2013 biochem endterm

Question 1

Which of the following zygomens is activated by autocatalysis in our body?
A) Pepsinogen
B) Chymotrypsinogen
C) Proelastase

Answer 1

A) Pepsinogen

Question 2

How does our body appose ketoacidosis during prolonged starvation?
A) increase production of ketone bodies
B) increase activity of urea cycle
C) increase release of ammonia from glutamine by the kidneys
D) Increase lipogenesis

Answer 2

C) increase release of ammonia from glutamine by the kidneys

Question 3

Where can you find complex carbohydrates in the plasma membrane?
A) Inner core
B) extracellular surface
C) Core leaflet
D) Intracellular surface

Answer 3

B) extracellular surface

Question 4

Phenylketonuria is what type of inborn error of metabolism?
A) amino acid metabolism
B) carbohydrate metabolism
C) lipid metabolism
D) purine metabolism
E) pyrimidine metabolism

Answer 4

A) amino acid metabolism

Question 5

What kind of mutation is mostly found in phenylalanine hydroxylase in PKU?
A) Deletion 
B) Missense 
C) Insertion 
D) Splice

Answer 5

B) Missense

Question 6

Cystic fibrosis is what type of inborn error of metabolism?
A) amino acid metabolism
B) carbohydrate metabolism
C) lipid metabolism
D) purine metabolism
E) pyrimidine metabolism

Answer 6

A) amino acid metabolism

Question 7

What is the genetic cause of cystic fibrosis?
A) Missense 
B) Insertion 
C) Deletion 
D) Splice

Answer 7

C) Deletion

Question 8

What is the use of ketones bodies during prolonged starvation?
A) Energy production in the brain
B) Energy production in the liver
C) Gluconeogenesis

Answer 8

A) Energy production in the brain

Question 9

Which of the following can be converted to 2-deoxyribose?
A) Adenosine
B) AMP 
C) ATP 
D) ADP

Answer 9

D) ADP

Question 10

What produces ketone bodies during prolonged starvation ( >21 days)?
A) Glycerol from adipose
B) fatty acids from adipose
C) Lactic from RBC
D) Branches chain amino acids from skeletal muscle

Answer 10

B) fatty acids from adipose

Question 11

What increases the fluidity in the plasma membrane?
A) Cis-unsaturated fatty acids
B) Trans-unsaturated fatty acids
C) Integral proteins

Answer 11

A) Cis-unsaturated fatty acids

Question 12

What is the most common product of transamination reactions?
A) Alanine 
B) Pyruvate 
C) Leucine
D) Glutamate
E) Trytophan

Answer 12

D) Glutamate

Question 13

What is the characteristic of aminotransferase?
A) must have glutamine or alpha-ketoglutarate
B) always net production of glutamate
C) can’t catalyze essential amino acids
D) uses pyridoxal phosphate as a cofactor

Answer 13

D) uses pyridoxal phosphate as a cofactor

Question 14

What carbohydrates is used in both de-novo synthesis of purine & salvage pathways?
A) Ribose-5-phosphate
B) Phosphribosylpyrophosphate
C) Adenosine

Answer 14

B) Phosphribosylpyrophosphate

Question 15

What is the most acidic phospholipid in the cell?
A) cardiolipin
B) sphingomyelin
C) PS 
D) PC

Answer 15

A) cardiolipin

Question 16

Which of these is a feature of Trans fats?
A) Absence in the mother’s milk
B) good substrate for lipase
C) Long half life
D) Can’t be absorbed by small intestine
E) Rapid degradation in the saliva

Answer 16

C) Long half life

Question 17

which set of desaturases are present in our body?
A) ∆ 4,5,6,9 desaturases
B) ∆ 3,5.6.9 desaturases
C) ∆ 4,6,9,12 desaturases

Answer 17

A) ∆ 4,5,6,9 desaturases

Question 18

which lipase needs a colipase?
A) pancreatic lipase 
B) phospholipase C 
C) hepatolipase
D) hormone sensitive lipase

Answer 18

A) pancreatic lipase

Question 19

What facilitates the packing of good cholesterol into HDL?
A) Cardiolipin
B) Leukotrienes
C) Phosphotidylcholine
D) LCAT

Answer 19

D) LCAT

Question 20

What is the effect of prolonged trans-fat consumption?

a. Suppressing the activity of LDL receptors
b. Activating the activity of LDL receptors

Answer 20

a. Suppressing the activity of LDL receptors

Question 21

Inhibition of which protein function results in an increase in HDL cholesterol & decrease in LDL cholesterol simultaneosly?
A) ApoE receptor
B) CETP 
C) INSIG
D) LDL receptors
E) SCAP

Answer 21

B) CETP

Question 22

Which of these substances cannot be absorbed from the GI tract?
A) Trans Fatty acid
B) Olestra
C) cis fatty acid

Answer 22

B) Olestra

Question 23

Which substance enhances the oxidation of odd-chain fatty acid? 
A) ATP
B) Citrate
C) Vitamin B12
D) NAD+

Answer 23

C) Vitamin B12

Question 24

What is the normal physiological function that will be affected if we block farnesylation of RAS protein to slow down cancer rate?
A) Alpha oxidation
B) Beta oxidation
C) glycosyl phosphatiydl inositol formation
D) HDL receptor acylation
E) Cholesterol formation

Answer 24

E) Cholesterol formation

Question 25

``` What is the main regulator of the Pentose Phosphate Pathway? A) NADP+/NADPH B) AMP/ATP C) NAD+/NADH D) Glucose 6-Phosphate ```

Answer 25

A) NADP+/NADPH

Question 26

The lack of fructokinase causes fructose intolerance even though hexokinase catalyzes the phosphorylation of fructose. What property of hexokinase causes fructose intolerance? A) high Km for fructose B) low Vmax C) feedback inhibition by fructose 6 phosphate D) feedback inhibition by glucose 6 phosphate

Answer 26

A) high Km for fructose

Question 27

``` What is produced in Fenton reaction? A) Hydroxyl radical B) Hydrogen peroxide C) Superoxide radical D) Peroxinitrite ```

Answer 27

A) Hydroxyl radical

Question 28

``` What are ketone bodies used for? A) Energy production in the brain B) Energy production in the liver C) Gluconeogenesis in the kidney D) Fatty acid synthesis in adipose tissue ```

Answer 28

A) Energy production in the brain

Question 29

``` What increases respiration? A) ADP B) NADH C) FADH2 D) queinone ```

Answer 29

A) ADP

Question 30

What product of PPP is critical for antioxidants function in the cell? A) NADPH B) ATP C) Ribose-5-phosphate

Answer 30

A) NADPH

Question 31

What property of the enzyme that catalyzes the first step of glycolysis allows the liver to buffer blood glucose? A) high Km B) inhibition by ATP C) inhibition by glucose-6-phosphate D) activation by fructose 1,6 bisphosphate

Answer 31

A) high Km

Question 32

``` What is the free electron carrier in the inner mitochondrial membrane? A) coenzyme A B) FADH2 C) NADH2 D) Fe-S chain ```

Answer 32

A) coenzyme A

Question 33

How are 2 phases of glycolysis synchronized? A) feedback inhibition of PFK-1 B) feed-forward activation of pyruvate kinase C) feedback inhibition of Pyruvate dehydrogenase D) phosphorylation of PFK-1

Answer 33

B) feed-forward activation of pyruvate kinase

Question 34

What is the function of Acyl CoA synthase?

Answer 34

Activate fatty acids for metabolic reactions

Question 35

``` What is increased when uncouplers are expressed? A) ATP synthesis B) Glucogenesis C) Proton gradient D) Thermogenesis ```

Answer 35

D) Thermogenesis

Question 36

Pyruvate carboxylase is activated by acetyl CoA. The effect is: A) pyruvate oxidation B) activation of gluconeogenesis

Answer 36

B) activation of gluconeogenesis

Question 37

``` From which component are ketone bodies produced? A) Acetyl CoA B) Lactate C) Glucose D)Triacylglycerol ```

Answer 37

A) Acetyl CoA

Question 38

What is the endogenous source for ROS in aerobic organisms? A) Radiation B) Quinones C) Respiration

Answer 38

C) Respiration

Question 39

Patients with peroxisomal disorders can’t break down which of the following? A) very long chain fatty acids (C=20) B) fatty acids with branches on Beta Carbon C) short chains of fatty acid

Answer 39

A) very long chain fatty acids (C=20)