Exam 2 Study Guide - General Biology | BIOL 1001, Study notes of Biology

Download Exam 2 Study Guide - General Biology | BIOL 1001 and more Study notes Biology in PDF only on Docsity! BIOLOGY 1001 S. CROUSILLAC EXAM 2 STUDY GUIDE Chapter 5 1. What are the 4 functions of the cell membrane? 1. Isolate the cell environment 2. Regulate exchange between inside and outside 3. Communicate with other cells 4. Identify the cell type 2. What 2 lines of evidence suggest that the cell membrane is a phospholipid bilayer with proteins associated with it? 1. The phospholipid content of red blood cells is just enough to cover the cell with two layers. 2. The red blood cell has no internal membranes. 3. Membranes isolated from red blood cells contain proteins in addition to lipids 3. Why is the cell membrane described as a fluid-mosaic? There is lateral movement and the Mosaic aspect of membranes means that there are proteins interspersed within the lipid bilayer. 4. Which directions do phospholipids move, and how often? They have lateral movement (107 times a second) and they flip flop once a month 5. What are 3 main functions of membrane proteins? 1. transport proteins channel proteins – pores, like a door, opens and closes to let things in and out carrier proteins – selective revolving doors, changes shape to let things inside 2. receptors 3. cell-to-cell recognition 6. What are glycoproteins, and what are they mainly used for? Glycoproteins are proteins which have a carbohydrate attached to them, used for cell communication (cell-to-cell recognition) 7. What are some examples and characteristics of passive transport? Passive transport- movement down a concentration gradient 1. movement is from greater concentration to lower concentration 2. the greater the concentration difference, the faster the diffusion 3. net movement continues until the system reaches equilibrium 4. usually occurs over short distances Ex) osmosis, facilitated diffusion 8. What are the factors that determine the permeability of the membrane to a molecule?  solubility characteristics of the substance crossing the membrane  facilitated diffusion by a carrier protein or a channel protein 9. What are aquaporins, and why are they necessary? Water is able to enter and exit the cell through specialized protein channels called aquaporins. 10. List and describe 3 mechanisms for facilitated diffusion. 1. Bind-and-release (facilitated diffusion through carrier proteins) 2. Selective channel (facilitated diffusion through channel proteins) A pore the size of the solute 3. Gated channel Like a selective channel only with a door 11. Understand everything about osmosis and be able to predict what happens to cells when placed in different environments and why. Osmosis- The tendency of water to move through a membrane from an area of lower concentration into an area of higher concentration solution, diluting it, until there is equal concentrations of fluid on both sides of the cell membrane. Principles of Osmosis 1. Osmosis is the diffusion of water across a differentially permeable membrane. 2. Water moves from low concentration of a solute to high concentration of a solute 3. Dissolved substances decrease the amount of free water molecules  Osmosis is the passive transport of water  Influenced by factors which govern diffusion 5. What is activation energy? Which type of reactions requires activation energy? How is this affected by enzymes? Activation energy- the amount of energy that reactant molecules must absorb to start a reaction (“starter energy”). Exergonic reactions require activation energy. Enzymes lower activation energy. 6. What are enzymes? What are they used for? Enzymes- biological catalysts which are usually proteins, speed up metabolic reaction by lowering energy barriers 7. Explain what happens in coupled reactions. Coupled reactions- chemical reactions which release energy can be coupled to chemical reactions which require energy Ex) glucose breakdown and protein synthesis 8. Metabolism includes which processes? Metabolism- the total of an organism’s chemical processes Processes:  Uptake of matter and energy  Conversion of usable forms  Synthesis of cellular materials  Elimination of waste products 9. What is the difference between an anabolic and a catabolic reaction? What are examples of each? Catabolic pathways- metabolic pathways which release energy by breaking down complex molecules to simpler compounds Ex) breaking down glucose, degradation, releases energy Anabolic pathways- metabolic pathways which consume energy to build complicated molecules from simpler ones Ex) photosynthesis, energy requiring 10. What is a substrate? Where does the substrate bind the enzyme? Substrate- the substance which enzymes act on, in the presence of the appropriate enzyme the substrates become more reactive The substrate binds to the active site of an enzyme. The active site is the restricted region of an enzyme molecule where the substrate is bound. 11. What are examples of coenzymes? What do they do? Coenzymes- small non-protein organic molecules that are required for proper enzyme catalysis Ex) vitamins 12. What happens during feedback inhibition? Feedback inhibition- the regulation of a metabolic pathway by its end product, which inhibits an enzyme at an earlier point in the pathway, prevents the cell from making something it has enough of already 13. What are allosteric enzymes? Where are they usually found? How are they regulated? Allosteric enzymes- have two conformations, one is active and the other is inactive Allosteric enzymes are often found at key regulatory positions in metabolic pathways, meaning at places where these enzymes can turn the pathway on or off Regulated by allosteric inhibition, non-competitive, binds somewhere other than enzyme 14. What is a competitive inhibitor? How does it affect enzyme activity? Competitive inhibitor- chemicals that resemble an enzyme’s normal substrate and compete with it for the active site Blocks the active site by binding but not reacting Chapter 7 1. What is photosynthesis? Where do the carbons come from? Where does the energy come from? What part of the plant does it take place in? Photosynthesis- transforms light energy trapped by chloroplasts into chemical bond energy and stores that energy in sugar and other organic molecules Uses CO2 as a carbon source and sunlight energy as an energy source Occurs in the chloroplast 2. What are stoma / stomata? Stoma- pores where CO2 and H2O enter the leaf 3. What is the purpose of the vascular bundle? Water is absorbed by the roots and transported to the leaves through the vascular bundles. (the water source is affected when vascular bundles aren’t there) 4. What is a pigment? Which pigments are most important in photosynthesis? Where are they found? Pigment- substance that absorbs visual light Chlorophyll is the pigment which is the key light-capturing molecule in thylakoid membranes. Other pigments, including carotenoids and phycocyanins, are called accessory pigments Found in the chloroplast 5. What are the 2 reactions of photosynthesis? Where do they take place? When do they take place? What enters each reaction? What comes out of each reaction? Light-dependent reactions- sunlight is converted into chemical energy that is stored in the energy-carrier molecules called ATP and NADPH, oxygen is released as a by-product, occurs in the thylakoid membranes (in the chloroplast), happens whenever light is there (sun) Light-independent reactions- the chemical energy in the carrier molecules (ATP and NADPH, CO2) is used to make glucose, and other organic molecules, takes place in stroma, which is the fluid-filled space outside the thylakoids within the chloroplast, happens 24/7 6. What is the chemical energy molecule produced by PSII? How is this generated? Be able to explain what happens during this process. PSII generates ATP by chemiosmosis (the coupling of electron flow down an electron transport chain to ATP production by creation of a gradient across the membrane) 7. What is the chemical energy molecule produced by PSI? PSI generates NADPH, gives cells to NADP 8. Why do plants need water? Plants need water to gain enough electrons to fuel the ETC 9. What is the relationship between wavelength and energy level of light? The shorter the wavelength light has the higher the energy, the greater the wavelength light has the lower the energy 10. Why do leaves change color in the Fall? During the spring and summer, chlorophyll A and B are the primary pigments being used while photosynthesis levels are high. During the fall, many plants go into a form of hibernation where photosynthesis levels are decreased. Chlorophyll A and B are broken down, and accessory pigments are the dominant pigment.