Cell Biology Questions
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The types of chemical reactions involved in the aerobic breakdown of glucose by a cell includeA). reductions.B). oxidations.C). oxidation-reduction reactions phosphorylations.D). reductions and phosphorylations.E). oxidations and phosphorylations.
Metabolic pathways in cells are typically far from equilibrium. Which of the following processes tend(s) to keep these pathways away from equilibrium?-The continuous removal of the products of a pathway to be used in other reactions-An input of free energy from outside the pathway-An input of heat from the environment-The first and second listed responses are correct.-The first, second, and third listed responses are correct.
Allosteric regulation of an enzyme means that the enzyme mayA). increase its activity as more enzyme is synthesized via translation of increased mRNA encoding the enzyme.B). decrease its activity as substrate of the enzyme decreases in concentration.C). decrease its activity in the presence of a product of the same or a different pathway.D). increase its activity as the result of dephosphorylation.E). increase its activity as the result of phosphorylation.
Under anaerobic conditions, pyruvateA). is fermented to lactate or alcohol.B). is converted to lactate or tricarboxylic acids.C). is broken down on the cell membrane.D). enters the citric acid cycle.E). is reduced to lactate.
What is the net free energy captured by 32 moles of ATP?
Refer to the figure showing mitochondrial ATP synthase. The figure illustrates how the central shaft-like polypeptide of the F1 subunit _______ as protons _______ through the channel formed by the F0 subunit.A). rotates; move from high to low concentrationB). rotates; move from low to high concentrationC). spins; use ATP to moveD). bends; move from the matrixE). bends; move from the intermembrane space
The free energy derived from the hydrolysis of ATP can be used to perform many kinds of cellular work. Which of the following is an example of the cellular work involved in the production of electrochemical gradients?-The chemical synthesis of ATP-Chromosome movement on microtubules-Proton movement against a gradient of protons-The beating of cilia-Facilitated diffusion
Which of the following reactions would be endergonic?-HCl → H+ + Cl--ATP → ADP + Pi-glucose + fructose → sucrose-C6H12O6 + 6 O2 → 6 CO2 + 6 H2O-All of the listed responses are correct.
When NADH is the electron donor to the respiratory chain, 2.5 ATP are formed, but when FADH2 is the electron donor, only 1.5 ATP are formed. This difference occurs because
When 1 mole of ATP is hydrolyzed in a test tube without an enzyme, about twice as much heat is given off as when 1 mole of ATP is hydrolyzed in a cell. Which of the following best explains these observations?-The amount of heat released by a reaction has nothing to do with the free energy change of the reaction.-In the cell, the hydrolysis of ATP is coupled to other endergonic reactions.-In cells, ATP is hydrolyzed to ADP and Pi, but in the test tube it is hydrolyzed to carbon dioxide and water.-Cells are less efficient at energy metabolism than reactions that are optimized in a test tube.-Cells have the ability to store heat; this cannot happen in a test tube.
In general, the hydrolysis of ATP drives cellular work by __________.-lowering the activation energy of the reaction-releasing free energy that can be coupled to other reactions-releasing heat-acting as a catalyst-changing to ADP and phosphate
Which list places the molecules, from left to right, from most oxidized to least oxidized?
Anaerobic conditions" means that there is an absence ofA). pyruvate.B). carbon dioxide.C). oxygen.D). lactate.E). glucose.
Refer to the table showing the products from the complete oxidation of glucose and the complete oxidation of palmitic acid (a fatty acid).The label "X" should be replaced withA). NADH.B). carbon dioxide.C). acetyl CoA.D). amino acid.E). oxygen.
Oxidative phosphorylation has two major components: _______ and _______.
In an experiment, the F1 portion of the ATP synthase was attached to a glass slide, and fluorescently labeled microfilaments were attached to its central peptide. The rotation of the ATP synthase was observed when ATP was added. Because there was no proton gradient to drive the molecular motor in the direction of ATP synthesis, ATP was hydrolyzed to ADP and Pi, and this energy caused the motor to spin. When ATP plus oligomycin was added to the slide, the rotation continued even though oligomycin can inhibit ATP hydrolysis in mitochondrial inner membrane vesicles containing ATP synthase (F1-F0). Based on your knowledge of ATP synthase, which hypothesis is supported by these observations?
Which molecule from glycolysis or the citric acid pathway serves as the building block for lipid synthesis?A). OxaloacetateB). PyruvateC). GlucoseD). α-KetoglutarateE). Acetyl CoA
An exergonic (spontaneous) reaction is a chemical reaction that __________.-cannot occur outside of a living cell-is common in anabolic pathways-releases energy when proceeding in the forward direction-leads to a decrease in the entropy of the universe-occurs only when an enzyme or other catalyst is present
Which of the following correctly states the relationship between anabolic and catabolic pathways?-The flow of energy between catabolic and anabolic pathways is reversible.-Degradation of organic molecules by anabolic pathways provides the energy to drive catabolic pathways.-Energy derived from catabolic pathways is used to drive the breakdown of organic molecules in anabolic pathways.-Anabolic pathways synthesize more complex organic molecules using the energy derived from catabolic pathways.-Catabolic pathways produce usable cellular energy by synthesizing more complex organic molecules.
Some poisons are compounds that interfere with metabolic pathways. Which poison would interfere with the citric acid cycle but not affect glycolysis?