Nucleic Acids

Question 1

Azidothymidine (AZT)

Answer 1

Anti-viral nucleosides (Thymidine); Kinase phosphorylation x 3 by host kinase; Lacking a 3’OH, so when the viral reverse transcriptase incorporates it into DNA, chain termination occurs.

Question 2

Didanosine

Answer 2

Anti-viral nucleosides (Adenosine); Kinase phosphorylation x 3 by host kinase; Lacking a 3’OH, so when the viral reverse transcriptase incorporates it into DNA, chain termination occurs.

Question 3

Tenofovir

Answer 3

Anti-viral nucleotides (Adenine); Kinase phosphorylation x 2 by host kinase; Gets incorporated into the newly forming DNA strand, terminating the process.

Question 4

Acyclovir

Answer 4

Guanoside analogue; Rx: Herpes simplex, varicella zoster (chickenpox, shingles); Inhibits Viral Pol; Gets phosphorylated first by viral thymidine kinase, then 2 more times by the host kinase. Lacking a 3’OH so terminates DNA synthesis when it gets incorporated;

Question 5

Cytosine Arabinoside (araC)

Answer 5

DNA Pol. inhibition; Rx: Cancer; Gets phosphorylated 3 times. Has a 3’OH which allows for DNA chain elongation, however a 2’OH group prevents this by causing steric hindrance.

Question 6

Adenosine arabinoside (araA)

Answer 6

DNA Pol inhibition; Rx: Acute lymphoblastic anemia; Gets phosphorylated 3 times. Has a 3’OH but the arabinoside group prevents DNA elongation.

Question 7

5-azacytidine

Answer 7

RNA Hypomethylating agent; Cytidine analogue; Rx: Myelodysplastic syndrome & Acute myeloid leukemia

Question 8

5-aza-2’deoxycytidine (Decitabine)

Answer 8

DNA hypomethylating; Rx: Myelodysplastic syndrome & Acute myeloid leukemia