L3: Nucleic Acid Structure & Function

Question 1

parts of a nucleotide

Answer 1

phosphate group
sugar
nitrogenous base

Question 2

which contains a phosphate group?
nucleosides
or
nucleotides

Answer 2

nucleotides

Question 3

ribose vs deoxyribose

Answer 3

ribose has OH

deoxy only H

Question 4

compare locations of glycosidic bond and phosphodiester bond to ribose/deoxyribose oxygen

Answer 4

glycosidic at C1’

OH at C2’

phosphodiester bond at 3’

Question 5

where does the phosphate group attach to nucleic acid

Answer 5

5’ carbon

opposite side as glycosidic bond

Question 6

compare purines to pyrimidines

Answer 6

purines have double rings

pyrimidines are single rings

Question 7

list the purines

Answer 7

Adenine

guanine

Question 8

list the pyrimidines

Answer 8

cytosine
thymine
uracil

Question 9

DNA characteristics

Answer 9

storage
double stranded
deoxy
A-T
G-C

Question 10

RNA characteristics

Answer 10

transport, catalysis, regulation
single stranded
ribose
A-U
G-C

Question 11

in DNA, purines always base pair with _______, creating an ?

Answer 11

pyrimidines

antiparallel double helix

Question 12

different forms of DNA helix structure

Answer 12

B form
A
Z

Question 13

base pair vs helix axis of the types of DNA

Answer 13

B form — bps are straight across from each other

A and Z — are tilted to 19 and 9 degrees

Question 14

nitrogenous base orientation of the types of DNA

Answer 14

B and A — normal, both face inwards

Z — purines face out and pyrimidines face in

Question 15

physiological relevance of the forms of DNA

Answer 15

B — the physiological relevant form

A — primarily seen in RNA

Z — very rare

Question 16

RNA is usually _____ stranded but can also be _____ stranded by ?

Answer 16

single

double stranded by folding back on itself to create hairpin loop

Question 17

what is the Mesehlson stahl experiment?

Answer 17

comparing models for DNA replication to discover the mechanism of replication

discovery = semi-conservative replication

Question 18

nontraditional structures

Answer 18

hairpins
cruciforms
triplexes
quadruplexes

Question 19

hairpin loops and cruciforms

Answer 19

requires a palindromic sequence = inverted repeat

created by superhelical strain in DNA

Question 20

triplexes

Answer 20

unknown if occurs in nature

requires homopurine-homopyrimidine duplex

uses hoogsteen hydrogen bonds

Question 21

quadruplexes

Answer 21

guanines only — meaning only consists of guanines hydrogen bonding to each other

occurs in telomeres and some promoters

Question 22

melting temp is the temp at which ?

Answer 22

half of the sample is denatured

Question 23

how does DNA go from 2 strands to single stranded?

Answer 23

starts with lose of A-T bonds

but once denaturation begins it can zipper apart quickly

Question 24

is absorbance higher in single or double stranded DNA?

Answer 24

single

Question 25

reforming post - denaturation

Answer 25

DNA can reform once cools down

but proteins cannot always reform

Question 26

summary of mutation mechanisms from special topics

Answer 26

there are 2 categories of mutations

1. altered H bond potentials
2. error prone repair of replication roadblocks