biology hw & quiz
Cells can use energy from fatty acids to make ATP, just like they can use energy from glucose to make ATP. When fatty acids are broken down via the beta-oxidation pathway, they produce acetyl-CoA. How many molecules of ATP will be produced by substrate level phosphorylation (i.e. NOT via oxidative phosphorylation) for each acetyl-CoA molecule provided by beta oxidation of fatty acids?
1
If 5000 molecules of glucose enter cellular respiration, how many molecules of ATP are produced by substrate-level phosphorylation in aerobic cellular respiration?
20,000
If 5000 molecules of glucose enter cellular respiration, how many net molecules of ATP are produced by substrate level phosphorylation in aerobic cellular respiration?
20,000
Consider a single-celled algae with chloroplasts like we have discussed in plants. How many lipid bilayers (membranes) does a molecule of CO2 have to pass across to diffuse from the atmosphere to its site of use in the Calvin Cycle?
3
How many net ATP have been produced from the very start of cellular respiration through the end of the citric acid cycle, not including oxidative phosphorylation? Note the question is asking for net ATP. 6 4 30-34 8 2
4
If 200 molecules of acetyl coA entered the citric acid cycle, how many carbon dioxide would be produced? 400 800 600 200
400
Consider a single-celled algae that has 1) chloroplasts like we have discussed in plants, as well as 2) mitochondria. In theory, a molecule of O2 (oxygen) produced during the light reactions of photosynthesis could diffuse out of the chloroplast, and be used during oxidative phosphorylation during aerobic cellular respiration in the mitochondria. Assuming it never leaves the cell, how many lipid bilayers (membranes) would this molecule of O2 have to pass across in order to diffuse from the the location where it is produced in the chloroplast to the location where it is used in the mitochondria. Draw this out, if it helps.
5
What is the overall equation for photosynthesis? 6 CO2 + Light energy --> C6H12O6 + 6 O2 + 6 H2O C6H12O6 + 6 O2 + 12 H2O + Light energy --> 6 CO2 + 12 H2O 6 CO2 + 12 H2O + Light energy --> C6H12O6 + 6 O2 + 6 H2O 12 H2O + Light energy --> C6H12O6 + 6 O2 + 6 CO2 + 6 H2O
6 CO2 + 12 H2O + Light energy --> C6H12O6 + 6 O2 + 6 H2O
Which of the following is the correct number of products produced from the Citric Acid Cycle, per glucose? 6 NADH, 2 FADH2, 2 ATP 2 NADH, 6 FADH2, 2 ATP 3 NADH, 1 FADH2, 1 ATP 2 NADH, 0 FADH2, 2 ATP
6 NADH, 2 FADH2, 2 ATP
How many of each of the following products are produced from the Citric Acid Cycle, per 1 glucose molecule? NADH: FADH2: ATP:
6; 2; 2
Mutations in components of the EGF signaling pathway often lead to cancer. If the Ras protein in the EGF signaling pathway was mutated so that it could not hydrolyze GTP (and was thus always bound to GTP), which of the following options would be a good choice as a potential chemotherapy drug to treat the cancer? A drug that promotes GDP exchange for GTP on Ras, so more GTP is bound A drug is not needed! If Ras remains bound to GTP, it will be always in the *inactive* state. A drug that binds to the EGF receptor and prevents dimerization A drug that inhibits the phosphorylation ability of one of the protein kinases in the protein kinase cascade.
A drug that inhibits the phosphorylation ability of one of the protein kinases in the protein kinase cascade.
Identify the common cellular energy intermediate from this list. glucose amino acids starch ATP
ATP
Of the options listed below, from which of these sources does the Calvin cycle directly get the energy necessary to produce carbohydrates and regenerate RuBP? Choose the single best answer. photons glucose H+ gradient pigment molecules ATP
ATP
The reaction diagram below shows two reactants (substrates) plus an enzyme reacting to yield two products. Hexokinase is an enzyme involved in the first step of glycolysis. In the reaction, ______________. the enzyme, hexokinase, affects the overall change in free energy level (G) between the reactants and products. ATP is the source of the phosphate in the phosphorylation of glucose, creating glucose-6-phosphate. the 'hump' in the middle represents the enzyme pushing the activation energy higher up. the reactants have less usable energy (less free energy) than the products.
ATP is the source of the phosphate in the phosphorylation of glucose, creating glucose-6-phosphate.
Which of the following are required substrates of Glycolysis (check any/all that apply)? citrate ATP glucose oxygen NAD+
ATP, glucose, NAD+
Which product enters the Citric Acid Cycle as a product of pyruvate breakdown? FADH2 NADH Oxaloacetate Carbon Dioxide Acetyl CoA
Acetyl CoA
Some anticancer drugs block signal transduction pathways activated by growth factors that target the EGF receptor. Which of the following would be a good target for such a drug? An inhibitor of adenylyl cyclase An inhibitor of phospholipase C An inhibitor of an enzyme in the protein kinase cascade. An inhibitor of Ca2+ release A phosphatase inhibitor (remember that phosphatases remove phosphates from proteins)
An inhibitor of an enzyme in the protein kinase cascade.
What would happen if an irreversible competitive inhibitor stopped complex IV (cytochrome oxidase) from working at all? Assume complex IV/cytochrome oxidase cannot accept or transfer any electrons. There would be no major effect on oxidative phosphorylation, as FADH2 and NADH don't directly donate electrons to complex IV in the electron transport chain. There would be no major effect on oxidative phosphorylation, as the other complexes in the electron transport chain would compensate and pump more H+ across the membrane Oxidative phosphorylation would still continue, but fewer H+ would be pumped across the membrane, so fewer ATP would be produced As complex IV could not receive electrons, the electron transport chain would "back up," and all previous steps would eventually not be able to receive or transfer electrons, thereby stopping H+ pumping and ATP production.
As complex IV could not receive electrons, the electron transport chain would "back up," and all previous steps would eventually not be able to receive or transfer electrons, thereby stopping H+ pumping and ATP production.
What is autophosphorylation, in the context of cell signalling?
Autophosphorylation is when a protein phosphorylates (transfers a phosphate to) itself! This is often done to pass on information in a signaling cascade. For example, EGFR phosphorylates itself to activate relay proteins.
Glyphosate (roundup) binds in the active site of the EPSPS enzyme, an essential enzyme for plant growth and survival. This herbicide kills weeds. Some weeds have evolved to survive the selective pressure of near-constant glyphosate spraying by making many more copies of EPSPS in their cells. Based on what you know about this inhibitor, why does this work? Because glyphosate is a noncompetitive inhibitor, there will be many more allosteric sites available for glyphosate to react with and form downstream product, avoiding feedback inhibition. Because there are so many enzymes in the glyphosate-resistant weeds, they can quickly cleave the glyphosate in half, inactivating it. the enzymes in the glyphosate-resistant weeds can work faster, "outrunning" the glyphosate by lowering the activation energy of the reaction. Because glyphosate is a competitive inhibitor, it must be bound to EPSPS to work. If there are more EPSPS enzymes than glyphosate molecules, with many copies some will be free to perform their catalytic reaction.
Because glyphosate is a competitive inhibitor, it must be bound to EPSPS to work. If there are more EPSPS enzymes than glyphosate molecules, with many copies some will be free to perform their catalytic reaction.
When a ligand binds to an enzyme-linked receptor, how is that analogous to when a substrate binds to a cytosolic enzyme's active site? Both events usually require require dimerization. Both events cause a conformational change that allows for catalysis. Both events cause the ligand and substrate to be converted to a product. Both events lead to irreversible binding. Both events always cause phosphorylation of the target protein.
Both events cause a conformational change that allows for catalysis.
After the whole process of cellular respiration, each of the six of the carbon atoms in a molecule of glucose eventually become part of ____________________. NADH pyruvate carbonic acid ATP CO2 O2
CO2
Reactants used in the Calvin cycle are _________________. (check any/all that apply) CO2 Ribulose bisphosphate (RuBP) O2 NADPH pigment molecules ATP H2O FADH2
CO2, Ribulose bisphosphate (RuBP), NADPH, ATP
You discover how to synthesize a molecule ("Compound Z") whose shape is very similar to ATP, but because of a special bond between phosphates, the phosphates cannot be cleaved off of Compound Z. If you had this molecule to cells translating and using Hexokinase, what do you expect to happen? Compound Z will lower the activation energy Compound Z will act as a cofactor, resulting in more product molecules. Compound Z will act as a non-competitive inhibitor, resulting in more product molecules. Compound Z will act as a competitive inhibitor of the enzyme, resulting in fewer product molecules.
Compound Z will act as a competitive inhibitor of the enzyme, resulting in fewer product molecules.
Briefly state whether cyclic electron flow in the light reactions produces more NADPH or more ATP, then explain why in no more than a few sentences. Your explanation should include the names of one or more proteins or protein complexes involved in the electron transport chain of the light reactions. Use your own words.
Cyclic electron flow would produce more ATP because cyclic electron flow is basically recycling through PSI which builds up an H+ electrochemical gradient which means that there is going to be a high concentration of H+ in the thylakoid lumen. This gradient is what is used to power the ATP synthase in the thylakoid membrane.
Which of these directly pumps (transports across the membrane) protons during the light reactions? Photosystem II NADP+ reductase Photosystem I Cytochrome complex Ferredoxin
Cytochrome complex
E1, E2, and E3 are enzymes. A, B, C, and D are metabolites. The following diagram represents a metabolic pathway. A -----E1-----> B -----E2-----> C -----E3-----> D Which of the following could serve to inhibit enzyme E2 by feedback inhibition? Chose the single best answer.
D
Look at the reaction diagram shown below. If the enzyme specific to the reactants is present, which statement below is INCORRECT? The reaction will be exergonic The reactants represented by letter A will react and form products more rapidly than in the absence of an enzyme B will instead be at the level of C D will change
D will change
If the enzyme specific to the reactants is present, which statement below is INCORRECT? The reactants represented by letter A will react and form products more rapidly than without the enzyme D will change in the enzyme-catalyzed reaction the activation energy will change from B to instead be C This enzyme can be used over and over to catalyze the reaction shown
D will change in the enzyme-catalyzed reaction
Steps in EGF signaling
EGF binds EGFR EGFr auto-phosphorylates itself Relay proteins transfer the signal between receptor and protein kinase cascade Ras activates protein kinase cascade Transcription factor activation via phosphorylation Cellular response and growth
Signal amplification via second messengers involves all except for one of the following steps in a signal cascade. Which step is NOT involved? Each activated protein kinase A can phosphorylate multiple targets. Each GPCR dimerizes with another GPCR, and both auto-phosphorylates each other in the dimer. Each cAMP molecule activates many protein kinase A enzymes. Adenylyl cyclase enzymes each synthesize many cAMP molecules, so that the concentration of cAMP significantly rises in the cytoplasm.
Each GPCR dimerizes with another GPCR, and both auto-phosphorylates each other in the dimer.
Sodium-Glucose cotransporters use high sodium concentrations outside the cell to import glucose into cells in the small intestine, even when glucose concentrations are higher inside these cells than outside the cells. Which type of energy is used by this example of secondary active transport? Light Mechanical Electrical/ion gradient Heat Chemical Potential
Electrical/ion gradient
Sodium-Glucose cotransporters use high sodium concentrations outside the cell to import glucose into cells in the small intestine, even when glucose concentrations are higher inside these cells than outside the cells. Which type of energy is used by this example of secondary active transport? Chemical Potential Electrichemical / ion gradient Heat Kinetic / Mechanical Light
Electrochemical/ion gradient
Why does each molecule of NADH produce more molecules of ATP than each molecule of FADH2? NADH enters the electron transport chain in the inner-mitrochondrial membrane, while FADH2 enters the electron transport chain in the outer membrane of the mitochondria. FADH2 electrons have less energy, and enter the electron transport chain at complex II instead of complex I, pumping fewer total H+ ions across the membrane. NADH and FADH2 have roughly equivalent free energy in the form of high-energy electrons. However, FADH2 must donate electrons to import of pyruvate, so it cannot contribute as much to generating the proton motive force.
FADH2 electrons have less energy, and enter the electron transport chain at complex II instead of complex I, pumping fewer total H+ ions across the membrane.
FAD is reduced (gains electrons) during the breakdown of pyruvate. True False
False
FAD is reduced during glycolysis True False
False
In the absence of an enzyme, when the temperature is very low, reactants will move and collide relatively more quickly and a reaction should thus proceed more quickly. True False
False
Phosphorylation is always used to activate enzymes during epinephrine signaling. True False
False
Phosphorylation is always used to activate enzymes involved in epinephrine signaling. True False
False
Signal amplification involves all except for one of the following steps in a signal cascade. Which step is NOT involved? Second messengers influence the activity of enzymes or genes in the cell. GPCR releases a signal into the extracellular environment Adenylyl cyclase enzymes synthesize cAMP, so that the concentration of cAMP significantly rises in the cytoplasm. Each cAMP molecule activates several protein kinase molecules.
GPCR releases a signal into the extracellular environment
If a yeast cell experiences an environment with elevated glucose levels, it will increase its uptake of glucose. Describe the mechanism by which the yeast can detect and then react to the presence of the extracellular glucose. Glucose binds to glucose receptors, which initiates the increase of glucose transporter proteins. ATP binds to the extracellular receptor, initiating a cascade response. DNA binding to the active site on the adenylyl cyclase enzyme initiates a glucose response. Glucose diffuses into the nucleus and binds to transcription factors.
Glucose binds to glucose receptors, which initiates the increase of glucose transporter proteins
Which of the following is a correct and complete list of the order of the four metabolic processes / stages that make up cellular respiration? Glycolysis, breakdown of pyruvate, citric acid cycle, oxidative phosphorylation Oxidative phosphorylation, citric acid cycle, breakdown of pyruvate, glycolysis. Glycolysis, citric acid cycle, breakdown of pyruvate, oxidative phosphorylation Breakdown of pyruvate, citric acid cycle, glycolysis, oxidative phosphorylation Citric acid cycle, breakdown of pyruvate, oxidative phosphorylation, glycolysis.
Glycolysis, breakdown of pyruvate, citric acid cycle, oxidative phosphorylation
Which of the following is a correct and complete list of the order of the four metabolic processes / stages that make up cellular respiration from glucose? Oxidation and decarboxylation of pyruvate, citric acid cycle, glycolysis, oxidative phosphorylation Citric acid cycle, oxidation and decarboxylation of pyruvate, oxidative phosphorylation, glycolysis. Glycolysis, oxidation and decarboxylation of pyruvate, citric acid cycle, oxidative phosphorylation Oxidative phosphorylation, citric acid cycle, oxidation and decarboxylation of pyruvate, glycolysis. Glycolysis, citric acid cycle, oxidation and decarboxylation of pyruvate, oxidative phosphorylation
Glycolysis, oxidation and decarboxylation of pyruvate, citric acid cycle, oxidative phosphorylation
If you could change all the tyrosine amino acids in the interior side (cytoplasmic side) of the EGF Receptor to another amino acid like lysine, what do you predict would happen if lots of EGF were present? Growth would never happen, as EGF signaling would be stopped Signaling would be "stuck on" and growth would happen continuously These mutations would not have an effect on signaling.
Growth would never happen, as EGF signaling would be stopped
Considering cellular respiration, briefly explain why you need to breath oxygen.
In cellular respiration, oxygen is an electron acceptor in the electron transport chain. It assists in moving electrons down the chain which builds up a gradient that allows for more ATP production.
You discover an enzyme (Lynxase) that catalyzes a chemical reaction whose product (let's call it product X), is a molecule needed for the anabolism of some amino acids. You test a hypothesis in the lab, and discover that the enzyme is inhibited by the amino acid isoleucine, but not other amino acids. You next hypothesize that this is a case of feedback inhibition. Which of the following would make this a case of feedback inhibition? Lynxase also catalyzes the cleavage of isoleucine, because of the lack of specificity of most enzymes. Isoleucine is part of the same metabolic pathway as product X, and is produced several steps before the formation of product X. Isoleucine is part of the same metabolic pathway as product X, and is produced several steps after the formation of product X. Isoleucine is produced in a different metabolic pathway than product X.
Isoleucine is part of the same metabolic pathway as product X, and is produced several steps after the formation of product X.
Which of the following is correct about the formation of ATP, described in this reaction: ADP + Pi →ATP ? It has a ΔG that is less than zero and will yield energy It has a ΔG that is greater than zero and must require some form of energy input It does not occur during cellular respiration It can be used to drive endergonic reactions It is spontaneous
It has a ΔG that is greater than zero and must require some form of energy input
The reaction diagram below shows two reactants (substrates) plus an enzyme reacting to yield two products. Hexokinase is an enzyme involved in the first step of glycolysis. What role does the enzyme play in the reaction? It reduces the ΔG of the reaction It increases the activation energy required for phosphorylation of glucose It provides an active site that brings ATP and glucose close together, thereby reducing the activation energy needed It reduces the rate of glucose phosphorylation
It provides an active site that brings ATP and glucose close together, thereby reducing the activation energy needed
During oxidative phosphorylation (check any/all that apply) NADH and FADH2 are electron acceptors oxygen is an electron donor water is an electron donor Multiple proteins in the electron transport chain are reduced and oxidized NADH and FADH2 are electron donors oxygen is an electron acceptor
Multiple proteins in the electron transport chain are reduced and oxidized, NADH and FADH2 are electron donors, oxygen is an electron acceptor
Isocitrate dehydrogenase is one of the enzymes in the citric acid cycle. Isocitrate dehydrogenase is regulated by feedback inhibition. Which of the following molecules do you predict will act as an inhibitor of isocitrate dehydrogenase (choose one best answer)? NADH and ATP NAD+ and ADP pyruvate and acetyl-CoA pyruvate acetyl-CoA FAD and ADP
NADH and ATP
A source of electrons feeding the electron transport chain (ETC) in mitochondria during cellular respiration is ________, while the source of electrons feeding the electron transport chain in chloroplasts during photosynthesis is __________. NADH, H2O O2, NADP+ FADH2, NADPH NADH, NADPH
NADH, H2O
A source of electrons feeding the electron transport chain (ETC) in mitochondria during cellular respiration is ________, while the source of electrons feeding the electron transport chain in chloroplasts during photosynthesis is __________. NADH, NADPH O2, NADP+ FADH2, NADPH NADH, H2O
NADH, H2O
What are the main products of glycolysis? Check any/all that apply. CO2 FADH2 NADH NAD+ pyruvate acetyl co-A hexokinase ATP phosphoenolpyruvate
NADH, pyruvate, ATP
When the sun goes down for the day, which of the following reactions in a leaf cell do you predict is likely to cease first? ATP --> ADP + Pi, in the stroma NADP+ reduction to NADPH in the stroma RuBP +CO2 --> 2X 3PG, in the stroma The production of ATP via cellular respiration, in mitochondria
NADP+ reduction to NADPH in the stroma
Would oxidative phosphorylation work if ATP synthase was flipped in the membrane, so that the big stalk (the alpha and beta subunits) faced the other side of the lipid bilayer? Why or why not?
No, oxidative phosphorylation would not work if ATP synthase was flipped in the membrane. The whole point of the electron transport chain is to build up a H+ gradient (the "proton motive force") in the intermembrane space. The energy from the electrons is used to pump H+ into the intermembrane space. Then, ATP synthase uses this gradient's energy, allowing H+ to flow back into the Matrix, and using the energy to rotate the stalk and synthesize ATP during the conformational change. If ATP synthase were flipped in the membrane, ATP synthase wouldn't have access to the side of the membrane with the high concentration of H+ ions, the H+ ions would not be able to flow "down" their gradient in the correct direction, and ATP synthase would not be able to use the energy stored in the H+ gradient to rotate and produce ATP.
In an enzyme-linked receptor, a ligand binds to the transmembrane protein, and substrates bind to the transmembrane protein. Are the ligand binding site and the active site the same place in the protein? Think about where a signal is received and where the enzymatic activity passes on the signal. Yes, the ligand and substrates will bind int he same place in the protein No, the ligand will bind to one part of the protein and the substrates will bind to a different part of the protein
No, the ligand will bind to one part of the protein and the substrates will bind to a different part of the protein
Suppose you could put a special atomic "label" on the oxygen atom in H2O. You grow a plant in a small chamber, and every time you water it, you use this labeled H2O. If you collect the plant tissue and the gas in the chamber after a few hours, where would you expect to find the most labeled Oxygen, based on what you know about photosynthesis? NO3- CO2 O2 glucose NADPH
O2
Which of the following molecules is neither used, nor produced, by the Calvin cycle portion of photosynthesis? CO2 NADP+ O2 ATP sugars
O2
Which of the following stages produces the most energy in the form of ATP? Oxidative phosphorylation Glycolysis substrate-level phosphorylation The citric acid cycle The breakdown of pyruvate
Oxidative phosphorylation
The reaction diagram below shows two reactants (substrates) plus an enzyme reacting to yield two products. Hexokinase is an enzyme involved in the first step of glycolysis. What should the X axis be labeled? Entropy Product concentration Velocity of the reaction Progress of the reaction Free energy (G)
Progress of the reaction
In normal EGF signaling, which of the following proteins must travel across TWO lipid bilayer in order to pass the signal on to the next component? GDP EGF Protein kinase 2 Ras Protein kinase 3
Protein kinase 3
Briefly explain how the Ras protein is similar to a G-protein that works with a G-protein coupled receptor.
Ras exchanges GDP in its inactive state for GTP in its active state, just like the alpha subunit of G-proteins. Both Ras and G-proteins are involved in signalling cascades (though Ras does not receive the signal directly from a receptor like G-proteins, instead requiring other relay proteins) Both Ras and G-proteins can be attached to the inner leaflet of the membrane. Both Ras and G-proteins can hydrolyze GTP to GDP to inactivate.
Select all the ways that directly contribute to building a H+ gradient from light reactions carried out in chloroplasts. (Select any/all that apply) Oxidation of NADPH during phase 2 of the Calvin cycle Correct! Removal of H+ ions by NADP+ reductase when NADPH is formed H+ import via the pyruvate / H+ symporter Correct! Splitting of water by PSII, producing H+ ions Correct! pumping of H+ ions by the cytochrome complex
Removal of H+ ions by NADP+ reductase when NADPH is formed, Splitting of water by PSII, producing H+ ions, pumping of H+ ions by the cytochrome complex
___________ is the key enzyme responsible for fixing CO2 during the Calvin cycle. ("Fixing CO2" is the process of incorporating the Carbon from CO2 gas into an organic molecule of multiple carbons) cytochrome C RuBP Ferredoxin NADP+ reductase Rubisco
Rubisco
How does the CO2 needed for photosynthesis get from the cytoplasm into the stroma? Primary active transport Secondary active transport A stomata Simple diffusion Facilitated Diffusion
Simple diffusion
elect all the ways that directly contribute to building a H+ gradient from light reactions carried out in chloroplasts. (Select any/all that apply) Pumping of H+ ions by NADH dehydrogenase Splitting of water by PSII, producing H+ ions Removal of H+ ions from the stroma by NADP+ reductase when NADPH is formed pumping of H+ ions by the cytochrome complex Oxidation of NADPH during phase 2 of the Calvin cycle
Splitting of water by PSII, producing H+ ions, removal of H+ ions from the stroma by NADP+ reductase when NADPH is formed, pumping of H+ ions by the cytochrome complex
The Calvin Cycle is sometimes called the "dark reactions," because these reactions do not directly require light energy. However, this is misleading, as plants will mostly regulate these reactions and shut off the Calvin Cycle at night time. That is, the Calvin Cycle does not actually happen in the dark much in plants. Why do plants regulate the Carbon Cycle this way, turning the Calvin Cycle reactions "off" during the night, even though they don't require light?
The Calvin Cylce requires both NADPH and ATP reactants in order to proceed, and these energy intermediates are produced by the light reactions. In the dark, NADPH and ATP production would cease, as these are both products of the light reactions that require light energy. Without a source of NADPH and ATP from the light reactions at night time, it would not be possible for the Calvin Cycle to function, so the cell shuts "off" these enzymes (regulates them) so that they are not active in the dark.
In the reaction diagram below, what would happen if a competitive inhibitor was present at high concentration? The energy needed for the reaction to progress would not change The energy needed for the reaction to progress would be "D" The energy needed for the reaction to progress would be "B" The energy needed for the reaction to progress would be "C"
The energy needed for the reaction to progress would be "B"
In the reaction diagram below, what would happen if the gene that provided the instructions to make the enzyme specific to the reaction had a mutation, and the enzyme was not present? DNA-->RNA-->Protein The energy needed for the reaction to progress would be "D" The energy needed for the reaction to progress would be "C" The reaction would change from an exergonic one to an endergonic one. The energy needed for the reaction to progress would be "B"
The energy needed for the reaction to progress would be "B"
If the pH of the mitochondrial matrix suddenly decreased, how would that affect the proton motive force (H+ gradient energy) and ATP production? The force might decrease due to a reduced difference in proton concentration on the two sides of the inner membrane, and ATP production would decrease. The force might increase due to an increase in the difference in proton concentration on the two sides of the inner membrane, and ATP production would increase. The force might decrease due to a reduced difference in proton concentration on the two sides of the inner membrane, and ATP production would increase. Nothing would happen as concentrations of H are dependent on factors other than pH. The force might increase due to an increase in the difference in proton concentration on the two sides of the inner membrane, and ATP production would decrease.
The force might decrease due to a reduced difference in proton concentration on the two sides of the inner membrane, and ATP production would decrease.
Why has the inner mitochondrial membrane evolved to have the shape that it does? Your brief but complete answer should be in your own words (don't copy and paste from somewhere) and should include at minimum these words: electron transport chain ATP synthase protons surface area
The inner mitochondrial membrane has a lot of folds and projections to it (called cristae) which give it a very high surface area. This is important, because the electron transport chain relies on a H+ gradient that builds up across this inner membrane. ATP synthase uses this gradient to then use ATP, so over the course of evolution, an inner membrane with this shape and large surface area has been selected for to make building and using energy from this gradient very efficient.
A mutation that alters a G-protein's affinity for GDP, making it less likely to release GDP even when stimulated by a receptor, will have what effect on the cell signaling pathway in which it is involved? The pathway will be activated, even in the absence of a signal. The pathway will be activated by other receptors, such as receptor tyrosine kinases. The pathway will be overactivated. The pathway will be underactivated. The cell will cease to activate the G-protein linked receptor.
The pathway will be underactivated
A mutation that alters a G-protein's affinity for GDP, making it less likely to release GDP even when stimulated by a receptor, will have what effect on the cell signaling pathway in which it is involved? The pathway will be activated by other receptors, such as receptor tyrosine kinases. The pathway will be activated, even in the absence of a signal. The pathway will be underactivated. The cell will cease to activate the G-protein linked receptor. The pathway will be overactivated.
The pathway will be underactivated.
__________________ is the source of energy used in the light reactions of photosynthesis. The sun's photons Glucose Glycogen Are you paying attention? NADPH Water
The sun's photons
What is true about the following reaction? Choose any/all that apply. ATP ⟶ ADP + Pi This is an endergonic reaction The ΔG of this reaction will be negative This is an exergonic reaction This reaction can be coupled to endergonic reactions to accelerate them The G of this reaction will be positive
The ΔG of this reaction will be negative, This is an exergonic reaction, This reaction can be coupled to endergonic reactions to accelerate them
In some cancers, the BCR-ABL kinase becomes overactive, catalyzing a reaction that signals to cells that they should grow and divide rapidly. Gleevec is a competitive inhibitor of this BCR-ABL enzyme. It works by blocking catalytic activity of the BRC-ABL kinase, which in turn means that cells no longer get the signal to grow and divide. We watched a short video showing this in class. For some patients that take Gleevec, their cancer cells become resistant to Gleevec (that is, Gleevec no longer works on these cells) because they have DNA mutations that change certain amino acids in the BCR-ABL kinase protein. Based on this information and what you know about enzymes and inhibitors, where in the BCR-ABL kinase protein do you think these changed amino acid mutations would primarily be found, and why?
These changed amino acid mutations would be found in the active site. The active site is where the competitive inhibitor would typically bind, so if there was a mutation on the active site, the competitive inhibitor wouldn't be able to bind to it.
Some proteins can "uncouple" the electron transport chain from ATP synthesis. These proteins are found, for example, in fat tissue of babies, and are a molecular mechanism that helps keep infants warm. Based on what you know about the Oxidative Phosphorylation, what do you predict the function of these uncoupling proteins is? That is, how and why do they "uncouple" the electron transport chain from ATP synthesis? Correct Answer These proteins are transmembrane proteins that are found in the inner mitrochondrial membrane, and they let H+ ions back into the matrix, turning this energy into heat instead of using it to generate ATP. These proteins increase the rate of proton pumping into the inner membrane space, thereby increasing the energy stored in the H+ gradient. This wouldn't convert the energy to heat. These proteins flip the ATPase orientation in the inner mitochondrial membrane, thereby making ATP only in the intermembrane space These proteins bind to electron carriers, and prevent electrons from being transferred from Complex IV to ATP synthase.
These proteins are transmembrane proteins that are found in the inner mitrochondrial membrane, and they let H+ ions back into the matrix, turning this energy into heat instead of using it to generate ATP.
What is true about the following reaction? Choose any/all that apply. ADP + Pi ⟶ ATP This is an exergonic reaction The ΔG of this reaction will be negative This reaction can be coupled to endergonic reactions to accelerate them This is an endergonic reaction The ΔG of this reaction will be positive
This is an endergonic reaction, The ΔG of this reaction will be positive
Why is H2O required in the light reactions of photosynthesis? Please note the difference in the possible answers between PSII -- photosystem IIandPSI -- photosystem I To donate electrons to pigments in PSI To receive electrons from pigments in PSI To receive electrons from pigments in PSII To donate electrons to pigments in PSII
To donate electrons to pigments in PSII
If one considers what is happening during cellular respiration, then it is accurate to say that we basically exhale the carbon as carbon dioxide from the food which we previously consumed. True False
True
Plants take in CO2 from their surroundings and produce O2 during photosynthesis, but they also produce CO2 and use O2 during cellular respiration in their mitochondria. True False
True
Plants take in CO2 from their surroundings and produce O2 during photosynthesis, but they also produce CO2 and use O2 during cellular respiration in their mitochondria. True False
True
Some herbicides are plant toxins, that work by inhibiting photosynthesis. Under which of the following scenarios would you predict that cyclic electron flow (also known as cyclic photophosphorylation) would be favored over linear electron flow by a toxin herbicide? When a toxin targets plastocyanin, inactivating it When a toxin targets PSII, inactivating it When a toxin targets Cytochrome complex, inactivating it When a toxin targets ferredoxin, inactivating it When a toxin targets PSI, inactivating it
When a toxin targets PSII, inactivating it
How would you explain the concept of induced fit to your classmate who missed that part of lecture?
When substrates bind to an enzyme, the enzyme goes through a conformational change that makes the substrates bind to the enzyme tighter. This binding of the substrates tighter is the induced fit, which brings the bonds in the substrates closer together. The substrates are then converted to products that won't fit as tightly as the original substrates had, so the products are able to diffuse out of the activation site.
Why has the inner mitochondrial membrane evolved to have the shape that it does? With a relatively high surface area to volume ratio, breakdown of pyruvate can happen more quickly With a relatively high surface area to volume ratio, it is easier for oxidative phosphorylation enzymes to build and use a H+ gradient With a relatively low surface area to volume ratio, the mitochondria can regulate the amount of oxidative phosphorylation that happens Because it looks so darn cool in Transmission Electron Microscopy images By building an inner membrane with the same shape as the outer membrane, the mitochondria can import pyruvate most efficiently into the matrix.
With a relatively high surface area to volume ratio, it is easier for oxidative phosphorylation enzymes to build and use a H+ gradient
effect of an enzyme on a reaction
X = uncatalysed reaction Y = catalysed reaction Z = overall energy change
With modern techniques, it is now fairly easy to add and remove genes from many different organisms. Imagine that you performed the following experiment: 1. Remove the DNA required for the transcription and translation of chloroplast ATP synthase polypeptides in a photosynthetic algae. The algae would NOT have the normal ATP synthase in chloroplast. 2. Add the DNA required for the transcription and translation of human mitochondiral ATP synthase polypeptides to the chloroplast. In other words, what if you swapped out the normal chloroplast ATP synthase, and replaced it with a human ATP synthase. Assuming the cells made the ATP synthase correctly, would the cells still be able to perform photosynthesis? Why or why not?
Yes, these cells could do photosynthesis. ATP production in the light reactions of photosynthesis utilizes the energy stored in a H+ gradient to produce ATP via ATP synthase. ATP synthase rotates as H+ ions flow from thylakoid lumen to stroma, and catalyzes the reaction ADP + Pi --> ATP in the stroma. The ATP synthase from human mitochondria performs the exact same function: it rotates as H+ ions flow from intermembrane space to matrix, and catalyzes the same reaction of ADP + Pi --> ATP in the matrix. In the end, ATP synthase from human mitochondria requires a membrane and a H+ gradient to catalyze ATP formation, and these requirements are the same in chloroplast. ATP synthase should work in the chloroplast thylakoid membrane just as well as in the inner membrane of mitochondria.
EGF (epidermal growth factor) is a transcription factor a recepetor a ligand a gene region on DNA
a ligand
EGF (epidermal growth factor) is an example of which of the following? a protein kinase an enzyme-linked recepetor a transcription factor a ligand
a ligand
When epinephrine binds to its G-protein linked receptor, the second messenger production for cell signaling occurs when __________________. kinase is activated producing transcription factor. phospholipase C is activated producing diacylglyceride. adenylyl cyclase is activated producing cyclic adenosine mono-phosphate (cAMP). kinase is activated producing calcium.
adenylyl cyclase is activated producing cyclic adenosine mono-phosphate (cAMP).
Which of the following may affect enzyme function? To answer this, think about what kind of macromolecule an enzyme is. I might help to think about what would affect an enzyme's structure in some cases. You might need to review the readings to answer this question. (choose any/all that are correct) coenzymes enzyme concentration temperature substrate concentration competitive inhibitors non-competitive inhibitors how acidic, neutral, or basic the solution around the enzyme is cofactors salinity
all of the above
The advantage of second messengers is best described as prevention of signal inhibition. replaces the role of protein phosphatases. amplification of the signal. enhanced specificity of the ligand. stabilization of ligand-receptor binding.
amplification of the signal
ATP is ___________________. (Choose one best answer) a substrate of all enzyme-catalyzed reactions an energy intermediate a molecule that can act as an enzyme only in an endergonic reaction a monomer for polypeptides a molecule that can act as an enzyme only in an exergonic reaction
an energy intermediate
The concept of induced fit implies that, for the enzyme-catalyzed reaction A + B --> C an enzyme will take part in more than one metabolic pathway, depending on where it fits in the larger metabolic map an enzyme will have one unchanging structure that has evolved (over millions or billions of years) a shape that has perfect affinity for substrates A+B. There is no conformational change necessary for catalysis. an enzyme will undergo a conformational change upon binding A and B an enzyme will undergo a conformational change only after producing C
an enzyme will undergo a conformational change upon binding A and B
The metabolic pathway that synthesizes glycogen from monosaccharides in the cell would be a(n) ___ pathway, and the reaction glycogen + glucose --> longer glycogen (glycogen synthesis) would be an ___ process.
anabolic; endergonic
Photosystem II and photosystem I serve to pump high-energy electrons across the thylakoid membrane reduce NADP+ pump high-energy protons across the thylakoid membrane oxidize NADP+ capture light energy and transfer it to high energy electrons
capture light energy and transfer it to high energy electrons
Which of the following key molecules is a reactant for RUBISCO, which helps facilitate successful sugar production during the Calvin Cycle? glucose oxygen Glyceraldehyde-3-phosphate water carbon dioxide
carbon dioxide
Of the choices below, which are overall products at the end of the 4 major stages of cellular respiration? (check any/all that apply) oxygen carbon dioxide ATP glucose water
carbon dioxide, ATP, water
What are the overall products after the 4 major stages of cellular respiration? (check any/all that apply) carbon dioxide water glucose pyruvate oxygen ATP
carbon dioxide, water, ATP
During extracellular signaling, ligands bind to cytoplasmic protein kinases cell surface receptors, on the interior of the plasma membrane nuclear membrane receptors hormones cell surface receptors, on the exterior of the plasma membrane
cell surface receptors, on the exterior of the plasma membrane
Where does the energy for enzymatically forming C-C bonds during the Calvin Cycle directly come from? chemical bond energy stored in glucose chemical bond energy stored in energy intermediates from the light reactions ATP produced in the mitochondria the powerhouse of the cell light-excited pigments that diffuse into the stroma
chemical bond energy stored in energy intermediates from the light reactions
Energy stored in the covalent bonds of a molecule of C6H12O6 would best be described as which of the following? oncentration gradient energy electrochemical energy / ion gradient kinetic / mechanical energy mechanical energy chemical potential energy heat energy
chemical potential energy
Where does the Calvin Cycle take place in normal C3 plants (C3 plants make up most of the plants on earth, and are what we spent the majority of time discussing)? chloroplast intermembrane space thylakoid lumen mitochondrial matrix thylakoid membrane chloroplast stroma
chloroplast stroma
In prokaryotes, glycolysis takes place in the ___. In eukaryotes, glycolysis takes place in the ___.
cytosol, cytosol
The structure of a signal molecule helps determines its mechanism of signaling? Signal molecules can interact with either intracellular or extracellular receptors. For a signal molecule to bind with an intracellular receptor it must be able to pass through the cellular membrane. Lipid soluble hormones such as estrogens bind their intracellular receptors primarily by _______________________. requiring specific gates to pass through the cell membrane. requiring a membrane receptor protein to enter the cell. entering the cell through active transport. working as ligands on the exterior surface of the cell membrane. diffusing through the cell membrane.
diffusing through the cell membrane
Insulin is normally secreted from the pancreas and then travels through your circulatory system to bind to receptors on (for examples) muscle cells, which then increase glucose uptake from the blood. This is an example of which of the following types of signaling? (You may need to go to the slides or your book for this. Please be aware of these terms, but I won't ask you to memorize them for a quiz or exam.) autocrine signaling. endocrine signalling. paracrine signaling. contact-dependent signaling.
endocrine signaling
Do you think enzymes are usually very specific for their substrates, or do you think they can typically catalyze many different reactions? If you are stuck, it might help you to think about: induced fit how enzymes lower activation energies how competitive inhibitors work enzymes can typically catalyze many different reactions enzymes are usually very specific for their substrates
enzymes are usually very specific for their substrates
The alpha subunit of the G-protein is activated by exchanging the GTP for GDP. the G-protein becoming phosphorylated. binding to calcium ions. exchanging the GDP for GTP. binding to the gamma and beta subunits.
exchanging the GDP for GTP.
Reaction (1) is A + B <--> C + H2O. It is endergonic with a ΔG = 6.9 kcal/mol Reaction (2) is ATP + H2O <--> ADP + Pi . It is exergonic with a ΔG = -7.3 kcal/mol If these two reactions are coupled, then the overall coupled reaction would be considered __________________. having overall positive free energy endergonic at maximum velocity in need of more energy exergonic
exergonic
How does ATP synthase directly get the energy it needs to rotate and catalyze this reaction? ADP + Pi ⟶ ATP from a proton gradient from a sodium gradient from NADH from glucose synthesis from ATP
from the proton gradient
The source of the carbon for cellular respiration is _____________, while the source of carbon for photosynthesis is ___________. glucose, CO2 glucose, carbohydrates (starch) glucose, glucose CO2 , glucose CO2, CO2
glucose, CO2
_________________ takes place in the cell cytosol, while __________________ takes place in the mitochondrial matrix. oxidative phosphorylation, the citric acid cycle glycolysis, the citric acid cycle citric acid cycle, pyruvate breakdown pyruvate breakdown, glycolysis
glycolysis, the citric acid cycle
ATP synthase is a large multi-subunit (more than one polypeptide) enzyme. Part of this molecular machine actually rotates during ATP synthesis. The large part of this enzyme containing the alpha (α) and beta (β) subunits is where catalysis and formation of ATP happens. Where is this part of the enzyme located? in the matrix in the transmembrane region, spanning the inner mitochondrial membrane in the transmembrane region, spanning the outer mitochondrial membrane in the inner membrane space in the cytosol
in the matrix
Diabetics can be given insulin as an injection which then travels through the blood and binds to receptors on cells throughout the body, thereby increasing glucose uptake. In this example, insulin is an example of a G-protein. transcription factor. ligand. receptor. kinase. a carbohydrate.
ligand
In which part of a eukaryotic cell does the electron transport chain occur? Put another way, where are the proteins of the electron transport chain located? the endoplasmic reticulum mitochondria inner membrane mitrochondria outer membrane mitrochondria matrix cytoplamsm plasma membrane
mitochondrial inner membrane
Both oxidative phosphorylation and the light reactions of photosynthesis use H+ gradients to synthesize ATP. Oxidative phosphorylation builds up high H+ concentrations in the ___, while photosynthesis builds up high H+ concentrations in the ___.
mitochondrial inter membrane space, thylakoid lumen
Both oxidative phosphorylation and the light reactions of photosynthesis use H+ gradients to synthesize ATP. Oxidative phosphorylation builds up high H+ concentrations in the __, while photosynthesis builds up high H+ concentrations in the __.
mitochondrial intermembrane space, thylakoid lumen
Which of the following are phosphorylated during normal EGF signaling. Select any/all that apply. nuclear transcription factors that promote cell growth. protein kinase 1 EGF receptor protein kinase 3 protein kinase 2 Relay proteins Ras
nuclear transcription factors that promote cell growth, EGF receptor, protein kinase 3, protein kinase 2
Rank the stages of cellular respiration in the correct order from least NADH produced to most NADH produced per glucose molecule. Choose the one best answer. oxidative phosphorylation, citric acid cycle, pyruvate breakdown/glycolysis oxidative phosphorylation, glycolysis or pyruvate breakdown, citric acid cycle glycolysis or pyruvate breakdown, oxidative phosphorylation, citric acid cycle glycolysis or pyruvate breakdown, citric acid cycle, oxidative phosphorylation
oxidative phosphorylation, glycolysis or pyruvate breakdown, citric acid cycle
Rank the stages of cellular respiration in the correct order from: least NADH produced to most NADH produced. glycolysis or pyruvate breakdown, oxidative phosphorylation, citric acid cycle oxidative phosphorylation, citric acid cycle, pyruvate breakdown/glycolysis glycolysis or pyruvate breakdown, citric acid cycle, oxidative phosphorylation oxidative phosphorylation, glycolysis or pyruvate breakdown, citric acid cycle
oxidative phosphorylation, glycolysis or pyruvate breakdown, citric acid cycle
During the Calvin Cycle, NADPH is _____________. oxidized, releasing electrons that are added to organic molecules in the cycle oxidized, taking on electrons released from organic molecules used in the cycle reduced, taking on electrons released from organic molecules used in the cycle reduced, releasing electrons that are added to organic molecules in the cycle
oxidized, releasing electrons that are added to organic molecules in the cycle
During the Calvin Cycle, NADPH is _____________. reduced, taking on electrons released from organic molecules used in the cycle oxidized, releasing electrons that are added to organic molecules in the cycle oxidized, taking on electrons released from organic molecules used in the cycle reduced, releasing electrons that are added to organic molecules in the cycle
oxidized, releasing electrons that are added to organic molecules in the cycle
Consider aerobic cellular respiration. After glycolysis, __ must cross __ total biological membranes to reach its destination for continuing the second stage of cellular respiration, and this process __ take energy to transport the molecule to its destination.
pyruvate, 2, does
A substrate binding to an enzyme is conceptually most similar to a signal molecule binding to a G-protein. receptor second messenger. transcriptional factor. kinase.
receptor
A substrate binding to an enzyme is conceptually most similar to a signal molecule binding to a kinase. G-protein. receptor transcriptional factor. second messenger.
receptor
exergonic reaction
releases energy
endergonic reaction
requires energy
We talked about several stages or steps of cell signaling in eukaryotes. Which of the stages described here typically occurs in the cytoplasm? transcription of DNA to produce mRNA ligands binding to membrane receptors transcription factor binding to DNA signal transduction, for example a protein kinase cascade
signal transduction, for example a protein kinase cascade
Noncompetitive inhibitors _________________. (choose any/all that apply) slow down enzyme-catalyzed reactions work by causing or inhibiting conformational changes in enzymes, which impairs enzyme activity or substrate binding work by binding in the active site speed up enzyme-catalyzed reactions work by binding at an allosteric site
slow down enzyme-catalyzed reactions, work by causing or inhibiting conformational changes in enzymes, which impairs enzyme activity or substrate binding, work by binding at an allosteric site
During cellular communication, the creation of second messengers in signal transduction offers at least two advantages, amplification and speed. specificity. affinity. reversibility.
speed
Compare mitochondrial and chloroplast structures to their functions during ATP synthesis in the two organelles. Considering only the H+ gradient used for ATP synthesis, the mitochondrial matrix plays a role most similar to the ________________. thylakoid lumen cytosol of mesophyll leaf cell stroma granum membrane chloroplast intermembrane space
stroma
The reaction ADP + Pi --> ATP during the light reactions happens in which location? thylakoid lumen cytosol stroma chloroplast intermembrane space
stroma
In the citric acid cycle, where do the carbons from Succinate end up? the 4 carbons are split into 2 molecules of Acetyl CoA the 4 carbons are split in half to form 2 molecules of pyruvate the 4 carbons are eventually re-used and put back into the cycle the 4 carbons are released as 4 CO2 molecules.
the 4 carbons are eventually re-used and put back into the cycle
If a drug inhibits complex II of the electron transport chain and blocks its normal function, which of the following processes might stop first in the cell? (This is a hard question.) the citric acid cycle glycolysis breakdown of pyruvate The transfer of electrons from Complex III to Complex IV
the citric acid cycle
A tyrosine kinase receptor is activated by which of the following? cAMP the phosphorylation of the ligand a transcription factor the phosphorylation of the receptor after binding the ligand
the phosphorylation of the receptor after binding the ligand
The tyrosine kinase receptor EGFR is activated by which of the following? the phosphorylation of the ligand, after binding to the receptor cAMP a transcription factor exchanging GDP for GTP. the phosphorylation of the receptor, after binding the ligand
the phosphorylation of the receptor, after binding the ligand
If a reaction is exergonic, then which of the following choices is correct? energy must be provided for the reaction to proceed the products have lower entropy (are more orderly) than the reactants/substrates the reaction must occur extremely quickly the products have lower free energy than the reactants
the products have lower free energy than the reactants
If a reaction is exergonic, then which of the following choices is correct? the products have lower entropy (are more orderly) than the reactants/substrates the reaction occurs extremely quickly the reactants have lower free energy than the products energy must be provided for the reaction to proceed the products have lower free energy than the reactants
the products have lower free energy than the reactants
When a receptor binds to a ligand, what actually causes activation and communication to occur? the receptor is a protein, which physically changes shape (conformational change) due to interaction with the ligand. the ligand is catalyzed into a product. the receptor is broken down and portions of it enter the cell cytoplasm the ligand changes shape due to biochemical interaction with the cell membrane
the receptor is a protein, which physically changes shape (conformational change) due to interaction with the ligand.
When a receptor binds to a ligand, what actually causes activation and communication to occur? the receptor is broken down and portions of it enter the cell cytoplasm the receptor is a protein, which physically changes shape (undergoes a conformational change) due to biochemical interaction with the ligand none of these are correct the ligand changes shape due to biochemical interaction with the cell membrane
the receptor is a protein, which physically changes shape (undergoes a conformational change) due to biochemical interaction with the ligand
In some cases, just a few hormone molecules binding to the surface of a cell can trigger a very large response. This large, fast response occurs primarily because __________. each hormone can bind to multiple receptors simultaneously causing amplification of the signal the hormone triggers the cell to release more hormones, amplifying the signal each hormone can bind to transcription factors simultaneously causing amplification of the signal the signal is amplified by activation of transcription factors that each catalyze multiple reactions the signal is amplified by second messenger activation of multiple enzymes that each catalyze multiple reactions
the signal is amplified by second messenger activation of multiple enzymes that each catalyze multiple reactions
When NADH and FADH2 are oxidized (lose electrons), they donate their electrons to proteins embedded in the inner mitochondrial membrane they donate their electrons to proteins embedded on the outer mitochonddrial membrane they gain electrons from proteins of the electron transport chain The electrons directly rotate ATP synthase to produce ATP this happens during enzymatic reactions of the citric acid cycle.
they donate their electrons to proteins embedded in the inner mitochondrial membrane
When a cell receives a signal, many different responses can result. If there is an activation in gene expression, then the protein group targeted was likely membrane-bound metabolic factors transcription factors enzymes structural proteins
transcription factors
Photosynthesis (select any/all that apply) uses CO2 as an electron source, and requires oxygen gas as a terminal electron acceptor uses CO2 from the atmosphere. produces sugar compounds. uses O2 as an electron acceptor uses water as an electron source, producing oxygen gas. uses light as an electron source
uses CO2 from the atmosphere, produces sugar compounds, uses water as an electron source, producing oxygen gas. uses light as an electron source
Noncompetitive inhibitors do which of the following (select any/all that apply)? work by causing conformational changes in enzymes that impair enzyme activity or substrate binding. slow down or stop enzyme-catalyzed reactions work by binding in the active site work by binding at an allosteric site speed up enzyme-catalyzed reactions
work by causing conformational changes in enzymes that impair enzyme activity or substrate binding, slow down or stop enzyme-catalyzed reactions, work by binding at an allosteric site
During normal EGF signaling, some kinases in the signal transduction pathway are themselves phosphorylated by other proteins. no, kinases are not proteins yes, this is why it is called a protein kinase cascade no, proteins that phosphorylate other proteins cannot themselves be the target of protein kinases no, only transcription factors are phosphorylated
yes, this is why it is called a protein kinase cascade
A certain biochemical reaction (A+B--> C ) must be coupled to the hydrolysis of at least two ATP molecules in order to occur. Which of the following is a possible ΔG for the A+B --> C biochemical reaction? Remember that hydrolysis of a single ATP has a ΔG of -7.3 kcal/mol. -7.3 kcal/mol +16 kcal/mol -14.6 kcal/mol -16 kcal/mol +9.2 kcal/mol
+9.2 kcal/mol
Reaction (1) is A + B <--> C + H2O. It is endergonic with a ΔG = 6.9 kcal/mol Reaction (2) is ATP + H2O <--> ADP + Pi . It is exergonic with a ΔG = -7.3 kcal/mol If these two reactions are coupled, what is the overall free energy for the reaction? -0.4 kcal/mol 0.5 kcal/mol -14.2 kcal 0.7 kcal/mol
-0.4 kcal/mol
Reaction (1) is A + B <--> C + H2O. It is endergonic with a ΔG = 6.3 kcal/mol Reaction (2) is ATP + H2O <--> ADP + Pi . It is exergonic with a ΔG = -7.3 kcal/mol If these two reactions are coupled, what is the overall free energy for the coupled reaction? -1.5 kcal/mol -13.6 kcal -1.0 kcal/mol 13.6 kcal/mol 1.0 kcal/mol
-1.0 kcal/mol
An exergonic reaction that occurs in the cell has a ΔG = -10.1 kcal/mol. If an enzyme reduces the activation energy by 7.9 kcal/mol, what is the ΔG of the enzyme-catalyzed reaction?
-10.1 kcal/mol
An exergonic reaction that occurs in the cell has a ΔG = -17 kcal/mol. If an enzyme reduces the activation energy by 4 kcal/mol, what is the ΔG of the enzyme-catalyzed reaction? -21 kcal/mol -17 kcal/mol 4 kcal/mol -13 kcal/mol
-7 kcal/mol