AP Biology: Cells
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Zareena5683 on April 19, 2011
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CliffsNotes Unit 2
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58 terms
Terms | Definitions |
|---|---|
 Cell | Basic functional unit of all living things |
| Cytoplasm | Consists of specialized bodies (organelles) suspended in a fluid matrix (cytosol) |
| Plasma Membrane | Separates internal metabolic events from the external environment; controls the movement of materials into and out of the cell (selective permeability); lipid bilayer with hydrophilic heads and hydrophobic tails, proteins, cholesterol to provide some rigidity, and a glycocalyx of glycolipids (lipids + oligosaccharides) and glycoproteins (proteins + oligosaccharides) |
| Peripheral Proteins | Proteins that attach to the inner or outer surface of the membrane |
| Integral Proteins | Proteins that extend into the membrane |
| Transmembrane Proteins | Integral proteins that span completely through the membrane; held in place by hydrophilic/hydrophobic regions |
| Fluid Mosaic Model | Describes structure of the plasma membrane; scattered proteins within a flexible matrix of phospholipids |
| Channel Proteins | Provide open passageways through the membrane |
| Ion Channels | Allow the passage of ions across the membranes; gated channels open and close in response to specific stimuli i.e. Na+ and K+ |
| Porins | Allow the passage of certain ions and small polar molecules; aquaporins increase the passage rate of water molecules |
| Carrier Proteins | Bind to specific molecules, undergo a change in shape, and then transfer the molecules across the membrane; i.e. the passage of glucose |
| Transport Proteins | Use ATP to transport materials through active transport; i.e. sodium-potassium pump maintaining higher sodium and potassium concentrations on opposite sides of the membrane |
| Recognition Proteins | Give each cell type a unique identification so it can distinguish between "self" and "foreign" cells |
| Adhesion Proteins | Attach cells to neighboring cells and give cell stability |
| Receptor Proteins | Provide sites that hormones or other trigger molecules can bind to in order to activate a cell response |
| Nucleus | Bounded by the nuclear envelope (consisting of two phospholipid bilayers); contains DNA in chromatin form; serves as the site of chromosome separation during cell division |
| Chromatin | Threadlike form of DNA |
| Chromosomes | Chromatin condenses during cell division into rod-shaped bodies |
| Nucleosomes | Before cell division, histones organize DNA into bundles |
| Nucleolus | Concentrations of DNA within the nucleus that are in the process of manufacturing components of ribosomes |
| Ribosomes | Consist of RNA molecules and proteins; the two subunits move across the nuclear envelope into the cytoplasm to be assembled; ribosomes assist in the assembly of amino acids into proteins |
| Rough Endoplasmic Reticulum | Stacks of flattened sacs with ribosomes; as ribosomes assemble polypeptides, polysaccharides are attached to them to create glycoproteins |
| Smooth Endoplasmic Reticulum | Without ribosomes; synthesizes lipids and hormones |
| Golgi Apparatus | Flattened sacs arranged like a stack of bowls; modify and package proteins and lipids into vesicles; these vesicles bud out from the Golgi apparatus, migrate to the surface, and merge with the plasma membrane to release contents |
| Lysosomes | Vesicles from the Golgi apparatus that contain digestive enzymes; break down food, debris, and foreign invaders; they DO NOT occur in plant cells |
| Peroxisomes | Break down substances (i.e. hydrogen peroxide, fatty acids, and amino acids) |
| Mitochondria | Carry out aerobic respiration to obtain ATP from carbohydrates |
| Chloroplasts | Carry out photosynthesis to convert energy from sunlight into carbohydrates |
| Microtubules | Made of tubulin; provide support and motility for cellular activities; found in spindle apparatus of mitosis, and in cilia and flagella |
| Intermediate Filaments | Provide support for the cell |
| Microfilaments | Made of actin; involved in motility of cell |
| Flagella and Cilia | Structures that protrude from the cell membrane and make wavelike movements; flagella are long, few and move in snakelike motion; cilia are short, numerous, and move with back-and-forth movement; "9 +2" array of microtubules |
| Centrioles and Basal Bodies | Act as microtubule organizing centers (MTOCs); a centrosome outside the nuclear envelope gives rise to microtubules making the spindle apparatus in cell division; basal bodies are at the base of cilia and flagella and are made of nine triplets of microtubules |
| Transport Vesicles | Move materials between organelles or between organelles and the plasma membrane |
| Food Vacuoles | Store nutrients temporarily; may merge with lysosomes which digest food with their enzymes |
| Storage Vacuoles | In plants; store starch, pigments, toxic substances (i.e. nicotine) |
| Central Vacuole | Large bodies in plant cells; exert turgor pressure on cell walls when full and maintain rigidity this way |
| Contractile Vacuole | Collect and pump excess water out of cell |
| Cell Wall | Provide support outside the plasma membrane; made of cellulose in plants; made of chitin in fungi |
| Anchoring Junctions | Protein attachments between adjacent animal cells; desmosomes bind adjacent cells together and are associated with protein filaments that extend into the cell interior to hold structures together |
| Tight Junctions | Tightly stitched seams between animal cells; prevents passage of materials between cells so that materials must pass through them |
| Communicating Junctions | Allow the transfer of materials; gap junctions between animal cells involve connexins which prevent cytoplasm from mixing but allow the passage of ions and small molecules; plasmodesmata between plant cells involves with a desmotubule surrounded by cytoplasm and plasma membrane going between the two cells, with exchange occurring through the cytoplasm |
| Solute | Substance being dissolved |
| Solvent | Substance that the solute is being dissolved in; i.e. water |
| Hypertonic Solution | The solution that has a higher concentration of solutes than the other solution |
| Hypotonic Solution | The solution that has the lower concentration of solutes than the other solution |
| Isotonic Solution | The solution has the same concentration of solutes as the other solution |
| Bulk Flow | Collective movement of substances in the same direction in response to a force or pressure |
| Passive Transport | Movement of substances from higher to lower concentration; does not require energy |
| Simple Diffusion | Random movement from high to low concentration |
| Osmosis | Diffusion of WATER molecules across a selectively permeable membrane |
| Dialysis | Diffusion of SOLUTES across a selectively permeable membrane |
| Plasmolysis | Movement of water out of a cell resulting in the cell's collapse |
| Facilitated Diffusion | Diffusion of solutes or water through channel proteins |
| Countercurrent Exchange | Diffusion of substances between two regions in which they are moving by bulk flow in oposite directions |
| Active Transport | Movement of solutes against a gradient, requiring the expenditure of energy |
| Exocytosis | Vesicles fuse with the plasma membrane and release their contents to the outside |
| Endocytosis | The plasma membrane engulfs a substance and enters the cytoplasm in a vesicle; phagocytosis (undissolved, solid material) and pinocytosis (dissolved, liquid material), receptor-mediated (specific molecules bind to receptors) |
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