AP Bio Unit 2 Review Shee1

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AP Bio Unit 2 Review Sheet VOCAB 1. Cytoskeleton- a network of microtubules, microfilaments, and intermediate filaments that branch throughout the cytoplasm and serve a variety of mechanical, transport, and signaling functions; provides structural support to the cells for cell motility and regulation; mechanical support to cell, helps cell maintain its shape 2. Tight junctions- fusion of adjacent cell membrane, prevents leakage between cells 3. Desmosome- anchoring junction w/ intermediate filaments cementing adjacent cells together 4. Plasmodesma- (plasmodesmata) an open channel in the cell wall of a plant through which strands of cytosol connect from an adjacent cell; allows cytoplasm of one cell to be continuous w/ cytoplasm of neighboring cell 5. Hypotonic- a solution w/ a lower solute concentration compared to that inside a cell 6. Hypertonic- a solution w/ a greater solute concentration than that inside a cell 7. Isotonic- a solution w/ an equal solute concentration compared to that inside a cell 8. Plasmolysis- phenomenon where a walled cell shrivels and the plasma membrane pulls away from the cell wall as the cell loses water to a hypertonic environment 9. Endocytosis- extracellular substances are incorporated into the cell in vesicles by an inward budding of the plasma membrane; forms a food vacuole 10. Exocytosis- vesicles fuse with the plasma membrane and dump their contents to the outside of the cell; cellular secretion of biological molecules 11. Receptor-mediated endocytosis- the process of importing specific macromolecules into the cell by the inward budding of vesicles form from coated pits; occurs in the response to the binding of specific ligands to receptors on the cell s surface; can take in various substances at once; more discriminating/specific than pinocytosis(celldrinking) 12. Chromatids- one of two identical copies of DNA making up a chromosome(1 chromosome=2 sister chromatids) 13. Centromere- specialized region of the chromosome where two sister chromatids are most closely attached 14. Centrosome- structure present in the cytoplasm of animal cells, important during cell division; functions as a microtubule organizing center, contains 2 centrioles; unit of centrioles and spindle fibers made of microtubules 15. Centriole- a structure in the centrosome of an animal cell composed of cylinders of microtubule triplets; a pair makes a centrosome 16. Spindle fibers- made of microtubules, part of the cytoskeleton, separates chromosomes during cell division 17. Kinetochore microtubules- a structure of proteins attached to the centromere that links each sister chromatid to the spindle fibers; pull/ push chromosomes where they are needed during mitosis 18. Nonkinetochore- elongates cell during mitosis 19. Cleavage furrow- first sign of cytokinesis; a shallow groove in the cell surface near the old metaphase plate 20. Cell plate- plant equivalent of cleavage furrow; a double membrane across the midline of a dividing plant cell, eventually forms cell wall 21. Restriction point- G1 checkpoint; at the end of the cell cycle's G1 phase, just before entry into S phase, making the key decision of whether the cell should divide, delay division, or enter a resting stage. Many cells stop at this stage and enter a resting state called G0 stage 22. Thylakoid membrane- flattened membranous sac inside a chloroplast; function in the steps of photosynthesis that initially convert light energy to chemical energy 23. Stroma- viscous (dense) fluid outside of the thylakoids inside chloroplast; involved in the synthesis of organic molecules from carbon dioxide and water

Study Questions 1. Know the structure and function of all major organelles in both plant& animal cells. Nucleus: contains a eukaryotic cell s genetic library; general conspicuous membrane-bound cellular organelle contains most of the genes that control the entire cell, enclosed by a nuclear envelope which separates contents from cytoplasm. Nucleolus: most visible structure in nucleus; functions in the synthesis of ribosomes Ribosome: a cytoplasmic organelle that is the site for protein synthesis complexes of RNA & protein, generally make proteins destined for membrane inclusion Endoplasmic reticulum: extensive network of tubules & sacs, continuous w/ outer membrane of nuclear envelope Smooth ER: cytoplasmic surface lacks ribosomes, participates in synthesis f lipids, phospholipids, & steroids; carbohydrate metabolism, stores calcium ions necessary for muscle contraction; (in liver) contains an enzyme that catalyzes final step in conversion of glycogen to glucose; detoxifies drugs and poisons Rough ER: cytoplasmic side studded w/ ribosomes, manufacturers secretory proteins & membrane Golgi Apparatus: contains stacks of membrane bound structures called cisternae modifies, stores, & routes products of ER, Cis face receives products by accepting transport vesicles from the ER, Trans face transports molecules to other sites, contain enzymes to modify products from ER, sorts products for secretion, Trans face vesicles fuse w/ plasma membrane Lysosome: membrane enclosed bag of hydrolytic enzymes, involved in breakdown of proteins, polysaccharides, lipids, nucleic acids, involved in intracellular digestion, phagocytosis, recycles cell s own organic material; selfeating, reuses what it digests Vacuole: membrane enclosed sac, larger than a vesicle Food vacuole: formed by phagocytosis, stores food Contractile vacuole: found in freshwater protists; pumps excess water from the cell Peroxisome: consumes oxygen, contains enzymes that transfer hydrogen from various substrates to oxygen, produces hydrogen peroxide H2O2 has by product form intracellular compartments, bounded by a lipid bilayer membrane that separates their contents from the cytosol, contain membrane proteins for various functions, primarily removing the toxic peroxides from the cell and the metabolism of fatty acids 2. What determines the size of the cell? Range limited by metabolic requirements, surface area must be large enough to provide an adequate exchange surface for oxygen nutrients &wastes, needs to be larger enough to contain ribosomes, DNA, & enzymes 3. What is the difference between prokaryotes & eukaryotes? Prokaryotes: found only in bacteria, no true nucleus, lacks nuclear envelope, genetic material in nucleoid region, no membrane bound organelles\ Eukaryotes: found in kingdom Protists, Fungi, Plantae, Animalia, true nucleus bound by nuclear envelope, nucleus contains genetic material, contains cytoplasm w/ cytosol (intracellular fluid) & membrane bound organelles 4. Know the difference between diffusion, facilitated diffusion, & active transport. Diffusion: tendency for molecules of any substance to spread out into available space; net movement down concentration gradient; in absence of other forces i.e. pressure, substance diffuses from high low concentration, , no energy required -Passive transport: diffusion of a substance across a biological membrane - Osmosis: passive transport of water Facilitated Diffusion: diffusion of solutes across a membrane w/ help of transport proteins >helps w/ diffusion of polar molecules/ions impeded by membrane s phospholipid bilayer >protein binds solute, deposits solute on the other side

Active Transport: always low to high, energy requiring, transport protein pumps a molecule across membrane against its concentration gradient, uses energy from ATP Ex) Sodium-potassium pump: translocates 3 NA+ ions out of cell for every 2 K+ ions pumped into cell (keeps inside of cell negative) 5. Which molecules pass through a selectively permeable membrane easily? Most difficult? Easily: water, nonpolar molecules, those neutral in charger, simple smaller molecules Difficult: ions (cations/anions) polar molecules, larger ex) carbs, larger sugars 6. Know the 5 phases of mitosis and what is occurring at the chromosome level. Interphase: nondividing stage, includes most of the cell s growth and metabolic activities; about 90% of cell cycle cell grows and copies its chromosomes in prep for cell division Prophase: chromatin condenses into a highly ordered structure called a chromosome in which the chromatin becomes visible; attached to each other at a DNA element present on every chromosome called the centromere;centrosomes will be pushed apart to opposite ends of the cell nucleus by the action of molecular motors acting on the microtubules; nuclear envelope breaks down to allow the microtubules to reach the kinetochores on the chromosomes, marking the end of prophase Prometaphase: chromatin attach to one another; centrosomes at opposite poles. Line up in perpendicular poles, line up at equator; nuclear envelope breaks into fragments and disappears; Microtubules emerging from the centrosomes at the poles (ends) of the spindle reach the chromosomes, now highly condensed Metaphase: which condensed & highly coiled chromosomes align in the middle of the cell before being separated into each of the two daughter cells; centromeres of the chromosomes convene themselves on the metaphase plate (or equatorial plate), an imaginary line that is equidistant from the two centrosome poles Anaphase: centromeres uncouple, sister chromatids move to opposite ends Telephase: Two daughter nuclei form in the cell. The nuclear envelopes of the daughter cells are formed from the fragments of the nuclear envelope of the parent cell. As the nuclear envelope forms around each pair of chromatids as the nucleoli reappear; In animal cellsa cleavage furrow develops where the metaphase plate used to be, pinching off the separated nuclei; in plant cell, cell plate appears, eventually forms cell wall

7. Know the 3 phase of interphase. G1= gap 1 junction: cells make sure all organelles have copied themselves, have enough cytoplasm, and are growing; restriction point is at the end of G1 phase. This point is a series of saf