2014 biochem endterm

Question 1

Which of the following is used in the oxidation of odd chain fatty acids?
A) Carnitine
B) Succinyl CoA
C) Vitamin B12

Answer 1

C) Vitamin B12

Question 2

What is the role of ATP-binding cassette transporter (ABCA-1)?
A) removal of excess cholesterol from cell
B) transport cholesterol between LDL and HDL
C) activate LPL

Answer 2

A) removal of excess cholesterol from cell

Question 3

What is the component used directly to make 2’ deoxy compound in DNA synthesis?
A) GTP 
B) GDP 
C) GMP 
D) cAMP

Answer 3

B) GDP

Question 4

high concentration in which amino acid will activate the urea cycle?
A) ornithine 
B) cetruline 
C) aspartate 
D) arginine

Answer 4

D) arginine

Question 5

Where are ketone bodies formed?
A) liver
B) blood
C) bones

Answer 5

A) liver

Question 6

What prevents glucose, synthesized in the liver by Gluconeogenesis, from being converted back to glucose-6-phosphate?
A) High Km of Glucokinase
B) lack of glucose-6-phosphatase

Answer 6

A) High Km of Glucokinase

Question 7

What is the main body system that is affected in cystic fibrosis? 
A) Circulatory system
B) Respiratory system
C) Musculoskeletal system 
D) nervous system

Answer 7

B) Respiratory system

Question 8

What is the consequence of prolonged consumption of trans-unsaturated fatty acid?
A) unable to absorb essential fatty acid
B) Reduced LDL receptors
C) decreased bile synthesis

Answer 8

B) Reduced LDL receptors

trans fat increases LDL, so they would produce less receptors

Question 9

What activated carbohydrate is required for de-novo synthesis of purine ring?
A) phosphoribosylpyrophosphate
B) Ribose-5-phosphate
C) glucose-6-phosphate

Answer 9

A) phosphoribosylpyrophosphate (PRPP)

Question 10

What substrate leads to the polymerization of the inactive Acetyl CoA Carboxylase (AAC)?
A) Citrate
B) Malonyl CoA
C) Acetyl CoA

Answer 10

A) Citrate

Question 11

Whats the oxidative stage product of pentose phosphate pathway?
A) ATP
B) NADPH
C) NADH

Answer 11

B) NADPH

Question 12

Patients with a deficiency in which enzyme should avoid prolonged fasting?
A) Acyl CoA dehydrogenase
B) Acyl CoA decarboxylase

Answer 12

A) Acyl CoA dehydrogenase

Question 13

What reaction is deactivated if the Sprechers shunt is blocked by a drug?
A) Oxidation of branched fatty acids
B) Transfer of acetyl CoA from mitochondria to cytosol
C) Retro inversion of fatty acid C: 24:6 to C: 22:6
D) Mitochondrial recycling of carnitine

Answer 13

C) Retro inversion of fatty acid C: 24:6 to C: 22:6

DPA to DHA

Question 14

Through which of the following are amino acids transported from the intestine cell to the interstitial fluid?
A) Facilitated transporter
B) K transporter
C) Na transporter

Answer 14

A) Facilitated transporter

Question 15

fructose-> fructose-1-phosphate (via fructose kinase (1))-> DHAP (via aldolase B (2))

If fructose was consumed, a deficiency in which enzyme would lead to severe problems in liver metabolism and why?
A) 1 due to rapid consumption of ATP
B) 2 due to lack of inorganic phosphate
C) 1 due to metabolism of fructose by hexokinase
D) 2 due to lack of DHAP

Answer 15

no answer given

Question 16

Which of the following zymogens is activated by autocatalysis?
A) Trypsinogen
B) Pepsinogen

Answer 16

B) Pepsinogen

Question 17

What is the main purpose of the non-oxidative stage of pentose phosphate pathway?
A) Production of ribose-5-phosphate
B) Reduction of NAD into NADH

Answer 17

A) Production of ribose-5-phosphate

Question 18

peroxinitrite is cell-damaging oxidant. Which reaction is the main source of peroxinitrite in humans?
A) O2- + NO >> ONOO-
B) 2NO+O2 >> 2NO2 
C) NO+NO2 >> N2O3 
D) NO- +NO >> ONNO-

Answer 18

A) O2- + NO&raquo_space; ONOO-

Question 19

Oxidation and decarboxylation of metabolites in the Krebs cycle release energy. What is the main portion of this energy used for?
A) Synthesis of GTP
B) Production of NADH 
C) Generation of heat
D) Oxidation of NADH to NAD+
E) Production of H2O2

Answer 19

B) Production of NADH

Question 20

What does the enzyme colipase assist?
A) Pancreatic Lipase
B) Ceramide
C) Sphingomyelin

Answer 20

A) Pancreatic Lipase

Question 21

What physiological process will be affected by the inhibition of the mutant RAS protein prenylation which is the attachment of farnesyl?
A) cholesterol synthesis
B) Beta oxidation

Answer 21

A) cholesterol synthesis

Question 22

PDH kinase phosphorylates PDH, what stimulates this step and how it affects PDH activity?
A) cAMP, inactivation
B) Acetyl-coA, inhibition
C) Pyruvate, inhibition

Answer 22

B) Acetyl-coA, inhibition

Question 23

What does a normal phosphatase defect in glucose translocase lead to?
A) accumulation of limit dextrin
B) hypoglycemia

Answer 23

B) hypoglycemia

Question 24

Which enzyme catalyzes the oxidative deamination?

a) glutamate dehydrogenase
b) glutamate lyase

Answer 24

a) glutamate dehydrogenase

Question 25

What is the effect of protein kinase on glycogen phosphorylase? A) PKA, activates it B) phosphoprotein phosphatase, activates it

Answer 25

A) PKA, activates it

Question 26

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

Answer 26

C) increase release of ammonia from glutamine by the kidneys

Question 27

What is a general characteristic of membrane lipid? A) amphipathic B) unsaturated fatty acids C) covalent bonding with proteins

Answer 27

A) amphipathic

Question 28

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

Answer 28

A) Cis-unsaturated fatty acids

Question 29

What is the function of Acyl CoA synthase?

Answer 29

Activate fatty acids for metabolic reactions

Question 30

Mr.Hamad visited his Dr. and found out that he was hyperglycemia. The doctor found normal levels of Apo CII, so what is the next thing he would need to check? A) lipoprotein lipase B) hormone-sensitive lipase C) HDL level

Answer 30

A) lipoprotein lipase (LPL)

Question 31

which of these is a feature of Trans fats? A) absent in the mother milk B) good substrate for lipase C) long half-life

Answer 31

C) long half-life

Question 32

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

Answer 32

B) Respiration

Question 33

``` Which of the following indicates the intracellular energy level? A) ATP B) AMP C) ADP D) cAMP ```

Answer 33

B) AMP | A was also accepted

Question 34

Which of the following is true about Marfan syndrome? A) Autosomal recessive B) Autosomal dominant C) X-linked recessive

Answer 34

B) Autosomal dominant

Question 35

``` Which of the following deals with signaling molecules and hormones? A) bioinformatics B) metabolomics C) proteomic D) genomics ```

Answer 35

B) metabolomics

Question 36

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

Answer 36

A) Acetyl CoA

Question 37

Defect in which of the following reaction results in Smith–Lemli–Opitz syndrome? A) lanosterol-> cholesterol B) acetyl CoA -> palmitoyl CoA

Answer 37

A) lanosterol-> cholesterol

Question 38

What is the effect of prolonged trans-fat consumption?

Answer 38

Suppressing the activity of LDL receptors

Question 39

Which of the following is a property of pyruvate kinase?

Answer 39

Link the 2 phases of glycolysis

Question 40

``` What is the amino acid involved in urea cycle? A- methionine B- glycine C- arginine D- glutamate ```

Answer 40

D- glutamate

Question 41

What is the main fuel used by the liver to provide energy for gluconeogenesis? a) glucagon b) ketone bodies c) amino acids d) fatty acids

Answer 41

c) amino acids