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115 Cards in this Set
- Front
- Back
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How are Phospholipids arranged in the membranes of cells?
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In bilayer oriented as follows:
a) The polar heads face outward b) The non-polar tails face inwards |
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What is the fluid mosaic model?
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The membrane is a fluid in which a variety of proteins are scattered
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Describe the membrane fluidity in the bilayer?
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1) within its layer, an individual phospholipid molecule can move horizontally with ease.
2)however, the molecules cannot flip spontaneously from one layer to the other |
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How about protein molecule movement in the membrane?
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1) some can move, slow since they are larger
2) others cannot move being anchored in place by the cytoskeleton |
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How is a membrane a mosaic?
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Variety of proteins are scattered in it
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What are the two major classes of membrane proteins? What qualities do they possess?
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a) Integral Proteins- proteins that are at least partly embedded within the lipid bilayer
b) Peripheral Proteins- proteins that do not penetrate the membrane but are attached to its surface |
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Are carbohydrates a contributing presence of the mosaic nature of membranes?
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Yes
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What function do carbohydrates have when attached to other molecules in the membrane
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Help recognize one cell from another
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What type of molecules can pass through the lipid bilayer?
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nonpolar molecules (steroids)
small polar molecules like water |
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How can large polar molecules or ions pass through the lipid bilayer?
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With the aid of transport proteins embedded in the bilayer
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What is passive transport?
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Diffusion across a cell membrane.
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What is diffusion?
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In the absence of other forces, a substance will diffuse from where it si more concentrated to where it is less concentrated
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What is the Second Law of thermodynamics?
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Disorder increases in a closed system
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What is simple diffusion?
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the phenomenon in which a molecule diffuses across a membrane without the help of a membrane protein. No energy is required
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What type of molecules does simple diffusion involve?
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nonpolar molecules
small polar molecules |
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What is Osmosis
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diffusion of water across a cell membrane
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What are the 3 categories for solutions?
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Hypertonic
Isotonic Hypotonic |
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What is a hypertonic solution?
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Solution that has a higher solute concentration than some reference solution.
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What is a isotonic solution?
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solution that has the same solute concentration as some reference solution
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What is a hypotonic solution?
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solution that has a lower solute concentration than some reference solution
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Define Facilitated diffusion
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process in which ions or large polar molecules diffuses across the membrane with the help of a membrane protein
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True/False:
Facilitated Diffusion Requires Energy |
False
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What are the classes of facilitated diffusion membrane proteins?
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a) Channel Proteins
b) Carrier Proteins |
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How do channel proteins work?
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They are membrane spanning proteins that contain a channel that lets things pass through.
Some are gated some are ungated. Those that are gated require the prober stimulus for the channel to open |
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How do carrier proteins work? (basic)
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Membrane spanning proteins- bind particles to be transported to other side of membrane.
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Do carrier protein change the bound particle's shape? Explain?
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Yes, Binding causes change of original particle. However when the bound particle reaches the other side it dissociates, returning particle to its regular shape
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Define Active Transport
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movement of a substance across membrane from a region of lower concentration to a region of higher concentration.
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True/False:
Active Transport requires energy. Does it require a transport protein? |
true, yes.
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What is endocytosis?
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Process in which material is brought into a cell by means of a vesicle
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What is exocytosis?
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Process in which a substance is released from a cell by a means of a vesicle
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What is energy? What energy types exist? Define their characteristics
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Energy: Ability to change things
Kinetic Energy- energy in motion potential energy- stored energy |
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What is the first law of thermodynamics?
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Energy cannot be created or destroyed. However, it can be transfered
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True/False:
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Heat energy is used for work
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What is energy change? (G)
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Gproducts - Greactants
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What are exerogenic reactions?
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negative energy change, spontaneous. Energy is released
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What are endogenic reactions?
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Positive change in energy. Require energy. Not spontaneous.
Gproducts> Greactants |
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What are enzymes?
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Proteins that act as catalysts
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What are catalysts?
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substance that speed up a reaction without being consumed in them
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How do enzymes speed up reactions?
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By lowering activation energy
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What is a substrate?
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the reactant that the enzyme works on
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Define active site? (enzymes)
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The cleft in surface of an enzyme molecule where it binds to the substrate
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List steps of catalytic cycle of an enzyme?
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1. Substrate bonds to active site
2. Binding causes enzyme to change shape (makes substrate fit better)-- called Enzyme substrate complex 3.@ Enzyme substrate complex, initial energy (Ea) is lowered 4. Substrate converts to Product 5. Product dissociates from active site |
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What affects enzyme activity?
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a) Environmental factors
b) cofactors c)Inhibitors or activators |
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Define Cofactors
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Non-protein enzyme helpers
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What kinds of cofactors exist?
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2 kinds. metal ions and small nonprotein organic molecules
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What are competitive inhibitors?
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Molecules similar in size and shape to substrate. Compete with substrate for active site, if they bind to active site they prevent substrate from binding
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What are noncompetitive inhibitions?
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regulatory molecule different in size and shape of substrate. Does not bind at active site but bind to regulatory site. Changing shape of enzyme.
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Define metabolism:
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total of all chemical reactions occurring in an individual (energy chain)?!
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How is metabolism organized?
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pathways
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Describe metabolic pathways
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1. each pathway produces a complex change over a series of small steps
2. Each step requires a different enzyme. 3. Products for 1 step serve as reactants for next |
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What are the 2 types of metabolic reactions? describe them
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Catabolic- break down more complicated molecules to yield more simple ones (releases energy)
Anabolic- use simple molecules to build more complicated molecules |
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True/False:
Oxygen has to be present for glycolysis to occur? |
False
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What steps lead to cellular respiration?
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OxygenPresent+gycolysis+ cellular respiration
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What steps lead to fermentation
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OxygentAbsent+glycolysis+fermentation
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What molecules start glycolysis?
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Mostly Glucose. Although other molecules can be used, however these are converted to glucose
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What does glycolysis do?
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Breaks a glucose molecule to yield 2 pyruvate molecules (yields small amount of energy)
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In general what does cellular respiration do?
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Takes pyruvate molecules and completely breaks them down. Releases a lot of energies
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List steps of cellular respiration
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1) pyruvate oxidation
2) Citric acid cycle 3) electron transport |
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In general what does fermentation do?
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pyruvate from glycolysis is converted into small organic molecules:
alcohol or lactic acid (no energy is released) |
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What 3 forms can energy be released as?
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1)ATP (adenosine triphosphate)
2)GTP (guanosine triphosphate) c)NADH (nicotinamide adenine dinucleotide d) FADH (flarin adenine dinucleotide) |
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How is ATP formed?
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ADP+P --> ATP
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What is ATP made off?
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5 carbon sugar: ribose
nitrogenous base: adenine 3 phosphate groups |
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How does GTP differ from ATP?
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GTP has a guanine base, ATP has an adenine base
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How is NADH formed? (formula)
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NAD(+) + 2H(+) + 2e(-) --> NADH + H(+)
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What is a redox reaction?
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reactions in which electrons are transferred from 1 molecule to another.
Areduced + Boxydized --> Aoxydized + Breduced |
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Why is NADH said to be an electron carrier?
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because it carries electrons from one reaction (in which it's reduced) to another reaction (in which it's oxydized)
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What is NADHs oxydized form?
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NAD(+)
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Where does glycolysis occur?
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in the cytosol
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What occurs in glycolysis? What energy is yielded?
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glucose molecule is broken down into 2 pyruvate molecules.
2ATP molecules and 2 NADH molecules are released |
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Where does pyruvate oxidation happen?
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inner mitochondrial membrane
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Describe the 3 steps of pyruvate oxidation
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1) Each 3-Carbon pyruvate is converted to a 2-carbon compound called acetyl coenzyme A
2. The third carbon in each pyruvate goes to a molecule of CO2 |
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Where does the citric-acid cycle occur?
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mitochondrial matrix
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Describe the reactions occurring in the citric-acid cycle?
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reaction 1: for each 2-carbon acetyl CoA
-2 carbons are transferred to a four carbon molecule, oxaloacetate -Result is a 6-carbon molecule citrate reaction 2-8: for each 6- carbon citrate -one four-carbon oxaloacetate molecule is regenerated -two extra carbons in each citrate go to produce 2 CO2 molecules |
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Where does electron transport occur?
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inner mitochondrial membrane
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What are the electron transport's functions?
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1) recycle electron carriers from the reduced form back to the oxidized form
2)make lots of atp |
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How does electron transport work? (basic)
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1. NADH or FADH deliver their electrons to initial molecule in chain
2. electrons are transferred from one molecule in the chain to the next 3. When electrons reach end of chain - they are transferred to O2 (oxygen) |
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What is the energy released during electron transport used for?
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actively transport H from the mitochondrial matrix to inter-membrane space. Results in an electrochemical gradient within the mitochondrion
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how does a H+ gradient form ATP?
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chemiosmosis
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what is chemiosmosis?
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process of ATP production by means of a H+ ion gradient
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What happens if cell has a lot of ATP during cellular respiration?
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1. High likelihood ATP is going to bind with phosphofructokinase
2. high likelyhood that phosphofructokinase is going to be inhibited. 3. results a) reduced flux thorough glycolysis b) reduced flux through cellular respiration c) reduced ATP production |
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What happens if cell has a small amount of ATP during cellular respiration?
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1. Low likelihood ATP is going to bind with phosphofructokinase
2. low likelihood that phosphofructokinase is going to be inhibited 3. result: a. no reduction flux through glycolysis b. no reduction in flux through cellular respiration c. no reduction in ATP production |
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What is a feeback inhibition
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process in which a product of a ptahway controls the rate of its own synthesis by inhabiting a pathway step
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what is the citric-acid cycle net reaction?
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2 acetyl Coa + 6 NAD + FAD + 2(GDP+ Pi) + 4H20 --> 4 CO2 + 2 CoA + 6(NADH +H) + 2 FADH + 2 GTP
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What is the overall reaction of glycolysis, pyruvate oxidation, the citric-acid cycle, and electron transport?
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C6H12O6 + 6O2 --> 6CO2 +6H20
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True/False:
No ATP is produced |
True
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What is an autotroph organism? what is a heterotroph?
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Autotrophs- make own food
Heterotrophs- get food from other organisms |
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Where does photosynthesis occur?
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Chloroplast (green plant parts)
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What is the photosynthesis summary reduction?
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6CO2 + 6H20 +light --> C6H12+06 + 02
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What are the 2 parts of photosynthesis?
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1. Light reactions
2. calvin cycles |
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Where do light reactions occur?
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thylakoid
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where do calvin cycles occur?
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stroma
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What is the range of visible light?
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300 = 700 nm
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Describe light energy
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1. comes in photons.
Low frequency light has low energy photons. (large wavelength) High frequency light has high energy photons (short wavelength) |
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What is a pigment?
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substance that observes some wavelenghts of light but not others
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what colors does chlorophyll want?
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violet-blue light and red light
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where are photosystems located? What are their components
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Thylakoid membrane
antenna complex reaction cycle |
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What is the function of the antenna complex?
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1. traps light energy
2. transfers captured energy to reaction center |
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How is light energy captured?
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1. light has to strike pigment molecules
2. exits electron in pigment molecule 3. exited electrons jump from lower energy shell to higher energy shell |
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True/False
The reaction center is made of 3 molecules 2 chlorophyll molecules, 1 primary electron acceptor |
true
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What is the energy from antenna complex used for?
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redox reaction.
1. Energy obtained from antenna complex excites electrons from one of the chlorophyll's in reaction center 2. excited electron jumps to higher energy shell 3. primary electron acceptor takes electron (a) reaction center chlorophyll is oxidized (b) primary electron acceptor is reduced |
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how do photosystem I and photosystem II differ? (molecularly)
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1. # of pigment molecules
2. different kinds of pigment molecules 3. chlorophyll molecules differ 4. primary electron acceptor differ |
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how do photosystem I and photosystem II differ? (functionally)
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1. Photosystem II produces oxygen. associated electron transport chain produces ATP
2. photosystem I. associated electron transport chain produces NADPH |
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What happens at the reaction center @ Photosystem II
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1. primary electron acceptor takes an electron from reaction center chlorophyll
2. reaction center misses an electron, creating a hole. 3. hole is filled by electron from H20 |
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What happens at the electron transport chain during Photosystem II
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1. transferred energy is released
2. released energy is used to actively transport Hydrogen ions 3. result is electrochemical gradient of hydrogen ions. d. chemiosmosis |
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What happens at the reaction center during Photosystem I
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1. primary electron acceptor takes an electron from reaction center chlorophyll
2. reaction center misses an electron, creating a hole. 3. hole is filed from electron from PS II |
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What happens during electron transport chain in Photosystem I
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electron from last molecule in chain bonds to NADP forming NADPH
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What is a cyclic electron flow?
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electrons from PSI are donated to PS2 producing ATP required for calvin cycles
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What are the 5 steps of the Calvin Cycle?
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1. Carbon fixation
2. phosphrylation 3. reduction 4. sugar reduction 5. regeneration of ribulose biphosphate |
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What happens during carbon fixation
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1. 6 CO2 are added to 5 ribulose biphosphate
2. catalyzed by rubisco 3. result into 6 6C molecules 4. 6 6C molecules break down to 12 3C molecules |
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What happens during phosphorylation?
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each of the 12 3C molecules are phosphorylated (phosphate group is added).
Phosphate group comes from ATP, results in the use of 12 ATP |
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what happens during reduction? (calvin cycle)
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each of the 12 3-C molecules is reduced. yielding 12 different 3C molecules (glyceraldehyde 3-phosphate (G3P))
Electrons come from 12 NAPDH |
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What happens during sugar production?
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2 G3P exit calvin cycle (exported to cytosol). Each can be used to make 1 glucose
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what happens during the regeneration of ribulose biphosphate?
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remaining 10 G3P are rearanged to form 6 5- carbon molecules.
2. each 5-c molecule is going to get phosphorylated (yields 6 ribulose biphosphate). 3. phosphate groups come from ATP, uses 6 ATP |
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How many ATP are generated in the electron transport cycle?
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roughly 34 ATP from 10 NADH and 2 FADH
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How many NADH are generated during glycolysis, pyruvate oxidation, citric acid cycle?
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2 glycolysis
2 pyruvate oxidation 6 citric acid cycle |
