Ch 1 - The Cell & Cell Processes

Transcription

1 Ch 1 - The Cell & Cell Processes

2 P All cells have Cell membrane - phospholipid bilayer surrounding cell parts Cytoplasm - everything between cell membrane + nucleus P Most cells have Nucleus - brain of the cell Contains DNA (instructions) P Prokaryotes Have no nucleus in cell(s) Ex. Bacteria, red blood cells The Cell P Eukaryotes Have well organized nucleus in cell(s) Ex. Most plant and animal cells

3 Nucleus Site of DNA replication + transcription P Nuclear membrane Membrane surrounding nucleus, has pores Controls what can enter or leave nucleus P Nucleoplasm Jelly-like material inside nucleus Helps give nucleus shape, support P Nucleolus (or nucleoli) Dense body rich in rrna + subunits Involved in ribosome production P Chromosomes (chromatin form) Each = protein core with DNA wrapped around it Contains instructions for cells; genes code for proteins ~ traits

4 Cell Membrane Selectively permeable phospholipid bilayer P Selectively permeable Controls what can enter and leave cell Hydrophilic Head Hydrophobic Tails P Phospholipid bilayer Phospholipids are special fats Hydrophobic tails, hydrophilic heads Arrange so protect hydrophobic parts Tails go inside, heads twd water Several proteins embedded in it Cholesterol also embedded ~ rigidity P Fluid Mosaic

5 Membrane Proteins embedded in phospholipid bilayer P Signature molecules (glycoproteins) have sugar part that sticks out for identification/recognition of cell P Gatekeepers Allow only certain materials to enter or leave cell P Receptor sites Hormones bind to receptor and initiate cell response P Enzymes Proteins that act as catalysts for reactions (speed up) P Transport proteins (move substances across membrane) Active transport - against [ ] gradient; requires ATP Passive transport - down [ ] gradient; no ATP needed

6 Cytoplasm P Contains: Water, nutrients, wastes Building blocks of materials needed by cell Organelles P Organelles small organs that work together to keep cell alive Each type has a special function Note: some differences between plant and animal cells

7 Organelles P Mitochondria (mitochondrion, s) powerhouse of the cell, oval shaped Double membrane, smooth outer Folded inner membrane Folds (cristae) allow for more SA Site of cellular respiration (food energy) P Ribosomes protein factory, site of protein synthesis Reads message (mrna) from nucleus and puts amino acids in proper order Some free in cytoplasm, some stuck on ER

8 Organelles P Endoplasmic reticulum Double membrane channel Transports materials through cytoplasm Smooth: no ribosomes attached (~ fats) Rough: ribosomes attached (~ proteins) P Golgi Body (Golgi Apparatus) processing & packaging factory Processes and packages into vesicles Contents sent to membrane or out of cell P Lysosomes suicide sacs, small round bodies containing enzymes fuse with old cell parts to break them down and recycle parts fuse with foreign particles to destroy them (ex. in WBCs) fuse with food vacuoles to help break down nutrients

9 Organelles Cytoskeleton Parts P Microfilaments Pipelike structures made of proteins (actin, myosin) Imp for structure + mvmt, changes in cell shape Ex. Muscle contraction, ameboid mvmt P Microtubules Hollow cylinders made of spherical protein, tubulin Transport materials through cytoplasm Part of cytoskeleton, helps give cell shape Involved in movement of cell (cilia or flagella) Cilia - tiny hairlike structures that aid movement (oars) Flagella - longer whiplike structures that propel cell forward

10 Organelles P Vacuoles Storage spaces within cell for food, water, or wastes Animals have a few small ones Plants have very large central one for water P Centrosome Microtubule organizing center Contains centrioles in animal cells Involved in spindle formation during cell division P Centrioles Only in animal cells Composed of microtubules Involved in spindle formation during cell division Centrioles Chromosome Work with spindle to pull chromosomes apart during division

11 Special Plant Cell Features P Cell Wall Outside layer provides support, protection, shape Composed of cellulose (provides roughage for us) P Plastids Associated with production and storage of food Usually contain pigments Cells reflect the color of the pigment they contain Chromoplasts - store pigments; yellow, orange, blue, red Amyloplasts - store starch; no pigment so colorless P Chloroplasts (another plastid) site of photosynthesis; contain chlorophyll (green pigment) Chlorophyll traps energy from sun for photosynthesis Grana = stacks of membranes that increase SA to trap light

12 Animal Cells vs Plant Cells Animal Cells 1. No cell wall 2. Few, v small vacuoles 3. Centrosome with centrioles 4. No plastids 5. No crystals 6. Store carbs as glycogen 7. Can change their shape Plant Cells 1. Have a cell wall 2. Large central vacuole 3. No centrosome or centrioles 4. Have plastids (ex. Chloroplast) 5. Have crystals (raphides, druse) 6. Store carbs as starch 7. Have fixed, rectangular shape

13 Animal Cell Pinocytotic vesicle Lysosome Golgi vesicle Mitochondrion Golgi Body / Apparatus Rough Endoplasmic Reticulum Smooth Endoplasmic Reticulum Centrosome Vacuole Cell Membrane Nucleolus Nucleoplasm Nuclear Membrane Centriole Microtubule Cytoplasm Ribosome Nucleus

14 Plant Cell Golgi vesicle Ribosome Smooth Endoplasmic Reticulum Nuclear Membrane Nucleus Nucleolus Nucleoplasm Rough Endoplasmic Reticulum Central Vacuole Amyloplast Cell Wall Cell Membrane Golgi Body / Apparatus Chloroplast Granum (grana, pl) Raphide Crystal Druse Crystal Mitochondrion Cytoplasm

15 Cell Processes P Passive Transport Diffusion Osmosis Solutions: hypotonic, hypertonic, isotonic P Active Transport Transport proteins Endocytosis (Phagocytosis, Pinocytosis) Exocytosis

16 Passive Transport Diffusion P Description Mvmt of substance from hi [ ] / pressure to low [ ] / pressure P Example O 2 diffuses fr blood ( [ ] ) to tissues (lo [ ] ), CO 2 opposite

17 Passive Transport Theory Behind Diffusion P Brownian motion Mculs move about randomly and collide Collisions force molecules to spread apart (to fill an area) P Factors that affect rate of diffusion Temperature - temp, speed of mculs, collisions, rate Concentration - [ ], # particles colliding, collisions, rate Pressure - pressure, bunched tog, collisions, rate

18 Passive Transport P Facilitated Diffusion Specialized carrier proteins aid and speed up mvmt of certain mculs across membrane Ex. Glucose diffusion across membranes Diffusion through Channel Facilitated by Carrier Protein

19 Passive Transport Osmosis P Description Mvmt of water mculs fr area of hi [ ] to low [ ] Note: mvmt of WATER molecules not solute particles Misconception: easy to confuse with diffusion (mvmt of solute) water mcul solute mcul Osmosis = mvmt of fr hi to low [ ]

20 Passive Transport Osmosis P Solution Descriptors Hypertonic solution - has more solute than the one being referred to Hypotonic solution - has less solute than the one being referred to Isotonic solution - has the same amount of solute

21 Which Way Will H 2 O Move? Solute particle Cell Container of solution Osmosis Cell in hypotonic solution H 2 O moves in, cell swells (In plant cells, causes turgor pressure) (In animal cells, may burst = cytolysis) Osmosis Cell in hypertonic solution H 2 O moves out, cell shrinks (plasmolysis)

22 Active Transport Capture and Release P Theory In some cases, transport proteins capture or bind solute mculs with proper shape and move them across the cell membrane

23 P Theory Active Transport Pumps Some transport proteins actively pump substrates across membrane Ex. Sodium-potassium pumps in nerve cells use energy to pump Na+ and K+ to proper sides of nerve cell membrane for nerve to fire 3 Na+ out for every 2 K+ in

24 Active Transport Endocytosis PGeneral Definition < Process by which materials too large to fit through pores or channels in membrane are moved from outside to inside cell PPinocytosis < Cell membrane pinches inward forming vesicle < Brings in liquid material (sm particles) PPhagocytosis < Cell membrane extends around large object < Forms vesicle as brings material in < Ex. Amoeba feeding < Ex. WBC capturing bacteria

25 Active Transport Exocytosis P General Definition Process by which large materials within the cell are transported to the outside of the cell Materials are carried inside vesicle to cell membrane Vesicle fuses with membrane and releases contents Ex. Removal of wastes, secretion of proteins, neurotransmitter release