2013 biochem

Question 1

Which of the following has a role in mRNA splicing?
A. SnoRNA
B. SnRNA
C. Ribozymes

Answer 1

B. SnRNA

Question 2

What is true about collagen protein?
A. Highly carboxylated
B. Highly glycosylated
C. Highly hydroxylated

Answer 2

C. Highly hydroxylated

Question 3

Which of the following activates PPP?
A.  NAD 
B.  AMP 
C.  NADP
D.  NADPH

Answer 3

C. NADP

Question 4

What’s the change that occurs in prion disease?
A. Increased Beta sheets
B. Increased alpha Helices

Answer 4

A. Increased Beta sheets

Question 5

Protein kinases add phosphates on which of the following amino acid residues?
A. Serine
B. Lysine

Answer 5

A. Serine

Question 6

A High-affinity competitive inhibitor has a resemblance to which of the following structures?
A.  Allosteric effector
B.  Substrate 
C.  Product 
D.  Cofactor
E.  Transition state

Answer 6

E. Transition state

Question 7

What is the structural motif in the DNA binding domain of the intracellular glucocorticoid receptor?
A. Leucine zipper
B. Helix-turn-helix
C. Zinc finger

Answer 7

C. Zinc finger

Question 8

What is the target sequence in lysosomal proteins?
A. Mannose 5-phosphate
B. Mannose 6-phosphate

Answer 8

B. Mannose 6-phosphate

Question 9

A patient with hypertriglyceridemia has normal lipoprotein lipase. What should be checked next?
A.  ApoE
B.  ApoA-II 
C.  ApoC-I 
D.  ApoC-II

Answer 9

D. ApoC-II

Question 10

A deficiency in which of the following causes hypocholesterolemia?
A.  ApoC-II 
B.  ABC
C.  ApoE 
D.  CETP
E.  LDL receptor

Answer 10

B. ABC

Question 11

In order to measure free (unesterified) cholesterol in the plasma, what should be included?
A. Cholesterol oxidase
B. Cholesterol oxidase + cholesterol peroxidase
C. Cholesterol esterase + cholesterol oxidase
D. Cholesterol peroxidase

Answer 11

B. Cholesterol oxidase + cholesterol peroxidase

measure free cholesterol= cholesterol oxidase + cholesterol peroxidase

measure total cholesterol= cholesterol oxidase + cholesterol peroxidase + cholesterol esterase

Question 12

What causes acidosis in prolonged starvation?
A. Ketone bodies
B. Fatty acid oxidation
C. Gluconeogenesis

Answer 12

A. Ketone bodies

Question 13

Which lipid is abundant in skin?
A. Ceramide
B. Sphingolipid

Answer 13

A. Ceramide

Question 14

Where are desaturases located inside the cell?
A.  Golgi apparatus
B.  nucleus
C.  Endoplasmic reticulum
D.  Mitochondria

Answer 14

C. Endoplasmic reticulum

Question 15

Where are S-S disulfide bonds formed?
A.  Golgi apparatus
B.  Nucleus
C.  Mitochondria
D.  Endoplasmic reticulum

Answer 15

D. Endoplasmic reticulum

Question 16

Where are ketone bodies synthesized?
A. Liver
B. Muscle

Answer 16

A. Liver

Question 17

A person has hypoglycemia due to a defect in aldolase B. what should be cut from his diet?
A. Glucose
B. Galactose
C. Fructose

Answer 17

C. Fructose

Question 18

What signals low energy level in the cell?

Answer 18

AMP

Question 19

Which amino acid is involved in the urea cycle?
A.  Arginine
B.  Glutamate 
C.  Methionine 
D.  Proline

Answer 19

A. Arginine

Question 20

Which process results in the formation of GTP in the TCA cycle?
A. Oxidative phosphorylation
B. Oxidative decarboxylation
C. Substrate level phosphorylation

Answer 20

C. Substrate level phosphorylation

Question 21

What is the benefit of glucose phosphorylation in the preparatory phase of glycolysis?
A. To decrease its energy
B. Trapping glucose inside the cell

Answer 21

B. Trapping glucose inside the cell

Question 22

Starting the synthesis of a new glycogen molecule requires a central molecule, which molecule is at the center of every glycogen?

Answer 22

Glycogenin

Question 23

Initiation of translation in eukaryotes is different from that of prokaryotes in which of the following?
A. Lower energy required
B. Lower number of factors
C. Scanning for the initiation code

Answer 23

C. Scanning for the initiation code

Question 24

How can nucleotide analogs slow down cancer growth rate?
A.  Inhibit helicase
B.  Inhibit DNA replication
C.  Inhibit telomerase
D.  DNA proof reading

Answer 24

B. Inhibit DNA replication

Question 25

``` Which enzyme catalyzes the rate limiting step of fatty aid synthesis? A. Fatty acid synthase B. Acyl CoA synthase C. HMG-CoA reductase D. Acetyl CoA carboxylase ```

Answer 25

D. Acetyl CoA carboxylase

Question 26

Which substrate activates acetyl CoA carboxylase when glucagon level is low? A. Citrate B. Fumerate

Answer 26

A. Citrate

Question 27

A figure shows Complex V of the electron transport chain. What part of Complex V binds the ATP? and what triggers it's phase changes? A. F0, Flow of H+ B. F0, ATP hydrolysis C. F1, Flow of H+

Answer 27

C. F1, Flow of H+

Question 28

A patient suffers from glycogen storage disease I (Von Gierke’s) due to a deficiency in glucose phosphatase in the liver. Which of the following is a symptom of this condition? A. low blood glucose B. Intolerance to exercise

Answer 28

A. low blood glucose

Question 29

``` Which of the following has been used in DNA finger printing? A. Alu family B. Telomeres C. Centromeres D. Hypervariable minisatellite DNA ```

Answer 29

D. Hypervariable minisatellite DNA

Question 30

What is inhibited by malonyl CoA to inhibit Beta-oxidation of fatty acids?

Answer 30

``` Carnitine Acetyltransferase (rate-limiting transport of fatty acyl CoA into mitochondrial matrix is called as “carnitine shuttle”, stopping the enzyme stops it) ```

Question 31

Which of the following is the main method to study lipidomics?

Answer 31

Mass spectrometry

Question 32

The genetic mutation in chloride channels that causes cystic fibrosis affects which of the following?

Answer 32

ATP binding domain

Question 33

What is the function of the BCR-ABL-encoded fusion protein?

Answer 33

Tyrosine kinase activity

Question 34

Which of the following is a mechanism of epigenetic inhibition? A. Acetylation B. Methylation

Answer 34

B. Methylation

Question 35

What is a characteristic of membrane rafts? A. No cholesterol B. Sphingolipid and protein

Answer 35

B. Sphingolipid and protein

Question 36

Palmitic acid has 16 carbons although its precursors give a total of 23 carbons. Where do the extra 7 carbons go?

Answer 36

Decarboxylated giving 7 CO2

Question 37

Boiling eggs result in solidification due to disruption of which bonds? A. S-S disulfide bonds B. Covalent bonds C. H-bonds

Answer 37

C. H-bonds