Question

A point mutation is _______________ that can convert a normal gene into a potent oncogene.

  

	A.	an integrase
	B.	palindrome
	C.	a translocation
	D.	single base pair substitution

The repetitive (TTAGGG) DNA–protein complexes at the ends of chromosomes, are crucial for the survival of cancer cells are maintained by the enzyme ______________.A.

superoxide dismutase

B.

catalase

C.

reverse transcriptase

D.

telomerase

Answer 1

1. D) Single base pair substitution

Substitution mutations usually exchange one base pair for another and can be of two types as transversions and transitions. They are called point mutations as they affect only one codon and one corresponding amino acid. Integrase is an enzyme produced by viruses to catalyze the integration of their DNA into the host cell DNA to form a provirus. Palindromic sequences are read the same backward and forward. Translocation is a type of chromosomal mutation.

2. D) Telomerase

A telomere is a region of repetitive nucleotide sequences at the end of chromosomes. Their function is to protect the end of the chromosome. Telomeres are maintained by the ribonucleoprotein, telomerase. Superoxide dismutase triggers the dismutation of the superoxide radical into molecular oxygen and hydrogen peroxide. Catalase is an enzyme that decomposes hydrogen peroxide to water and oxygen. Reverse transcriptase helps to synthesize complementary DNA from an RNA template.