Chapter 10 + Quiz Questions Flashcards

1
Q

What are four physiological roles of nucleotides?

A

1) Energy currency (ATP)
2) Signaling molecules (cAMP)
3) Enzyme co-factors (NAD, FAD)
4) Building blocks of nucleic acids

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2
Q

What are two physiological roles of nucleic acids?

A

1) Genetic information (DNA, RNA)
2) Protein synthesis (DNA, mRNA, tRNA, rRNA)

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3
Q

Nucleotides all share 3 components:

A

1) Ribose sugar (ribose or deoxyribose)
2) Nitrogenous base (purine or pyrimidine)
3) Phosphate(s)

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4
Q

All nucleotides contain a _____ backbone

A

ribose

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5
Q

Ribose within nucleotides is in a _____ form

A

cyclized (β-D-ribofuranose)

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6
Q

For DNA, 2’ carbon of the ribose is in the ____ form

A

deoxy

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7
Q

RNA contains _____; DNA contains _____

A

ribose, deoxyribose

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8
Q

What are the two families of nitrogenous bases?

A

Purines and pyrimidines

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9
Q

Which of these has a single ring, and which has a two ring system: purines or pyrimidines?

A

Pyrimidines: single ring
Purines: two ring system

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10
Q

Nitrogenous bases are ____ and relatively ___-____

A

planar, non-polar

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11
Q

There are five standard nitrogenous bases, which is common to DNA and RNA, and what differs?

A

Common: adenine, guanine, cytosine
Different: DNA=thymine, RNA=uracil

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12
Q

Which of the bases are purines?

A

Adenine and Guanine

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13
Q

Which of the bases are pyrimidines?

A

cytosine, uracil, thymine

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14
Q

Nitrogenous bases link to ribose through _______ bonds

A

N-glycosidic

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15
Q

All the nitrogenous bases link to ___ of the sugar

A

C1’

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16
Q

In purines, N-glycosidic bond is to __ of nitrogenous base; in pyrimidines, N-glycosidic bond is to ___ of nitrogenous base

A

N9, N1

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17
Q

Nucleotides and nucleosides differ in whether they are..?

A

phosphorylated at the C5’ position

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18
Q

Nucleotides are _____ nucleosides

A

phosphorylated

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19
Q

For the nomenclature of nucleosides and nucleotides, what are three things to look at..?

A

1) Which nitrogenous base is present (base name)
2) Is the sugar ribose or deoxyribose (deoxy prefix)
3) Are there phosphoryl groups (suffix of -osine from nucleosides; -ylate for nucleotides)

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20
Q

Describe energy transfer in nucleotides? (x2)

A

1) Anhydride linkages in ATP are high energy bonds
2) The energy released from the hydrolysis of these bonds drives many biochemical reactions

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21
Q

Describe signal transduction in nucleotides? (x2)

A

1) Cyclic AMP, formed from ATP in a reaction catalyzed by adenylyl cyclase
2) Common intracellular messenger produced in response to hormones

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22
Q

Nucleotides form linear nucleic strands through 3’-5’ _____ linkages

A

phosphodiester

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23
Q

3’-5’ phosphodiester bonds are ____ in DNA
and RNA

A

identical

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24
Q

3’-5’ phosphodiester linkages are identical, ____ of the nucleotides being joined

A

independent

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25
Q

The strand of sugars linked by phosphodiester bridges is called the _____ of nucleic acid

A

backbone

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26
Q

What uniquely characterizes a nucleic acid?

A

The sequences of bases

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27
Q

Nucleic acid strands have a direction and their sequences are presented __ -> __

A

5’, 3’

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28
Q

Sequences of bases is a form of ____ information

A

linear

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29
Q

RNA is single-stranded but can adopt..?

A

complex three-dimensional structures

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30
Q

This kind of RNA is an integral part of ribosomes, ~80% of RNA in cells, what is it?

A

Ribosomal RNA (rRNA)

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31
Q

This kind of RNA carries activated amino acids to ribosomes for protein synthesis (small molecules 73-95 nucleotides long), what is it?

A

Transfer RNA (tRNA)

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32
Q

This kind of RNA is a code for proteins; contains triplet codons that specify the amino acid sequence of a protein, what is it?

A

Messenger RNA (mRNA)

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33
Q

This kind of RNA are short oligonucleotides (22-24 nts in length) that function in transcriptional and post-transcriptional regulation of gene expression, what is it?

A

Micro RNA (miRNA)

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34
Q

The 2’ hydroxyl group of RNA increases its susceptibility to base hydrolysis at the ______ linkage

A

phosphodiester

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35
Q

Two helical DNA strands coiled around a common axis forming a ____-handed double helix.

A

right

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36
Q

The strands run in ____ directions and are ____ to each other

A

opposite, complimentary

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37
Q

Sugar-phosphate backbones are on the ___ of the helix, nitrogenous bases on the ____

A

outside, inside

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38
Q

Base pairs are _____ to helix axis

A

perpendicular

39
Q

Watson-Crick base pairing matches a ____ with a ____ to give a constant helix diameter

A

purine, pyrimidine

40
Q

The specificity of Watson-Crick base pairing is largely determined by the ____ bonding groups of the nitrogenous bases

A

hydrogen

41
Q

What is the formula for Chargaff’s Rule?

A

A+G=T+C

42
Q

Number of purines ? the number of pyrimidines in duplex DNA

A

=

43
Q

The A-T and G-C hydrogen bonded pairs are ___ and have ____ dimensions

A

planar, same

44
Q

What are the weak forces stabilize the double helix?

A

1) Hydrophobic effects
2) Stacking interactions
3) Hydrogen bonds
4) Charge-Charge interactions

45
Q

What are the hydrophobic forces that stabilize the double helix?

A

Burying the purine and pyrimidine rings in the interior of helix

46
Q

What are the stacking interactions that stabilize the double helix?

A

Stacked base pair form Van de Waals contacts

47
Q

What are the hydrogen bonds that stabilize the double helix?

A

Hydrogen bonding between base pairs

48
Q

What are the charge-charge interactions that stabilize the double helix?

A

Electrostatic repulsion of negatively charged phosphate groups is decreased by cations and cationic proteins

49
Q

Many proteins bind DNA in a _____-_____ fashion
(restriction enzymes, transcription factors)

A

sequence-specific

50
Q

A double helix has two grooves of unequal width: ___
groove and ____ groove

A

major, minor

51
Q

_____ ____ recognize and cleave specific DNA sequences

A

Restriction endonucleases

52
Q

Host cells protect their own DNA by ____ _____ of bases at the restriction site (e.g. methylation)

A

covalent modification

53
Q

Restriction enzymes cut at ____ sequences

A

palindrome

54
Q

Treating DNA from different individuals with restriction enzymes will..?

A

break DNA into pieces

55
Q

What is Denaturation?

A

Complete separation of double-stranded DNA by heat or chemical agents

56
Q

Denaturation of DNA is a _____ process

A

cooperative

57
Q

What is Annealing?

A

Reforming the double-stranded helix from single strands.

58
Q

What is it called when the temperature at which half the DNA has become single stranded

A

Melting point (Tm)

59
Q

Melting temperatures reflect sequence compositions; the ___ the GC content the ___ the Tm

A

higher, higher

60
Q

DNA and RNA ____ are the primary enzymes for synthesizing nucleic acids

A

polymerases

61
Q

All polymerases synthesize nucleic acids in
the __ to __ direction

A

5’, 3’

62
Q

Incoming residues are added to the __ end of the growing strand

A

3’

63
Q

Incoming residues are selected to be _____ to the template strand

A

complimentary

64
Q

_______ takes advantage of the ability for each DNA strand to serve as a template for production of a complimentary strand.

A

Polymerase Chain Reaction (PCR)

65
Q

PCR uses ____-____ enzymes to make new
DNA

A

heat-stable

66
Q

A first level of DNA packaging involves formation of _____

A

nucleosomes

67
Q

Nucleosome “beads” are..?

A

DNA-histone complexes on a “string” of double-stranded DNA

68
Q

What are histones?

A

DNA packaging proteins

69
Q

Histones are highly ____ and _____ charged

A

conserved, positively

70
Q

What are the five histone proteins?

A

H1, H2A, H2B, H3, and H4.

71
Q

Nucleosome composed of..?

A

Two molecules of each H2A, H2B, H3, H4 and 146 base pairs of DNA

72
Q

__ binds the region of linker DNA

A

H1

73
Q

Histones are ____ modified to regulate their
interaction with DNA

A

reversibly

74
Q

Size of a gene may be estimated from the size of the..?

A

corresponding protein

75
Q

Describe the bacterial genome (x4)

A

1) Millions of base pairs
2) Closed, circular genome
3) No internal interruptions (introns)
4) Bacteria may have additional genetic info in the for of plasmids

76
Q

What are plasmids?

A

1) Plasmids are non-chromosomal DNA
2) Many plasmids encode info for resistance to antibiotics
3) May be isolated and manipulated

77
Q

Describe the eukaryotic genome (x3)

A

1) Different organisms have different numbers of chromosomes
2) Each chromosome has a characteristic set of genes
3) Linear

78
Q

What are telomeres?

A

Ends of chromosomes containing repeating sequences

79
Q

Some organelles may contain additional DNA distinct from that of the nucleus, what are 2 examples?

A

Mitochondria, chloroplasts

80
Q

Most eukaryotic genes interrupted by non-coding intervening sequences called?

A

introns

81
Q

__ contain protein-coding information

A

Exons

82
Q

Introns vary in ___, _____ and _____

A

size, number, position

83
Q

Introns removed from mRNA ____ translation

A

prior

84
Q

In response to environmental influences, our genetic
material can be _____ modified

A

covalently

85
Q

Can modification of DNA be heritable?

A

Yes

86
Q

Epigenetics refers to..?

A

Functionally relevant changes to the genome that do not involve a change in the nucleotide sequence

87
Q

Epigenetic changes can alter patterns of gene expression (and associated phenotypes) without altering the..?

A

underlying DNA sequence

88
Q

Denaturation of DNA is _____?

A

cooperative

89
Q

Nucleosomes form through..?

A

electrostatic complexes between histone proteins and DNA

90
Q

Bacterial and human genomes are structurally similar in that they both..?

A

are made from double-stranded DNA

91
Q

The DNA strand 5’-ATGCTCA-3’ could form a stable duplex with which RNA strand?

A

5’-UGAGCAU -3’

92
Q

A nucleic acid sample has a composition of 30%A, 25%C, 20% G and 25% U. What is the most likely conclusion?

A

The sample is likely single stranded RNA

93
Q

For a DNA strand of the sequence 5’-TCCTACA-3’ the complementary strand will be..?

A

5’-TGTAGGA -3’