General Biology - Exam 2 Study Guide

Exam 2 Study Guide 1. Why do we describe the plasma membrane as a fluid mosaic model? - The fluid mosaic model states that a membrane is a fluid structure with a “mosaic” of various proteins embedded in it - Phospholipid bilayer= cell membrane(plasma) → fluid mosaic model: plasma membrane is fluid, mosaic= *phospholipids, proteins, cholesterol. 2. What direction do the lipids in the membrane normally move? - Drift laterally, rarely a lipid may flip-flop transversely across the membrane 3. How does cholesterol help maintain fluidity in hot and cold temperatures? - At warm temperatures (such as 37°C), cholesterol restrains movement of phospholipids - high temp, decrease fluidity - At cool temperatures, it maintains fluidity by preventing tight packing - low temp, increase fluidity 4. How are peripheral proteins and integral (transmembrane) proteins different? - Peripheral proteins are bound to the surface of the membrane - only one side of the membrane - Integral proteins penetrate the hydrophobic core Integral proteins that span the membrane are called transmembrane proteins - all the way through the membrane 5. What is the role of unsaturated fatty acid tails in maintaining fluidity of the membrane? - Membranes rich in unsaturated fatty acids are more fluid than those rich in saturated fatty acids - unsaturated fats, increase fluidity - saturated fats, decrease fluidity 6. Which types of molecules pass through the cell membrane the easiest? - Hydrophobic (nonpolar) molecules, such as hydrocarbons, can dissolve in the lipid bilayer and pass through the membrane rapidly 7. What does it mean when we say the membrane is selectively permeable? - Selective permeability is a property of cellular membranes that only allows certain molecules to enter or exit the cell. - regulates cells molecular traffic - A selectively permeable cell membrane is one that allows certain molecules or ions to pass through it by means of active or passive transport. 8. What is diffusion? - Diffusion is the tendency for molecules to spread out evenly into the available space - Solute → salt,potassium, magnesium - Simple diffusion= through the plasma membrane, no protein, lipid-soluble or hydrophobic substances - Facilitated diffusion= through a protein, water-soluble or hydrophilic substances or ions 9. What is osmosis? - Diffusion of water across a selectively permeable membrane 10. What happens to cells placed in isotonic solutions? Hypertonic solutions? Hypotonic solutions? - Isotonic solutions: Solute concentration is the same as that inside the cell; no net water movement across the plasma membrane - Water passes through evenly - animal= normal, plant= flaccid (limp) - Hypertonic solutions: Solute concentration is greater than that inside the cell; cell loses water - Cell loses water which might cause it to shrivel - animal= shriveled, plant= plasmolyzed - Hypotonic solutions: Solute concentration is less than that inside the cell; cell gains water - Cell gains water which might have the cell SWELL LIKE A HIPPO - animal= lysed, plant=turgid (normal/firm) 11. How does the sodium- potassium pump work? - The sodium-potassium pump uses active transport to move molecules from a high concentration to a low concentration. - The sodium-potassium pump moves sodium ions out of and potassium ions into the cell. This pump is powered by ATP. For each ATP that is broken down, 3 sodium ions move out and 2 potassium ions move in. 12. What is phagocytosis? Pinocytosis? - Phagocytosis: Cell engulfs a food particle (cellular eating) - Pinocytosis: Cell gulps drops of water with solutes (cellular drinking) 13. What is active transport? - Needs energy - low to high concentration= against concentration gradient 14. What is a catabolic pathway? Anabolic pathway? - Catabolic Pathway: Breaks down complex molecules, releases energy, ex) cellular respiration **Crazy cat shreds pieces** - Anabolic Pathway: Build complex molecules, needs energy, ex) Photosynthesis 15. What is the first law of thermodynamics? Second law of thermodynamics? - First law of thermodynamics(Conservation of energy): Energy can be transferred or transformed but can’t be created or destroyed - Second law of thermodynamics: Every energy transfer or transformation increases entropy(disorder) of the universe 16. What happens if our metabolism was to reach equilibrium? - maximum stability, cells don’t do any more work - metabolism never reaches equilibrium 17. What is an exergonic reaction? Endergonic reaction? - Exergonic: release of free energy, spontaneous - Endergonic: absorbs free energy, non=spontaneous 18. What is ATP and why is it important? - ATP (adenosine triphosphate) is the cell’s energy shuttle - ATP is composed of ribose (a sugar), adenine(a nitrogenous base), and three phosphate groups - ATP drives endergonic reactions by phosphorylation, transferring a phosphate group to some other molecule, such as a reactant - ATP is an important molecule in metabolism because its terminal phosphate bond has higher energy than the other two. It provides energy coupling between exergonic and endergonic reactions. ... They supply energy, primarily in the form of ATP, for the cell's work. 19. What happens to most of the heat that is generated during a chemical reaction? - absorb energy? it is lost 20. How do enzymes work to speed up a chemical reaction? - Enzymes catalyze reactions by lowering the activation energy barrier - The lower the activation energy for a reaction, the faster the rate. 21. What is meant when we talk about lock and key analogy for enzymes? - It's specific so the substrate molecule and enzyme must fit like a lock and key 22. What is the active site of the enzyme? - Where substrate binds 23. What is induced fit? - Once substrate binds to active site the enzyme-substrate complex changes shape to increase catalytic effect 24. How do competitive inhibitors work? Noncompetitive inhibitors? - Competitive inhibitors: Binds to the active site, competing with substrate of an enzyme - Noncompetitive inhibitors: Bind to the enzyme and change the shape of the active site 25. When ATP is broken down to ADP what happens to the inorganic phosphate? - In order to release its energy to the body, ATP breaks down into ADP [Adenosine Diphosphate(2 phosphates)] and an inorganic phosphate group and releases energy from the pyrophosphate bond. ADP is an exergonic molecule which means that it yield energy when formed. 26. What are the products of glycolysis? - breaks down glucose into two molecules of pyruvate) - Produces 2 ATP (4 ATP produced − 2 ATP used up), 2 NADH, and 2 pyruvate molecules 27. What are redox reactions? What is oxidation? What is reduction? - Redox Reactions: Chemical reactions that transfer electrons between reactants are called oxidation-reduction reactions, or redox reactions - Oxidation: loses  electrons **LEO the lion says - Reduction: gains electrons GER** 28. How many ATP are used in glycolysis? - 2 29. How many TOTAL ATP are made in glycolysis? - 4 30. What are the products of the citric acid cycle? - 1 ATP, 3 NADH, 1 FADH, CO2 31. What are the 2 electrons carries for cellular respiration? - NADH and FADH2 - These two electron carriers donate electrons to the electron transport chain, which powers ATP synthesis via oxidative phosphorylation 32. Know the correct pathway of the steps in cellular respiration - Glycolysis: In cytosol→ input: glucose, 2 ATP→ output: 2 pyruvate, 4 ATP, 2 NADH, 2H2O→ gross: 4 ATP, net: 2 ATP - Prep step: mitochondria→ input: 2 pyruvate→ output: acetyl COA, CO2, NADH→ no ATP - Citric acid cycle: mitochondria matrix→ input: acetyl COA→ output: 1 ATP, 3 NADH, 1 FADH, CO2→ ATP: 1 per acetyl COA, 2 for glucose (The most CO2 is produced in this step) - Oxidative Phosphorylation→ mitochondrial membrane→ input: NADH, FADH, Oxygen→ output: a lot of ATP, and water→ 30 ATP (The most ATP is produced in this step) 33. How is oxygen used in cellular respiration? - Most cellular respiration requires O2 to produce ATP - Without O2, the electron transport chain will cease to operate - In that case, glycolysis couples with anaerobic respiration or fermentation to produce ATP 34. How many ATP are made by 1 glucose molecule? - 30-38 35. Know which steps of cellular respiration need oxygen and which ones do not. - NEEDS OXYGEN - prepstep (pyruvic acid conversion) - Citric acid cycle (krebs cycle) - Oxidative Phosphorylation (electron transport chain and chemiosmosis) - NO OXYGEN - glycolysis - fermentation 36. Know where each step of cellular respiration and fermentation take place. - After glycolysis 37. What are the products of fermentation? (remember there are 2 types) - Alcohol → ethanol, releases co2, yeast, uses NADH - Lactic Acid → ferm/lactate, uses NADH 38. Where does beta oxidation occur? What is beta oxidation? - If glucose can’t not get in and have o2 beta oxidation happens (Occurs in aerobic) - ↓ or no carbs - fatty acid→ acetyl CoA - per gram fats have more energy, produces acidic ketone bodies 39. How do cells make ATP without oxygen? - Fermentation 40. How do cells make ATP without glucose? - Beta oxidation 41. What colors of visible light are used by plants? - Any color that isn’t the color of the plant (ROYBIV) - best colors for plants: blues,violets,reds 42. What are the products of the light reaction? Reactants? - Product of light reactions: o2, ATP, NADPH - Reactants/input: solar energy, water, (NADH+,ADP+) 43. What are the products of the calvin cycle? Reactants? - Products:G3p, Glucose - Reactants/input:ATP, NADPH, CO2 44. Where does photosynthesis take place? Light reactions? Calvin cycle? - Photosynthesis: Chloroplasts - Light reactions: Thylakoid - Calvin cycle: Stroma 45. How is oxygen produced in photosynthesis? - During the light reactions, an electron is stripped from a water molecule freeing the oxygen and hydrogen atoms - SPLIT OF H2O→ O2 RELEASED!!!! 46. What is the adaptation for CAM plants? - CAM plants open their stomata at night, incorporating CO2 into organic acids - Carbon fixation happens at night, which conserves H2O - Stomata close during the day, and CO2 is released from organic acids and used in the Calvin cycle 47. Importance of Photosynthesis - The energy entering chloroplasts as sunlight gets stored as chemical energy in organic compounds - Sugar made in the chloroplasts supplies chemical energy and carbon skeletons to synthesize the organic molecules of cells - Plants store excess sugar as starch in structures such as roots, tubers, seeds, and fruits - In addition to food production, photosynthesis produces the O2 in our atmosphere 48. Light vs dark (calvin cycle reactions) - Light Reactions - In the thylakoid membranes→ Convert light energy to the chemical energy of ATP and NADPH→ Split H2O and release O2to the atmosphere - Dark (Calvin Cycle) - Take place in the stroma→ Use ATP and NADPH to convert CO2 to the sugar G3P→ Return ADP, inorganic phosphate,and NADP+ to the light reactions 49. Why are CAM and C4 plants photosynthesis considered a compromise? - C4 compromises on water loss and CAM compromises on photorespiration. Each one both minimizes photorespiration and optimizes the Calvin cycle. CAM plants allow more water loss, while C4 plants allow less CO2 into the plant. 50. What is photophosphorylation and where does it occur? - The phosphorylation of ADP to form ATP using the energy of sunlight is called photophosphorylation - Occur in light reactions (thylakoid) 51. What types of cells have mitochondria? Chloroplasts? : Plant and animal, plants