Unit 4 Chapters 24, 25, 26, 27

This type of muscle fiber (fast twitch) uses lactic acid fermentation

11b

This type of muscle fiber is rich in glycogen phosphorylase

11b

This type of muscle fiber (slow twitch) uses cellular respiration

1

Acetoacetate spontaneously decarboxylates to form ________________. A) acetone B) acetate C) acetyl CoA D) oxaloacetate

A

Animals are not capable of converting fatty acids into glucose because A. Fatty acid degradation through the citric acid cycle does not lead to a net increase in oxaloacetate. B. They cannot convert acetyl-coenzyme A into pyruvate to initiate the gluconeogenesis pathway. C. Fatty acid degradation does not produce sufficient energy in the form of ATP to drive gluconeogenesis. D. The liver will not have to expend as much energy to produce glucose.

A

Conversion of glucose 1-phosphate to glucose 6-phosphate is carried out by the enzyme: A) phosphoglucomutase. B) kinase 1-P. C) phosphoglycerate mutase. D) All of the above. E) None of the above.

A

Glutathione combats ______________ in the organism. A. ROS B. GSH C. GSSG D. NADPH

A

How is phosphorylase b converted into phosphorylase a? A) through the addition of a phosphate to a serine residue B) through dimerization, which forms the active-site pocket C) through cleavage of 10 amino acids from the N-terminal end of the protein D) All of the above. E) None of the above.

A

Insulin stimulates glycogen synthase by inactivating __________________. A) glycogen synthase kinase B) protein kinase A C) protein phosphatase 1 (PP1) D) glycogen synthase phosphatase

A

The __________________ creates a 1,6-glycosidic bond. A) branching enzyme B) glucose transferase C) glycogen isomerase D) glycogen synthase E) None of the above.

A

The attachment of glucose to UDP (glucose-1-phosphate + UTP ↔ UDP-glucose + pyrophosphate) is a readily reversible reaction. What provides the driving force in favor of the synthesis of UDP-glucose? A. The energy from the subsequent hydrolysis of the pyrophosphate B. The energy from the subsequent transfer of glucose to the growing glycogen molecule C. The hydrolysis of the UDP released during transfer of glucose to the growing glycogen molecule to UMP and phosphate D. The buildup of one of the reaction's substrates, UTP

A

The enzyme transketolase transfers a _________________carbon fragment from a ketose to an aldose. A) two B) four C) three D) five

A

The fact that liver tissue contains glucose-6-phosphatase while muscle tissue does not is physiologically important because A. One of the major functions of the liver is to maintain the blood glucose level. B. The muscle tissue does not use glucose as an energy source. C. Glycogen is found only in the liver and not in muscle tissue D. The liver will not have to expend as much energy to produce glucose.

A

The purpose of the pentose phosphate pathway is to: A) generate NADPH and synthesize five-carbon sugars B) generate ATP C) synthesize fivecarbon sugars D) generate NADPH

A

What is the function of liver glycogen degradation? A) to export glucose to other tissues when glucose levels are low B) to maintain glucose levels after a large meal C) to provide for the large energy needs of the liver D) All of the above. E) None of the above.

A

Which enzyme(s) is/are required to synthesize alpha-1,4-glycosidic bonds in glycogen? A) glycogen synthase B) UDP-glucose phosphorylase C) branching enzyme D) A and B E) B and C

A

Which liver enzyme is deficient in Hers disease? A) phosphorylase B) transferase C) glucosidase D) phosphoglucomutase E) None of the above.

A

Which of the following occur after a carbohydrate-rich meal? A) Blood-glucose levels increase, leading to glycogen storage in the liver. B) Blood-glucose levels increase, leading to glycogen storage in the muscle. C) Glycogen storage in the muscle shuts down. D) All of the above. E) None of the above.

A

_____ initiates breakdown of lipids.

ATGL

. The beta-oxidation of an 18-carbon saturated fatty acid would be expected to yield how many NADH and FADH2 per fatty acid molecule? A. 7 B. 8 C. 9 D. 6

B

ATP is called the energy currency. The currency of reducing power is: A) AMP B) NADPH C) ADP D) NADH

B

An incorrect, tight binding of PP1 to glycogen synthase would result in: A) a hyperactive glycogen synthase. B) hyper-glycogen levels. C) increased insulin action. D) high blood glucose. E) activated glycogen synthase.

B

At the center of a glycogen molecule is: A) glucose. B) glycogenin. C) UDP-glucose. D) glycogen synthase. E) glycogen phosphorylase.

B

Enzymes that digest the triacylglycerols into free fatty acids and monoacylglycerol are called: A) All of the others B) lipases C) glyases D) hydrases

B

Glycogen synthase adds glucose units to growing glycogen molecules using A. Free glucose B. UDP-glucose C. Glucose-1-phosphate D. Glucose-6-phosphate

B

How many rounds of β oxidation would be required for a 16-carbon fatty acyl chain to be degraded to acetyl CoA? A) 15 B) 7 C) 8 D) 16

B

In order for regulation of glycogen metabolism to function, there must also be a means to reverse the regulatory effects of the various kinases. Reversal of kinase activation is accomplished by protein phosphatase 1, an enzyme which A. Transfers the phosphate from a modified enzyme back to ADP. B. Hydrolyzes the phosphate from the modified enzyme. C. Recombines cyclic AMP and pyrophosphate to turn off the signal activating the kinases. D. Inactivates the GTP bound to Gs by hydrolyzing GTP to GDP.

B

The enzyme acyl CoA synthetase catalyzes: A) All of the others B) ATP-dependent activation of fatty acids using CoA C) lipolysis to release free glyceraldehyde D) ATP-dependent reduction prior to activation

B

The key enzyme in glycogen degradation is: A) glycogen phosphatase. B) glycogen phosphorylase. C) glucose 1-phosphate synthase. D) All of the above. E) None of the above.

B

Triacylglycerol stored in adipose tissue is used by the liver and other tissues for: A) glycerol for pyruvate and glucose in liver B) All of the others C) ATP production via the citric acid cycle in muscle D) conversion to acetyl CoA and ketone bodies during starvation for the brain

B

Two critical hormones that signal for glycogen breakdown are: A) insulin and epinephrine. B) glucagon and epinephrine. C) glucagon and insulin. D) All of the above. E) None of the above.

B

Which is the true glucose-level sensor in the cell? A) insulin B) phosphorylase a C) glucagon D) glycogen synthase E) protein phosphatase 1

B

Which of the following is NOT true of acetoacetate and D-3-hydroxybutyrate? A. They can provide energy for brain cells. B. They allosterically modify other enzymes. C. They are produced from the acetyl CoA of fats. D. They share a precursor with cholesterol synthesis.

B

Why is the T state of glycogen phosphorylase less active? A) The adjacent amino acids are not phosphorylated; thus the catalysis cannot be carried out. B) The active site is partially blocked. C) ATP cannot be bound by the T state. D) All of the above. E) None of the above.

B

During a period of exercise, which of the following enzymes will dominate in muscle? A. Phosphorylase b B. Protein phosphatase I C. Glycogen synthase b D. Insulin-linked protein kinases

C

Glucose 6-phosphate dehydrogenase is inhibited by low levels of: A) NADPH B) ribose 5phosphate C) NADP+ D) NADP+ and ribose 5phosphate

C

In eukaryotes, the degradation of fatty acids occurs in the ________________. A) mitochondrial outmembrane B) cytoplasm C) mitochondrial matrix D) endoplasmic reticulum

C

The first phase of the pentose phosphate pathway involves the _________ generation of _________. A. Oxidative; NADH B. Oxidative; FADH2 C. Oxidative; NADPH D. Nonoxidative; NADH

C

The glycogen branching enzyme moves a block of __________________ (or so) glucose residues to from a branch point at least four residues from a preexisting branch. A) two B) three C) seven D) nine

C

The glycogen phosphorylase enzyme carries out a phosphorolysis reaction resulting in the formation of A. Free glucose B. Glucose-6-phosphate C. Glucose-1-phosphate D. Maltose

C

The hormone __________ induces lipolysis, whereas the hormone __________ inhibits the process. A) epinephrine; adrenocorticotropic hormone B) insulin; norepinephrine C) glucagon; insulin D) epinephrine; glucagon

C

The two key components required for growth are _________________ and biochemical reducing power. A) 6 carbon sugars B) galctose sugars C) ribose sugars D) glucose sugars

C

Type I diabetes leads to ______________ in the liver. A) increased glucose transport B) increased glycogen synthesis C) a decrease in fructose 2,6-phosphate D) a decrease in gluconeogenesis E) All of the above.

C

What physiological conditions render phosphorylase b less active? A) high ATP, high AMP, and glucose 6-phosphate levels B) high ATP and low calcium ion levels C) high ATP and high glucose 6-phosphate levels D) All of the above. E) None of the above.

C

Which molecule(s) must be excluded from the active site of glycogen phosphorylase? A) glucose B) glucose 1-phosphate C) water D) All of the above. E) None of the above.

C

Calcium binds and leads to the activation of which enzyme in glycogen degradation? A) phosphorylase B) phosphoglucomutase C) protein kinase C D) phosphorylase kinase E) glycogen phosphorylase

D

Fatty acids are activated by attachment to coenzyme A at the outer mitochondrial membrane, but the resulting fatty acyl-coenzyme A is not degraded until it reaches the mitochondrial matrix. The fatty acyl-coenzyme A A. Freely crosses the inner mitochondrial membrane due to its hydrophobic character. B. Is reconverted to the free fatty acid on one side of the inner mitochondrial membrane, then is reattached to coenzyme A on the other side of the membrane. C. Binds to the inner mitochondrial membrane to facilitate degradation. D. Is transferred to another molecule that is involved in transport of the fatty acid into the mitochondrial matrix.

D

Glucose-6-phosphate can be utilized by either the glycolytic or the pentose phosphate pathway. What is the major factor regulating how the use of glucose-6-phosphate is distributed between these two pathways? A. The ratio of ATP to AMP in the cell B. The different location of the two pathways within the cell C. Allosteric inhibition of the glucose-6-phosphate dehydrogenase enzyme by ATP D. The relative levels of NADP+ and NADPH

D

Glycogen breakdown and synthesis are said to be reciprocally regulated. This means that A. The same effectors affect both processes in the same direction. B. Different effectors control the two processes. C. The effectors control the reactions only at one point. D. The same effectors affect both processes but in opposite directions.

D

Glycogen breakdown can be regulated hormonally when _________ is secreted from the _________. A. Glucagon; pancreas B. Glucagon; adrenal medulla C. Epinephrine; adrenal medulla D. Both A and C

D

In the nonoxidative stage of the pentose phosphate pathway, intermediates of _____________ are produced. A) glycogen degradation B) all of the others C) the citric acid cycle D) glycolysis

D

Muscle phosphorylase is mostly inactive when: A) the enzyme is in the b conformation B) in the R state. C) bound to AMP. D) All of the above. E) None of the above.

D

Possible fates for the glucose 6-phosphate produced during glycogen breakdown include: A. Entering glycolysis B. Entering the pentose phosphate pathway C. Formation of glucose through the action of glucose 6-phosphatase D. All of the above

D

The complete oxidation of a glucose residue from glycogen produces ________________ ATP. A) 28 B) 38 C) 30 D) 31

D

The enzyme that begins the kinase cascade, activating glycogen degradation, is: A) glycogen synthase. B) phosphorylase kinase. C) PKC. D) PKA. E) tyrosine kinase.

D

The major site(s) of glycogen storage is (are): A) adipose tissue. B) liver. C) skeletal muscle. D) B and C. E) A, B, and C.

D

Three rounds of fatty acid oxidation results in: A) the complete oxidation of palmitate B) the formation of enoyl CoA C) two acetyl CoA molecules D) three acetyl CoA molecules

D

Under what conditions might the pentose phosphate pathway produce large amounts of NADPH without significant net production of ribose 5-phosphate? A) All of the others B) when pyruvate is synthesized to generate ATP C) when cells are rapidly dividing D) synthesis of fatty acids in the liver

D

Which biosynthetic pathway requires NADPH? A) nucleotide B) cholesterol C) fatty acid D) All of the others

D

Which enzyme(s) is/are required to synthesize α-1,4-glycosidic bonds in glycogen? A) branching enzyme B) UDP-glucose phosphorylase C) glycogen synthase and branching enzyme D) glycogen synthase

D

______________ results from a loss or inactivation of insulin receptors. A) Hypoglycemia B) Hyperinsulinemia C) Type I diabetes D) Type II diabetes E) None of the above.

D

After exercise, muscle cell glycogen metabolism is regulated by: A) insulin. B) phosphorylase a. C) glucagon. D) glycogen synthase. E) protein phosphatase 1.

E

Glycogenin: A) consists of dimmer proteins. B) self-assembles eight glycosyl units. C) is the primer for glycogen synthase. D) B and C. E) All of the above.

E

Phosphorylase kinase is regulated by: A) calcium ions. B) cAMP-activated PKA (protein kinase A). C) glycogen levels. D) A, B, and C. E) A and B.

E

The activated glucose donor of glycogen synthesis is: A) glucose 1-phosphate. B) glucose. C) ATP. D) UTP. E) None of the above.

E

What is required to remove branches in glycogen? A) a debranching enzyme B) a transferase enzyme C) a glycosidase enzyme. D) A and C E) All of the above.

E

________ is the defective enzyme in von Gierke disease.

Glucose 6 phosphatase

________ is the glucose donor in glycogen synthesis.

UDP-glucose

These two enzymes are required for the degradation of unsaturated and odd-chain fatty acids.

isomerase reductase