Biochemistry Answers

Which of the reactions catalyzed by the listed enzymes does not produce ammonia? 

a. glutamate pyruvate amino transferase 

b. glutamate decarboxylase 

c. glutamine hydrolase 

d. aspartate deaminase 

e. glutamate dehydrogenase 

At pH 2, most proteins lose biological activity. Why? (select one or more) 

a. the distribution of salt bridges changes 

b. denaturation occurs due to unfolding of the polypeptide chain 

c. the side chains are protonated and the charge of the protein changes 

d. decompose 

The enzyme fumarase catalyzes the reversible hydration of fumarate to L-malate, but not the hydration of maleic acid (cis-isomer) of fumarate. This is an example of (select one) 

a. chiral activity 

b. stereoisomerism 

c. biological activity 

d. stereospecificity 

e. racemization 

Which of the following compounds is not a cofactor of pyruvate dehydrogenase and α-ketoglutarate dehydrogenase? (select one) 

a. NAD 

b. lipoate 

c. FAD 

d. ATP 

e. CoASH 

Which of the following statements about the accuracy of protein biosynthesis is NOT true (select one) 

a. aminoacyl tRNA synthetases hydrolyze misloaded mRNAs 

b. Riobosomes contain exopeptidase activity that performs a corrective function 

c. the error rate in protein biosynthesis is approximately 1 / 10,000 

d. the codon-anticodon interaction ensures the entry of the correct mRNA into the A-site 

e. the binding of mRNA to αα-mRNA synthetases is very specific

A reversible inhibitor that can bind both free enzyme (E) and enzyme-substrate complex (ES) is referred to as: (select one) 

a. catalytic 

b. uncompetitive 

c. suicidal 

d. uncompetitive 

e. competitive 

Which of the following compounds are not cholesterol derivatives? (select one or more) 

a. ketone bodies 

b. vitamin D 

c. prostaglandins 

d. progesterone 

The following statements apply to natural higher unsaturated fatty acids: (select one or more) 

a. they usually contain an even number of carbon atoms 

b. are cis-isomers  

c. some representatives cannot be synthesized in the human body 

d. are broken down into separate pathways that are not related to the β-oxidation of saturated fats 

e. contain conjugated double bonds 

The Michaelis-Menten hypothesis: (select one or more) 

a. postulates the formation of an enzyme-substrate complex 

b. shows that the reaction rate depends on the substrate concentration 

c. allows to determine the pl of the enzyme 

d. shows that the rate of the chemical reaction can be independent of the substrate concentration 

The enzyme through which the pentose phosphate pathway is linked to glycolysis is: (select one) 

a. glucanase

b. xylanase

c. acetalase

d. transcarbomylase

e. transketomylase

f. metallase