I. What is the structure of the plasma membrane and what functions does it make possible?

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1 Subquestions: I. What is the structure of the plasma membrane and what functions does it make possible? A. What is the structure of the membrane? B. What are the following terms, how does the membrane structure make them possible, and why are they important? 1. Selective permeability 2. Diffusion 3. Osmosis

2 transfer -- endocyt, etc diffusion transport overview

3 make possible? A. What is the structure of the membrane? Bilayer fluid mosaic (made up of different components, mostly phospholipids and proteins, constantly moving, self-repairing) polar heads contact polar cytoplasm and interstitial fluid, inner portion is nonpolar allows for setting up ion gradients across membrane (nerves, muscles, mitochondria) B. What are the following terms, how does the membrane structure make them possible, and why are they important? 1. Selective permeability Lets some substances cross but not others only small and nonpolar substances can cross without special mechanisms because the inner portion of the membrane is nonpolar (fatty acid tails) 2. Diffusion Movement of substance from area of greater concentration to area of lesser concentration, does not require energy; oxygen and carbon dioxide diffuse across cell membrane to and from blood without energy expenditure, blood needs to have more oxygen than cells and less carbon dioxide for this to work

4 3. Osmosis Movement of water across semipermeable membrane from area of its higher concentration to area of its lower concentration; area w/ more dissolved solute will pull in water, no energy required To avoid movement of water, you want tears, eye drops, saline solution to have same % of salt that eye cells have (called isotonic) 4. Facilitated diffusion Movement of substance from area of higher concentration to lower concentration, requires carrier molecule (glucose carried across cell membrane by specific carrier), no energy required 5. Active transport Requires ATP, movement of substance across membrane using molecular pump (integral protein), 40% of energy we generate is used for pumps to establish ion gradients, requires energy because it's working against the ion gradient (working against diffusion) 6. Endocytosis Important for white blood cells to swallow bacteria (like Pac Man) this swallowing called phagocytosis Pinocytosis -- cell drinking endocytosis of droplets receptor mediated endocytosis requires cell to have receptor on its surface, when enough correct molecules bind the endocytosis is triggered brings in vitamins, some amino acids way HIV gets into cell, those w/ mutation lacking HIV receptor are immune to AIDS HDL s (good cholesterol) will bind lipids on receptors and remove them from blood; without receptors, mutated HDL s can t absorb lipids and they increase in blood and can build up in vessels

5 7.Exocytosis Secretions such as from pancreas happen with this mechanism, reverse of phagocytosis, takes substances out of cell when vesicle fuses w/ cell membrane and releases its cargo outside of cell -- requires fluid mosaic October 27, 2011

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7 II. How and why do the mitochondria generate ATP? A. What s the point of ATP? short-term energy storage, can be used by any organelle, like money (like an ATM) B. How does the form of the mitochondria follow its function? 1. Cristae -- folded membrane greatly increases surface area where respiration takes place, membrane divides mitochondria into 2 areas which allows for gradient electron transport animation 2nd electron transport

8 2. DNA -- codes for some of enzymes mitochondria needs 3. Cells with greater energy needs have more mitochondria C.How do the mitochondria generate ATP? (see book p. 429) facilitated diffusion 1. Aerobic respiration -- C 6 H 12 O 6 + 6O 2 --> 6CO 2 + 6H 2 O + 38 ATP moves by diffusion osmosis breakdown of C 6 H 12 O 6 yields CO ATP + high energy molecule NADH and FADH 2 Thanks to diffusion and osmosis, don't use energy for transport required for making energy.

9 b. Electron transport chain -- use energy from glucose to set up H + gradient, energy of H+ ions running through channel can be harnessed to make 38 ATP (similar to water wheel in flowing river) 2. Anaerobic respiration -- in absence of oxygen -- stop in middle because lack oxygen to take H's away and maintain gradient B. What diseases are associated with the mitochondria? mitochondrial diseases -- see website above, many places mutations can disrupt mitochondrial activity so many different diseases, but similar results in lack of energy (some diseases worse than others in how badly mitochondrial activity is affected)

10 III. DNA and the nucleus A. What is differentiation and how does it come about? original cell 1. Definition -- process whereby cells gain specialized structures and functions, sometimes lose structures and functions (e.g. red blood cells have no nuclei) 2. Process -- some genes are turned on and others turned off in progressively specialized manner 3. Stem cells-- undifferentiated cells, can become any tissue; could be source for regrowing nerves, organs; controversial unless get adult stem cells (more likely to use cells from embryos) karyotyping activity B. What form does a karyotype take and what diseases can it show? culture cells from amniocentesis, etc., encourage them to divide then arrest them in middle of mitosis, drop on slide to break open nucleus, take picture of chromosomes, arrange chromosomes largest to smallest, pair up using size, band patterns, and position of centromere find trisomy diseases (13, 18, 21, XXY, XXX, XYY) and missing chromosomes (XO)