Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

BISC 320 > DNA Structure > Flashcards

DNA Structure Flashcards

1
Q

What is the name of a nucleotide?

A

2’-deoxyadenosine 5’-monophosphate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What do nucleotides comprise of?

A

a base, a sugar, and phosphate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What do nucleosides comprise of?

A

base+sugar

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the functions of nucleotides?

A

energy storage (ATP), enzymatic co-factors (NAD, NADPH)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What sugar does RNA have?

A

ribose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the structure of ribose?

A

five carbon atoms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What sugar does DNA have?

A

deoxyribose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the structure of deoxyribose?

A

lacks hydroxyl group at 2’ carbon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is a glycosidic bond?

A

in DNA/RNA, the base is attached to the 1’ carbon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What joins the nucleotides together into a linear strand?

A

3’ and 5’ positions will form covalent bonds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are two types of bases in DNA and RNA?

A

purines and pyrimidines

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are purines?

A

adenina, guanine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are pyrimidines?

A

cytosine, thymine, and uracil

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the nucleoside form of adenine?

A

adenosine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the nucleoside form of guanine?

A

guanosine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the nucleoside form of cytosine?

A

cytidine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is the nucleoside form of thymine?

A

thymidine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the nucleoside form of uracil?

A

uridine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

How do purines make glycosidic bonds?

A

through the 9 position of the base to the 1’ carbon of the sugar

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

How do pyrimidines make glycosidic bonds?

A

through the 1 position of the base to the 1’ carbon of the sugar

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is the backbone of DNA or RNA?

A

repeating of sugar and phosphate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

How are nucleotides joined?

A

a phosphodiester bond between the 3’ hydroxyl of one sugar and the phosphate attached to the 5’ hydroxyl of the next sugar

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

How are nucleic acid strands asymmetric?

A

one end has an exposed 3’ hydroxyl, the other end has an exposed 5’ phosphate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What are nucleic acid sequences written?

A

in the 5’ to 3’ direction (the DNA strand to the right has the sequence: ATGC)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

How do DNA strands associate?

A

via non-covalent hydrogen bonds to form double-stranded DNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

How many H-bonds bond A and T?

A

2 H-bonds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

How many H-bonds bond C and G?

A

3 H-bonds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What type of base pairs are AT and GC?

A

Watson-Crick base pairs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Why are strands complementary?

A

the sequence of one strand dictates the sequence of the other strand

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What direction are two strands?

A

antiparallel - one strand runs from 5’ to 3’ while the other runs 3’ to 5’

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What is the most energetically favorable formation of double stranded DNA?

A

two strands to wind around one another in a right-handed double helix

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What is the orientation of hydrophobic bases in the center of DNA?

A

cluster, away from the aqueous cellular environment

33
Q

What is the orientation of hydrophilic sugar-phosphate backbone?

A

on the outside

34
Q

What are base pairs?

A

planar molecules that are perpendicular to the axis of the helix and form a stack in the interior of the helix

35
Q

What stabilizes the helix of DNA?

A

Van der Waals interactions between p-orbitals of the bases

36
Q

What is the diameter of the helix?

A

~20 A

37
Q

T or F: A-T and G-C base pairs have similar widths

A

true

38
Q

What is the predominant configuration of DNA?

A

B-DNA

39
Q

What is the frequency of B-DNA?

A

repeats every 10.5 base pairs, and base pairs are 3.4 A apart

40
Q

What is the structure of B-DNA?

A

the helix forms a major groove (~13 A) and a minor groove (~9 A) accessible from the outside of the molecule

41
Q

What governs the interactions between DNA and other molecules?

A

the shape and size of the major and minor groove

42
Q

What nucleotides lead to more flexibility?

A

regions rich in A-T

43
Q

T or F: the sequence of bases in DNA can influence structure

A

true

44
Q

What exposes the genetic information in DNA?

A

major and minor grooves

45
Q

What are exposed in the major and minor grooves of the DNA helix?

A

chemical groups of the bases

46
Q

What do each base pair have?

A

a characteristic set of groups that is available for interaction

47
Q

T or F: DNA-binding proteins recognize specific DNA sequences through the major and minor grooves by separating the two DNA strands

A

false, without separating the two DNA strands

48
Q

What does B-DNA represent?

A

the prototypical or most common DNA conformation

49
Q

What is A-DNA?

A

a right-handed helix with 11 base pairs per turn; grooves are more evenly sized. the A conformation can be induced by DNA binding proteins

50
Q

What is Z-DNA?

A

a left-handed helix, favored by methylation of cytosine torsional stress, and high salt concentrations. its biological significance is unclear

51
Q

How do DNA relieve tension?

A

twists into supercoils

52
Q

What are relaxed DNA?

A

open, uncoiled circular DNA

53
Q

What induces supercoiling?

A

untwisting or overtwisting

54
Q

What initiates the overwinding or underwinding of a closed circular DNA molecule?

A

at least one strand of DNA must be cut, and the strands twisted relative to each other, and re-ligated together

55
Q

Why does DNA supercoil?

A
  1. changes the number of bases per turn
  2. restores the preferred number of bases per turn
56
Q

T or F: supercoiling can be positive or negative

A

true

57
Q

When do linear segments of DNA supercoil?

A

if one end is immobile

58
Q

What creates negative supercoils?

A

unwinding the DNA helix of a constrained DNA molecule creates negative supercoiling to compensate for the strain on the molecule

59
Q

When do supercoils release?

A

if one of the DNA strands is cut or otherwise free to rotate

60
Q

What are the names of supercoiled structures?

A

toroidal or interwound (plectonemic)

61
Q

What stabilizes the structure of DNA?

A

stabilized by complementary base-pairing and the combination of many weak, non-covalent interactions

62
Q

What makes DNA less reactive and more stable compared with RNA?

A

the absence of hydroxyl

63
Q

Why can one strand carry the entire code necessary to restore the other strand?

A

complementary base-pairing

64
Q

How can two strands be separated?

A

held together only by non-covalent interactions

65
Q

How is base information chemically readable?

A

in the major and minor grooves even without separating the two strands

66
Q

What is supercoiling due to?

A

due to over- or under-winding which are caused by molecular mechanisms of replication and transcription

67
Q

What is linkage number?

A

the number of times one strand of DNA wraps round the other

68
Q

How often does B-DNA wrap around each other?

A

every 10.5 base pairs

69
Q

T or F: linkage number can change in a closed circular DNA

A

false

70
Q

What is twist?

A

the number of turns in a fragment of DNA (+1 per 360 twist)

71
Q

How often does B-DNA twist?

A

+1 for each repeat of the double helix

72
Q

What does a positive number denote in twist?

A

a right-handed helix

73
Q

What does a negative number denote in a twist?

A

a left-handed helix

74
Q

What is writhe?

A

a supercoiling of closed circular DNA or constrained linear DNA

75
Q

What is the writhe of a relaxed plasmid?

A

zero

76
Q

What is the writhe of a positively coiled DNA?

A

Wr > 0

77
Q

What is the writhe of a negatively coiled DNA?

A

Wr < 0

78
Q

What is the formula for linking number?

A

Lk = Tw + Wr

79
Q
A

BISC 320 (20 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions