MCQ Flashcards by Niamh O'Grady

ATP can be generated from ADP + Pi (inorganic phosphate)
by coupling to a highly favourable reaction
by hydrolysis
by enzymes called isomerases
through the reduction of fats and carbohydrates

by coupling to a highly favourable reaction

How well did you know this?

Not at all

Perfectly

The oxidation of food releases energy because
carbon-oxygen bonds become reduced
carbon dioxide goes into the atmosphere and causes global warming
catabolism builds up complex molecules from simple precursors
carbon-hydrogen bonds become oxidized

carbon-hydrogen bonds become oxidized

How well did you know this?

Not at all

Perfectly

NADH (nicotinamide adenine dinucleotide hydride)
is not involved in glycolysis
serves as a hydride carrier
is required for isomerization reactions
is an enzyme

serves as a hydride carrier

How well did you know this?

Not at all

Perfectly

Why is energy input required for the reaction of ADP + Pi (inorganic phosphate) to form ATP?
a carbon atom in ADP must be reduced to form ATP and this requires energy
a high-energy phosphoric anhydride bond is formed
the reaction is spontaneous and does not require energy input
energy is required only if no enzyme is available to catalyze the reaction

a high-energy phosphoric anhydride bond is formed

How well did you know this?

Not at all

Perfectly

What is the yield from glycolysis of one glucose molecule?

2 ATP + 2 NADH
1 ATP + 2 NADH
2 ATP + 1 NADH
1 ATP + 1 NADH

2 ATP + 2 NADH

How well did you know this?

Not at all

Perfectly

The enzyme hexokinase accomplishes energy coupling by
hydrolyzing ATP completely to ADP + Pi
converting lactate to pyruvate in the liver
concerted transfer of a high-energy phosphate group from ATP to glucose
transferring a hydride ion to NAD+

concerted transfer of a high-energy phosphate group from ATP to glucose

How well did you know this?

Not at all

Perfectly

Glycolysis
has a net positive DG
includes two steps where ATP is consumed, not produced
creates an end product, pyruvate, which cannot be metabolized further
converts 2 three-carbon sugars into 1 six-carbon product

includes two steps where ATP is consumed, not produced

How well did you know this?

Not at all

Perfectly

In stage 1 of glycolysis (steps 4 and 5)
lactate is produced
two ATP molecules are produced per glucose molecule
a six-carbon sugar is cleaved to 2 three-carbon products
one intermediate, DHAP (dihydroxyacetonephosphate), cannot be salvaged

a six-carbon sugar is cleaved to 2 three-carbon products

How well did you know this?

Not at all

Perfectly

The enzyme PFK (phosphofructokinase)
is unaffected by ATP levels
processes a metabolite in glycolysis without involvement of ATP
catalyzes a step in glycolysis that harvests energy
catalyzes the first committed step in glycolysis

catalyzes the first committed step in glycolysis

How well did you know this?

Not at all

Perfectly

Muscle converts pyruvate to lactate
under aerobic conditions (ample oxygen)
by a 10-step pathway
by a reaction that consumes ATP
to regenerate NAD+

to regenerate NAD+

How well did you know this?

Not at all

Perfectly

The last step of glycolysis, the conversion of PEP (phosphenolpyruvate) to pyruvate,
occurs only in muscle
is accompanied by oxidation of NADH to NAD+
has a positive DG of +14.8 kcal/mol
releases energy that is coupled to drive formation of ATP

releases energy that is coupled to drive formation of ATP

How well did you know this?

Not at all

Perfectly

Metabolic regulation of glycolysis
is favored by exactly the same factors as in gluconeogenesis
requires that every step of the pathway is carefully controlled
does not change in resting muscle compared to exercising muscle
includes feedback inhibition by ATP

includes feedback inhibition by ATP

How well did you know this?

Not at all

Perfectly

Gluconeogenesis
generates energy
occurs in the liver
utilizes exactly the same steps as glycolysis, just in reverse
is not regulated

occurs in the liver

How well did you know this?

Not at all

Perfectly

During arduous exercise
glucose travels from the liver to the muscle where it is converted to lactate
liver utilizes glycolysis to generate ATP
muscle cells synthesize glucose from pyruvate
energy production in cardiac muscle occurs solely by glycolysis

glucose travels from the liver to the muscle where it is converted to lactate

How well did you know this?

Not at all

Perfectly

A type of reaction unique to gluconeogenesis compared to glycolysis is
isomerization between DHAP (dihydroxyacetone phosphate) and GAP (glyceraldehyde-3-phosphate)
decarboxylation of pyruvate to acetaldehyde, releasing CO2 bubbles
hydrolysis of phosphosugars
phosphorolysis to generate G-1-P (glucose-1-phosphate)

hydrolysis of phosphosugars

How well did you know this?

Not at all

Perfectly

The conversion of pyruvate to PEP (phosphoenolpyruvate)

does not require energy input
occurs in two steps to overcome a steep energy barrier
is a direct reversal of the opposite reaction, PEP to pyruvate
is free from metabolic regulation

occurs in two steps to overcome a steep energy barrier

How well did you know this?

Not at all

Perfectly

Glycogen
is a linear (unbranched) polymer of glucose units
is found in trace amounts in skeletal muscle
can be extended or degraded from the ends of the chain
is found in trace amounts in liver cells

can be extended or degraded from the ends of the chain

How well did you know this?

Not at all

Perfectly

The chemical linkages holding glucose units in glycogen
are exactly the same for every single glucose unit
cannot be broken by phosphorolysis
are different in end units compared to branch points
include peptide bonds

are different in end units compared to branch points

How well did you know this?

Not at all

Perfectly

Glycogen breakdown
uses phosphorolysis to release glucose-1-phosphate units
returns unmodified glucose to the glycolytic pathway
does not require debranching activity
uses hydrolysis to break the chain at any location

uses phosphorolysis to release glucose-1-phosphate units

How well did you know this?

Not at all

Perfectly

Glycogen synthesis includes
removal of an end glucose unit by phosphorolysis
hydrolysis of G-1-P (glucose-1-phosphate) to glucose
phosphorylation of F-6-P (fructose-6-phosphate) to F-1,6-BP (fructose-1,6-bisphosphate
activation of glucose-1-phosphate to UDP-glucose

activation of glucose-1-phosphate to UDP-glucose

How well did you know this?

Not at all

Perfectly

Which statement about NADH is FALSE?
a) It is a coenzyme derived from a B vitamin
b) It serves as a hydride carrier
c) NADH stands for nicotinamide adenine dinucleotide hydride
d) Once used up, NADH is not regenerated

d) Once used up, NADH is not regenerated

How well did you know this?

Not at all

Perfectly

Step 4 of glycolysis involves cleavage of fructose-1,6-bisphophate (F-1,6-BP) into what
products?
a) glucose-6-phospate (G-6-P) and ADP
b) 1,3-bisphosphoglycerate (1,3-BPG) plus NADH
c) 3-phosphoglycerate (3-PG) plus ATP
d) glyceraldehyde-3-phosphate (GAP) plus dihydroxyacetone phosphate (DHAP)

d) glyceraldehyde-3-phosphate (GAP) plus dihydroxyacetone phosphate (DHAP)

How well did you know this?

Not at all

Perfectly

Which of these is NOT a feature of phosphorylation of glucose to glucose-6-phosphate (G-
6P)?
a) traps glucose inside the cell
b) does not require energy investment from ATP
c) is catalyzed by the enzyme hexokinase
d) utilizes energy coupling to drive the reaction forward

b) does not require energy investment from ATP

How well did you know this?

Not at all

Perfectly

Why does PEP (phosphoenolpyruvate) have such a high phosphoryl-transfer potential?
a) Because of the negative charges
b) Three carbon molecules are favored in glycolysis
c) The phosphoryl group traps PEP in an unstable form
d) The transfer potential is only average for phosphoryl transfer, not high

c) The phosphoryl group traps PEP in an unstable form

How well did you know this?

Not at all

Perfectly

Glycogen a) is an unbranched polymer of glucose units b) is found in trace amounts in liver cells c) can be accessed only at the ends of the chain by metabolic enzymes d) is formed primarily when glucose is scarce

c) can be accessed only at the ends of the chain by metabolic enzymes

During photosynthesis the light harvesting reactions takes place ... a. in two steps using two different photosystems, photosystem I and II. b. in chloroplast using ATP and NADPH. c. in chloroplasts using photosystem I, mitochondrial ATP synthase plus light for its reactions. d. in chloroplasts using photosystem II alone but not photosystem I.

a. in two steps using two different photosystems, photosystem I and II.

The step at which acetyl CoA enters the citric acid cycle is classified as a _________________ reaction. condensation decarboxylation dehydrogenation substrate level phosphorylation

condensation

In photosynthesis, the formation of ATP is a/an _________________ reaction in plants dark anaerobic light dependent light independent

light dependent

Conversion of a-Ketoglutarate to Succinyl CoA by the a-ketoglutarate dehydrogenase complex requires the cofactors ….. FAD, NADP+ and lipoic acid Thiamine pyrophosphate, FAD and lipoic acid Thiamine pyrophosphate, FAD and NADP+ Thiamine pyrophosphate, NADP+ and lipoic acid

Thiamine pyrophosphate, FAD and lipoic acid

ATP synthase is located in the ____________________ of the mitochondrion. intermembrane space inner membrane outer membrane matrix

inner membrane

What is the main role of the reaction catalysed by rubisco (Ribulose-1,5-bisphosphate carboxylase/oxygenase) in the Calvin cycle? To produce ribose 5-phosphate To fix CO2 To produce ATP To split water

to fix CO2

Which citric acid cycle enzyme catalyses the conversion of citrate to isocitrate? aldolase aconitase citrate isomerase citrate synthase

aconitase

Which complex of the electron transport chain does not directly contribute to the proton gradient and thus ATP production? Complex II Complex I Complex III Complex IV

Complex II

The production of O2 from water supplies an electron first for __________________________________. cytochrome bf complex plastocyanin photosystem I photosystem II

photosystem II

Which of the following is not an electron transfer complex? Complex IV Complex III Complex I Complex VI

complex VI

The site of the light-dependent reactions in the chloroplast is ____________________. the stroma the thylakoids the outer membrane the lumen

the thylakoids

The mitochondrial ATP synthase consist of two essential elements: a proton channel and a multisubunit enzymatic centre a heme group and iron protein subunits and RNA lipids and carbohydrates

a proton channel and a multisubunit enzymatic centre

Which of the following molecules is not a product of the citric acid cycle? lactate isocitrate succinyl-CoA CO2

lactate

The products of the oxidative decarboxylation reaction of pyruvate by pyruvate dehydrogenase are: ATP, NADPH, Acetyl-CoA H2O, NADPH, Acetyl-CoA CO2, NADH, Acetyl-CoA H2O, NADH, Acetyl-CoA

CO2, NADH, Acetyl-CoA

Which of the following enzymes has a prosthetic group that has a direct role in the citric acid cycle and the electron transport chain … Succinyl-CoA + GDP + Pi to Succinate + GTP + CoA-SH Phosphoenylpyruvate + GDP + Pi to Pyruvat + GTP 1,3 Biphospho-glycerate + GDP + Pi to 3 Phospho-glycerate + GTP Fumarate + GDP + Pi to Malate + GTP

Succinyl-CoA + GDP + Pi to Succinate + GTP + CoA-SH

In the citric acid cycle the reaction from isocitrate to α-ketogluterate is a/an ________ reaction, which produces _______. reductive isomeration; NADPH and H2O oxidative decarboxylation; NADH and CO2 oxidoreduction; NADPH and H2O oxidative decarboxylation; NADH and H2O

oxidative decarboxylation; NADH and CO2

The ATP-Synthase in chloroplasts is a component of __________________ . the outer membrane the inner membrane the thylakoid membrane the intermembrane space

the thylakoid membrane

During photosynthesis in plant chloroplasts, electrons are transferred from ........ to Photosystem I a. Plastocyanin. b. Cytochrome bf complex. c. Plastoquinone. d. NADP+.

a. Plastocyanin.

The first step of the citric acid cycle involves ... a. A condensation reaction between Oxaloacetate and Citrate b. An oxidation reaction of Malate to form Oxaloacetate c. Hydration of Fumarate to Malate d. A condensation reaction between Oxaloacetate and Acetyl CoA

d. A condensation reaction between Oxaloacetate and Acetyl CoA

The formation of -Ketogluterate from Isocitrate is regulated by ... a. NADH and FAD b. ATP and NADPH c. Acetic Acid and ATP d. ATP and NADH

d. ATP and NADH

What does the term ‘chemiosmotic coupling’ mean? a. A pH gradient across the endoplasmatic reticulum membrane exists and is used to synthesise ATP. b. A pH gradient across the inner mitochondrial membrane exists and is used to synthesise ATP. c. A voltage gradient across the outer mitochondrial membrane exists and is used to synthesise NADPH. d. The photosynthesis in chloroplast and the ATP synthesis in mitochondria are coupled by a voltage gradient.

b. A pH gradient across the inner mitochondrial membrane exists and is used to synthesise ATP.

The Electron Transfer Complex II transfers electrons to ... a. Cytochrome C. b. Electron Transfer Complex I. c. Ubiquinone. d. Water.

c. Ubiquinone.

The Pyruvate Dehydrogenase complex contains ... a. Lactate dehydrogenase b. Dihydrolipoyl transacetylase c. Pyruvate kinase d. Dihydrolipoyl transaldolase

b. Dihydrolipoyl transacetylase

During the generation of Acetyl-CoA from Pyruvate, by the Pyruvate Dehydrogenase complex, Dihydrolipoamide is oxidised to Lipoamide by ... a. Lipoic acid b. Thiamine pyrophosphate c. NADH d. FAD

d. FAD

The hydrolysis of ATP to ADP + Pi a) requires coupling to a highly favourable reaction b) has a positive ΔG c) involves NAD+ d) releases energy by breaking a high-energy bond

d) releases energy by breaking a high-energy bond

Oxidation of fats releases more energy than oxidation of carbohydrates because a) the carbon atoms in carbohydrates are partially oxidized to start with b) there are more oxygen atoms per molecule of fat than in carbohydrate c) the carbon atoms in fats are fully oxidized to start with d) carbohydrates cannot be oxidized

a) the carbon atoms in carbohydrates are partially oxidized to start with

The phosphorylation of glucose to glucose-6-phosphate (G-6P) a) is accompanied by formation of NADH b) prevents that glucose molecule from being stored as glycogen c) is catalyzed by an enzyme called an isomerase d) traps the glucose inside the cell

d) traps the glucose inside the cell

Steps 1-3 of glycolysis convert glucose to fructose-1,6-bisphosphate (F-1,6-BP). These reaction types include a) dehydrogenation, isomerization b) phosphorylation, isomerization c) phosphorylation, dehydration d) cleavage, dehydrogenation

b) phosphorylation, isomerization

The energy yield of glycolysis is doubled a) by hydrolysis of phosphosugars b) by reducing C-O bonds c) by rearranging DHAP to GAP d) solely in the liver

c) by rearranging DHAP to GAP

During glycolysis, the oxidation of the aldehyde group in GAP (glyceraldehyde-3- phosphate) a) is accompanied by production of ATP from ADP + Pi b) is catalyzed by an enzyme called a kinase c) is accompanied by reduction of NAD+ to NADH d) does not change the number of carbon-oxygen bonds

c) is accompanied by reduction of NAD+ to NADH

Glycolysis makes an ATP profit a) by storing glucose into glycogen for later use b) without reduction of NAD+ to NADH c) in step 10, conversion of PEP (phosphoenolpyruvate) to pyruvate d) in step 1, conversion of glucose to G-6P (glucose-6-phosphate)

c) in step 10, conversion of PEP (phosphoenolpyruvate) to pyruvate

Under anaerobic conditions, yeast a) converts pyruvate to ethanol to regenerate NAD+ b) converts pyruvate to lactate in two steps c) stops performing glycolysis d) converts pyruvate to PEP (phosphoenolpyruvate) with energy input

a) converts pyruvate to ethanol to regenerate NAD+

A unique feature of gluconeogenesis compared to glycolysis is a) gluconeogenesis occurs primarily in muscle b) gluconeogenesis begins with glucose and produces pyruvate c) gluconeogenesis is not regulated d) gluconeogenesis costs energy

d) gluconeogenesis costs energy

During extreme conditions such as strenuous exercise, muscle and liver a) both expend energy to synthesize glucose b) both hydrolyze phosphosugars c) cooperate by interconverting pyruvate and lactate d) oxidize glucose aerobically

c) cooperate by interconverting pyruvate and lactate

The overall process of gluconeogenesis can best be described as a) glucose yields energy + reducing power b) pyruvate + energy + reducing power yields glucose c) pyruvate + reducing power yields ethanol + CO2 d) lactate + NAD+ yields pyruvate + NADH

b) pyruvate + energy + reducing power yields glucose

Glycogen breakdown a) releases end units through a reaction called phosphorolysis b) involves hydrolysis of phosphosugars c) does not change any branch points in glycogen d) requires ATP hydrolysis

a) releases end units through a reaction called phosphorolysis

The elongation of fatty acids is a repetition of three reactions adding carbons from _______ after each cycle until completion. a) malonyl CoA b) malonyl ACP c) acetyl CoA d) acetyl ACP

b) malonyl ACP

Fatty acid synthesis is different in bacteria than in eukaryotic cells because: a) bacteria do not form malonyl CoA b) eukaryotes use acetyl CoA to form malonyl CoA c) bacteria do not form acetyl ACP d) bacteria do not form acetoacetyl CoA

c) bacteria do not form acetyl ACP

The first step in fatty acid synthesis is the formation of __ from acetyl CoA and carbon dioxide. a) acetyl ACP b) acetoacetyl ACP c) malonyl CoA d) acetoacetyl CoA

c) malonyl CoA

Which of the following is not a stage of fatty acid synthesis? a) condensation of precursors b) dehydration c) reduction d) isomerisation

d) isomerisation

Linoleate is an essential fatty acid in mammalian diets because mammalian cells: a) synthesize it from arachidonate b) do not use this acid for biosynthesis c) can use it to synthesize eicosanoids d) do not have a desaturase that acts beyond the carbon-9 position

d) do not have a desaturase that acts beyond the carbon-9 position

Phosphatidate is an intermediate in the synthesis of _____ . a) triacylglycerols and glycerophospholipids b) glycerophospholipids only c) sphingolipids d) cholesterol

a) triacylglycerols and glycerophospholipids

Which of the following is a true statement, concerning HMG-CoA reductase? a) It is regulated by covalent modification of a serine in its active site. b) It catalyzes the first committed step in cholesterol biosynthesis. c) It causes the production of NADPH. d) The product of the reaction it catalyzes is acetoacetyl CoA.

b) It catalyzes the first committed step in cholesterol biosynthesis.

Cholesterol is a precursor for each of the following, except a) bile salts. b) vitamin D. c) testosterone. d) vitamin C

d) vitamin C

Which lipid form is transported across the inner mitochondrial membrane before β-oxidation? a) acylcarnitine b) fatty acyl CoA c) acetoacetyl CoA d) lysophospholipid CoA

a) acylcarnitine

Fatty acids are oxidized in the ______ . a) mitochondrial matrix b) cytosol c) endoplasmic reticulum d) mitochondrial inner membrane space

a) mitochondrial matrix

What is the fate of most glycerol that is released during the hydrolysis of triacylglycerols from adipocytes? a) It is transported to the kidneys and excreted in the urine. b) It is used in the synthesis of sphingolipids. c) It is converted to glucose via gluconeogenesis in the liver. d) It is absorbed by the chylomicrons.

c) It is converted to glucose via gluconeogenesis in the liver.

The main function of the bile salts is to _____. a) transport lipids to the intestinal wall b) act as counterions for the ionized forms of lipids c) cleave the ester bonds in triacylglycerols to release free fatty acids d) form the surface layer of chylomicrons

a) transport lipids to the intestinal wall

The largest lipoproteins are the a) chylomicrons b) VLDLs c) LDLs d) HDLs

a) chylomicrons

Which do you expect to have the highest protein content by percent? a) VLDLs b) IDLs c) HDLs d) All of the lipids above have about the same protein content

c) HDLs

Which is not a ketone body? a) dihydroxyacetone b) acetoacetate c) acetone d) β-hydroxybutyrate

a) dihydroxyacetone

The disease phenylketonuria (PKU) is caused by defect in ………. breakdown urea alpha-ketoglutarate phenylalanine tyrosine

phenylalanine

With regard to the individual reactions of the urea cycle, which of the following is correct? arginine is formed from citrulline citrulline is formed from ornithine argininosuccinate is formed from ornthine ornithine is formed from citrulline

citrulline is formed from ornithine

Which of the following compounds does not serve as an intermediate for the entry of amino acid carbon chains into the TCA (citric acid) cycle? fumarate glyceraldehyde oxaloacetate alpha-ketoglutarate

glyceraldehyde

Which best describes the synthesis of purine nucleotides? The basic ring structure, orotate, is synthesised stepwise on ribose. This is then modified to produce either GMP or AMP The basic ring structure, inosine, is synthesised first and then linked to glucose. This is then modified to produce ATP The basic ring structure, orotate, is synthesised first and then linked to ribose. This is then modified to produce either UMP or CMP The basic ring structure, inosine, is synthesised stepwise on ribose. This is then modified to produce either GMP or AMP

The basic ring structure, inosine, is synthesised stepwise on ribose. This is then modified to produce either GMP or AMP

Which one of the following is associated with pyrimidine synthesis? Synthesis of the base while ribose is attached Attachment of ribose after the base is synthesised Formation of ATP Use of glycine as a precursor

Attachment of ribose after the base is synthesised

Which amino acid is the precursor of dopamine, norepinephrine and epinephrine? glycine lysine arginine tyrosine

tyrosine

Where does the urea cycle primarily occur? the mitochondrial inner membrane and cytosol of the kidney cell the mitochondrial inner membrane and cytosol of the liver cell the mitochondrial inner membrane and matrix of the liver cell the mitochondrial matrix and cytosol of the liver cell

the mitochondrial matrix and cytosol of the liver cell

Dihydrofolate reductase and thymidylate synthetase are major targets for anticancer drugs because: these enzymes are not present in cancer cells cancer cells are very dependent upon the activities of these enzymes these enzymes are unique to cancer cells these enzymes donate one-carbon group

cancer cells are very dependent upon the activities of these enzymes

The two nitrogens in urea arise directly from: lysine and aspartate ammonia and ATP arginine and glutamate ammonia and aspartate

ammonia and aspartate

In the process of amino acid degradation, the enzyme glutamate dehydrogenase catalyses the: conversion of glutamate and ammonia to glutamine conversion of glutamine to glutamate and ammonia conversion of glutamate to α-ketoglutarate and ammonia conversion of isocitrate to α-ketoglutarate

conversion of glutamate to α-ketoglutarate and ammonia

Transamination reactions require which coenzyme? TPP FMN ATP PLP

PLP

If an amino acid is glucogenic, it will not be degraded to ________. oxaloacetate fumarate pyruvate acetoacetate

acetoacetate

In amino acid catabolism the α-amino groups are initially released as ________. glutamine nitrous oxide ammonium ion nitrate ion

ammonium ion

Which amino acids are purely ketogenic? valine and isoleucine arginine and glutamine lysine and leucine all essential amino acids

lysine and leucine

Which statement(s) apply to urea? All of the above highly soluble in water produced in the liver compound used as a means of removing excess nitrogen

All of the above

________ is hydrolytically cleaved to directly yield urea in the urea cycle. Glutamate Ornithine Arginine Carbamoyl phosphate

Arginine

The first nucleotide product in the de novo biosynthetic pathway of purines is XMP. IMP. GMP. AMP.

IMP.

Which amino acid is not directly involved in the de novo synthesis of purines? glutamine arginine aspartate glycine

arginine

The conversion of UTP to CTP involves ________. addition of a ribose sugar oxidation of an OH group transfer of an NH2 group hydrolysis of a phosphate group

transfer of an NH2 group

High levels of ________ will almost totally inhibit the rate-limiting enzyme in pyrimidine biosynthesis. CTP and UTP ADP and UDP GMP and IMP ATP and GTP

CTP and UTP

Why are triacylglycerols able to provide more energy than carbohydrates? The triacylglycerols have an extremely high group transfer potential. The carbohydrates are already in a more oxidized state than the triacylglycerols. The carbohydrates contain fewer carbon-carbon bonds. The triacylglycerols are less soluble in water than the carbohydrates

The carbohydrates are already in a more oxidized state than the triacylglycerols.

What is the main function of the carnitine shuttle system? To transport fatty acids into the mitochondrion. To transport newly synthesized sphingolipids to the blood. To carry cholesterol from its site of synthesis in the endoplasmic reticulum to the plasmamembrane. To aid in the assembly of chylomicrons.

To transport fatty acids into the mitochondrion.

Fatty acids are oxidized in the mitochondrial inner membrane space endoplasmic reticulum cytosol mitochondrial matrix

mitochondrial matrix

What is the correct order of function of the following enzymes of β-oxidation? 1. β-hydroxyacyl-CoA dehydrogenase 2. thiolase 3. enoyl-CoA hydratase 4. acyl-CoA dehydrogenase 1,2,3,4 3,1,4,2 4,2,3,1 4,3,1,2

4312

How many cycles of β-oxidation are required to completely process a saturated C18 fatty acid? 8 9 18 6

How many ATP equivalents approximately are produced in the conversion of the fatty acid palmitate (C16) to carbon dioxide via β-oxidation, the citric acid cycle and oxidative phosphorylation? 3 32 106 800

106

Which enzyme is needed for the oxidation of odd-chain saturated fatty acids that is not needed for even-chain fatty acids? methylmalonyl-CoA mutase propionyl-CoA carboxylase methylmalonyl-CoA racemase proprionyl-CoA mutase

propionyl-CoA carboxylase

A fatty acid with an odd number of carbons will enter the citric acid cycle as acetyl CoA and .........._______________ α-ketoglutarate succinyl-CoA malate citrate

succinyl-CoA

Which of the following molecules is not specifically required in the synthesis of fatty acids? Biotin Acetyl-CoA Malonyl-CoA NADH

NADH

The rate limiting step of fatty acid synthesis is.......... formation of acetyl-CoA the reaction catalysed by acetyl-CoA carboxylase condensation of acetyl-CoA and malonyl-CoA the formation of malonyl-CoA from malonate and coenzyme A.

the reaction catalysed by acetyl-CoA carboxylase

Which of the following is not true of fatty acid elongation system of vertebrate cells? It involves the same four-step sequence seen in fatty acid synthase complex. It uses malonyl-CoA as a substrate. The immediate precursor of the added carbons is acetyl CoA. It produces steroyl-CoA by extension of palmitoyl-CoA.

The immediate precursor of the added carbons is acetyl CoA

Cholesterol is synthesized from Acetyl-CoA Malate Oxalate Choline

Acetyl-CoA

A 30-carbon precursor of the steroid nucleus is Isopentyl pyrophosphate Squalene geranyl pyrophosphate farnesyl pyrophosphate

Squalene

Isopentenyl pyrophosphate is the precursor for which of the following? quinones ketones lactones phospholipids

quinones

Linoleate is an essential fatty acid in mammalian diets because mammalian cells...... synthesize it from arachidonate. do not use this acid for biosynthesis. can use it to synthesize eicosanoids. do not have a desaturase that acts beyond the carbon-9 position

do not have a desaturase that acts beyond the carbon-9 position

Drugs called statins lower cholesterol levels because they……. degrade HMG-CoA reductase bind serum cholesterol inhibit HMG-CoA reductase bind bile salts

inhibit HMG-CoA reductase

Most lipids in the average human diet are……. unsaturated fatty acids. triacylglycerols. glycerophospholipids. saturated fatty acids.

triacylglycerols

Elevated levels of which hormone stimulates the conversion of triacylglycerols stored in adipose cells to free fatty acids and monoacylglycerols to provide energy when carbohydrate stores are depleted? insulin glucagon ergosterol epinephrine

epinephrine

In amino acid degradation, the first reaction for many amino acids is: a) Decarboxylation requiring thiamine pyrophosphate (TPP) b) Transamination requiring pyridoxal phosphate (PLP) c) Hydroxylation requiring nicotinamide adenine dinucleotide phosphate (NADPH) d) Oxidative deamination requiring nicotinamide adenine dinucleotide (NAD+)

b) Transamination requiring pyridoxal phosphate (PLP)

In the process of amino acid degradation, the enzyme glutamate dehydrogenase catalyses the: a) Conversion of glutamate to α-ketoglutarate and ammonia b) Conversion of glutamate and ammonia to glutamine c) Conversion of glutamine to glutamate and ammonia d) Conversion of α-ketoglutarate and ammonia to glutamate

a) Conversion of glutamate to α-ketoglutarate and ammonia

Haem synthesis requires which two precursors: a) Glycine and succinyl CoA b) Alanine and acetyl CoA c) Glycine and acetyl CoA d) Alanine and succinyl CoA

a) Glycine and succinyl CoA

Which of the following is not associated with pyrimidine synthesis? a) An orotic acid intermediate b) Stimulation of synthesis by purines c) Synthesis of the base while ribose is attached d) Inhibition by pyrimidines

c) Synthesis of the base while ribose is attached

The first committed step (rate-limiting step) in purine biosynthesis is: a) IMP formation b) Phosphoribosylpyrophosphate formation c) AMP formation d) Phosphoribosylamine formation

d) Phosphoribosylamine formation

What is the source of the ribose sugar in purine nucleotides? a) ATP b) PRPP c) AMP d) Glucose

b) PRPP

Which best describes the synthesis of purine nucleotides? a) The basic ring structure, inosine, is synthesised first and then linked to ribose. This is then modified to produce either GMP or AMP b) The basic ring structure, orotate, is synthesised stepwise on ribose. This is then modified to produce either GMP or AMP c) The basic ring structure, inosine, is synthesised stepwise on ribose. This is then modified to produce either GMP or AMP d) The basic ring structure, orotate, is synthesised first and then linked to ribose. This is then modified to produce either UMP or CMP

c) The basic ring structure, inosine, is synthesised stepwise on ribose. This is then modified to produce either GMP or AMP

Which is a method by which the synthesis of AMP or GMP is regulated? a) Covalent modification b) Feedback inhibition c) Feed-forward activation d) Competitive inhibition

b) Feedback inhibition

Which sentence best defines signal transduction in a biochemical context? a) Alteration of cell functions in response to the environment b) Generation of a chemical change in response to information c) Induction of cell death upon nutrient starvation d) Responses to stimuli

b) Generation of a chemical change in response to information

Which statement is correct? a) G protein-coupled receptors produce second messengers indirectly while receptor enzymes catalyse second messenger generation b) Second messengers stimulate the activity of G protein-coupled receptors. c) Receptor enzymes produce second messengers through activation of G protein- coupled receptors. d) Receptor enzymes do not catalyse second messenger generation

a) G protein-coupled receptors produce second messengers indirectly while receptor enzymes catalyse second messenger generation

What second messenger is bound by calmodulin? a) cAMP b) cGMP c) Calcium d) Diacylglycerol

c) Calcium

cAMP is degraded by: a) Adenylate cyclase b) ATP c) Cyclic nucleotide phosphodiesterase d) Protein kinase C

c) Cyclic nucleotide phosphodiesterase

G-protein coupled receptors contain: a) Tyrosine kinase activity b) Adenylate cyclase activity c) No cell surface receptor domain d) 7 transmembrane helices

d) 7 transmembrane helices

How can G-protein coupled receptor signalling be turned off? a) Hydrolysis of GTP bound to Gsα b) Activation of adenylate cyclase c) Formation of cAMP d) Hydrolysis of GTP bound to Giα

a) Hydrolysis of GTP bound to Gsα

Phosphatidylinositol 4,5-bisphosphate is converted into inositol 1,4,5- trisphosphate and diacylglycerol by: a) Calmodulin b) Protein kinase C c) Calcium d) Phospholipase C 3

d) Phospholipase C 3

Pertussis toxin: a) Prevents GDP release from Giα, causing increased cAMP synthesis b) Prevents GDP release from Giα, inhibiting adenylate cyclase c) Decreases Gsα binding of GTP, causing increased cAMP synthesis d) Degrades adenylate cyclase

a) Prevents GDP release from Giα, causing increased cAMP synthesis

The β subunit of the insulin receptor: a) Is located on the extracellular side of the membrane b) Binds to insulin c) Contains a tyrosine kinase domain d) Activates Gsα binding of GTP

c) Contains a tyrosine kinase domain

Which of the following statements is true? a) Intracellular [K+] > extracellular [K+] b) Intracellular [Na+] > extracellular [Na+] c) Intracellular [Ca2+] > extracellular [Ca2+] d) Intracellular [Cl-] > extracellular [Cl-]

a) Intracellular [K+] > extracellular [K+]

Which statement is incorrect? a) Na+K+ ATPase maintains a transmembrane electrical potential b) Binding of acetylcholine to its receptor allows the allosteric gating of a Na+ channel c) Binding of acetylcholine to its receptor blocks the opening of a voltage-gated Na+ channels. d) The direction of spontaneous Na+ movement is into the cell

c) Binding of acetylcholine to its receptor blocks the opening of a voltage-gated Na+ channels.

Where is the ligand-binding domain of receptor tyrosine kinases found? a) Within the endoplasmic reticulum b) On the extracellular side of the plasma membrane c) On the cytosolic side of the plasma membrane d) In the nucleus

b) On the extracellular side of the plasma membrane

Activated IRS-1 is bound a) By activated adenylate cyclase b) By the SH2 domain on GRB2 c) By insulin d) By GTP-bound Ras

b) By the SH2 domain on GRB2

Which symptoms are not characteristic of diabetes mellitus? a) Excessive thirst, frequent urination b) Overproduction of ketone bodies c) Inefficient uptake of blood glucose d) Massive fluid and Na+ electrolyte efflux

d) Massive fluid and Na+ electrolyte efflux

Type I (insulin-dependent) diabetes mellitus: a) Is caused by mutations in the gene that encodes the insulin receptor 4 b) Is caused by impaired insulin receptor signalling c) Is caused by insufficient insulin production by the pancreatic β cells d) Is caused by mutations in the gene that encodes IRS-1.

c) Is caused by insufficient insulin production by the pancreatic β cells