Test 18 (Biochemistry)
1. With regard to histones:
a. they are basic proteins

b. they are essential for the formation of stable DNA

c. mitochondria do not contain histones

d. in the chromosomes, the weight of the histones equal to that of the 

e. the amino acid composition of histones show great variability 
    amongst different human races


2. In the regulation of genes:

a. more than 90% of the base sequences in human DNA have not 
    known function

b. extrons are the part of the gene that code for amino acids found in 
    the final proteins.

c. introns usually begins with the nucleotide sequence GT

d. splicing cut out the mRNA coded by introns.

e. promoters are responsible for initiating gene transcription


3. Thromboxane A2(TXA2):
a. is derived from the membrane phospholipid

b. requires lipoxygenase for its production

c. its production is decreased by non-steroidal anti-inflammatory 

d. causes platelet aggregation

e. causes vasodilatation


4. In the lens:

a. the capsule is made up of type IV collagen

b. most metabolism is carried out in the anterior pole

c. hexokinase is a rate-limiting enzyme in carbohydrate metabolism

d. anaerobic glycolysis is the main source of energy

e. pentose phosphate pathway metabolizes 30% of the available 


5. The following are true about the oxidation of glucose:

a. glycolysis produces 3% of the energy ultimately obtained from 

b. the first stage of glycolysis involves phosphorylation of glucose to 
    1,6-fructose biphosphate.

c. glycolysis occurs within the mitochondria

d. glucose enters the Kreb's cycle as pyruvate

e. the Kreb's cycle generates 36 ATP molecules.

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