Biochemistry. All living things are made up of four major kinds of biomolecules: carbohydrates, lipids, proteins, and nucleic acids.

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1 Biochemistry All living things are made up of four major kinds of biomolecules: carbohydrates, lipids, proteins, and nucleic acids. Carbohydrates - made up of carbon, hydrogen, and oxygen in a 1:2:1 ratio. Some carbohydrates provide quick energy (simple sugars), while some store energy (like starches and glycogen), and others provide structure (cellulose and chitin). Building blocks of carbohydrates are called monosaccharides, while complex carbohydrates are called polysaccharides. A common ending for carbohydrates is ose. Ex: glucose and sucrose Lipids - made mostly from carbon and hydrogen atoms, and are formed by glycerol and fatty acid chains. Lipids do not dissolve in water. Cells utilize lipids for long-term energy storage. Lipids also provide insulation and make up cell membranes (phospholipid bilayer). Lipids include fats, oils, cholesterol (and other steroids), and waxes. Proteins - made of carbon, hydrogen, oxygen, and nitrogen. The subunits of proteins are called amino Proteins control multiple cell functions, defend the organism (antibodies),provide structure, transport molecules, and are involved in movement. o Enzymes are special proteins that act as catalysts to the rate of chemical reactions. They lower the activation energy, or energy required for the reaction to proceed. Each enzyme has a specific function that is determined by its shape. Any factor changes the shape of an enzyme (like temperature or can alter its function. A common ending for enzymes is ase. Ex: DNA polymerase, RNA polymerase, amylase, lipase acids. control that ph)

2 Nucleic acids - made up of subunits called nucleotides (which consist of a sugar, a phosphate, and a nitrogenous base). The two types of nucleic acids are DNA (deoxyribonucleic acid) and RNA (ribonucleic acid). Nucleic acids store information that determines how an organism will grow and develop. The sequence of nitrogen bases determines the sequence of amino acids in proteins. DNA is shaped like a double helix or twisted ladder. The two strands of DNA are held together by weak hydrogen bonds. Compare and contrast DNA and RNA. Identify both similarities and differences. 1. What do all lipids have in common? a. They produce quick energy c. They don t dissolve in water b. They have the same R- groups d. They are saturated with hydrogen 2. A protein-digesting enzyme mixes with cholesterol in the digestive tract. What effect does the enzyme have on the cholesterol? a. Breaks the cholesterol into amino acids b. Converts the cholesterol into energy c. Breaks the cholesterol into simple sugars d. No effect 3. Enzymes speed up a chemical reaction by a. Lowering the amount of energy it needs to get started b. Producing complex carbohydrates c. Changing the shape of the substrate d. Producing heat 4. DNA and RNA are composed of a. Chains of nucleotides b. Chains of simple sugars c. Twisted chains of amino acids d. Three very long carbon-hydrogen chains attached to a glycerol molecule 5. What kind of molecule is an enzyme? Why are enzymes important in a cell? 6. Compare and contrast carbohydrates and lipids. Cells

3 The cell theory states that cells are the basic unit of life, all living things are made up of one or more cells, and that cells come only from other living cells. Eukaryotic cells are cells that have internal membrane- bound structures. Plants, animals, and fungi are made up of eukaryotic cells. The structures found inside of eukaryotic cells are called organelles (little organs), and each organelle has a particular function linked to cell survival. Golgi apparatus Plasma (cell) membrane Endoplasmic reticulum (ER) Mitochondria Nucleolus Nucleus Nucleus- contains DNA, which holds the instructions for how to make proteins (all cell parts depend on proteins to function, so the nucleus can be considered the control center of the cell) The blueprints for protein production are contained in chromatin- strands of DNA Chromatin Nucleus Nucleolus nucleolus- the dark sphere within the nucleus, where ribosomes are made Ribosomes- the site of protein synthesis (where proteins are made) Once ribosomes are made in the nucleolus, they move to the cytoplasm (the jellyregion outside of the nucleus). Ribosomes can then attach to the endoplasmic reticulum (ER), a series of highly folded membranes that act as the highway of the Once proteins are made by the ribosomes, the proteins travel through the ER, and cell. like are transferred to the Golgi apparatus. The Golgi apparatus is a series of flattened membrane sacs that sorts and distributes proteins. Vacuoles- store things (enzymes, food, and other materials) within the cell Lysosomes- contain enzymes that digest or break down worn out cell parts, excess particles, and invading bacteria or virsues Flagella- some cells have whip-like extensions that they helps them move Plant cells look different than animal cells because plants have cell walls and and also usually have a large central vacuole used to store water. food chloroplasts, vacuole mitochondrion

4 Prokaryotic cells, such as bacteria, lack internal membrane- bound structures. (A prokaryotic cell does not have a nucleus or organelles.) Prokaryotes do synthesize proteins, so they do contain ribosomes. Cell wall Ribosomes DNA Plasma (cell) membrane 1. Which part of the cells acts as a barrier to control what enters and leaves the cell? a. cell membrane b. cytoplasm c. DNA d. Nucleus 2. Which of the following is a main difference between prokaryotic and eukaryotic cells? a. smaller size of eukaryotes b. absence of a membrane-bound nucleus in prokaryotes c. absence of ribosomes in prokaryotes d. absence of organelles in eukaryotes 3. Which statement is false? a. Eukaryotes are much more complex than prokaryotes b. The components inside a prokaryotic cell lack membranes c. Prokaryotes were the first organisms on Earth d. Prokaryotes lack genetic material 4. Muscle cells require a great deal of energy. Therefore, they are likely to have a high number of. a. Golgi b. Mitochondria c. ER d. Lysosomes

5 5. This cell is most likely a member of which Kingdom a. Fungi b. Animalia c. Protista d. Plantae 6. If a cell was unable to produce ribosomes, which of the following would it be unable to make? a. carbohydrates b. proteins c. nucleic acids d. lipids 7. Which organelle is most like a miniature stomach inside of the cell? a. Vacuole b. Endoplasmic reticulum c. Lysosome d. Chloroplast 8. Which of the following is not a cell organelle? a. mitochondrion b. cytoplasm c. endoplasmic reticulum d. lysosome 9. Which of the following would you find in a plant cell but not in an animal cell? a. cell membrane b. endoplasmic reticulum c. nucleus d. chloroplast 10. Cellulose is which type of organic compound? a. carbohydrate b. lipid c. nucleic acid d. protein 11. How are eukaryotes different from prokaryotes?

6 Transport of Materials Into and Out of the Cell Plasma (cell) membrane- the boundary between the cell and its environment, controls entry of nutrients and removal of wastes- maintains homeostasis ***Homeostasis- balance; an ideal internal environment *** Selective permeability- the cell membrane is picky- some molecules are allowed to enter a cell while others are kept out Phospholipid bilayer- The plasma (cell) membrane is made up of two layers, each layer contains phosphate groups and lipids (fats) that allow the membrane to be flexible and picky about what enters and what exits. There are also proteins in the membrane that can help substances move through. Phospholipid bilayer Membrane protein (transport channel) Passive Transport Some substances can move without using energy. This is called passive transport. If you place a drop of ink in a beaker, the ink will soon spread farther and farther out until it is evenly distributed. The ink did not have to use energy to spread out. Instead, the random movement of particles caused the crowded (highly concentrated) ink molecules to move to less crowded (less concentrated) areas. This movement of solute (dissolved substance) from an area of greater concentration to an area of less concentration is called diffusion. Water molecules can also diffuse. Diffusion of water is called osmosis. Water also moves from where there is more water to where there is less water. Look at the diagram below. The dialysis membrane is similar to a plasma membrane in that it is selectively permeable. Water molecules are small enough to pass through, but starch molecule are too large. Because there is a greater concentration of water in side B (100%) than in side A (95%), water will move from side B to side A, and the water level in side A will rise. (100% water) (95% water)

7 Active Transport Some molecules are too large to enter or exit the cell, or their charges prohibit them from passing through the plasma membrane. If this is the case, the cell can still move them, but it must use energy. Movement of substances that requires energy is called active transport. Sometimes proteins in the plasma membrane are used to pump materials out. Sometimes, materials enter and exit the cell using vesicles (pockets of the cell membrane). Endocytosis uses vesicles to bring materials (like nutrients) into the cell. Exocytosis uses vesicles to move materials (like products) out of the cell. waste Summary: 1. A thermostat maintains an ideal temperature of a room. What cell process is similar to this situation? a. Food storage c. Active transport b. Protein synthesis d. Homeostasis 2. If a saltwater fish (90% water) is placed in fresh water (100% water), water will likely move into the fish cells and kill the fish. This is most likely due to. a. facilitated transport c. endocytosis b. osmosis d. exocytosis 3. Which process allows large molecules to enter a cell? a. endocytosis c. osmosis b. exocytosis d. facilitated diffusion 4. Passive transport requires energy / does not require energy (circle one), while active transport requires energy / does not require energy (circle one). Passive transport move molecules down / against their concentration gradient, while active transport moves molecules down / against their concentration gradient.

8 5. What does it mean that the plasma (cell) membrane is selectively permeable? 7. Which would most likely cause the liquid in Tube A to rise? a. Starch concentrations being equal on each side of the membrane b. Water passing from a region of lower starch concentration to one of higher starch concentration c. Water and starch volumes being the same d. Solute in the tubes changing from a higher temperature to a lower temperature 8. If the cell in the beaker is permeable to only water, the cell will probably. a. grow and possibly explode b. shrink c. stay the same Cell: 98% water Solution: 75% water 9. Facilitated diffusion is a. the same as endocytosis c. a process that requires the cell s energy b. a special kind of osmosis d. a type of passive transport 10. Which of the following is not a part of a prokaryotic cell? a. Cytoplasm c. DNA b. Cell membrane d. Organelle

9 Cellular Energy All organisms need energy, but only some living things can directly use the energy of sunlight. Autotrophs (producers) make their own food by obtaining energy from sunlight (or inorganic compounds). Heterotrophs (consumers) cannot make their own food, and must get their energy from food sources. Photosynthesis- carried out in the chloroplasts of plants; uses carbon dioxide to store energy in the form of glucose (organic molecules); produces oxygen 6CO H 2 O C 6 H 12 O 6 + 6O 2 Chloroplasts- found in the cells of green plants- convert light into chemical energy, stores energy in food molecules. Chloroplasts contain the pigment chlorophyll, which absorbs blue and red light, and reflects green and yellow (giving plants green appearance). energy mostly their Photosynthesis occurs in two stages: Light-dependent stage- occurs in the thyl Calvin cycle (light-independent stage)- occurs in the stroma, uses the energy from the first stage and CO 2 to form glucose. The rate of photosynthesis can be affected by: The amount of water available The amount of sunlight available Temperature (must be within an optimal range since the reactions of photosynthesis depend on enzymes) The plant uses the energy stored in the sugar molecule to carry out life processes. The sugar molecule is also used to build more complex carbohydrates, which can be used in growth and development. Why are pigments important to the process of photosynthesis? How is the Calvin cycle dependent on the first stage of photosynthesis? Why is photosynthesis important? The glucose made in photosynthesis is the starting point for cellular respiration. Cellular respiration should not be confused with the process of breathing. Breathing simply involves taking in oxygen and eliminating carbon dioxide, but cellular respiration is a series of chemical reactions that change glucose into a usable form of chemical energy (ATP).

10 Cellular (aerobic) respiration- occurs in mitochondria; uses oxygen to release energy (ATP) from food molecules; produces carbon dioxide C 6 H 12 O 6 + 6O 2 6CO H 2 O ***ATP is energy that drives chemical reactions in cells.*** Cellular respiration begins with a series of steps called glycolysis, which converts glucose into pyruvate. If oxygen is present, pyruvate enters aerobic respiration, and a great deal of ATP is produced. If there is no oxygen present, some cells can undergo anaerobic (without oxygen) respiration to make ATP. Some microorganisms, such as yeast, carry out alcohol fermentation, which produces ATP and alcohol. In humans, however, muscle cells carry out lactic acid fermentation. For example, if your muscles are fatigued and run out of oxygen they will produce lactic acid, which causes muscle cramps. Only a small amount of ATP is produced in anaerobic respiration. Mitochondria- in both plants and animals, breaks down food molecules and food into energy (ATP)= the powerhouse of the cell transforms Why is cellular respiration important? What is the importance of ATP in a cell? Comparison of Cellular Respiration and Photosynthesis Process Reactants Products Energy Change Photosynthesis Cellular Respiration Carbon dioxide, water Glucose, oxygen Glucose, oxygen Carbon dioxide, water Light energy to chemical energy Chemical energy to other chemical energy

11 1. Energy flows through an ecosystem from a. the sun to autotrophs to heterotrophs b. the sun to heterotrophs to autotrophs c. autotrophs to heterotrophs and back to autotrophs d. heterotrophs to autotrophs and back to heterotrophs 2. Which of the following is not an autotroph? a. Blue-green bacteria c. Plants b. Algae d. Humans 3. Which compound serves as the major energy compound for a cell? a. DNA c. ATP b. Water d. Carbon dioxide 4. During photosynthesis, the light reactions take place in the, while the Calvin cycle takes place in the. a. stroma, thylakoid c. grana, thylakoid b. thylakoid, stroma d. stroma, grana 5. Cellular respiration involves an energy conversion. Which of the following represents the energy conversion that occurs during cellular respiration? a. light energy to glucose c. ATP to glucose b. ATP to light energy d. glucose to ATP 6. What do both glycolysis and fermentation have in common? a. They require oxygen b. They produce lactic acid and ethyl alcohol c. The require light energy d. They produce ATP 7. Glucose is the starting point for cellular respiration. Which type of biomolecule is glucose? a. carbohydrate c. protein b. lipid d. nucleic acid 8. Each chemical reaction that occurs in cellular respiration relies on an enzyme. What role does an enzyme play in cellular respiration? a. an enzyme reverses a chemical reaction b. an enzyme converts light energy into chemical energy c. an enzyme speeds up a chemical reaction d. an enzyme contains the genetic information needed for the chemical reaction to occur 9. The organelle responsible for photosynthesis is called a, and the organelle responsible for cellular respiration is called a. a. chloroplast; mitochondrion c. central vacuole; ribosome b. chloroplast; ribosome d. chlorophyll; lysosome 10. Which of the following statements is TRUE? a. Aerobic respiration requires oxygen and produces less energy per glucose than anaerobic respiration. b. Anaerobic respiration does not require oxygen and produces less energy per glucose than aerobic respiration. c. Only prokaryotic cells can perform aerobic respiration. d. Glycolysis only occurs when cells perform aerobic respiration.

12 Viruses Viruses are made up of nucleic acids (DNA or RNA) surrounded by a protein coat. They are smaller than the smallest bacterium. Viruses consist of nucleic acid (genetic material) surrounded by a capsid (protein coat). Most scientists consider viruses to be nonliving because they can t carry out the most basic processes of life. Viruses can t metabolize (break down) food to release energy (carry out respiration) or grow. The only thing that viruses can do is replicate (copy themselves), but to do that they need the help of a living cell. The living cell in which a virus replicates is called its host cell. There are proteins on the surface of a virus that allow it to attach to a host cell. (The shape of the protein on the virus must fit the shape of the receptor on the host.) For example, the virus shown below could infect the cell pictured because their shapes would fit together. proteins Host cell When a virus infects a host cell, it injects its DNA or RNA into the host and takes control. If the host cell makes many copies of the virus (replicates viral DNA), the new viruses explode from the cell and kill the host. The lytic cycle is characterized by viral infection, replication and cell destruction. Sometimes, when a virus infects a host cell, it may stay inside the cell but not make new viruses. This is called the lysogenic cycle. The virus DNA becomes a part of the host cell s DNA, and every time the host cell copies

13 and divides, it also copies viral DNA. The viral DNA may remain inactive (a provirus) for a long time, but it can become active when it frees itself from the host s chromosome, which triggers the lytic cycle. Relationship Between Lytic and Lysogenic Replication Cycles Viruses cause human diseases, many of them serious. Some examples of diseases caused by viruses are AIDS, the common cold, rabies, influenza (flu), hepatitis, chicken pox, and warts. Doctors cannot use antibiotics to treat viruses; antibiotics are used to treat bacterial diseases. Antibiotics attack certain life processes that nonliving viruses do not carry out. Doctors can prevent some viruses using vaccines. Vaccines are harmless viruses that stimulate your immune system to fight off harmful viruses. Remember that viruses have proteins on their surfaces that allow them to infect their host cells. Some viruses do not change very often, so the vaccines for these viruses remain effective- smallpox, polio, and measles are all easily prevented using vaccines. However, some viruses have surface proteins that mutate (change) often, and the immune system can t recognize constantly changing surface proteins. You may be vaccinated today against the flu, but after the virus mutates and forms a new strain, you could become infected again. HIV, the virus that causes AIDS, is one of the most rapidly changing viruses, which is why it is not possible at this time to develop a vaccine against it. AIDS (Acquired Immune Deficiency Syndrome) attacks the body s helper T cells, a part of the immune system- the body is unable to defend itself against infections. Most people infected with HIV only develop symptoms years after that have been infected, so an HIV infected person can feel healthy but still spread the disease to others 1. Viruses can reproduce only under which of the following conditions? a. When they are outside a living organism c. When they grow or move b. When they carry out respiration d. When they are inside a host cell

14 2. What is the main function of the projections on the surface of a virus? a. They aid in respiration. c. They help the virus invade its host. b. They help the virus grow. d. They help the virus digest food molecules. 3. Which of the following cannot metabolize nutrients? a. Viruses c. Animals b. Fungi d. Bacteria 4. What do viruses have in common with living cells? They both a. store genetic information in DNA and RNA b. have chloroplasts c. use glucose for cellular respiration d. have endoplasmic reticulum 5. Which of the following statements is true? a. Viruses have no DNA or RNA. c. Viruses contain no proteins. b. Viruses use host cells to reproduce. d. Viruses can be killed by antibiotics. 6. Which of the following happens as part of both the lytic cycle and the lysogenic cycle? a. New viruses are made b. The host cell dies c. The entire virus infects the cell d. The virus injects its nucleic acid into the host cell 7. The lytic cycle involves several steps. Which of the following is the final step of the lytic cycle. a. the host cell bursts b. the virus injects its nucleic acid c. new viruses begin to be made d. the viral DNA becomes part of the host cell s DNA 8. What type of cell does HIV attack? 9. Why don t antibiotics work against the flu? 10. Why do scientists consider viruses to be nonliving?

15 The Cell Cycle The cell cycle is a sequence of several phases through which a cell passes a it grows, prepares for division, and divides. Interphase- the stage where the cell spends most of its time, divided into o G1 (first growth) phase- cell undergoes growth, energy conversions, transport or molecules, and synthesis of new molecules (normal cellular functions) o S (synthesis) phase- a copy of each chromosome is made. One complete set of genetic information will be given to one nucleus that forms as a result of mitosis, and the other complete set will be given to the other nucleus. (DNA is the instruction manual for the cell. Exact copies of DNA are passed on to the next generation of cells each time a cell divides. The overall process of DNA replication (DNA copying itself to make new DNA for new cells) is shown in the diagram below) 1. DNA molecule is unzipped (bonds between the nitrogen bases are broken by enzymes) 2. Free floating nucleotides are added to their complementary bases 3. Formation of two identical DNA molecules o G2 (second growth) phase- cell prepares for mitosis

16 Once interphase is complete, the cell is ready to enter mitosis Mitosis (M phase)- the process in which a nucleus divides to form two nuclei o Chromosomes condense o Chromosomes line up along the middle of the cell o Each member of a chromosome pair moves to the opposite end of the cell o The nucleus divides. Each nucleus ends up with the same number of chromosomes as the original cell. o The cytoplasm divides (cytokinesis), resulting in two identical cells. While the events of the cell cycle are usually carefully regulated, mutations may lead to loss of control of the cell cycle. Uncontrolled cell division is known as cancer. 1. The cell cycle includes mitosis. What happens during mitosis? a. each chromosome makes a copy of itself b. the cell cytoplasm divides to produce two cells c. the cell prepares to divide d. the nucleus divides so that each cell will receive a complete set of genetic information 2. A yeast cell can complete a cell cycle every 90 minutes. Starting with just one cell, how many yeast cells should be present after 6 hours? a. 2 c. 8 b. 4 d During the very early stages of a person s life, the rate of cell division proceeds rapidly. During this time, cells show little growth. What can you conclude from this information about the cell cycle during thses very early stages of development? a. the cell cycle consists mainly of a long G1 phase b. the cell cycle consists mainly of M and S phases c. most cells exit the cell cycle d. most cells will not undergo mitosis 4. During the cell cycle, DNA is copied. Which type of biomolecule is DNA? a. carbohydrate c. protein b. lipid d. nucleic acid

17 5. The cell cycle requires energy. Which process supplies this energy so that the cell cycle can take place in all living things? a. respiration c. homeostasis b. transport d. fermentation 6. Part of the cell cycle involves growth. Growth involves assembling smaller molecules to make large ones. Which process is responsible for making these larger molecules from smaller ones? a. transport c. synthesis b. respiration d. homeostasis 7. The cell cycle involves the division of the nucleus. Which type of cell undergoes mitosis? a. prokaryotes c. bacterial cells b. eukaroytes d. only plant cells 8. Which of the following lists the stages of mitosis in the correct sequence? a. anaphase, prophase, metaphase, telophase b. telophase, anaphase, metaphase, prophase c. prophase, telophase, metaphase, anaphase d. prophase, metaphase, anaphase, telophase 9. Which of the following correctly describes the results of mitosis? a. two daughter cells that are genetically identical to the parent cell b. two daughter cells that are genetically different from the parent cell c. two daughter cells that contain half of the number of chromosomes as the parent cell d. four daughter cells that contain the same number of chromosomes as the parent cell 10. Why must each chromosome make a copy of itself before the M phase begins? 11. What happens during the M phase of the cell cycle? 12. Why is the cell cycle important to the growth of an organism?