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COMP EXAM 2022 > 560B BIOCHEMISTRY & NUTRITION > Flashcards

560B BIOCHEMISTRY & NUTRITION Flashcards

1
Q

The lack of which muscle enzyme causes glucose when phosphorylated in the muscle to be trapped?

a. glucokinase
b. glucose-6-phosphatase
c. glycerol-3-phosphatase
d. hexokinase

A

D. Hexokinase

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2
Q

You eat a cheeseburger and a fresh salad. Which of the following molecules in your food is NOT normally oxidized in aerobic respiration to generate ATP?

a. lipids
b. amino acids
c. nucleic acids
d. carbohydrates

A

c. nucleic acids (DNA/RNA)

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3
Q

Which hormone triggers the muscle to breakdown glycogen and carry out glycolysis over the longer term?

a. insulin
b. growth hormone
c. epinephrine
d. glucagon and epinephrine

A

b. growth hormone

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4
Q

Which hormone[s] cause[s] the liver to breakdown glycogen and carry out gluconeogenesis?

a. insulin
b. glucagon
c. epinephrine
d. glucagon and epinephrine

A

d. glucagon and epinephrine

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5
Q

Which hormone[s] trigger[s] adipose tissue to store fatty acids as triacylglycerols?

a. insulin
b. glucagon
c. epinephrine
d. glucagon and epinephrine

A

A. Insulin

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6
Q

Catalysts that change the rate of reactions are what category of physiological proteins?

a. hormones
b. enzymes, which don’t alter the equilibrium
c. enzymes, which alter the equilibrium
transport proteins

A

b. enzymes, which don’t alter the equilibrium

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7
Q

T or F: For every amino acid, there is a specific, unique transport system for digestion.

A

False

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8
Q

The hemoglobin molecule is ____ easily saturated with oxygen than is myoglobin, at a given partial pressure of oxygen.
A. More
B. Less

A

B. Less

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9
Q

T or F: Ammonia formed from muscle amino acid degradation is transferred in the blood in the form of glutamine.

A

True

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10
Q

Thermodynamically speaking, which value most specifically and directly defines whether a biochemical reaction is spontaneous or not?

A

ΔG (gibbs free energy)

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11
Q

When pyridoxal phosphate amine is formed, that means that:

A

Transamination is occurring

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12
Q

What are 3 metabolic sources of ammonia?

A

purines and pyrimidines, diet, bacterial degradation of urea

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13
Q

Activation Energy is the required energy to reach the transition state. How does it work?

A

Enzymes speed up chemical reactions by lowering the activation energy

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14
Q

Enzyme-Substrate Complex

A

Enzymes hold substrate by:
· Hydrogen bonds
· Van der Walls forces
· Electronic attractions
· Conformation of the active site determines the specificity of the enzyme
· Only the substrate that fits, will enter the chemical reaction

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15
Q

Cofactors (which activate the enzymes) are small molecules that some enzymes require for activity.
The 2 main classes of cofactors are:

A

· Coenzymes (organic molecules derived from vitamins)
· Metals

Holoenzyme: an enzyme with its cofactor
Apoenzyme: an enzyme without the cofactor

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16
Q

The hemoglobin molecule is ____ easily saturated with oxygen than is myoglobin, at a given partial pressure of oxygen.
A. More
B. Less

A

B. Less

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17
Q

T or F: Ammonia formed from muscle amino acid degradation is transferred in the blood in the form of glutamine.

A

True

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18
Q

What 3 parts are attached to the central carbon of an amino acid?

A

a hydrogen atom, a carboxyl group, an amine group

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19
Q

The urea cycle takes place partly in the ____ and partly in the ____.

A

Mitochondria, cytosol

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20
Q

During transamination, one product is always?

A

Glutamate

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21
Q

What are 3 metabolic sources of ammonia?

A

purines and pyrimidines, diet, bacterial degradation of urea

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22
Q

The _____ forms of amino acids are incorporated into human protein.

A

L isomer

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23
Q

The electrochemical, oxidative/reductive environment is closely related to local pH, which is a critical factor in:

A

the way a protein folds

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24
Q

With regard to ALT and AST:

  1. they are two muscle proteins that allow muscle contraction
  2. they have little clinical diagnostic value in the case of liver damage
  3. they are used in the oxidative deamination process
  4. they both require pyridoxal phosphate (vitamin B-6) as a coenzyme
A
  1. they both require pyridoxal phosphate (vitamin B-6) as a coenzyme
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25
Q

Amino acids within a given protein that do not differ from species to species are defined as _____, because they are essential to the function of that protein.

A

Invariant

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26
Q

With regard to the different forms of water in the cell, which is not true?

  1. water at the surface of a protein can bare on how much of a particular ion binds to that protein
  2. sodium and potassium both being positive would be expected to bind to a proteins surface to the same degree
  3. water is responsible, at least in part, for formation of microenvironments within the cell
  4. the high specific heat of water helps maintain body temperature in cases where some of the heat energy that is produced from a biochemical reaction (and that is not used for driving other biochemical reactions) is given off as heat
  5. the ATP-requiring sodium/potassium pump only partly explains the partitioning of sodium and potassium outside and inside the cell membrane, respectively
A
  1. sodium and potassium both being positive would be expected to bind to a proteins surface to the same degree
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27
Q

Which is correct regarding protein structure?
A. there are at least two subunits that are needed to form quaternary structure
B. most tertiary structures contain a hydrophobic inner center
C. multiple subunits make repair of the protein easier, as less energy is wasted repairing places that are not in need of repair
D. all of the above are true

A

D. all of the above are true

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28
Q

Which is true regarding protein?

  1. amino acid pools are small in part because protein is not the main body fuel
  2. amino acid pools are small in part because there are no proteins and their related enzyme systems designed specifically for amino acid storage
  3. urea is formed in the liver, because there is a great deal of amino acid degradation there
  4. all of the above are true
A
  1. all of the above are true
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29
Q

True/false: The Km is a measure of the enzyme’s velocity at the substrates concentration that allows the reaction to reach maximum velocity.

A

False; Km is defined as the substrate concentration at 1/2 the maximum velocity

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30
Q

True/false: the straight line portion of the Michaelis/Mention represents the initial velocity.

A

True

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31
Q

True false: Regarding enzymes, the sigmoidal shape curve kinetics represents a multi-subunit and/or multi-active site enzyme, which could be subject to both enzyme induction and feedback regulation (inhibition).

A

True

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32
Q

A change in the activity and conformation of an enzyme resulting from the binding of a compound at a site on the enzyme other than the active binding site; can be associated with taut and relaxed state.

A

Allosterism

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33
Q

Collagen is composed of about one third _____ because that amino acid is small and the collagen is compact.

A

Glycine

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34
Q

Electrophoresis of a person’s _____ can identify a patient with sickle cell trait vs. one with full blown sickle cell anemia.

A

Hemoglobin

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35
Q

Regarding antibody structure:
A. the variable region is the only part of the structure that differs among antibodies, thus being thermodynamically efficient regarding their synthesis
B. the antibody fits with its antigen according to the lock and key theory
C. the C regions of an antibody vary considerably from antibody type to antibody type
D. all of the above are true

A

A. the variable region is the only part of the structure that differs among antibodies, thus being thermodynamically efficient regarding their synthesis

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36
Q

Regarding Insulin:
A. it is composed of a single polypeptide chain of 51 amino acids
B. it is not synthesized in zymogen form, because it is not a potentially destructive enzyme
C. its structure is stabilized by disulfide bonds
D. it is synthesized as an inactive precursor known as peptide

A

C. its structure is stabilized by disulfide bonds

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37
Q

Regarding enzymes:
A. the activity of the enzyme can be affected by what’s associated with its domains
B. lyases catalyze the formation of bonds, such as C-O and C-S, accompanied by the use of ATP
C. enzymes alter the equilibrium of a reaction
D. allosteric enzymes show a hyperbolic-shape curve
E. all of the above are true

A

A. the activity of the enzyme can be affected by what’s associated with its domains

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38
Q

Regarding enzymes:
A. a whole metabolic pathway can be controlled by controlling the activity of a key enzyme that is involved in that pathway
B. a transition state is one where the enzyme is complexed to a very high-energy level, relatively unstable intermediate
C. for thermal effects upon enzymes, a bell shaped curve would be expected
D. all of the above are true

A

D. all of the above are true

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39
Q 
Myoglobin shows which kind of structure?
A. Primary
B. Secondary
C. Tertiary
D. Quaternary
A

C. Tertiary

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40
Q

True/False: protein phosphatases can remove phosphate groups from enzymes.

A

True

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41
Q

True/False: Internal respiration centers on the fact that oxygen is the final electron acceptor in the electron transport system.

A

True

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42
Q

True/False: The electron transport system is located within the mitochondrial matrix.

A

False; it is found in the inner mitochondrial membrane

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43
Q

Pyruvate can be converted to _____ when there is insufficient oxygen in the tissue and when there is a high NADH/NAD+ ratio, as occurring in heavily-exercising muscle, for example.

A

Lactate

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44
Q

Fructose 2,6-bisphosphate strongly stimulates phosphofructokinase and inhibits fructose 1,6-bisphosphatase. Hence, _____ is accelerated and _____ is diminished in the fed state.

A

Glycolysis, gluconeogenesis

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45
Q

True/false: The covalent regulation of both glycogen synthase and glycogen phosphorylase depends upon their respective states of phosphorylation.

A

True

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46
Q

Which steps in glycolysis release ATP?

A

1) 1,3-BPG to 3-PG

2) PEP to Pyruvate

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47
Q

In this equation of Bronsted-Lowrey (B-L) acid/base formula, select the TRUE answer:
NH3 + H2O = NH+4 + OH-

A. NH3 is the B-L conjugated base, and H20 is the B-L acid.
B. NH+4 is the B-L conjugated acid, and Oh- is the B-L conjugated base.
C. Nh3 is the B-L acid, and Oh- is the B-L base
D. Nh+4 is the B-L acid and Oh- is the B-L base

A

B. NH+4 is the B-L conjugated acid, and Oh- is the B-L conjugated base.

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48
Q

Select the FALSE answer:
A. Cellular membranes are made up of various phospholipids that affect the fluidity of the membrane
B. Exergonic reactions require energy to go to completion.
C. Compartmentalization is a way for cells to create smaller parts for protecting specialized reactions to occur with in an area.
D. In the end, entropy wins and the organism dies.

A

B. Exergonic reactions require energy to go to completion.

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49
Q

Select the TRUE answer:
A. Endergonic reactions are spontaneous.
B. Water lines up along the surface of a protein with the hydrogen ion binding to the positive on the surface of the protein.
C. Exothermic reactions consume energy and heat.
D. Compartmentalization is the way for the cell to increase surface area without being small.

A

D. Compartmentalization is the way for the cell to increase surface area without being small.

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50
Q

Select the TRUE answer:
A. Under certain chronic conditions an individual may not be able to synthesize certain amino acids.
B. A buffer should have a pH very different from the pH that you want to maintain.
C. When the intake of protein is greater than the excretion of nitrogen, the person is in a negative nitrogen balance.
D. Essential amino acids can be synthesized by our body.

A

A. Under certain chronic conditions an individual may not be able to synthesize certain amino acids.

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51
Q 
Match the following amino acids to it's classification of essential or non-essential:
Phenylalanine
Argenine
Lecuine
Lysine
Taurine
Methionine
Tyrosine
Tryptophan
Glycine
Glutamine
A 
Phenylalanine - essential
Argenine - non-essential
Lecuine - essential
Lysine - essential
Taurine - non-essential
Methionine - essential
Tyrosine - non-essential
Tryptophan - essential
Glycine - non-essential
Glutamine - non-essential
52
Q 
Which of the following affect structure/function of a cell membrane?
A. osmolarity
B. pH
C. Distance between phospholipids
D. Diet
E. All of the above
A

E

53
Q

Select the TRUE statement about transaminase:
A. B6 dependent
B. Reversible
C. Forms glutamate in the form of alpha-keto-glutamate
D. A new product amino acid is formed
E. All are true

A

E

54
Q 
The co-factor for deamination of glutamate is:
A. pyridoxine (B6)
B. Glutamine
C. Cyanocobalamin (B12)
D. B3/niacin (NADH)
A

D. B3/niacin (NADH)

55
Q

The formation of a peptide bond:
A. involves a dehydration reaction
B. Involves removing an oxygen from the carboxyl group and two hydrogens from the amine group.
C. Makes for a quite strong bond that is not denatured easily such as cooking at high temperatures.
D. All are true

A

D. All are true

56
Q

Which is correct regarding protein structure?
A. At least 4 subunits are required for a quartenary structure
B. Most protein structures have a hydrophobic inner center
C. Multiple subunits require more free energy than more simple protein structures
D. The peptide bonds have a positive charge in order to instruct amino acids conformation around them.

A

B. Most protein structures have a hydrophobic inner center

57
Q 
Quartenary protein structure is stabilized by:
A. Urea
B. Prions
C. Hydrophobic interactions
D. Amyloid proteins
A

C. Hydrophobic interactions

58
Q

What factor influence the binding of oxygen to myoglobin?
A. The concentration of the bicarbonate ion HCO3-
B. The partial pressure of oxygen, pO2
C. The concentration of hemoglobin present
D. The concentration of 2.3-BPG

A

B. The partial pressure of oxygen, pO2

59
Q 
The purpose of protein folding is to:
A. increase entropy
B. Store energy in the hydrogen bonding.
C. Increase organization
D.. Increase potential energy stored as heat.
A

C. Increase organization

60
Q

Select the TRUE statement regarding Positive Cooperativity:
A. Changes the conformation between two peptide units so that when they interact, it causes conformational change in the second subunit.
B. Results in a 180 degree shift in the conformation of the molecule.
C. Makes the Taut (T) form more active.
D. None of the above are true.

A

A. Changes the conformation between two peptide units so that when they interact, it causes conformational change in the second subunit.

61
Q

Select the FALSE statement:
A. Hb(F) gives the fetus preferential access to oxygen from the mother’s circulatory system.
B. One hemoglobin molecule binds 2 oxygen molecules.
C. As protons bind to heme, oxygen is displaced.
D. The Bohr Effect is the displacement of oxygen from Hb by protons binding to Hb that changes the position of the heme in relationship with the alpha and beta subunits.

A

B. One hemoglobin molecule binds 2 oxygen molecules.

62
Q

Coupling is:
A. A way to shift the equilibrium of a reaction to be more favorable.
B. Is how energy is produced in ATP formation
C. A way for transform energy from one form to another in living cells.
D. All of the above are TRUE.

A

D. All of the above are TRUE.

63
Q

The Km value of Glut3 (glucose transporter for the brain) is 1.6 mM, which is considered a low Km value. The low Km value suggests that under normal physiological conditions when blood plasma glucose levels are above the Glut3 Km value that…
A. Glut3 has a lower affinity for glucose.
B. Glut 3 is at least half saturated under this condition.
C. Glut3 is not active.
D. Glut3 is not delivering sufficiency glucose to the brain.

A

B. Glut 3 is at least half saturated under this condition.

64
Q

A competitive inhibitor:
A. Requires more substrate to achieve Vmax since they compete for the active site.
B. Involves allosterism and does not achieve inhibition at the active site.
C. Vmax could never be achieved.
D. There is no way to reserve this inhibition.

A

A. Requires more substrate to achieve Vmax since they compete for the active site.

65
Q

A critical feature of Michaelis-Menton mode of enzyme catalysis is:
A. Decreasing the probability of product formation
B. Preventing a reaction from occurring.
C. Formation of ES complex.
D. Causes a low affinity of the enzyme to substrate.

A

C. Formation of ES complex.

66
Q 
What type(s) of inhibition can be reversed?
A) competitive
B) noncompetitive
C) uncompetitive
D) All of the above
A

D) All of the above

67
Q 
Glucose-6-phosphate is converted to glucose in the following organs:
A. Brain
B. Liver
C. Muscle
D. Kidney
A

B. Liver

68
Q 
The body's trigylcerols are stored in:
A. Cell membranes of skeletal muscle
B. Adipose tissue
C. Liver
D. Blood
A

B. Adipose tissue

69
Q

Cellular respiration:
A. An anaerobic process that involves formation of lactate.
B. Mitochondrial process in which oxygen is utilized.
C. Breathing, or taking oxygen into lungs.
D. All of the above.

A

B. Mitochondrial process in which oxygen is utilized.

70
Q

Which statement is FALSE?
A. Sugars usually exist in cyclic form in the body.
B. Cardiac muscle depends on energy solely from ketones
C. Most of the energy used in the brain is to maintain the Na+/K+ pump for neural impulse.
D. The brain uses ketones as a backup energy source when glucose is in short supply.

A

B. Cardiac muscle depends on energy solely from ketones

71
Q

Which statement is FALSE?
A. The purpse of the kidney is to remove waste and maintain osmotic fluid balance.
B. Renal tubules filter blood plasma about 60 times per day.
C. In glycolysis two molecules of glucose is converted to one molecule of pyruvate.
D. For every glucose oxidized, two glyceraldehyde-3 P are formed.

A

C. In glycolysis two molecules of glucose is converted to one molecule of pyruvate.

72
Q

Select the INCORRECT answer about the pentose phosphate pathway:
A. One of the purposes of the PPP is to produce NADPH an NADP+
B. THE PPP offers an alternative pathway to glycogenesis
C. Glucose 6-Phosphate is the starting metabolite.
D. The result of the first Phase of PPP is D isomer of the ribulose-5-P.

A

B. THE PPP offers an alternative pathway to glycogenesis

73
Q

Select the correct answer:
A. Fructose absorption is not energy requiring.
B. Fructose-6-P is the major fuel source for the liver.
C. Affinity of glucokinase is 20 times greater for glucose than for fructose
D. Fructose is converted into galactose in order to enter glycolysis.

A

C. Affinity of glucokinase is 20 times greater for glucose than for fructose

74
Q 
The intermediate formed in the NON-oxidative phase of the Pentose Phosphate Pathway is:
A. Water
B. NADPH
C. Carbon dioxide
D. RiBose-5-phosphate
A

D. RiBose-5-phosphate

75
Q

Select the TRUE answer:
A. PPP inter-converts 3,4,6,7 carbon sugars
B. G-3-P is isomerized in the PPP to form G-6-P
C. All reactions in the PPP are irreversible
D. High NADPH levels blocks glutathione production.

A

A. PPP inter-converts 3,4,6,7 carbon sugars

76
Q

Which of the following are TRUE concerning glycogen?
A. The breakdown of glycogen does not yield glucose molecules directly.
B. Glycogen is found in the cytosol as granules.
C. More glycogen overall is stored in the muscle than in the liver.
D. All of the above are true.

A

D. All of the above are true.

77
Q

Select the TRUE answer for the Glucose-6-P from glycogenolysis:
A. Enters glycolysis
B. Goes to the Pentose Phosphate Pathway
C. Converted to glucose and released into the blood stream.
D. All of the above are true.

A

D. All of the above are true.

78
Q

Which of the following are FALSE statements concerning glycogen?
A. Glycogen is a large branched glucose polymer that can indirectly be converted to glucose.
B. Branches in glycogen occur every 10 residues due to alpha, 1-6-glycosidic bond formation.
C. Alpha-glycosidic linkages form fibrils.
D. Glycogen is not reduces as are fatty acids.

A

C. Alpha-glycosidic linkages form fibrils.

79
Q

Which of the following are TRUE statements regarding pyruvate?
A. Is a reversibly converted to lactate with NADH as the co-factor
B. Pyruvate kinase of glycolysis is reversible.
C. Pyruvate is converted to oxyoacetate by pyruvate oxaloacetate in the mitochondria that adds CO2.
D. The first step of gluconeogenesis is to convert pyruvate into phophoennolpyruvate (PEP)

A

A. Is a reversibly converted to lactate with NADH as the co-factor

80
Q

Select the INCORRECT statement about the regulation of carbohydrate metabolism:
A. High insulin levels favors high glucose production from gluconeogenesis or from gylcogen breakdown.
B. Pyruvate dehydrogenase is deactivated by high ATP levels.
C. Glucokinase and pyruvate kinanse are the two enzymes that drive glycolysis and are activated by insulin.
D. Oxaloacetate can not cross the mitochondrial membrane.

A

A. High insulin levels favors high glucose production from gluconeogenesis or from gylcogen breakdown.

81
Q

Select the TRUE answer:
A. High levels of insulin favors glycogenolysis.
B. When the ratio of NAD+/NADPH is high, the inter-conversion of lactate and pyruvate favors lactate.
C. In a solution with pH of 2 you would expect NAD+ to convert NADH.
D. Gluconeogenesis has a negative G (free energy), thus is exergonic.

A

C. In a solution with pH of 2 you would expect NAD+ to convert NADH.

82
Q 
Kreb's cycle:
A. Anerobic
B. Most likely to go in either direction
C. formation of Acetyl Co A is reversible.
D. Produces NADH
A

D. Produces NADH

83
Q

Which statement concerning Krebs cycle is INCORRECT?
A. Two carbons leave the cycle in the form of Co2 in successive decarboxylations, catalyzed by dehydrogenations.
B. Two molecules of water are consumed.
C. Four pairs of hydrogen atoms leave the cycle. Two pair utilizing NAD+ and Two pair utilizing FAD.
D. GTP is formed by cleaving the thioester (S) linkage in succinyl CoA.

A

C. Four pairs of hydrogen atoms leave the cycle. Two pair utilizing NAD+ and Two pair utilizing FAD.

84
Q

Which statement is true about the Kreb’s cycle at the ETC?
A. The protonmotive force drives the Kreb’s cycle in a counter-clockwise direction.
B. NO matter where the block is in the ETC from an inhibitor, ultimately the electrons will eventually make their way to be delivered to oxygen at Complex V.
C. All electron carriers before the the block of rotenone and carbon monoxide remain in the fully reduced state.
D. All statements are true.

A

C. All electron carriers before the the block of rotenone and carbon monoxide remain in the fully reduced state.

85
Q 
The inner mitochondrial membrane provides a transporter for all of the following except for:
A. malate
B. phosphate
C. oxaloacetate
D. ATP
A

C. oxaloacetate

86
Q

Select the TRUE answer:
A. The electron transport system is located within the mitochondrial matrix.
B. The primary reason the kreb’s cycle turns in one direction is because of the side pathways that generate other products from the krebs cycle.
C. The net ATP production from one molecule of glucose is 36.
D. ATP synthase reaction happens at Complex 1.

A

C. The net ATP production from one molecule of glucose is 36.

87
Q

Regarding free radicals and antioxidants:
A. Free radical production is a normal process of the immune response.
B. All free radicals are harmful.
C. The human brain is the only place where there is an enzyme that allows for synthesis of Vitamin C.
D. vitamin E alone can protect the oxidation of LDL.

A

A. Free radical production is a normal process of the immune response.

88
Q

Select the INCORRECT answer:
A. The Kreb’s cycle produces 2 ATP from the oxidation of 1 molecule of glucose.
B. As the Kreb’s cycle progresses clockwise, the negative free energy decreases and the last half of the cycle after Succinate is energy requiring.
C. The energy derived from ETC helps to drive the completion of the energy required to convert Oxaloacetate back to Citrate for another turn of the cycle.
D. The proton motive gradient drives the ETC forward.
E. Ubiquinone (CoQ10) is at Complex IV.

A

E. Ubiquinone (CoQ10) is at Complex IV.

89
Q 
Adipose lipases are activated by all of the following EXCEPT :
A. Epinephrine
B. Glucagon
C. Insulin
D. ACTH
A

C. Insulin

90
Q

Activation of fatty acids involve the following except:
A. LInking of the CoA to each fatty acid by an acyl CoA synthase enzyme
B. The cost of one ATP
C. Activation occurs in the cytosol.
D. Allows fatty acids to be stored as fatty acid Acyl CoA.

A

D. Allows fatty acids to be stored as fatty acid Acyl CoA.

91
Q

Regarding Beta-oxidation and fatty acid synthesis, select the FALSE statement:
A. More energy is derived from saturated than unsaturated fatty acids of equal carbon length.
B. NADPH is an essential reducing equivalent for fatty acid SYNTHESIS.
C. Biotin and B12 are co-factors required for beta-oxidation of ODD-CHAINED fatty acids.
D. Beta-oxidation of even numbered chained fatty acids require B2 (FAD+) B3 (NAD+) and Biotin as cofactors

A

D. Beta-oxidation of even numbered chained fatty acids require B2 (FAD+) B3 (NAD+) and Biotin as cofactors

92
Q

During long-term fasting:
A. Insulin rises continuously
B. Glucose levels start to fall after 30 days
C. Beta-hydroxybutyrate levels rise higher than free fatty acids or acetoacetate.
D. Glucagon levels will fall.

A

C. Beta-hydroxybutyrate levels rise higher than free fatty acids or acetoacetate.

93
Q

Which is (are) true?
A. The liver can convert glucose to triglycerols.
B. Glucagon inhibits glycogenesis.
C. Insulin favors liopgenesis.
D. Citrate is the most important regulatory factor for DE NOVO fatty acid synthesis.
E. All are True

A

E. All are True

94
Q

Regarding glycerol:
A. It is produced by triaglycerol hydrolysis via hormone-sensitive lipase.
B. Insulin signals trigylceride synthesis from gylcerol and fatty acids.
C. Glycerol kinase is only found in the liver, and not in the muscle.
D. It represents a connection between carbohydrate and lipid metabolism.
E. All of the above are true.

A

A. It is produced by triaglycerol hydrolysis via hormone-sensitive lipase.

95
Q

Which is true?
A. The first step of the activation of fatty acids is attaching carnitine.
B. Medium chain fatty acids do not require carnitine to enter the mitochondria.
C. Lipolysis is inhibited by hormones such as epinephrine and glucagon.
D. The target enzyme for statin drugs is triaglyceride lipase

A

B. Medium chain fatty acids do not require carnitine to enter the mitochondria.

96
Q

Which statement is false?
A. The formation of Malonyl CoA is the committed step in fatty acid synthesis .
B. Glycerol-3-P is the link between excess carbohydrate intake and triglyceride formation and storage.
C. HMGCoA reductase is inhibited by the cholesterol-lowering statin drugs, thus decreasing cholesterol synthesis.
D. Fatty acid beta-oxidation occurs in the cytosol.

A

D. Fatty acid beta-oxidation occurs in the cytosol.

97
Q

Which statement is TRUE?
A. During DNA synthesis, the tri-nucleotides, provide two phosphates that are removed to supply the energy needed for the synthesis.
B. RNA contains our genetic code that is passed on to offspring.
C. RNA is double stranded.
D. The DNA length in human is much shorter than in prokaryotic organisms.

A

A. During DNA synthesis, the tri-nucleotides, provide two phosphates that are removed to supply the energy needed for the synthesis.

98
Q

Which statement is false?
A. The carbons of the purines and pyrmidines are derived from the carbon dioxide, amino acids, and from vitamin derivatives.
B. There is no base pairing with a complementary strand in RNA
C. The ribose in RNA contains an OH group on Carbon #2 position. Otherwise, the sugars (pentoses) are the same in DNA.
D .Whereas DNA contains the G, C, A, and U nitrogen bases and RNA contains G, C, A, and T

A

D .Whereas DNA contains the G, C, A, and U nitrogen bases and RNA contains G, C, A, and T

99
Q

Select the FALSE statement:
A. The Pyrimidine base, thymine is in the DNA
B. Thymine is replaced by uracil (U) in RNA
C. U is complementary to A in RNA, just the way G is complementary to C in DNA.
D. RNA sugar is deoxyribose

A

D. RNA sugar is deoxyribose

100
Q 
What holds the two neucleotide strands of DNA together?
A. Covalent bonds
B. Hydrogen bonds
C. Magnesium
D. Manganese
A

B. Hydrogen bonds

101
Q 
Clover shaped:
A. mRNA
B. tRNA
C. rRNA
D. none of the above
A

B. tRNA

102
Q

Which is true?
A. RNA polymerase synthesize new RNA in their 5’ to 3’ direction
B. mRNA will be read in quadruplets
C. Promoter sites with a TATAAA consensus sequence is called the CAAT box
D. There is no U in RNA

A

A. RNA polymerase synthesize new RNA in their 5’ to 3’ direction

103
Q

Which is true?
A. Poly-A tails is unique to mRNA
B. mRNA acts as a messenger transporting the information in the gene in DNA
C. RNA polymerases need: a template, activated precursors, and Mag++/or Mn++
D. All are true

A

D. All are true

104
Q

Which statement is TRUE?
A. TATA boxes are signals which genes are transcribed.
B. Codon UAA and UAG are codon stop signals.
C. mRNA will be translated in the 5’ to 3’ direction of the mRNA
D. mRNA is read in triplets called codons.
E. All are true

A

E. All are true

105
Q

Which is FALSE regarding the urea cycle?
A: both carbamoyl phosphate and L-Citrulline are produced within the mitochondria
B: urea is formed early in the urea cycle before L-aspartate enters the cycle
C: L-ornithine and L-Citrulline can be found in the cytosol and mitochondria
D: the urea cycle is endothermic requiring some ATP to be utilized

A

B: urea is formed early in the urea cycle before L-aspartate enters the cycle

106
Q

AA are conected with what type of bond?

Disulfide
Peptide
Hydrogen

A

Peptide

107
Q

How many AA are essential and must come from the diet?

A

9

108
Q

What is the sugar in DNA?hint d

A

Deoxyribose

109
Q

Monosaccharides are the simplest sugars, what are they? Hint fruit

A

Glucose
Fructose
Galactose

110
Q

Define chirality

A

Central carbon has 4 different groups attached.

111
Q

What metabolic pathways occur in the cytoplasm?

A

glycolysis and fermentation

112
Q

What is gluconeogenesis?

A

the synthesis of glucose from non-carbohydrate substances. Occurs in the liver (kidney also)

113
Q

What is glycogenolysis?

A

Degradation of glycogen to produce glucose.

114
Q

What is glycogenesis?

A

Synthesis of glycogen

115
Q

Main anabolic hormone of the body?

A

Insulin

116
Q

Main catabolic hormone of the body?

A

Define glucagon

117
Q

What is beta-oxidation?

A

the catabolic process by which fatty acid molecules are broken down in the mitochondria to generate acetyl-CoA, which enters the CAC, and NADH and FADH2, which are co-enzymes used in the electron transport chain to form energy.

118
Q

With regard to the different forms of water in the cell, which is not true?

  1. water at the surface of a protein can bare on how much of a particular ion binds to that protein
  2. sodium and potassium both being positive would be expected to bind to a proteins surface to the same degree
  3. water is responsible, at least in part, for formation of microenvironments within the cell
  4. the high specific heat of water helps maintain body temperature in cases where some of the heat energy that is produced from a biochemical reaction (and that is not used for driving other biochemical reactions) is given off as heat
  5. the ATP-requiring sodium/potassium pump only partly explains the partitioning of sodium and potassium outside and inside the cell membrane, respectively
A
  1. sodium and potassium both being positive would be expected to bind to a proteins surface to the same degree
119
Q

A _____ inhibitor diminishes the rate of catalysis by reducing the proportion of enzyme molecules bound to a substrate.

A

Competitive

120
Q 
The best theoretical cure for sickle cell anemia would be:
A. bone marrow transplants
B. gene replacement therapy
C. transfusions
D. all of the above are equally viable
A

B

121
Q

Regarding turnover number of an enzyme:
A. carbonic anhydrase is one of the fastest enzymes in the cell
B. digestive enzymes would tend to have lower turnover numbers, because the digestive process must not proceed too quickly, or absorption of nutrients would be theoretically be impaired
C. as long as the concentration of active sites of an enzyme are known, then the Vmax reveals the turnover number of that enzyme
D. all of the above are true

A

D. all of the above are true

122
Q

What is the use of NADPH produced in HMP? Is it used in anabolic or catabolic reactions?

A

1) Fatty acid and steroid synthesis

2) Anabolic reactions

123
Q

What two pathways is Biotin involved in?

A

Fatty acid synthesis and gluconeogenesis

124
Q

In _______ inhibition, the inhibitor binds only to the ES (substrate) complex.

A

Noncompetitive

125
Q

In ______ inhibition the substrate and the inhibitor can bind simultaneously to the enzyme at different locations.

A

Noncompetitive

126
Q

A low Km value means that the enzyme has a [high/low] affinity for the substrate.

A

High

127
Q

A _______(or proenzyme) is an inactive enzyme precursor hint z

A

Zymogen

COMP EXAM 2022 (15 decks)

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