Lesson 2 - DNA and RNA Flashcards

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1
Q
  • informational molecules of all living organisms
  • long, chain-like polymers assembeld from repeating subunits, nucleotides
A

nucleic acids

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2
Q

Two types of nucleic acids

A
  1. Deoxyribonucleic Acid (DNA)
  2. Ribonucleic Acid (RNA)
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3
Q

a unit of only the base and sugar without phosphates

A

nucleoside

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4
Q

nucleosides of DNA

A
  1. deoxyadenosine
  2. deoxyguanosine
  3. deoxycytidine
  4. deoxythymidine
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5
Q

nucleosides of RNA

A
  1. adenosine
  2. guanosine
  3. cytidine
  4. uridine
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6
Q

Three components of nucleotides

A
  1. nitrogenous base
  2. five-carbon sugar
  3. phosphate group
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7
Q

two types of nitrogenous bases

A
  1. purine
  2. pyrimidine
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8
Q

six membered ring made up of carbon and nitrogen atoms

A

pyrimidines

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9
Q

uracil

A

2,4-dioxypyrimidine

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10
Q

thymine

A
  • 2,4-dioxy-5-methylpyrimidine or
  • 5-methyluracil
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11
Q

cytosine

A

2-oxy-4-aminopyrimidine

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12
Q

six-membered ring fused to a five-memberd ring

A

purines

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13
Q

adenine

A

6-aminopurine

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14
Q

guanine

A

2-amino-6-oxypurine

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15
Q
  • reversible change of one DNA base isomer to another
  • shift in the location of H atoms and double bonds
A

tautomeric shift in DNA bases

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16
Q

2 forms of the same molecule differing only in the location of a proton and a double bond

A

tautomers

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17
Q

in DNA bases, what are the usual forms

A
  • amino (NH2)
  • keto (C=O)
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18
Q

in DNA bases, what are the rare forms

A
  • imino (NH)
  • enol (C-OH)
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19
Q

links covalently to nitrogenous bases

A

five-carbon sugar (pentose)

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20
Q

a chain of 1,2, or 3 phosphates linked to the pentose sugar at its 5’ carbon

A

phosphate group

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21
Q

where is the phosphate group linked to

A

5’ carbon

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22
Q

bonds between base pairs in the interior of the molecule

A

numerous hydrogen bonds

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23
Q
  • β-N-glycosidic bond (sugar to base)
  • phosphodiester bond (nt to nt)
A

covalent bonds

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24
Q

sugar to base bond

A

β-N-glycosidic bond

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25
Q

phosphate to sugar base bond

A

phosphodiester bond

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26
Q

Primary Structure of DNA

A
  1. linear sequence of nucleotides
  2. sugar-phosphate backbone on the outside
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27
Q

Secondary Structure of DNA

A
  1. two intertwined antiparellel strands
  2. major and minor grooves
  3. right-handed helix
  4. constant diameter of 20 Å
  5. base pases are perpendicular to axis
  6. hydrophobic associations form stable non-polar environment
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28
Q

essential for binding of proteins

A

major and minor grooves

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29
Q

length between bases

A

0.34 nm

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30
Q

One complete turn of the double helix

A
  • 3.4 nm long
  • 10 base pairs
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31
Q

what is formed between the hydrophobic associations of base pairs

A

stable non-polar environment

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32
Q

Different DNA conformations

A
  1. A DNA
  2. B DNA
  3. C DNA
  4. D DNA
  5. Z DNA
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33
Q

Why are there different DNA conformations

A

adapt to stress

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34
Q

most common DNA conformation in nature

A

B DNA

35
Q

A DNA: overall proportion

A

short and broad

36
Q

A DNA: helix rotation

A

right

37
Q

A DNA: bp per turn

A

11

38
Q

A DNA: conditions of occurrence

A
  • 75% humidity
  • K+, Na+, Ca++
39
Q

B DNA: overall proportion

A

long and thin

40
Q

B DNA: helix rotation

A

right

41
Q

B DNA: bp per turn

A

10

42
Q

B DNA: conditions of occurrence

A
  • 92% humidity
  • low salt
43
Q

C DNA: overall proportion

A

long and thin

44
Q

C DNA: helix rotation

A

right

45
Q

C DNA: bp per turn

A

9.33

46
Q

C DNA: conditions of occurrence

A

66% humidity

47
Q

Z DNA: overall proportion

A

elongated and slim

48
Q

Z DNA: helix rotation

A

left

49
Q

Z DNA: bp per turn

A

12

50
Q

A DNA: helix diameter

A

23 A

51
Q

A DNA: major groove

A

extremely narrow, very deep

52
Q

A DNA: minor groove

A

very broad, shallow

53
Q

A DNA: found in

A
  1. dsRNA
  2. RNA-DNA duplexes
  3. rRNA
  4. tRNA
  5. viral RNA
  6. polypurine strand
54
Q

B DNA: helix diameter

A

20 A

55
Q

B DNA: major groove

A

wide, intermed

56
Q

B DNA: minor groove

A

narrow, intermed

57
Q

B DNA: found in

A
  1. biologically dominant
  2. polypyrimidine strand
58
Q

C DNA: helix diameter

A

20 A

59
Q

C DNA: found in

A
  1. in vitro
  2. dehydrated conditions
60
Q

Z DNA: helix diameter

A

18 A

61
Q

Z DNA: major groove

A

flattened out on helix surface

62
Q

Z DNA: minor groove

A

extremely narrow, very deep

63
Q

Z DNA: found in

A
  1. dCGCGCG in vitro
  2. in vivo
  3. methylated DNA
64
Q
  • exists largely as single-stranded chains in living cells
  • genetic material of some viruses
A

ribonucleic acid (RNA)

65
Q

bases in RNA

A
  1. cytosine
  2. guanine
  3. adenine
  4. uracil
66
Q

Segments of RNA molecules may

A
  1. form RNA-DNA hybrid
  2. pair temporaily in double-helical form
  3. fold back on themselves to set up extensive double-helical regions
67
Q

where can RNA-DNA hybrid repeat be found

A

during transcription

68
Q

Peculiar NA sequences

A
  1. mirror repeat
  2. inverted repeat
69
Q

symmetrical sequence within each strand

A

mirror repeat

70
Q

two copies of an identical sequence present in the reverse orientation

A

inverted repeats = palindrome

71
Q

More Secondary Structures of DNA and RNA

A
  1. internal loops
  2. bulge loops
  3. cruciform
  4. hairpin
  5. stem-and-loop
  6. cloverleaf
72
Q

when there are bases that cannot pair on both sides of the helix

A

interal loops

73
Q

unpaired bases occur only on one side of the helix

A

bulge loops

74
Q
  • non-B DNA structure characterized by cross-shaped conformations that are observed in inverted repeat sequence features.
  • in DNA with a region of dyad symmetry in which the axis of symmetry separates the inverted repeats
A

cruciform

75
Q
  • when it folds back on itself to form a double-helical segment in the region of the sequence
  • in ssDNA molecule with an inverted repeat or
  • in an RNA molecule copied from a palindromic DNA
A

hairpin

76
Q
  • similar with hairpin structure but occurs when the loop at the end would have many unpaired bases
  • plays an important role in attenuation
A

stem-and-loop structure

77
Q
  • characteristic conformation of the tRNA molecule
  • made up of three stem-loops
  • has four arms
A

cloverleaf structure

78
Q

four base-paired arms of tRNA

A
  1. Acceptor arm
  2. D-arm
  3. TΨC arm
  4. Anticodon arm
79
Q
  • end of a tRNA molecule to which an amino acid becomes bound
  • contains both the 5’ and 3’ ends of the tRNA.
A

acceptor arm

80
Q
  • recognition process is the primary purpose
  • serves as a recognition site for the enzyme aminoacyl-tRNA synthetase
  • contains the modified nucleotide dihydrouridine.
A

D-loop

81
Q

specialized region on the tRNA molecule which acts as a special recognition site for the ribosome

A

TΨC arm

82
Q
  • a trinucleotide sequence located at one end of a transfer RNA (tRNA) molecule
  • complementary to a corresponding codon in a messenger RNA (mRNA) sequence.
A

anticodon arm

83
Q

Significance of other secondary and tertiary structures of DNA/RNA

A
  1. stabilize genome structure
  2. serve as recognition site for initiation and termination
  3. important in the function of the nucleic acid made from it
  4. form core of catalytic RNA molcules as binding sites for substrates and cofactors
84
Q

catalytic RNA molecules

A

ribozymes