How does ultraviolet radiation in sunlight typically damage DNA?
A. It breaks hydrogen bonds between the two strands of DNA.
B. It converts cytosine into uracil.
C. It causes two adjacent pyrimidine bases to become covalently linked.
D. It removes bases from nucleotides in DNA.
E. It breaks the sugar-phosphate backbone of DNA.
Ans: C. It causes two adjacent pyrimidine bases to become covalently linked.
You might also like to view...
The fever paroxysms of malaria correlate with
A. the entry of sporozoites into the blood following the bite of an infected mosquito. B. the synchronized rupture of infected blood cells and release of merozoites. C. the release of merozoites from infected liver cells during the exoerythrocytic cycle. D. the production of gametocytes within infected erythrocytes.
Most of the active functions of plasma
membranes are carried out by
a. cholesterol. b. proteins. c. hydrophilic heads. d. hydrophobic tails. e. carbohydrates
Uracil will pair with
a. ribose. b. adenine. c. cytosine. d. thymine. e. guanine
The Drosophila regulatory segment that defines the location of Eve stripe 2 contains binding sites for four different transcription regulators: two repressors (Giant and Krüppel) and two activators (Bicoid and Hunchback). For Eve to be efficiently expressed in stripe 2, both repressors must be absent and both activators present. What would you expect to see in flies that lack the gene that encodes Bicoid? (Assume that Bicoid does not influence the expression of Hunchback, Giant, or Krüppel.)
A. Stripe 2 would become narrower. B. All 7 stripes would disappear. C. Stripe 2 would become fainter. D. Stripe 2 would expand toward the tail of the embryo. E. Stripe 2 would expand toward the head of the embryo.