Nucleic acids

Question 1

what are phages

Answer 1

viruses that infect bacteria

Question 2

draw the lifecycle of a virulent phage

Answer 2

2.15 page 1

Question 3

what are the 2 orientations of adenosine

Answer 3

syn and anti

Question 4

how does DNA compare with RNA on reactivity

Answer 4

DNA is inert as it can resist changes in pH whereas RNA is very chemically sensitive as half life decreases rapidly in the wrong conditions

Question 5

what are stacking interactions

Answer 5

usually composed of alternating double bonds which produces the ability to stack one base pair on top of another because bases are flat making DNA molecule long and fibrous

Question 6

describe the structure of B DNA

Answer 6

2 grooves running alonf outside of the molecule and due to its stacking tendency there is distortion of the double helix so one groove is flat and wide (major groove) and the other is narrow (minor groove) antiglycosidic bond comformation

Question 7

describe the structure of A DNA

Answer 7

grooves are more even but there is a tilt in base pairs and they oscillate backwards and forwards depending on which leg of the molecule antiglycosidic bond comformation

Question 8

describe the structure of Z DNA

Answer 8

starts with a different sugar (may not be present in living tissue)

Question 9

what are the common cations found in the phosphate backbone

Answer 9

Li+
K+
Na+
Mg++
Mn++
Co++

Question 10

what controls DNAs precise conformation

Answer 10

local base sequence

Question 11

what are the roles of RNA

Answer 11

structural components
protein synthesis (transcription & translation)
regulatory RNA

Question 12

whats the structure of RNA duplexes

Answer 12

A form helical structure interrupted by loops (joining base), paired stems and bulges creating a series of junctions marking the ends of duplexes

Question 13

what is the form of dsRNA

Answer 13

A form