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Bio 161 Exam 2 ch 5-8
Terms in this set (80)
What is the structure of a phospholipid?
glycerol, 3 carbon polyalcohol, 2 fatty acids attched to glycerol phosphate group
What is the phospholipid bilayer?
Why are the phospholipids arranged the way they are?
bc of polar and non polar interactions
What holds the layers together?
List the four components of cellular membranes. What does each component consist of?
1.Phospholipid bilayer•Flexible matrix, barrier to permeability
2.Transmembrane proteins•Integral membrane proteins
3.Interior protein network•Peripheral or intracellular membrane proteins
4.Cell surface markers•Glycoproteins and glycolipids
What factors influence the fluidity of the phospholipid bilayer?
-Saturated fatty acids make the membrane less fluid than unsaturated fatty acids
-Warm temperatures make the membrane more fluid than cold temperatures
-Lipid composition of the ER membrane, Golgi stack & plasma membrane are distinct
List the functions of membrane proteins. ***
1.Transporters 2.Enzymes 3.Cell-surface receptors 4.Cell-surface identity markers 5.Cell-to-cell adhesion proteins 6.Attachments to the cytoskeleton
What are anchoring molecules and what do they do?
Anchoring molecules are modified lipids with
1.Nonpolar regions that insert into the internal portion of the lipid bilayer
2.Chemical bonding domains that link directly to proteins
What is the transmembrane domain of the integral membrane protein?
What are pores? What is their structure?
extensive nonpolar regions within a transmembrane protein, interior is polar
Describe passive transport.
Passive transport is movement of molecules through the membrane in which
-No energy is required
-Molecules move in response to a concentration gradient
Diffusion is movement of molecules from high concentration to low concentration
2.What is facilitated diffusion?
Molecules that cannot cross membrane easily may move through proteins
-Move from higher to lower concentration
3. What is facilitated diffusion?
1. What are ion channels?
Allow the passage of ions
2. What 3 conditions determine the direction ions will travel through gated channels? ***
Relative concentration on either side of membrane
•Voltage differences across membrane
•Gated channels - channel open or closed
What is saturation?
rate of transport limited by number of transporters
1. Describe osmosis.
2. What is osmotic concentration?
net diffusion of water across a membrane toward a higher solute concentration
3. What are the three different states of osmotic concentration and what do they mean?
Hypertonic solution has a higher solute concentration
-Hypotonic solution has a lower solute concentration
•When two solutions have the same osmotic concentration, the solutions are isotonic
What is osmotic pressure? How can that affect a cell?
Force needed to stop osmotic flow, can cause water to flow out
Explain some ways that cells maintain osmotic balance.
-Some cells use extrusion in which water is ejected through contractile vacuoles
-Isosmotic regulation-adjusting to surrounding
-Plant cells use turgor pressure to push the cell membrane against the cell wall and keep the cell rigid
What is active transport? Name the active transport system discussed in class. (You will not be expected to describe this system in detail.)
-ATP is used directly or indirectly to fuel active transport
•Moves substances from low to high concentration
•Requires the use of highly selective carrier proteins
What is coupled transport?
uses ATP indirectly
What are endocytosis and exocytosis? What are the two types of endocytosis?
-Movement of substances into the cell
-Movement of substances out of cell
What is thermodynamics?
Branch of chemistry concerned with energy changes
1. How is energy defined?
capacity to do work
2. What is the difference between potential and kinetic energy?
3. What is the most convenient way to measure energy?
Name the four points described by the First Law of Thermodynamics. ***
Energy cannot be created or destroyed
•Energy can only change from one form to another
•Total amount of energy in the universe remains constant
•During each conversion, some energy is lost as heat
What is entropy? How does that relate to the Second Law of Thermodynamics?
thermodynamic quanitity,Entropy (disorder) is continuously increasing
Describe the free energy equation. What does it mean when ∆G is positive? Negative?
∆G = ∆H - TS
-Products have more free energy than reactants
-H is higher or S is lower
-Not spontaneous, requires input of energy
-Products have less free energy than reactants
-H is lower or S is higher or both
-Spontaneous (may not be instantaneous)
What is activation energy?
Extra energy required to destabilize existing bonds and initiate a chemical reaction
What are catalysts?
Substances that influence chemical bonds in a way that lowers activation energy
Describe the structure of ATP. Where is the energy stored in an ATP molecule?
Composed of-Ribose - 5 carbon sugar-Adenine-Chain of 3 phosphates, stored in phosphate
What are enzymes? What is the active site on an enzyme?
Most enzymes are protein, Pockets or clefts for substrate binding
Where can enzymes be found?
suspended in the cytoplasm or attached to cell membranes and organelles
What is a multi-enzyme complex?
subunits work together to form molecular machine
What are ribozymes? What are the two kinds?
981 discovery that certain reactions catalyzed in cells by RNA molecule itself
• 2 kinds
1.Intramolecular catalysis - catalyze reaction on RNA molecule itself
2.Intermolecular catalysis - RNA acts on another molecule
What are some factors affecting enzyme function?***
Optimum temperature&Optimum pH
What is an inhibitor? Explain the difference between competitive and non-competitive inhibition.
substance that binds to enzyme and decreases its activity, competitive competes w substrate for active site and non competitive binds to another site
What are allosteric enzymes? What do allosteric activators/inhibitors do?
enzymes exist in active and inactive forms,
Allosteric inhibitor - binds to allosteric site and reduces enzyme activity•
Allosteric activator - binds to allosteric site and increases enzyme activity
What is feedback inhibition?
End-product of pathway binds to an allosteric site on enzyme that catalyzes first reaction in pathway
What is the difference between anabolism and catabolism?
Anabolism: The buildup of complex organic molecules from simpler ones, reactions are called anabolic or biosynthetic. They involve dehydration synthesis (release water) and are endergonic.
Catabolism: The breakdown of complex organic molecules into simpler ones.
What is the difference between autotrophs and heterotrophs?
autotrophs produce on materials and heterotrophs don't
1. What is cellular respiration?
Cellular respiration is a series of reactions
2. What is a dehydrogenation reaction?
lost electrons are accompanied by protons
What is NAD+/NADH? Which is the oxidized form and which is the reduced form?
nicotinamide adenosine dinucleotide, NADH
What is the final electron acceptor in aerobic respiration? What about in anaerobic respiration and in fermentation?
oxygen, inorganic molecule, organic molecule
What is the reaction for the aerobic respiration of one molecule of glucose?
C6H12O6 + 6O2 → 6CO2 + 6H2O
What are the two mechanisms for ATP synthesis that are used in respiration? What does each one entail?
substrate- Transfer phosphate group directly to ADP•During glycolysis
oxidative phosphorylation-ATP synthase uses energy from a proton gradient
List the four major steps in the complete oxidation of glucose.
Where does glycolysis take place? How many steps are involved in this pathway? What are the end products? How much (net) ATP and NADH is generated?
2. Pyruvate oxidation
3. Krebs cycle
4. Electron transport chain & chemiosmosis
What are the two possible fates for the pyruvate molecules that come out of glycolysis?
In aerobic respiration, what is pyruvate converted to? Where does this end product go? Is anything else formed in this reaction? Where does this process take place?
How many steps are there in the Krebs cycle? How many electron carriers/ATP are generated? How many times does this cycle turn following the breakdown of one molecule of glucose through glycolysis? Where does this take place?
9 steps, 38,
How does the electron transport chain work? Where does this process take place?
series of membrane- bound electron carriers, inner mitochondrial membrane
What is chemiosmosis? Approximately how many ATP molecules are generated through this process for each molecule of glucose that enters glycolysis? Where does this happen?
movement of ions across a semipermeable membrane, 32 per glucose, mitochondria
Describe the two ways in which respiration is regulated.
glycolisis, Krebs cycle
What are the two forms of fermentation?
ethanol, lactic acid
How are proteins catabolized? Give two specific examples.
Amino acids undergo deamination to remove the amino group
-Alanine is converted to pyruvate
-Aspartate is converted to oxaloacetate
How are fats broken down? How does this process yield more energy than the respiration of glucose?
broken down to fatty acids and glycerol, 20% more energy
What is the summary equation for photosynthesis?
carbon dioxide + water —> glucose + oxygen + water.
Name the two stages of photosynthesis.
light dependent, carbon fixation/light independent
Describe the structure of a chloroplast.
Thylakoid membrane, grana, stroma lamella, stroma
1. What is a photon?
particle of light
2. What is the photoelectric effect?
removal of an electron from a molecule by light
What is the wavelength range of visible light?
What is a particle's absorption spectrum?
range and efficiency of photons molecule is capable of absorbing
1. What is the difference between chlorophyll a and chlorophyll b?
a= main pigment
b= secondary pigment
2. What is the unique structural feature of the chlorophyll molecule? What does this structure do?
Porphyrin ring-Complex ring structure with alternating double and single bonds-Magnesium ion at the center of the ring
What are carotenoids?
Carbon rings linked to chains with alternating single and double bonds
1. What do photosystems do? Name and define the two components of photosystems.
Antenna complex•Hundreds of accessory pigment molecules•Gather photons and feed the captured light energy to the reaction center
-Reaction center•1 or more chlorophyll a molecules•Passes excited electrons out of the photosystem
2. What are the two photosystems used during photosynthesis? What does each do? Which one happens first?
1- transfers electrons
2- oxidizes water
2 happens first
What are the four steps in the light-dependent reactions? What happens at each step? ***
What is cyclic photophosphorylation?
primary photoevent- light is captured in pigment
charge seperation- energy is tranferred
electron transport- electrons move through carriers
chemiosmosis- produce ATP
What are the steps in the Calvin cycle/light-independent/carbon fixation reactions? How many times does it have to turn to generate one molecule of glucose?
carbon fixation, reduction phase, carbohydrate formation, and regeneration phase,
What is rubisco? What does it do?
enzyme involved in the first major step of carbon fixation,
What is the C4 pathway? What are some examples of plants that use this pathway?
add co2 to PEP to form 4 carbon molecule, ex. flower
What are CAM plants?
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