BIOL 1441 1st EditionExam # 2 Study Guide Lectures: 11-18Lecture 11 (February 17)1. What is the protein that makes up microfilaments? Microtubules? Intermediate filaments?- Microfilaments: Actin- Microtubules: Tubulin- Intermediate filaments: Keratin2. What are the major functions of microfilaments? Microtubules? Intermediate filaments?- Microfilaments: muscle contraction, cell motility (pseudopodia), cell division-cleavage furrow- Microtubules: cell motility (cilia/flagella), separate chromosome-division- Intermediate filaments: make up nuclear lamina3. What is extracellular matrix (ECM)? Is it found in animal cells, plants cells, or both?- The ECM is found in animal cells(covers because they lack cell walls)-it repairs, divides, and rebuilds tissue instead of scarringi. Functions: support, adhesion, movement, tissue regeneration4. What are the 4 main protein or carbohydrate structures in the ECM? How are they connected?-5. What is the main structural protein in the ECM?- Fibronectin6. What are the 3 intercellular junctions in animal cells?- Tight junction: membranes of neighboring cells are pressed together, preventing leakageof extracellular fluid (prevents things from going in between cells)- Desmosomes(anchoring junctions): fasten cells together into strong sheets (hold cels together/keep things from going in between)- Gap junctions: provide cytoplasmic channels between adjacent cells-RARE (things moving between cells)i. Ex. Heart/intestines7. What is the intercellular junction in plant cells?- Plasmodesmata 8. What intercellular junctions are similar in plant and animal cells?-9. What happens to an animal cell in a hypertonic solution? Hypotonic? Isotonic?- Hypertonic: fluid rushes OUT and it shrivels- Hypotonic: fluid rushes IN and it bursts (lysed)- Isotonic: GOOD-WHERE IT SHOULD BE10. What happens to a plant cell in a hypertonic solution? Hypotonic? Isotonic?- Hypertonic: plasma membrane pulls away (plasmolyzed)- Hypotonic: GOOD-WHERE IT SHOULD BE (TURGID)- Isotonic: flaccid (wilted)11. What happens to a red blood cell in a hypotonic solution?- bursts12. Explain diffusion.- When molecules spread out evenly into the available space-natural movement of anything from high to low concentration (doesn’t have to be across a membrane)13. How does heat, molecule size and concentration gradient affect the rate of diffusion?- Heat: Increase heat=increase molecular colisions=increased diffusion ratei. DIRECT RELATIONSHIP- Size: smaller molecules move faster than large moleculessmaller molecules will diffusefasteri. INVERSE RELATIONSHIP- Concentration gradient: steeper gradient(higher concentration on one side compared to low concentration on other side)=faster diffusioni. DIRECT RELATIONSHIP14. What are the major biological molecules that make up cell membranes?- Lipids (mostly), proteins, carbohydrates15. How does temperature affect the fluidity of a membrane? - As temperatures cool, membranes switch from a fluid state to a solid state-molecules start slowing down and pack tightly into a solid16. How do cell membranes remain fluid in cold temperatures?- In cold temperatures, CHOLESTEROL helps maintain fluidity by preventing tight packing by inserting itself between tails to keep them from packing too tightly17. How do cell membranes prevent too much fluidity in cell membranes when it’s too hot?- In hot temperatures, CHOLESTEROL restrains movement of phospholipids which makes them less fluid. Cholesterol acts as a speed bump and slows molecules down when they hit cholesterol.18. What are the 6 functions of membrane proteins?- Transport, enzymatic activity, signal transduction, cell to cell recognition, intercellular joining, attachment to cytoskeleton/ECM19. What is an amphipathic molecule?- Containing hydrophobic and hydrophilic regionsLecture 12 (February 19)1. What is the difference between active and passive transport?- Passive transport: requires no energy from the cell to make it happeni. High to low concentrations (natural movement)ii. Channel proteins/carrier proteins- Active transport: requires energy (usually ATP)i. Low to high concentrationsii. ONLY carrier proteins2. What is the difference between diffusion and facilitated diffusion?- Diffusion: molecules spread out evenly into the available space- Facilitated diffusion: passive diffusion aided by transport proteins (channel/carrier proteins and ion channels)3. What is an electrogenic pump? Give 2 examples- Electrogenic pump: transport protein that generates the voltage across a membranei. Sodium-potassium pumpii. Proton pump4. Where is the Na+/K+ pump located in a cell?- Cell membrane5. How does the Na+/K+ pump work? What are the gradients set up (meaning there is Na+ high and where is it low? Where is K+ high and where is it low?)- Inside of the cell is NEGATIVE- Inside of the cell has LOW sodium concentration (NA+)- Inside of the cell has HIGH potassium concentration (K+)- If NA+ channels are opened, NA+ diffuses INTO the celli. Pumps 3 NA+ OUT of cell- If K+ channels are opened, K+ diffuses OUT of the celli. Pumps 2 K+ INTO cell- The concentration gradient is the ENERGY SOURCE- Sodium-potassium pump maintains these gradients6. What types of molecules can cross the cell membrane and why?- Hydrophobic, Nonpolar, no charge, hydrocarbons/steroids (diffusion-passive transport)7. What types of molecules cannot cross the cell membrane and why?- Hydrophilic, Polar, ions, charged molecules, water (facilitated diffusion/active transport)8. What is the difference between channel and carrier proteins? Which can do passive transport? Which can do active transport?- Channel proteins: provide corridors that allow a specific molecule or ion to cross the membrane- Carrier proteins: undergo change in shape that translocates the solute-binding site across the membrane- Passive transport uses BOTH- Active transport ONLY carrier9. What is osmosis?- Diffusion of water across a selectively permeable membrane- Water is diffusing on its OWN concentration gradient - From an area of low solute concentration (high water) to an area of high solute concentration (low water)i. WATER WILL ALWAYS FLOW TO A HIGH SOLUTE CONCENTRATION (LOW WATER)10. What is voltage?- Electrical potential energy, separation of opposite charges11. What is membrane potential? Why is it important in cells?- Voltage difference across a