Chapter 4 Study Questions
Cellular respiration results in a(n) ______________ in entropy as glucose is broken down to form carbon dioxide. A. increase B. decrease C. no change
A
Decreased phenylalanine metabolism causes A. albinism. B. hypercholeteremia. C. lactose intolerance. D. Tay-Sachs disease.
A
During reduction, a molecule or atom A. gains protons or gains electrons. B. loses protons or gains electrons. C. gains protons or loses electrons. D. loses protons or loses electrons.
A
Elevated plasma aldolase could be indicative of A. muscular dystrophy. B. pancreatitis. C. pernicious anemia. D. prostate cancer.
A
Energy can change forms, but cannot be created or destroyed is a statement of the A. first law of thermodynamics. B. second law of thermodynamics. C. law of mass action. D. third law of thermodynamics.
A
Energy transformations result in a(n) ______________ in entropy. A. increase B. decrease C. no change
A
Enzymes which remove hydrogen atoms from their substrates are referred to as A. dehydrogenases. B. hydrolases. C. catalases. D. peroxidases.
A
FAD and NAD are coenzymes that act as _______ in biochemical reactions. A. hydrogen carriers B. oxygen carriers C. energy carriers D. vitamin carriers
A
Oxidized nicotinamide adenine dinucleotide (NAD) has ______________ two hydrogens. A. lost B. gained C. shared
A
Reactant molecules of enzyme action are called A. substrates. B. allosteric inhibitors. C. cofactors. D. products.
A
The greatest increase in entropy occurs A. when starch is degraded to glucose. B. when amylase produces maltose. C. when glucose is converted to galactose. D. when ATP is synthesized.
A
The process that yeast uses to make alcohol from glucose is A. fermentation. B. aerobic respiration. C. photosynthesis. D. catalysis.
A
Which of the following does NOT affect the activity of an enzyme? A. the organ the enzyme is in B. concentration of enzyme and substrate molecules C. concentration of cofactors and coenzymes D. pH and temperature
A
______________ occurs when the product of a metabolic pathway binds to an enzyme and decreases enzymatic activity. A. Allosteric inhibition B. End-product therapy C. Second messaging D. Coupling
A
The phosphatase found in bone would have a pH optimum that is ______________ than the pH optimum of the phosphatase found in the prostate gland. A. higher B. lower C. the same as
A (in bone, it's pH 9.0; in prostate it's 5.5) reminder: phosphatase removes a phosphate group
A defect in the enzyme which converts phenylalanine into tyrosine is characteristic of the disease A. phenylketonuria. B. albinism. C. lactose intolerance. D. maple-syrup disease.
A.
A defect in the enzyme that catalyzes the formation of melanin from DOPA results in A. phenylketonuria. B. albinism. C. lactose intolerance. D. maple-syrup disease.
B
Chemically reduced FAD has __________ extra hydrogen atom(s) bound to it. A. one B. two C. three D. no
B
Energy transformations increase the entropy of a system is a statement of the A. first law of thermodynamics. B. second law of thermodynamics. C. law of mass action. D. law of conservation of energy.
B
Enzymes ______________ the rate of a specific chemical reaction. A. decrease B. increase C. have no effect on
B
Hydrolysis reactions are catalyzed by A. dehydrogenases. B. hydrolases. C. isomerases. D. synthases.
B
If NAD becomes reduced it is a(n) A. reducing agent. B. oxidizing agent. C. zymogen. D. allosteric inhibitor.
B
In an enzymatic reaction, when temperature is increased past the point of "optimal temperature," the enzyme starts to A. increase its catalytic activity. B. reduce its catalytic activity. C. increase its allosteric properties. D. increase product formation.
B
In the reaction (H2O + CO2 <> H2CO3), increasing the concentration of H2O would A. decrease the concentration of H2CO3. B. increase the concentration of H2CO3. C. increase the concentration of CO2. D. have no effect on either CO2 or H2CO3 concentrations.
B
NAD is derived from the vitamin A. B-12, cobalamin. B. B-3, niacin. C. B-2, riboflavin. D. B-6, pyridoxine
B
The model that explains how an enzyme and substrate fit together is the A. enzyme-substrate model. B. lock-and-key model. C. conformational model. D. None apply.
B
The rate at which a chemical reaction can be increased is by either ______________ the temperature or ______________ the activation energy. A. increasing, increasing B. increasing, decreasing C. decreasing, decreasing D. decreasing, increasing
B
What technique has been affective in the treatment of inborn errors of metabolism such as SCID? A. allosteric inhibition B. gene therapy C. coenzyme activation D. None of the choices is correct.
B
Which of the following is NOT true of catalysts? A. They are unchanged by the reaction catalyzed. B. They allow endergonic reactions to become exergonic reactions. C. They increase the amount of energy released by a chemical reaction. D. They lower the activation energy of the reaction.
B
Which of the following statements about enzymes is NOT true? A. Enzymes increase chemical reaction rates. B. Enzymes are consumed during a chemical reaction. C. Enzymes decrease the free energy of activation of specific reactions. D. Enzymes have unique pH and temperature optima.
B
Endergonic reactions cause the amount of entropy in the products to be A. increased. B. decreased. C. unchanged.
B Endergonic means the products will have more free energy. If free energy is increased, entropy is decreased.
. ______________ is the universal energy carrier. A. Glucose B. ATP C. ADP D. GTP
B (adenosine triphosphate)
Free energy is ______________ when exergonic reactions proceed. A. increased B. decreased C. unchanged
B (the energy is released)
An inborn error in lipid metabolism may cause all of the following diseases EXCEPT A. Tay-Sachs disease. B. homocystinuria. C. hypercholesteremia. D. Gaucher's disease.
B. (homocystinuria is an AA metabolism error, not lipid)
A common reducing agent used to couple chemical reactions in cells is A. riboflavin. B. niacin. C. NADH. D. FAD.
C
A food calorie (Calorie) is equivalent to which metric measurement of heat? A. calorie B. joule C. kilocalorie D. watt
C
Addition of substrate when enzyme reaction rate is maximal results in A. additional product formation. B. less product formation. C. no change in product formation. D. enzyme destruction.
C
Biological catalysts A. decrease reaction rates. B. alter a reaction product. C. remain unchanged at the end of the reaction. D. All apply.
C
FAD is derived from vitamin A. B-12. B. B-3, niacin. C. B-2, riboflavin. D. B-6.
C
In bioenergetic pathways, as intermediates are acted upon by enzymes, the ultimate result is the release of A. lactate. B. ATP. C. free energy. D. enzymes.
C
In response to increased concentration of the final product of a metabolic pathway A. all enzymes in the pathway become more active. B. intermediate enzymes become more active. C. the final product acts as an allosteric regulator of one enzyme in the pathway. D. all enzymes in the pathway become less active.
C
Ribozymes are RNA molecules that act as A. hormones. B. cofactors. C. enzymes. D. inhibitors.
C
The flow of energy in living systems is termed A. entropy. B. enthalpy. C. bioenergetics. D. bioluminescence.
C
The level of protein structure primarily involved in determining enzyme activity is the A. primary structure. B. secondary structure. C. tertiary structure. D. quaternary structure.
C
The model that describes how an enzyme can adjust its shape to fit the shape of the substrate is the A. lock-and-key model. B. enzyme-substrate model. C. induced-fit model. D. conformational model.
C
Which of the following is NOT a characteristic of a catalyst? A. is not changed itself at the end of the reaction B. does not change the nature of the reaction C. can change the final result of the reaction D. increases the rate of the reaction
C
______________ are inactive forms of digestive enzymes. A. Cofactors B. Coenzymes C. Zymogens D. Both cofactors and zymogens are correct
C
The breakdown of hydrogen peroxide is catalyzed by A. aldolase. B. amylase. C. catalase. D. kinase.
C. (In perioxisomes!)
A ______________ is the amount of heat required to raise the temperature of one cubic centimeter of water one degree on the Celsius scale. A. specific heat B. meter C. boiling point D. calorie
D
A common oxidizing agent used to couple chemical reactions in cells is A. riboflavin. B. niacin. C. NADH. D. FAD.
D
An enzyme elevated in the plasma of men with prostate cancer is A. alkaline phosphatase. B. catalase. C. creatine kinase. D. acid phosphatase.
D
Dehydration synthesis reactions are catalyzed by A. dehydrogenases. B. hydrolases. C. isomerases. D. synthases.
D
During oxidation, a molecule or atom A. gains protons. B. loses protons. C. gains electrons. D. loses electrons.
D
Metal ions such as magnesium or calcium can serve as enzyme A. coenzymes. B. ribozymes. C. substrates. D. cofactors.
D
When an enzyme catalyzes a chemical reaction A. the enzyme binds to the substrate's active site. B. the enzyme's active site binds the product. C. amino acids in the substrate allow for interaction with the product. D. amino acids in the enzyme's active site interact with substrate molecules
D
Which of the following is NOT true about enzymes? A. As the temperature increases from 25 C to 37 C enzyme activity decreases. B. Very few enzymes require cofactors. C. Most enzymes are not sensitive to changes in pH. D. All are not true
D
The enzyme with the lowest pH optimum is A. acid phosphatase. B. lipase. C. monoamine oxidase. D. pepsin.
D (STOMACH ACID)
Elevated plasma amylase could indicate A. osteitis deformans. B. a myocardial infarct. C. obstructive jaundice. D. a perforated peptic ulcer.
D (also pancreatitis)
The substrate binds to the ______________ of the enzyme. A. allosteric site B. acidic site C. neutral site D. active site
D (the lock portion of the lock and key analogy)
Regulation of a metabolic pathway by the final product of the pathway is termed A. allosteric inhibition. B. end-product inhibition. C. negative feedback. D. Both end-product inhibition and negative feedback are correct.
D.
Pancreatic amylase catalyzes the breakdown of oligosaccarides to disaccharides with the addition of water. What classification of enzymes would amylase be in? A. dehydrogenase B. isomerase C. synthase D. hydrolase
D. (This is a hydrolysis reaction because you are adding water to break something down. Hydrolysis reactions are catalyzed by hydrolase enzymes)
Addition of phosphate groups to a particular molecule is catalyzed by A. transaminases. B. phosphatases. C. isomerases. D. kinases.
D. (phosphatases remove!)
A reducing agent A. donates protons to an atom or molecule. B. donates electrons to an atom or molecule. C. accepts protons from an atom or molecule. D. accepts electrons from an atom or molecule. E. Both donates electrons and donates protons are correct.
E
Consuming extra niacin and riboflavin in the diet will provide extra energy for body functions.
False
Isomers are different forms of an enzyme.
False
Abnormally high concentration of the BB form of creatine phosphokinase is associated with a myocardial infarction.
False (It's CK-MB for myocardial infarction CKBB is damaged brain and lungs, CK-MM is damaged skeletel muscles. diseased organs release this into the blood.
The pH optimum for enzymes secreted by the stomach is higher than the pH optimum for enzymes secreted by the pancreas.
False (Lower in stomach because it's acid and lower pH = more acidic. Pancreas is more basic, so you want a higher optimum pH for pancreatic enzymes)
Oxidation means that oxygen is part of the reaction.
False (Oxygen is just a common oxidation agent - so commonly accepts electrons)
A molecule that gains a hydrogen is also oxidized.
False (it's reduced)
Most enzymatic reactions in the body are one step processes.
False (many follow a metabolic pathway)
(T/F) Most enzymes are lipids.
False (most enzymes are proteins)
Isoenzymes bind different substrates and catalyze different chemical reactions.
False (they catalyze the same reactions and bind the same substrates)
Enzymes in a metabolic pathway act antagonistically to produce a final product.
False (they work cooperatively)
The pH optima for all digestive enzymes are approximately equal to the pH of blood.
False (think of Pepsin in stomach or Trypsin in pancreatic juice)
The principle that reversible reactions will be driven from the side of the equation where the concentration is lower to the side where the concentration is higher is known as the law of mass action.
False - it's where the side of the equation where the concentration is higher is driven to the lower side (always trying towards equilibrium)
Active enzymes are often called zymogens.
False - zymogens are inactive
The reaction of adenosine diphosphate and phosphate generates adenosine triphosphate and energy.
False. Formation of ATP is an endergonic reaction. This endergonic reaction is fueled by the many exergonic reactions happening around it.
An enzyme-catalyzed reaction in the body at 50 C will proceed at a faster rate than at 37 C.
False. Body temp is 37 degrees, which is the optimum temp for most reactions. 50 degrees would be too high and would alter teritiery structur of enzymes)
2. Know the amino acids involved in maple syrup disease and is the pathophysiology of maple syrup disease
The amino acids in Maple Syrup Disease are Isoleucine, Leucine, and Valine. (I Love Vermont). The pathophysiology of MSD is that there is a deficiency in the BCKDC chain, leading to a buildup of isoleucine, leucine, and valine amino acids, and their toxic biproducts (ketoacids) in blood and urine. Maple syrup pee smell.
Know the enzyme responsible for PKU
The enzyme responsible for PKU (Pheylketonuria) is phenylalanine hydroxylase. The enzyme converts phenylalanine into the AA Tyrosine. In PKU, the enzyme is defective. Phenylalanine acculumates and is converted instead into phenylpyruvic acid. Can cause mental retardation/epilepsy. 2. Short description: a. Normal: phenylalanine AA + phenylalanine hydroxylase enzyme = tyrosine Patho (no phenylalanin hydroxylase) : phenylalanine AA -> phenylpyruvic acid
(T/F) During a chemical reaction, a catalyst increases the rate at which the reaction occurs.
True
. Exergonic reactions proceed with the release of energy.
True
A reducing agent donates electrons to a molecule.
True
An atom or molecule that is oxidized is also a reducing agent.
True
Another name for the first law of thermodynamics is the law of conservation of energy.
True
In general, decreased body temperature causes the rate of enzymatic reactions to decrease.
True
Oxidizing agents accept electrons from molecules undergoing reduction.
True
Reduction and oxidation are always coupled.
True
End-product inhibition usually involves allosteric inhibition of an enzyme.
True Allosteric inhibition is where the final product inhibits an earlier enzymatic step in it's own pathway.
Coenzymes are organic molecules that are required for proper function of some enzymes.
True Coenzymes are organic molecules (derived from vitamins) that are needed for the functions of particular enzymes. They participate in enzyme catalyzed reactions by transporting hydrogen atoms and small molecules from one enzyme to another.
Free energy is the only type that can be used to perform cellular work.
True (
(T/F) Catalysts increase reaction rates by lowering the activation energy of a reaction.
True (Activation energy is the energy required for a reaction to proceed.)
The amount of entropy increases as bonds are broken to generate glucose from glycogen.
True (Second law of thermodynamics stats that the amount of entropy increases in every energy transformation. Free energy decreases as entropy increases)
The conversion of glucose to galactose is catalyzed by an isomerase.
True (an isomerase is an enzyme that catalyzes the same reaction, but whose amino acid composition is differs based on what organ it functions in)
(T/F) In some instances RNA can act as an enzyme.
True (as ribozyme - ribosomal RNA molecules serve as enzymes in many of the reactions that require ribosomes for protein synthesis
Enzymes are specific for a given substrate.
True (substrates are the molecules that are reacting with the enzyme)
The MM isoenzyme of creatine phosphokinase is found in diseased skeletal muscle.
True! CK-MM - damaged skeletel muscle CK-MB - myocardial infarction CK-BB - damaged brain and lungs
A deficiency of dietary copper could limit the activity of some enzymes.
True. Copper is a cofactor. Cofactors are metal ions that create conformational changes in enzymes that allows them to bind with their substrates
Pyruvate dehydrogenase catalyzes the removal of hydrogen from pyruvic acid.
True. (A dehydrogenase enzyme an catalyzes the removal of hydrogen atoms from a particular molecule. Pyruvate tells you it acts on pyruvic acid.)
At saturation, enzyme activity is maximal.
true
