness. DON T DO THIS n Exam Day: DON T leave any free respnses questins blank. Even if the questin seems dd r yu draw a temprary blank, find the cre bilgical tpic being addressed and elabrate n it. Remember that all students in the natin will be in the same bat with a difficult r unclear questin. DON T bsess ver crrect grammar. There are n deductins fr grammatical imperfectins. DON T write intrductry r clsing paragraphs. N pints are earned fr thesis statements r tpic sentences. DON T ramble. Get t the pint. D nt waste time describing yur feelings abut hw glad yu are that the AP Cllege Bard asked yu abut phtsynthesis. If anything, this will anny the reader. DON T write nly in utline frmat. Yur answers must be in paragraph frm. DON T ver-answer the sub-questins f a free respnse questin. Remember that fr any given questin requiring sub-questin respnses, each respnse is alltted a maximum number f pints. Writing mre than is necessary will nt earn yu mre pints.

5 AP Bilgy Equatins and Frmulas

6 AP Bilgy Equatins and Frmulas

7 AP Bilgy - AP Exam Review Chapter 1 - Explring Life Bilgy the scientific study f life Characteristics f Living Organisms (life is impssible t define) 1. Highly rdered structure 2. Evlutinary adaptatin 3. Respnse t the envirnment (irritability) 4. Regulatin (hmestasis, cnstant bdy temperature fr warm-blded rganisms) 5. Energy prcessing 6. Reprductin 7. Grwth and develpment (DNA ges alng with this) Levels f Bilgical Organizatin (either directin simplest t cmplex r vice versa) 1. Bisphere the area arund the earth where living rganisms are fund) 2. Ecsystems cnsists f all the living thins in a particular area, alng with all the nnliving cmpnents with which living rganisms interact 3. Cmmunities the entire array f rganisms inhabiting a particular ecsystem 4. Ppulatin all the individuals f a species living within the bunds f a specified area 5. Organisms individual living things are called rganisms 6. Organs and Organ Systems an rgan is a bdy part cnsisting f 2 r mre tissues; an rgan system is a team f rgans that cperate in a specific functin 7. Tissues a tissue is a grup f similar cells 8. Cells the basic unit f structure and functin f all living things 9. Organelles the functinal cmpnents that make up cells 10. Mlecules a mlecule is a chemical structure cnsisting f tw r mre small chemical units called atms Ecsystem Dynamics Tw Majr Prcesses 1. Cycling f nutrients 2. Flw f energy frm sunlight t prducers (plants and ther phtsynthetic rganisms that cnvert light energy t chemical energy) t cnsumers (feed n prducers and ther cnsumers) Systems Bilgy - seeks t create mdels f the dynamic behavir f whle bilgical systems. With such mdels, scientists are able t predict hw a change in ne part f the system will affect the rest f the system Feedback Regulatin 1. In negative feedback, accumulatin f an end prduct slws the prcess that prduces the prduct 2. In psitive feedback, the end prducts speeds up its prductin Discvery Science - describes natural structures and prcesses as accurately as pssible thrugh bservatin and data analysis Inquiry a search fr infrmatin ften fcusing n a specific questin Inductive Reasning generalizatins based n a large number f specific bservatins Deductive Reasning start with generalizatins and mve t specifics (If.then) Scientific Methd Independent Variable tested - x-axis Dependent Variable measured y-axis

8 Themes That Unify Bilgy 1. The cell 2. Heritable infrmatin 3. Emergence f bilgical systems 4. Regulatin 5. Interactin with the envirnment 6. Energy and life 7. Unity and diversity 8. Evlutin 9. Structure and functin 10. Scientific inquiry 11. Science, technlgy, and sciety Chapter 2 - The Chemical Cntext f Life ( simple chemistry ) Matter anything that takes up space and has mass Element a substance that cannt be brken dwn t ther substances by chemical reactins 92 naturally ccurring elements Cmpund tw r mre different elements cmbined in a fixed rati Essential Elements (O, C, H, N, Ca, P, K, S, Na, Cl, and Mg) Trace Elements required in small quantities Atm smallest unit f matter that still retains the prperties f an element, cmpsed f prtns, neutrns, & electrns Atmic Number = number f prtns Atmic Mass = prtns + neutrns Istpe same element with different number f neutrns Valence Electrns invlved in bnding utermst s and p Electrn Orbital where an electrn has a strng chance f being lcated Chemical Bnd hlds atms tgether Cvalent Bnd sharing f pairs f valence electrns (single, duble, and triple bnds) Plar vs Nnplar Bnds due t unequal sharing f electrns Inic Bnd electrstatic attractin between a psitive and negative in Hydrgen Bnd relatively weak attractin between H in ne mlecule (r part f a mlecule) with F, O, r N in anther mlecule (r part f a mlecule) Van der Waals Frces - dispersin frces, IMF s The structure f a mlecule determines the functin f the mlecule. Chemical Reactin the making and breaking f chemical bnds, leading t changes in the cmpsitin f matter. The transfrmatin f reactants int prducts

9 Chapter 3 - Water and the Fitness f the Envirnment Structure f water the plarity f the mlecule leads t the unique characteristics f water Why is water s imprtant t living rganisms? 1. Chesive 2. Adhesive 3. Evaprative clant 4. Less dense as a slid than as a liquid 5. Gd slvent 6. High specific heat H 2 O H + + OH - (Dissciatin f a water mlecule - this is the basis f acids and bases) Acid increases the H + cncentratin f a slutin Base reduces the H + cncentratin f a slutin ph scale - based n the [H + ] lg scale (ph f 14 = ph f 1 = 10-1 ) ph f 7 is cnsidered neutral, 1-7 is acidic, and 8 14 is alkaline r basic ging dwn the scale (frm base t acid), the [H + ] cncentratin increases 10x the poh scale wuld be based n the cncentratin f the OH - in A buffer keeps the ph cnstant by shuffling H + (release f these ins makes things mre acidic, pick up f these ins makes the slutin mre basic) Chapter 4 - Carbn and the Mlecular Diversity f Life Organic chemistry is carbn-based because carbn can bnd with up t 4 ther atms. Carbn skeletn r carbn backbne leads t a variety f structures carbn can frm single bnds, duble bnds, triple bnds, straight chain mlecules, branching mlecules, and rings. Hydrcarbns - mlecule that cnsists nly f carbn and hydrgen (majr cmpnents f fssil fuels, fats and phsphlipids have hydrcarbn tails) Ismers - mlecules that have the same structural frmula but different arrangement f mlecules Functinal Grups (See Figure 4.10 n pp ): Knw the structure and functinal prperties f the fllwing: Hydrxyl, Carbnyl, Carbxyl, Amin, Sulfhydryl, Phsphate Chapter 5 - The Structure and Functin f Macrmlecules Mnmer - building blck unit Plymer - many mnmers jined tgether Dehydratin Synthesis r Cndensatin Reactins a building prcess mnmers are jined tgether a mlecule f water is remved in the prcess Hydrlysis Reactins a break-dwn prcess plymers are brken int mnmers thrugh the additin f a mlecule f water Carbhydrates sugars and plymers f sugars. Characterized by the presence f multiple hydrxyl grups and a carbnyl grup. If the carbnyl grup is at an end, the sugar is an aldse sugar because f the presence f an aldehyde. If the carbnyl grup is in the middle, the sugar is a ketse sugar because f the presence f a ketne.

10 Mnsaccharide simple sugar generally has a frmula that is a multiple f the unit CH 2 O A simple sugar typically has 3 7 carbns in its carbn skeletn Glucse (C 6 H 12 O 6 ) is the mst cmmn mnsaccharide Disaccharide cmbinatin f tw mnsaccharides held tgether with a glycsidic linkage - cvalent bnd between tw mnsaccharides frmed by dehydratin synthesis. Plysaccharide many mnsaccharides bnded tgether Starch plant energy strage Glycgen animal energy strage Cellulse structural carbhydrate, majr cmpnent f a cell wall Chitin structural carbhydrate, majr cmpnent f arthrpd exskeletns, als fund in the cell walls f fungi Lipids - n affinity fr water mstly hydrcarbns imprtant strage mlecule fr cells Fats made up f glycerl and fatty acids Fatty Acids saturated r unsaturated Saturated Fatty Acids - cntain maximum number f hydrgen atms, are typically frm animals, and are slids at rm temperature. Unsaturated Fatty Acids - have sme duble and triple bnds, are typically frm plants, and are liquids at rm temperature. Phsphlipid ne f the fatty acids f a triglyceride is replaced by a phsphate grup majr cmpnent f cell membranes Sterid carbn skeletn made up f 4 fused rings Chlesterl cmpnent f animal cell membrane precursr f many ther hrmnes Prteins made f 20 different amin acids jined by peptide bnds (als called plypeptides ) Functins f Prteins 1. Structural cmpnents 2. Enzymes 3. Hrmnes 4. Strage 5. Transprt (thrugh membranes) 6. Defense prteins 7. Receptr prteins Levels f Prtein Structure Primary chain f amin acids (as the prtein is frmed n the ribsme) Secndary result f hydrgen bnding between the cmpnents f the plypeptide backbne (Alpha helix & Beta pleated sheet) Tertiary Structure result f interactins between the cmpnents f the R chain (van der Waals frces, hydrphbic interactins, etc.) Quarternary Structure results frm the aggregatin f plypeptide subunits Denaturatin - prteins are denatured (brken dwn) by heat, acids, and high in cncentratins

11 Chapter 6 - A Tur f the Cell Cell Thery 1. The cell is the basic unit f structure and functin f all living rganisms. 2. Everything is made up f cells. 3. Cells cme frm ther cells as the result f cell divisin. Micrscpy Magnificatin rati f the bjects image t its real size Reslutin measure f the clarity f the image Light Micrscpe visible light is passed thrugh the specimen and thrugh glass lenses which bend the light rays in such a way that the image is magnified as it is prjected nt the eye. Light micrscpes are limited t arund 1000X magnificatin - limited by the shrtest wavelength used t illuminate the specimen. Electrn Micrscpe fcuses a beam f light thrugh r n the surface f the specimen SEM scanning electrn micrscpe study details f the surface f the specimen TEM transmissin electrn micrscpe study the internal ultrastructure f a specimen Cell Fractinatin uses an ultracentrifuge t take cells apart and separate the majr rganelles Eukarytic vs. Prkarytic Cells (study this it is ften n the test in sme frm) All cells have a plasma membrane, cytsl (cytplasm), chrmsmes, and ribsmes Prkarytic Cells Eukarytic Cells Lack a nucleus Chrmsmes in a membrane-bund nucleus Lack membrane-bund rganelles Membrane-bund rganelles Single, circular chrmsme Linear chrmsmes Bth have a cell wall, cilia, and flagella, but the structures are different Surface-t-vlume rati - cells are limited in size by the fact that the internal vlume increases mre rapidly that the surface area f the cell membrane Cell Structures/Organelles: Nucleus cntrl center f the cell cntains the chrmsmes/dna Nuclear Membrane r Envelpe separates the nucleus frm the cytplasm selective Nuclelus dark-staining bdy in the nucleus where ribsmes are frmed Ribsmes site f prtein synthesis Endmembrane System (als called Cytmembrane System) synthesis f prteins and their transprt in and ut f the cell metablism and mvement f lipids detxificatin f pisns Endplasmic Reticulum extensin f the membranes thrughut the cytplasm a netwrk f membranes and sacs called cisternae A. Rugh ribsmes fund in the flds B. Smth lacks the ribsmes Glgi apparatus mdifies, stres, and ships prteins Vessicles membrane-bund transprt materials thrughut cytplasm

12 Lyssmes digest and destry Vacules fluid-filled cntainer carries ut hydrlysis fd vacules (frmed by phagcytsis), cntractile vacules (pump ut excess water), large central vacule (plant cell membrane arund it is called the tnplast) Mitchndria site f cellular respiratin Chlrplast site f phtsynthesis Perxismes cntain enzymes that transfer hydrgen frm varius substrates t xygen, prducing hydrgen perxide as a by-prduct Cytskeletn gives a cell shape, mechanical supprt and allws fr mvement Micrtubles made up f tubulin subunits maintains cell shape, cell mtility (cilia and flagella, chrmsme mvement during mitsis and meisis, rganelle mvement Micrfilaments made up f actin subunits maintains cell shape, changes in cell shape, muscle cntractins, cytplasmic streaming, cell mvement (pseudpds), and cell divisin Intermediate Filaments fibrus prteins superciled int thicker cables maintains cell shape, anchrs the nucleus and certain ther rganelles Centrsme micrtubules grw frm this pair f centriles Cilium shrt structures prjecting frm a cell and cntaining bundles f micrtubules that mve a cell thrugh its surrundings r mve fluid ver the cell's surface Flagellum - lng, thin, whip-like structures, with the same cre f micrtubules as cilia Bth cilia and flagella are cmpsed f a special arrangement f micrtubules arrangement (nine pairs f micrtubules arranged arund a central pair). The surrunding micrtubules are linked t the neighbring pairs by dynein arms the cilia beats. When the dynein arm walks up the neighbring micrtubule, causing it t bend. Plant Cell Wall prtects, maintains shape, and prevents excess water intake althugh the structure varies, it is primarily cmpsed f cellulse Plasmdesmata penings between adjacent plant cells that allws materials t pass back and frth Extracellular matrix (animal cells) Glycprteins - cllagen is the mst abundant Fibrnectin -bind t cell surface receptrs Integrins - span the cell membrane and bind t micrfilaments f the cytskeletn) Tight Junctin the membranes f neighbring cells are very tightly pressed against each ther, bund tgether by specific prteins Desmsmes anchring junctins that fasten cells tgether in strng sheets Gap junctin cmmunicating junctins that prvide cytplasmic channels frm ne cell t the adjacent cell

13 Chapter 7 - Membrane Structure and Functin Phsphlipid bilayer - duble layer hydrphbic tails and hydrphilic heads (referred t as an amphipathic mlecule) Fluid Msiac Mdel f the Cell Membrane 1. Fluid phsphlipids in the membrane are is mtin, changing places, switching sides unsaturated tails in the hydrphbic area increase fluidity by preventing the mlecules frm packing tgether chlesterl in the membrane decreases fluidity 2. Msaic there are many prteins embedded in the membrane Integral Prteins penetrate the membrane Peripheral Prteins nt embedded, but lsely bund t the membrane surface Transprt Prteins span the membrane serve as a channel fr the mvement f certain materials thrugh the membrane Enzyme Activity Prteins prteins built int the membrane may be enzymes with the active site available fr a reactin t take place Signal Transductin Prteins binding site fr a chemical messenger Cell-cell Recgnitin Prteins identificatin tags Intercellular Jining Prteins hk cells tgether - adhesin Attachment Prteins cnnect the cytskeletn t the extracellular matrix 3. Membrane Carbhydrates Glyclipids and glycprteins help in cell recgnitin Passes easily thrugh a cell membrane: carbn dixide, xygen, nnplar mlecules that wuld disslve the hydrphbic (fat) layer Des nt pass easily thrugh a cell membrane: plar mlecules, ins, cmplex mlecules, transprt mlecules have t mve these thrugh Diffusin mvement f a substance frm an area f high cncentratin t an area f lw cncentratin dwn a cncentratin gradient Osmsis diffusin f water thrugh a semipermeable membrane Tnicity the ability f a slutin t cause a cell t gain r lse water The fllwing terms are relative t each ther: Istnic interir and exterir f cell have the same cncentratin equal exchange f water mlecules Hypertnic high cncentratin f slute, lw water tends t gain water Hyptnic lw cncentratin f slute, high water tends t lse water Osmregulatin the cntrl f water balance In a hyptnic envirnment, an animal cell wuld gain water. Enugh water culd cause the cell t burst (cntractile vacules are adaptatins t remve this excess water). Because f the cell wall, and a plant cell stiffens (turgr pressure) t much excess water simply flws back ut because f the cell wall. In a hypertnic envirnment, bth plant and animal cells wuld shrink (plasmlysis)

14 Facilitated Diffusin certain substances enter and leave the cell because f the assistance f transprt prteins (energy is nt required in either case) Channel Prteins simply serve as a pathway thrugh which these mlecules travel Carrier Prteins shuttle mlecules thrugh the membrane because f a change in the shape f the prtein Active Transprt requires energy and is typically thrugh a membrane prtein ften frm a lwer cncentratin t a higher cncentratin Sdium-Ptassium Pump requires ATP, which bnds (ne f the phsphate grups) t the channel prtein and changes its shape 3 sdium ins are pumped t the utside and are released the phsphate grup is released, allwing tw ptassium ins t enter the channel and mve int the cell Prtn Pump the mvement f hydrgen ins thrugh the membrane against the cncentratin gradient Cupled Transprt The mvement f hydrgen ins gives the energy fr ther mlecules t mve back int the cell Endcytsis the mvement f large mlecules thrugh a cell membrane engulfed Excytsis the release f large mlecules by a cell Chapter 8 - An Intrductin t Metablism Metablism all f the chemical reactins in an rganism Metablic Pathways a sequence f events, each cntrlled by an enzyme, that cnverts a specific mlecule t a prduct thrugh these pathways the cell transfrms and creates rganic mlecules that prvide the energy and material needed fr life Catablic Pathways release energy stred in cmplex mlecules thrugh the breaking dwn these mlecules int simpler cmpunds Anablic pathways (bisynthetic pathways) require energy t cmbine simpler mlecules int mre cmplex mlecules fueled by the energy that is released in catablic pathways Bienergetics study f hw rganisms transfrm energy Energy capacity t cause change (sme types f energy can d wrk) Kinetic Energy energy f mtin Heat r Thermal Energy the kinetic energy f randmly mving mlecules Ptential Energy the capacity f matter t cause change as a cnsequence f its lcatin r arrangement Chemical Energy a frm f ptential energy stred in the arrangement f atms in mlecules and available fr release in chemical reactins Thermdynamics the study f energy transfrmatins First Law f Thermdynamics energy cannt by created r destryed, it can nly change frm the ttal energy in the universe remains cnstant Secnd Law f Thermdynamics every energy transfrmatin r transfer results in increasing disrder in the universe (entrpy is the measure f disrder)

15 In every energy transfer r transfrmatin, sme f the energy is cnverted t heat, the lwest frm f energy. Fr a prcess t ccur spntaneusly (withut the input f external energy) it must result in an increase in entrpy. A nnspntaneus prcess will ccur nly if energy is added t a system. An rganism may becme mre rdered as it develps, but it des s with an increase in the entrpy in its surrundings. An rganism takes in and uses highly rdered rganic mlecules as a surce f energy. It returns heat and the simple mlecules f carbn dixide and water t the envirnment. Free Energy the prtin f a system s energy available t perfrm wrk when the system s temperature and pressure are cnstant. When ΔG is negative, the final state has less free energy than the initial state; thus the final state is less likely t change and is mre stable. A system rich in free energy has a tendency t change spntaneusly t a mre stable state. Exergnic Reactin same as exthermic (-ΔG) prceeds with a net release f free energy and is spntaneus Endergnic Reactin same as endthermic (+ΔG) are nnspntaneus they must absrb free energy frm the envirnment Energy Cupling using exergnic prcesses t pwer endergnic prcesses ATP (adensine triphsphate) cnsists f the nitrgenus base adenine cnnected t the a ribse sugar and a chain f 3 phsphate grups In a cell, the free energy released frm the hydrlysis f ATP is used t transfer the phsphate t anther mlecule, prducing a phsphrylated mlecule that is mre reactive. The phsphrylatin f mlecules by ATP frms the basis fr almst all cellular wrk. ATP ADP Cycle

16 Enzymes bilgical catalysts that speed the rate f a reactin but are unchanged by the reactin Activatin Energy (Free Energy f Activatin) the energy required t start the reactin Enzyme-Substrate Mdel Cfactrs small mlecules that bind with enzymes are necessary fr the enzyme t functin Cenzymes rganic mlecules that are cfactrs Inhibitrs disrupt the actin f the enzyme Cmpetitive Inhibitrs cmpete with the substrate fr the active site f the enzyme Nncmpetitive Inhibitrs bind t an part f the enzyme away frm the active site and change the frmatin f the enzyme, thus slwing r stpping the actin f the enzyme Allsteric Regulatin mlecules inhibit r activate by binding t a site ther than the active site Chapter 9 - Cellular Respiratin: Harvesting Chemical Energy Fermentatin ccurs withut xygen and is the partial breakdwn (degradatin) f sugars and release f energy Cellular Respiratin - uses xygen in the breakdwn f sugars, prducing energy, heat, carbn dixide, and water Write the Equatin fr Cellular Respiratin (yu shuld have this memrized!):

17 Oxidatin-Reductin Reactins (Redx Reactins) - invlve the partial r cmplete transfer f ne r mre electrns frm ne reactant t anther Oxidatin - the lss f electrns Reductin - the additin f electrns The substance that lses electrns becmes xidized and acts as a reducing agent (electrn dnr) t the substance that gains electrns. By gaining electrns, a substance acts as an xidizing agent (electrn acceptr) and becmes reduced. Oxygen strngly attracts electrns and is a pwerful xidizing agent. As electrns shift tward a mre electrnegative atm, they give up ptential energy. Chemical energy is released in a redx reactin that shuffles electrns clser t xygen. Organic mlecules that cntain many hydrgen atms are rich in hilltp electrns that release their ptential energy when they fall clser t the xygen. At certain stages in the xidatin f glucse, 2 hydrgen atms are remved by enzymes called dehydrgenases 2 electrns and a prtn are picked up by the cenzyme NAD + (nictinamide adenine dinucletide) it is reduced t NADH. Cellular Respiratin Takes Place in 3 Stages: 1. Glyclysis - ccurs in the cytplasm (utside the mitchndria) - Glyclysis is cmmn t fermentatin and respiratin. It prbably evlved in ancient prkarytes befre xygen was present. 2. Krebs r Citric Acid Cycle - ccurs in the matrix f the mitchndria 3. Electrn Transprt Chain and Chemismsis (Oxidative Phsphrylatin) - ccurs in the inner membranes f the mitchndria Glyclysis Glucse is brken dwn int 2 mlecules f pyruvate. An energy input f 2 mlecules f ATP is required t start the prcess 4 mlecules f ATP are prduced, fr a net gain f mlecules f ATP. The ATP is prduced by substrate level phsphrylatin, in which an enzyme transfers a phsphate grup frm the substrate t ADP. In additin, 2 NADH are prduced. Input: glucse, 2 ATP, 2 ADP, and 2 NAD + Output: 2 pyruvate (pyruvate is a 3C mlecule), 4 ATP, and 2 NADH Acetyl-CA Frmatin: A carbxyl grup is remved frm each pyruvate mlecule and is released as carbn dixide. The remaining acetate mlecule is picked up by cenzyme A, frming acetyl-ca. NAD + picks up electrns and a hydrgen in t frm NADH. Input: 2 pyruvate, 2 NAD +, 2 CA Output: 2 acetyl-ca, 2 NADH, and 2 CO 2 Citric Acid Cycle r Krebs Cycle: One mlecule f acetyl CA enters the citric acid cycle. The 2-carbn fragment f acetyl CA attaches t the 4-carbn mlecule xalacetate in the first reactin f the cycle. This frms citrate. In a series f steps, bnds break and refrm. Tw carbn atms are released, ne at a time, in mlecules f carbn dixide. Electrns are carried ff by mlecules f NADH and FADH2. One step prduces an ATP mlecule by substrate-level phsphrylatin. A 4-carbn xalacetate mlecule is regenerated. Since tw acetyl CA mlecules are prduced fr each glucse mlecule brken dwn, a secnd acetyl CA enters the citric acid cycle. The same series f reactins ccurs, releasing carbn dixide and prducing mre NADH, FADH2, and ATP. The cell has gained tw ATPs that can be used directly. Hwever, mst f the energy riginally cntained in the bnds f glucse is nw carried by the NADH and FADH2 mlecules. Input: 2 acetyl-ca, 2 ADP, 4 NAD +, and 2 FAD (flavin adenine dinucletide) Output: 4 CO 2, 2 ATP, 4 NADH, and 2 FADH 2

18 Oxidative Phsphrylatin Occurs in Tw Parts Part 1 - Electrn Transprt Chain: Electrn transprt chains are embedded in the cristae (inflding f the inner mitchndrial membrane). Mst f the chain cnsists f prteins with tightly bnded nnprtein prsthetic grups. The electrn carriers shift between reduced and xidized states as they accept and dnate electrns. The electrns are dnated frm NADH and FADH 2. At the end, the electrns are passed t xygen which als picks up H ins. These cmbine and are released as water. One f the grups f carrier mlecules in the membrane is called cytchrme. Part 2 - Chemismsis: A prtein cmplex embedded in the inner membrane accepts the hydrgen ins frm NADH and FADH 2. The H ins are pumped thrugh the membrane. These build up in a high cncentratin (a prtn gradient that can be referred t as the prtn-mtive frce). The hydrgen ins mve thrugh a prtein channel with ATP synthase, frming ATP. Input: 8 NADH, 2 FADH 2, O 2 Output: 34 ATP, 8 NAD +, 2 FAD, H 2 O Fermentatin anaerbic respiratin generates ATP by substrate level phsphrylatin f glucse, resulting in the frmatin f 2 ATP and the regeneratin f NAD +, the xidizing agent fr glyclysis Alchlic Fermentatin pyruvate (the prduct f glyclysis) is cnverted int acetaldehyde and then ethanl. CO 2 is released (the 2 ATP f glyclysis are prduced) Lactic Acid Fermentatin pyruvate is brken dwn t frm lactic acid (ATP frm glyclysis). Muscle cells make ATP by this prcess when energy demand is high and the xygen supply is lw. Fats, Prteins, and Carbhydrates Can All be Used by Cellular Respiratin Prteins brken t amin acids amine grup remved can enter respiratin in several lcatins Fats brken int glycerl, which is cnverted int an intermediary in glyclysis, and fatty acids, which enter the citric acid cycle as acetyl-ca The carbn skeletns f fd mlecules are used in bisynthesis Chapter 10 - Phtsynthesis Auttrphs self-feeders make their wn rganic mlecules frm inrganic raw materials Hetertrphs cnsumers Write the Equatin fr Phtsynthesis (yu shuld have this memrized!): In the leaf f a plant, chlrphyll is fund predminantly in the mesphyll cells. Carbn dixide enters the leaf and xygen exits thrugh an pening called the stmata. Water is delivered t the leaves thrugh veins (specifically, the xylem) and the prducts f phtsynthesis are distributed thrugh these veins (specifically, the phlem). The chlrplast cnsists f a membrane system called the thylakid membrane system. Part f the prcess f phtsynthesis takes place in the inner membrane space. Thylakid sacs stacked n tp f each ther are referred t as the grana. The fluid surrunding the thylakid is the strma.

19 It was determined experimentally (by C.B. van Neil) that water is the surce f hydrgen ins and electrns and that the water prvides the xygen that is released in phtsynthesis. Sunlight - Electrmagnetic energy (radiatin) travels as rhythmic wave disturbances f electrical and magnetic fields. The distance between the crests (r trughs) f waves is the wavelength. The electrmagnetic spectrum cnsists f shrt gamma rays t lng radi waves. Visible light is frm 380 t 750 nm. Light behaves as if it cnsists f discrete particles called phtns, which have a fixed quantity f energy. The amunt f energy in a phtn is inversely related t its wavelength. A spectrphtmeter measures the amunt f light absrbed by a pigment. Chlrphyll a is the main pigment in phtsynthesis it absrbs vilet-blue and red light the best. Chlrphyll b and ther accessry pigments, such as cartenids, absrb different light waves t increase the range f phtsynthesis. Sme cartenids prtect plants by absrbing excessive light energy that might damage chlrphyll r interact with xygen t frm reactive mlecules (they act as antixidants). When a pigment mlecule absrbs phtns f light energy, the electrns in the mlecule jump t a higher energy level. This excited state is unstable and energy is released as heat as the electrn returns t its grund state. Smetimes this energy is given ff as light r flurescence. Phtsystems are lcated in the thylakid membrane and cntain light harvesting cmplexes and reactin centers, a prtein cmplex with chlrphyll a and b as well as a primary electrn acceptr. When sunlight hits the light harvesting cmplex, the energy is passed frm pigment t pigment until it reaches the reactin center and becmes excited. In a redx (xidatin-reductin reactin), the excited electrn is accepted by the primary electrn acceptr befre it returns t its grund state. There are tw phtsystems, phtsystem II r P680 and phtsystem I r P700 (these are named after the wavelength f light that is best absrbed). Light-Dependent Reactins (First Phase f Phtsynthesis) In these reactins, hydrgen ins are pumped thrugh the thylakid membrane and ATP is frmed thrugh chemismsis. Nncyclic Electrn Flw: Water serves as the surce f hydrgen ins and electrns. The prcess thrugh which the water is brken dwn is called phtlysis. The hydrgen ins and electrns are used in the nncyclic flw. Oxygen is given ff as a waste prduct. Electrns cntinuusly pass frm water t NADP + - an excited electrn f P680 in phtsystem II is trapped by the primary electrn acceptr. The primary electrn acceptr passes the excited electrn t an electrn transprt chain made up f plastquinne (Pq), a cytchrme cmplex, and plastcyanin (Pc). The energy released as the electrn falls t its grund state is used t frm ATP. At the bttm f the electrn transprt chain, the electrns are passed t phtsystem I. The electrns are passed dwn a secnd electrn transprt chain thrugh ferredxin (Fd). The electrns are eventually passed t NADP +, frming NADPH. Cyclic Electrn Flw: Electrns excited in phtsystem II pass frm Fd t the cytchrme cmplex and then back t phtsystem II. Oxygen and NADPH are nt frmed. Additinal ATP needed fr the Calvin cycle may cme frm this prcess in additin t the nncyclic flw.

20 Light Independent Reactins (Secnd Phase f Phtsynthesis) The Calvin r Calvin-Bensn Cycle uses ATP and NADPH t cnvert CO 2 t sugar. Calvin Cycle: The Calvin cycle turns 3 times t fix 3 mlecules f CO 2 and prduce a 3 carbn sugar called glyceraldehyde-3-phsphate (G3P). Nine mlecules f ATP and 6 mlecules f NADPH are required t synthesize ne G3P. 3 Stages f the Calvin Cycle: 1. Carbn Fixatin: CO 2 is added t a five carbn sugar, ribulse bisphsphate (RuBP) in a reactin catalyzed by the enzyme RuBP carbxylase (rubisc). The unstable 6-carbn mlecule immediately splits int 2 mlecules f 3-phsphglycerate (PGA), each with 3 carbn atms. Because the first stable mlecule has 3 carbns, this can be referred t as C3 phtsynthesis. 2. Reductin: Each mlecule f PGA is then phsphrylated by ATP. Tw electrns frm NADPH reduce this cmpund t frm G3P. It takes 3 turns f the cycle t frm 1 G3P. 3. Regeneratin f RuBP: The rearrangement f 5 mlecules f G3P int 3 mlecules f RuBP. Phtrespiratin: When C3 plants clse the stmata n a ht, dry day t limit water lss, the CO 2 cncentratin in the leaf rises, slwing the Calvin cycle. As mre xygen accumulates, rubisc adds O 2 instead f CO 2 t RuBP. The prduct f this prcess is a 2-carbn sugar that is brken dwn t release CO 2 a wasteful prcess. C4 Plants: CO 2 is first added t a 3-carbn cmpund PEP that has a high affinity t CO 2. The resulting 4- carbn cmpund (xalacetate) is transprted t bundle-sheath cells that are tightly packed arund the veins f the leaf. The cmpund is brken dwn t release CO 2, creating cncentratins high enugh fr rubisc t accept CO 2 rather than O 2. These plants fix CO 2 twice. CAM Plants (Crassulacean Acid Metablism): Many succulent plants clse their stmata during the day t prevent water lss. At night, they pen their stmata t pick up CO 2 and incrprate it int a variety f rganic acids. Chapter 11 - Cell Cmmunicatin Signal Transductin Pathway the series f steps invlved in the cnversin f a cell surface signal t a cellular respnse - similarities amng the pathways in bacteria, yeast, plants, and animals suggest an early evlutin f cell-signaling mechanisms Paracrine Signaling - in animals, a signaling cell releases messenger mlecules int the extracellular matrix fluid and these lcal regulatrs influence nearby cells. Synaptic signaling - a nerve cell releases neurtransmitter mlecules int the synapse separating it frm its target cell. Hrmnes - are chemical signals that travel t mre distant parts f an rganism. Stages in Cell Signaling: 1. Receptin a chemical signal binds t a receptr prtein n the surface f the cell r inside 2. Transductin chemical pathway 3. Respnse activatin f cellular prcesses

21 Chemical signals may be cmmunicated between cells thrugh direct cytplasmic cnnectins (gap junctins, plasmdesmata) r thrugh cntact f surface mlecules. Receptin Ligand binds t a receptr prtein and usually induces a change in the receptr s shape Intracellular Receptrs hydrphbic chemical messengers may crss a cell s plasma membrane and bind t receptrs in the cytplasm r nucleus f target cells. Sterid Hrmnes - activate receptrs in target cells that functin as transcriptin factrs t regulate gene functin Receptrs in the Plasma Membrane there are 3 majr types membrane receptrs that bind with watersluble signal mlecules and transmit infrmatin int the cell 1. G-Prtein Linked Receptrs the varius receptrs that wrk with the aid f a G-prtein A GTP-binding prtein that relays signals frm a plasma membrane signal receptr, knwn as a G- prtein-linked receptr, t ther signal transductin prteins inside the cell. When such a receptr is activated, it in turn activates the G prtein, causing it t bind a mlecule f GTP in place f GDP. Hydrlysis f the bund GTP t GDP inactivates the G prtein. Are structurally similar, with 7 helices spanning the plasma membrane. Binding f the apprpriate G extracellular signal t a G-prtein-linked receptr activates the receptr, which binds t and activates a specific G prtein lcated n the cytplasmic side f the plasma membrane. Occurs when a GTP nucletide replaces the GDP bund t the G prtein. The G-prtein then activates a membrane-bund enzyme, after which it hydrlyzes its GTP and becmes inactive again. The activated enzyme triggers the next step in the pathway t the cell s respnse 2. Receptr Tyrsine Kinases receptr prteins with enzymatic activity that can trigger several pathways at nce Part f the receptr prtein is tyrsine kinase, an enzyme that transfers phsphate grups frm ATP t the amin acid tyrsine n a prtein. 3. The Binding f a Chemical Signal t a Ligand gated in channel pens r clses the prtein pre, thus allwing r blcking the flw f specific ins thrugh the membrane The resulting change in in cncentratin inside the cell triggers a cellular respnse Neurtransmitters ften bind t ligand-gated in channels in the transmissin f nervus signals Transductin a cascade reactin. Multistep Signal Pathways - allw a small number f extracellular signal mlecules t be amplified t prduce a large cellular respnse. Signal Transductin Pathways the relay mlecules in a signal transductin pathway are usually prteins, which interact as they pass the message frm the extracellular signal t the prtein that prduces the cellular respnse. Prtein Phsphrylatin and Dephsphrylatin prtein kinases are enzymes that transfer phsphate grups frm ATP t prteins, ften t the amin acid serine r threnine relay mlecules in transductin are ften prtein kinases, which are sequentially phsphrylated, prducing a structural change that activates each enzyme prtein phsphatases are enzymes that remve phsphate grups frm prteins they shut dwn signaling pathways when the extracellular signal is n lnger present

22 Secnd Messengers - Small mlecules and ins ften functin as secnd messengers, which rapidly relay the signal frm the membrane receptr int the cell s interir Respnse Signal transductin pathways may lead t the activatin f cytplasmic enzymes r ther prteins r may lead t the synthesis f such prteins by affecting gene expressin. A signal transductin pathway can amplify a signal in an enzyme cascade, as each successive enzyme in the pathway can prcess multiple mlecules that then activate the next step. As a result f a particular set f receptr prteins, relay prteins, and effectr prteins, different cells can respnd t different signals r can exhibit different respnses t the same mlecular signal. Scafflding prteins are large relay prteins t which ther relay prteins attach, increasing the efficiency f signal transductin in a pathway. Chapter 12 - The Cell Cycle A cell s cmplete cmplement f DNA is called its genme. Diplid rganisms have a characteristic number f chrmsmes in each smatic cell while each gamete has half that number f chrmsmes. Each chrmsme is a very lng DNA mlecule with assciated prteins (histnes) this DNA-prtein cmplex is called chrmatin. Befre cell divisin, a cell cpies its DNA and each chrmsme densely cils and shrtens. Each replicated chrmsme cnsists f tw identical sister chrmatids attached in their cndensed frm at regins called centrmeres. Phases f the Cell Cycle G1 Phase: gap phase - grwth phase befre DNA duplicated nrmal cell activities G0 Phase: a permanent G1 phase fr cells that d nt divide S Phase: chrmsmes are duplicated thrugh DNA replicatin G2 Phase: grwth phase after the DNA is duplicated nrmal cell activities M Phase: mittic phase Mitsis (divisin f the chrmsmes) Cytkinesis (divisin f the cytplasm) Mittic Spindle - cnsists f fibers made f micrtubules and assciated prteins begins in the centrsme. Phases f Mitsis: Prphase: the nucleli disappear and the chrmatin fibers cil and fld int visible chrmsmes nuclear membrane disappears Prmetaphase: Spindle micrtubules attach t each chrmsmes kinetchre chrmsmes begin mving t the equatr f the cell Metaphase: Chrmsmes line up at the equatr f the cell Anaphase: Sister chrmatids separate and begin migrating t the ples f the cell Telphase: Sets f chrmsmes reach the ples f the cell, nuclear membrane reappears, nucleli reappear, chrmsmes lengthen and disappear, cytkinesis begins Cytkinesis divisin f cytplasm Plant Cells: cell plate frms t separate tw plant cells Animal Cells: cleavage furrw separates tw animal cells

23 Cntrl f the Cell Cycle A cell cycle cntrl system, cnsisting f a set f mlecules that functin cyclically. Imprtant internal and external signals are mnitred t determine whether the cell cycle will prceed past the 3 main checkpints in the G1, G2, and M phases. Cancer - Lss f Cntrl f the Cell Cycle: Cancer cells escape frm the bdy s nrmal cntrl mechanisms. When grwn in tissue culture, cancer cells d nt shw density-dependent inhibitin and may cntinue t divide indefinitely. When a nrmal cell is transfrmed r cnverted t a cancer cell, the bdy s immune system nrmally destrys it. If it prliferates, a mass f abnrmal cells develps. Benign Tumrs - remain at their riginal site and can be remved by surgery. Malignant Tumrs - cause cancer as they invade and disrupt functins f ne r mre rgans. Malignant tumrs may have abnrmal metablism and/r unusual chrmsme numbers. These cells may metastasize, mving frm the riginal lcatin t ther rgans, ften thrugh the bld and lymphatic system. Chapter 13 - Meisis and Sexual Life Cycles Genes discrete units f infrmatin cded in segments f DNA Gene Lcus - specific lcatin f a gene n a chrmsme Asexual Reprductin a single parent passes cpies f all its genes n t its ffspring Clne grup f genetically identical ffspring f an asexually reprducing individual Sexual Reprductin an individual receives a unique cmbinatin f genes inherited frm 2 parents Diplid - duble set f chrmsmes - ne frm each parent = 2n Haplid - single set f chrmsmes = 1n Smatic Cells - diplid cells cntaining 2 chrmsmes f each type Gametes haplid cells cntaining 1 chrmsme f each type Hmlgus Chrmsme ne f a matching pair f chrmsmes, ne inherited frm each parent, als knwn as hmlgues. A gene cntrlling a particular trait is fund at the same lcus n each chrmsmes f a hmlgus pair Karytype - an rdered display f an individual s chrmsmes Sex Chrmsmes - determine the sex f a persn. In humans, females have 2 hmlgus X chrmsmes and males have an X and a Y. Autsmes - chrmsmes ther that the sex chrmsmes Fertilizatin - the fusin f egg and sperm cells prduces a zygte Meisis a special type f cell divisin that reduces the number f chrmsmes by ne half

24 Phases f Meisis Interphase I each chrmsmes replicates, prducing 2 genetically identical sister chrmatids that are attached at the centrmere Meisis I Reduces the number f chrmsmes (2n 1n) Prphase I hmlgus chrmsmes synapse, frming tetrads, crssing ver may ccur Metaphase I chrmsmes pairs (tetrads) line up at the equatr f the cell Anaphase I hmlgus pairs separate and begin mving t the ples f the cell Telphase I chrmsmes (still duplicated) reach the ples f the cell Cytkinesis ccurs, but n replicatin f chrmsmes (smetimes called interkinesis) Meisis II just like mitsis, except that the cells that begin the prcess are haplid Mitsis Meisis Genetically identical daughter cells Genetically different daughter cells 2n 2n 2n 1n 2 daughter cells 4 daughter cells 1 divisin 2 divisins Chapter 14 Mendel and the Gene Idea An analysis f genetic crsses depends upn an understanding f Mendel's tw laws: The Principle f Segregatin (First Law): The tw members f a gene pair (alleles) segregate (separate) frm each ther in the frmatin f gametes. Half the gametes carry ne allele, and the ther half carry the ther allele. The Principle f Independent Assrtment (Secnd Law): Genes fr different traits assrt independently f ne anther in the frmatin f gametes. In practice, the manifestatin f Mendel's laws is seen by characteristic ratis f phentypic classes, such as 3:1 and 9:3:3:1. Further, the Mendelian principles just stated include the simple assumptin that ne allele is dminant t the ther allele. In the time since Mendel's riginal experiments, we have cme t learn that there are extensins t Mendelian principles, including the fact that sme alleles are incmpletely dminant, that sme genes are sex-linked, and that sme pairs f genes d nt assrt independently because they are physically linked n a chrmsme. Imprtant Genetic Terminlgy: Allele - ne f a number f different frms f the same gene fr a specific trait Phentype - the physical characteristics f an rganism Gentype - the genetic makeup f an rganism Hmzygus - a wrd describing an rganism that has tw identical alleles fr a particular trait Heterzygus - a wrd describing an rganism that has tw different alleles fr a particular trait Dminant an allele that is expressed even if present with a cntrasting recessive allele Recessive an allele that is nly expressed when tw cpies are present Testcrss breeding f an rganism f unknwn gentype with a hmzygus recessive individual t determine the unknwn gentype. The rati f phentypes in the ffspring determines the unknwn gentype.

25 Patterns f Inheritance Incmplete Dminance - ne allele f a pair is nt fully dminant ver its cunterpart (als called "intermediate inheritance") Intermediate Inheritance - in this inheritance pattern, heterzygtes have a phentype intermediate between the phentypes f the tw hmzygtes (als called "incmplete dminance") Cdminance - bth alleles are expressed fully Multiple Alleles - mre than tw alleles fr a gene are fund within a ppulatin Epistasis - ne gene alters the effect f anther gene Plygenic Inheritance - many genes cntribute t a phentype Gene Linkage - genes n the same chrmsme are linked and thus will nt be srted ut independently f each ther Sex Linkage - if a male gets a recessive (r dminant) allele n the X chrmsme frm his mther, he will express that trait Chapter 15 The Chrmsmal Basis f Inheritance Chrmsme Thery f Inheritance: In the early 1900s, several researchers prpsed that genes are lcated n chrmsmes and that the behavir f chrmsmes during meisis accunts fr Mendel s laws f segregatin and independent assrtment. Genetic Recmbinatin and Linkage: Each chrmsme has hundreds r thusands f genes. Genes n the same chrmsme whse alleles are s clse tgether that they d nt assrt independently are said t be linked. The alleles f unlinked genes are either n separate chrmsme r s far apart n the same chrmsme that they assrt independently. Recmbinant ffspring exhibit new cmbinatins f traits inherited frm tw parents. Because f the independent assrtment f chrmsmes and randm fertilizatin, unlinked genes exhibit a 50% frequency f recmbinatin. Even with crssing ver between nnsister chrmatids during the first meitic divisin, linked genes exhibit recmbinatin frequencies less than 50%. Alteratins f Chrmsme Number r Structure Cause Sme Genetic Disrders Nndisjunctin an errr in meisis r mitsis, in which bth members f a pair f hmlgus chrmsmes r bth sister chrmatids fail t mve apart prperly (Dwns Syndrme) Mnsmic referring t a cell that has nly ne cpy f a particular chrmsme, instead f the nrmal tw Trismic referring t a cell that has three cpies f a particular chrmsme, instead f the nrmal tw Plyplidy a chrmsmal alteratin in which the rganism pssesses mre than tw cmplete chrmsme sets Chapter 16 The Mlecular Basis f Inheritance Histry f DNA Research Frederick Griffith: In 1928, a scientist named Frederick Griffith cmpleted a prject that pened a dr t the mlecular wrld f inheritance. Griffith's experiment invlved mice and tw types f pneumnia, a pathgenic and a nn-pathgenic strain. He injected the pathgenic pneumnia int a muse, and the muse died. Next, he injected the nnpathgenic pneumnia int a muse, and the muse lived. After this, he heated the pathgenic bacteria t kill it and injected it int a muse. This muse lived. Last, he mixed nnpathgenic pneumnia and pathgenic pneumnia that had been heated and killed and injected this mixture int a muse. This muse died. Why? Griffith thught that the dead pathgenic bacteria had passed n a characteristic t the nn-pathgenic bacteria t make it pathgenic. He thught that this characteristic was in the inheritance mlecule. He called the prcess he had bserved transfrmatin.

26 Oswald Avery: In 1944, a scientist named Oswald Avery cntinued with Griffith s experiment t see what the inheritance mlecule was. He purified varius types f mlecules frm the heat-killed pathgenic bacteria and then tried t transfrm live nnpathgenic bacteria with each type. Only DNA caused transfrmatin t ccur. Avery had fund that the inheritance mlecule was DNA. Erwin Chargaff: In 1947, anther scientist named Erwin Chargaff nticed a pattern in the amunts f the fur bases: adenine, guanine, cytsine, and thymine. He tk samples f DNA f different cells and fund that the amunt f adenine was almst equal t the amunt f thymine, and that the amunt f guanine was almst equal t the amunt f cytsine. Thus yu culd say: A=T, and G=C. This discvery later became Chargaff s Rule. Alfred Hershey and Martha Chase: In their famus 1952 experiment, they used radiactive sulfur and phsphrus t trace the fates f the prtein and DNA, respectively, f T2 phages that infected bacterial cells. They fund radiactivity in the bacteria that had been infected with the T2 phage cntaining radiactively labeled DNA. Frm this, they cncluded that nucleic acids are the hereditary material. Rsalind Franklin and Maurice Wilkins: In the early 1950s, these tw scientists used X-ray diffractin t understand the physical structure f the DNA mlecule. James Watsn and Francis Crick: In 1953, this pair f scientists used the images prduced by Franklin t deduce that DNA is a duble-helix. The beauty f the mdel they presented was that the structure f DNA suggested the basic mechanism f it replicatin. DNA Structure: The DNA mlecule has tw cmplementary strands. Each nucletide base is paired by hydrgen bnding with its specific partner, A with T and G with C. Review building blcks and their arrangement DNA Replicatin 1. The first step in replicatin is separatin f the tw DNA strands. 2. Each parental strand nw serves as a template that determines the rder f nucletides alng a new, cmplementary strand. 3. The nucletides are cnnected t frm the sugarphsphate backbnes f the new strands. Each daughter DNA mlecule cnsists f ne parental strand and ne new strand (this is knwn as semicnservative replicatin.) Chapter 17 Frm Gene t Prtein The central dgma f mlecular bilgy describes the tw-step prcess, transcriptin and translatin, by which the infrmatin in genes flws int prteins: DNA RNA prtein. The Genetic Cde: Genetic infrmatin is encded as a sequence f nn-verlapping base triplets, r cdns. A cdn in messenger RNA (mrna) either is translated in an amin acid (61 cdns) r serves as a translatinal stp signal (3 cdns). Cdns must be read in the crrect reading frame fr the specified plypeptide t be prduced.

27 Transcriptin: Invlves the synthesis f an RNA cpy f a segment f DNA. RNA is synthesized by the enzyme RNA plymerase in the nucleus f the cell. RNA Prcessing (eukarytes nly): The gene transcript is prcessed t remve extra sequences (intrns) befre it leaves the nucleus. The pre-mrna is prcessed t remve the intrns and splice the exns tgether int a translatable mrna. Translatin: The ribsme binds t the mrna at the start cdn (AUG) that is recgnized nly by the initiatr trna. During the elngatin phase, cmplexes cmpsed f an amin acid linked t trna sequentially bind t the apprpriate cdn in mrna by frming cmplementary base pairs with the trna anticdn. The ribsme mves frm cdn t cdn alng the mrna. Amin acids are added ne by ne, translated int plypeptidic sequences dictated by DNA and represented by mrna. At the end, a release factr binds t the stp cdn, terminating translatin and releasing the cmplete plypeptide frm the ribsme. The Cntrl f Gene Expressin The expressin f genes can be turned ff and n at any pint alng the pathway frm gene t functinal prtein. Genes in heterchrmatin (which is highly packed) usually are nt transcribed this is ne frm f gene cntrl. DNA methylatin (the adding f methyl grups) is ne way in which the transcriptin f genes is cntrlled. Apparently methylatin f DNA is respnsible fr the lng-term inactivatin f genes. In histne acetylatin, acetyl grups are added t amin acids f histne prteins this makes the chrmatin less tightly packed and encurages transcriptin. Transcriptin initiatin is anther imprtant cntrl pint in gene expressin. At this stage, DNA cntrl elements that bind transcriptin factrs (needed t initiate transcriptin) are invlved in regulatin. Gene cntrl als ccurs after transcriptin and during RNA prcessing, in alternative RNA splicing. The cntrl f gene expressin als ccurs bth prir t translatin and just after translatin, when prteins are prcessed. Mutatins A pint mutatin is a change in ne DNA base pair, which may lead t prductin f a nnfunctinal prtein r n prtein at all. Base-pair substitutins can cause missense r nnsense mutatins. Base-pair insertins r deletins may prduce frameshift mutatins. Spntaneus mutatins can ccur during DNA replicatin, recmbinatin, r repair. Chemical and physical mutagens can als alter genes.