Biology Exam 3 Flashcards
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Questions and Answers

What type of interaction is shown in box W?

What type of interactions are shown in V?

Which of the following statements concerning the interaction labeled Y is/are true?

  • Neither A nor B is correct.
  • This type of interaction would be disrupted at pH 1.0.
  • Both A and B are correct. (correct)
  • It is an example of an ionic interaction.

    • What is the item labeled Z?

    <p>Both A and B are correct.</p> Signup and view all the answers

    The formation of a disulfide bond is an example of what type of reaction?

    <p>oxidation</p> Signup and view all the answers

    Which of the following is NOT a valid interpretation of Met-enkephalin's primary structure?

    <p>The amino group of methionine (Met) is not joined to any other amino acid.</p> Signup and view all the answers

    Which statement regarding O2 binding by myoglobin and hemoglobin is INCORRECT?

    <p>At low oxygen concentrations, hemoglobin binds oxygen more tightly than myoglobin.</p> Signup and view all the answers

    Which statement regarding sickle cell anemia is FALSE?

    <p>Sickle cell hemoglobin binds only half as much oxygen as normal hemoglobin.</p> Signup and view all the answers

    Which of the following statements about protein structure is INCORRECT?

    <p>Fibrous proteins stretch easily.</p> Signup and view all the answers

    Which of the following statements is CORRECT about Enzyme A (Km = 10 micromolar) and Enzyme B (Km = 0.1 micromolar)?

    <p>Enzyme B has a higher affinity for its substrate compared to Enzyme A.</p> Signup and view all the answers

    What is the effect of an enzyme on the equilibrium constant for the reaction it catalyzes?

    <p>it has no effect on the equilibrium constant</p> Signup and view all the answers

    Which of the following is NOT an example of allosteric binding or regulation?

    <p>Binding of oxygen to myoglobin at low O2 concentration.</p> Signup and view all the answers

    Which of the following statements regarding enzymes is/are CORRECT?

    <p>Both A and B are correct.</p> Signup and view all the answers

    Which statements below correctly describe isozymes?

    <p>Both A and B are correct.</p> Signup and view all the answers

    Metal ions such as Zn++ and Mg++ are often required for enzyme activity. What are these ions examples of?

    <p>cofactors</p> Signup and view all the answers

    Which of the following statements is FALSE concerning enzymes and their reactions?

    <p>Most enzymes can work on a large number of different substrates.</p> Signup and view all the answers

    Which statement about phosphorylation is FALSE?

    <p>Carried out by phosphatase.</p> Signup and view all the answers

    In living organisms, related chemical reactions are often organized into metabolic pathways. Which of these is NOT usually a feature of a metabolic pathway?

    <p>All enzymes are irreversible.</p> Signup and view all the answers

    __________ are substrates for plants (autotrophs), __________ are substrates for animals (heterotrophs), while __________ is the source of all energy.

    <p>CO2 and water; glucose and O2; solar energy</p> Signup and view all the answers

    Which phrase about an activated intermediate in an enzyme reaction is INCORRECT?

    <p>Accumulates in the reaction.</p> Signup and view all the answers

    Which statement about bioenergetics is INCORRECT?

    <p>Both A and B are incorrect.</p> Signup and view all the answers

    What is maltose?

    <p>disaccharide with alpha 1--&gt;4 glycosidic link</p> Signup and view all the answers

    What is amylopectin?

    <p>polysaccharide with alpha 1--&gt;4 and alpha 1--&gt;6 glycosidic links</p> Signup and view all the answers

    What is cellulose?

    <p>polysaccharide with only beta 1--&gt;4 glycosidic links</p> Signup and view all the answers

    Humans store glucose as what?

    <p>glycogen</p> Signup and view all the answers

    What is lactose?

    <p>disaccharide of glucose and galactose, found in milk</p> Signup and view all the answers

    What does digestion of starch and glycogen involve?

    <p>hydrolysis of glycosidic links between adjacent glucose monomers</p> Signup and view all the answers

    Why is the branched-chain structure of glycogen a wise metabolic strategy?

    <p>it allows for very rapid mobilization of free glucose monomers</p> Signup and view all the answers

    Which statement about carbohydrate digestion is CORRECT?

    <p>Involves di-saccharidases in the small intestine.</p> Signup and view all the answers

    Which statement about transport across membranes is INCORRECT?

    <p>All are correct.</p> Signup and view all the answers

    Absorption of glucose from the gut through the intestinal epithelial cells into the blood involves all of the following EXCEPT:

    <p>Phosphorylation of glucose as soon as it enters the epithelial cells.</p> Signup and view all the answers

    Why can't humans obtain metabolic energy from cellulose?

    <p>humans do not have an enzyme that can hydrolyze the beta 1--&gt;4 glycosidic links in cellulose polymers</p> Signup and view all the answers

    Individuals that present with bloating, diarrhea, and dehydration after consumption of dairy products are most likely deficient in what?

    <p>lactase</p> Signup and view all the answers

    Which statement is INCORRECT?

    <p>After dietary glucose enters the blood, it travels immediately to red blood cells.</p> Signup and view all the answers

    Study Notes

    Types of Interactions

    • Interaction shown in box W is unspecified but represents a particular type of molecular interaction.
    • Interaction shown in box V is also unspecified, highlighting another molecular interaction type.

    Interaction Y

    • Interaction Y is an ionic interaction, disrupted at a low pH of 1.0.

    Item Z

    • Item Z is part of a protein's secondary structure, folded into an alpha helix.

    Disulfide Bonds

    • Formation of a disulfide bond is categorized as an oxidation reaction.

    Met-Enkephalin

    • Met-enkephalin's sequence comprises Tyr-Gly-Gly-Phe-Met. The amino group of methionine is not bonded to another amino acid, which is a notable insight about its structure.

    O2 Binding

    • At low oxygen concentrations, hemoglobin displays a lower affinity for oxygen compared to myoglobin, which is an incorrect statement regarding oxygen binding.

    Sickle Cell Anemia

    • Sickle cell hemoglobin's oxygen binding capacity is reduced to half when compared to normal hemoglobin.

    Protein Structure

    • Fibrous proteins are characterized by their rigidity, not their ability to stretch easily, making this statement incorrect.

    Enzyme Affinity

    • Enzyme A exhibits a higher substrate affinity with a Km of 10 micromolar compared to enzyme B, which has a Km of 0.1 micromolar.

    Enzymatic Equilibrium

    • Enzymes do not alter the equilibrium constant of the reactions they catalyze.

    Allosteric Binding

    • Oxygen binding to myoglobin at low O2 concentrations does not qualify as allosteric regulation.

    Enzyme Characteristics

    • Enzymes enhance reaction speeds by decreasing activation energy and by raising the local concentration of substrates.

    Isozymes

    • Isozymes catalyze the same biochemical reactions and can be distinguished from each other via electrophoresis.

    Cofactors

    • Metal ions such as Zn++ and Mg++ function as essential cofactors for enzyme activities.

    Substrate Specificity

    • Most enzymes are specific and generally act on limited, chemically similar substrates.

    Phosphorylation

    • Phosphorylation is performed by kinases, not by phosphatases, indicating the falsity of that statement.

    Metabolic Pathways

    • Typical features of metabolic pathways do not usually include the regulation of each enzyme in the pathway.

    Energy Sources

    • Autotrophs utilize CO2 and water, while heterotrophs derive energy from glucose and O2, with solar energy serving as the primary energy source for ecosystems.

    Activated Intermediates

    • Activated intermediates in enzymatic reactions do not accumulate; they are transient.

    Bioenergetics

    • Incorrect statements about bioenergetics include misconceptions about spontaneous reactions and energy levels of products versus reactants.

    Carbohydrates

    • Maltose is a disaccharide with an alpha 1→4 glycosidic link.
    • Amylopectin features alpha 1→4 and alpha 1→6 glycosidic links, while cellulose solely contains beta 1→4 glycosidic links.
    • Humans store glucose in the form of glycogen.
    • Lactose is a disaccharide comprised of glucose and galactose, typically found in milk.

    Digestion and Absorption

    • Starch and glycogen breakdown occurs through the hydrolysis of glycosidic bonds between glucose monomers, leading to efficient energy release.
    • Glycogen's branched structure facilitates rapid glucose mobilization.
    • Carbohydrate digestion features di-saccharidases active in the small intestine.

    Membrane Transport

    • Statements regarding membrane transport clarify that small hydrophobic molecules can diffuse freely, and energy is necessary for active transport against gradients.
    • Absorption of glucose into the bloodstream does not involve immediate phosphorylation inside intestinal epithelial cells.

    Cellulose Digestion

    • Humans lack the enzyme to digest cellulose, which is attributed to the inability to break down beta 1→4 glycosidic links.

    Lactase Deficiency

    • Symptoms such as bloating and diarrhea after dairy ingestion indicate lactase deficiency, impeding lactose digestion.

    Glucose Circulation

    • Upon dietary glucose absorption, it does not directly enter red blood cells but goes through other metabolic processes.

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    Prepare for your Biology Exam 3 with these flashcards. Each card presents important terms and definitions related to interactions in biology. Test your understanding and enhance your knowledge on essential concepts!

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