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Genetics > Chapters 7, 8, 9 > Flashcards

Chapters 7, 8, 9 Flashcards

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Biology 101 flashcards
1
Q

DNA is a simple molecule made up of only four building blocks called

A

nucleotides

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2
Q

Discovered double helical stucture

A

Watson & Crick

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3
Q

Who used a pneumonia-causing bacteria to discover that the genotype and phenotype can transformed by mixing it with heat-killed strain?

A

Frederick Griffith

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4
Q

Who discovered that DNA is the genetic material in bacteria?

A

Avery, MacLeod & McCarty

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5
Q

The demonstration that DNA is the transforming agent was the first evidence that genes (the hereditary material) are…

A

Composed of DNA

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6
Q

Who infected two E. coli cultures with many phage particles and found that the radioactivity ended up inside the bacterial cells, indicating that phage DNA entered the cells?

A

Hershey & Chase

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7
Q

3 components of DNA

A

1.) phosphate
2.) deoxyribose
3.) 4 nitrogenous bases

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8
Q

Name the 4 bases

A

adenine, guanine, cytosine, and thymine

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9
Q

The sugar in DNA is called “deoxyribose” because it contains ribose sugars that are…

A

Missing an oxygen atom

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10
Q

Two of the bases, adenine and guanine, have a double-ring structure characteristic of a class of chemicals called _____.

A

purines

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11
Q

Two of the bases, cytosine and thymine, have a single-ring structure characteristic of another class of chemicals called ______.

A

pyrimidines

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12
Q

All nucleotides have (3 things)

A

phosphate, sugar, base

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13
Q

The chemical subunits of DNA

A

deoxynucleotides

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14
Q

Who established certain empirical rules about the amounts of each type of nucleotide found in DNA?

A

Chargaff

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15
Q

DNA contains _____ of A and T nucleotides and G and C nucleotides

A

an equal amount

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16
Q

Organisms ____ in the relative amount of A + T versus G + C, but different tissues in the same organism have ____ relative amount of A + T versus G + C.

A

vary; the same

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17
Q

Whose X-ray data showed that DNA is helical, like a spiral staircase, long and skinny, and has two similar parts that are parallel to each other?

A

Rosalind Franklin

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18
Q

Nucleotide bases pair by:

A

Hydrogen bonding

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19
Q

complementary bases

A

Refers to specific pairing between adenine and thymine, guanine and cytosine, and adenine and uracil.

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20
Q

DNA is a ____-handed helix

A

right

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21
Q

On the outside of the double helix, the backbone of each strand is formed by alternating phosphate and deoxyribose sugar units that are connected by

A

phosphodiester linkages

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22
Q

Each sugar–phosphate backbone is said to have a ____ polarity, or direction

A

5′-to-3′

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23
Q

In double-stranded DNA, the two backbones are in ____ orientation

A

anti-parallel

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24
Q

A–T base pairs have ___ hydrogen bonds, and G–C base pairs have ___.

A

2; 3

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25
Q

Shallow _____ grooves occur where the sugar–phosphate backbones are far apart, and deep ____ grooves occur where they are close together

A

major, minor

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26
Q

Function of grooves

A

Protein binding

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27
Q

semiconservative replication

A

The established model of DNA replication in which each double-stranded molecule is composed of one parental strand and one newly polymerized strand.

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28
Q

the original strand

A

parental molecule

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29
Q

the new strand

A

daughter molecule

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30
Q

two other modes of replication that were also hypothesized

A

1.) conservative replication
2.) dispersive replication

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31
Q

Whose experiment set to allow parental DNA containing nucleotides of one density to replicate using nucleotides of a different density?

A

Meselson & Stahl

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32
Q

base linked to a sugar

A

nucleoside

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33
Q

Bacterial chromosomes are (shape)

A

Circular

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34
Q

The ends of the thick curve of dots defined two sites of ongoing DNA replication and are referred to as

A

replication forks

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35
Q

Whose experiment provided additional evidence for semiconservative replication and also demonstrated that replication in bacteria begins at one site in the genome and spreads bidirectionally by means of two replication forks?

A

Cairns

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36
Q

enzymes that disrupt hydrogen bonds that hold the two strands of the double helix together

A

Helicase

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37
Q

Prevents overwinding

A

topoisomerases

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38
Q

Unwound DNA is stabilized by

A

single-strand DNA-binding (SSB) proteins

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39
Q

Example of topoisomerase

A

DNA gyrase

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40
Q

The point of a specific sequence at which DNA replication is initiated.

A

origin of replication

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41
Q

it is easier to separate (melt) the double helix at stretches of DNA that are enriched in ___ base pairs

A

A-T

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42
Q

Who isolated a DNA polymerase from E. coli and demonstrated its enzymatic activity in vitro?

A

Kornberg

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43
Q

A bacterial enzyme that synthesizes DNA to connect Okazaki fragments during DNA replication.

A

DNA polymerase I

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44
Q

A bacterial enzyme that is the primary DNA polymerase during DNA replication.

A

DNA polymerase III

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45
Q

DNA synthesis must be initiated by this short chain of nucleotides that forms a segment of duplex nucleic acid:

A

Primer

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46
Q

Primers are synthesized by a set of proteins called a

A

Primosome

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47
Q

a central component of primosome is an RNA polymerase called

A

Primase

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48
Q

In DNA replication, the strand that is made in the 5′-to-3′ direction by continuous polymerization at the 3′ growing tip.

A

leading strand

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49
Q

A small segment of single-stranded DNA synthesized as part of the lagging strand in DNA replication.

A

Ozaki fragments

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50
Q

In DNA replication, the strand that is synthesized apparently in the 3′-to-5′ direction by the ligation of short fragments synthesized individually in the 5′-to-3′ direction.

A

Lagging strand

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51
Q

Because DNA replication is continuous for the leading strand and discontinuous for the lagging strand, the overall process is described as

A

semidiscontinuous

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52
Q

An enzyme involved in DNA replication and repair that seals the DNA backbone by catalyzing the formation of phosphodiester bonds.

A

DNA ligase

53
Q

Responsible for proofreading

A

DNA pol I and DNA pol III

54
Q

the _____ is more likely than DNA to contain errors

A

RNA primer

55
Q

A molecular machine called the _____ carries out DNA synthesis

A

Replisome

56
Q

A protein that encircles the DNA, keeping the enzyme DNA pol III attached to the DNA molecule at the replication fork, converting it from a distributive to a processive enzyme.

A

𝛃 clamp / sliding clamp

57
Q

An enzyme that can add only a limited number of nucleotides before falling off the DNA template.

A

distributive enzyme

58
Q

the behavior of DNA polymerase III, which can perform thousands of rounds of catalysis without dissociating from its substrate (the template DNA strand).

A

processive enzyme

59
Q

The β clamp converts DNA polymerase III from a _____ to a _____ enzyme.

A

distributive; processive

60
Q

Replication proceeds in both directions from hundreds or thousands of origins on

A

linear eukaryotic chromosomes.

61
Q

DNA synthesis takes place only in ___ (synthesis) phase of the eukaryotic cell cycle

A

S

62
Q

A eukaryotic complex that binds to origins of replication to initiate DNA replication.

A

origin recognition complex (ORC)

63
Q

DNA replication in eukaryotes requires ____________, proteins that are only available during late mitosis (M) and G1 phase, ensuring that the genome is only replicated once per cell cycle.

A

Cdc6 and Cdt1

64
Q

An enzyme that, with the use of a small RNA as a template, adds repetitive units to the ends of linear chromosomes to prevent shortening after replication.

A

Telomeres

65
Q

An enzyme that, with the use of a small RNA as a template, adds repetitive units to the ends of linear chromosomes to prevent shortening after replication.

A

Telomerase

66
Q

The discovery that the ends of chromosomes are made up of sequences repeated in tandem was made in 1978 by

A

Blackburn & Gall

67
Q

An enzyme that catalyzes the synthesis of a DNA strand from an RNA template.

A

reverse transcriptase

68
Q

A structure at the end of a telomere that masks the end from the factors that detect DNA breaks.

A

telomeric loop

69
Q

Telomeres and telomerase are associated with _____ and _____

A

aging; cancer

70
Q

Unlike DNA, RNA has a ____ rate of turnover within cells.

A

high

71
Q

RNA has ____ sugar in its nucleotides

A

ribose

72
Q

What replaces thymine in RNA?

A

Uracil

73
Q

single-stranded but base pairs to itself to form double-stranded regions.

A

RNA

74
Q

An RNA molecule transcribed from the DNA of a gene; a protein is translated from this RNA molecule by the action of ribosomes.

A

mRNA (messenger RNA)

75
Q

RNA that is not translated into protein.

A

noncoding RNA (ncRNA)

76
Q

A class of small RNA molecules that carry specific amino acids to the ribosome in the course of translation; an amino acid is inserted into the growing polypeptide chain when the anticodon of the corresponding tRNA pairs with a codon on the mRNA being translated.

A

tRNA (transfer RNA)

77
Q

Several different noncoding RNAs that are components of the ribosome and are essential for protein synthesis.

A

ribosomal RNAs (rRNAs)

78
Q

snRNA

A

small nuclear RNA

79
Q

lncRNA

A

long noncoding RNA

80
Q

miRNA

A

micro RNA

81
Q

siRNA

A

small interfering RNA

82
Q

The site at which the double helix is unwound so that RNA polymerase can use one of the DNA strands as a template for RNA synthesis.

A

transcription bubble

83
Q

The strand of DNA that is copied (i.e., transcribed) by RNA polymerase.

A

template / noncoding strand

84
Q

The nontemplate strand of a DNA molecule having the same sequence as that in the RNA transcript.

A

coding strand

85
Q

An enzyme that catalyzes the synthesis of an RNA strand from a DNA template

A

RNA polymerase

86
Q

The three distinct stages of transcription

A

initiation
elongation
termination

87
Q

A DNA sequence that defines where transcription by RNA polymerase will begin.

A

promoter

88
Q

Refers to a DNA or RNA sequence located on the 5′ side of a point of reference.

A

upstream

89
Q

A _____ site is located closer to the 3′ end of a transcription unit.

A

downstream

90
Q

Nucleotide positions upstream of the initiation site are indicated by a _____ sign

A

negative

91
Q

In bacteria, promoters are bound by RNA polymerase ____ factors

A

sigma

92
Q

A type of transcription termination mechanism in bacteria that involves the protein Rho.

A

Rho-dependent termination

93
Q

Special sequences within the ____ of an mRNA direct transcription termination

A

3′ UTR

94
Q

The abundance of an RNA in cells is determined by _____ and _______

A

transcription; decay

95
Q

The first step of decay in bacteria is carried out by an _______, which cuts an RNA into two pieces

A

endonuclease

96
Q

the next step of decay is carried out by ______, which digest the RNA pieces into single nucleotides starting at their 3′ end.

A

exonucleases

97
Q

Eukaryotes have many genes that are

A

spaced far apart

98
Q

Eukaryotes have ___ RNA polymerases

A

3

99
Q

Transcription in eukaryotes takes place in the

A

Nucleus

100
Q

DNA in eukaryotes is packaged with proteins into ______

A

chromatin

101
Q

One of the main functions of ______ is to recruit a specific RNA polymerase and position it to begin RNA synthesis at the transcription start site.

A

general transcription factors (GTFs)

102
Q

In the _____, initiation of rDNA gene transcription by RNA polymerase I is regulated by UCE and Core promoter elements and UBF, SL1, and TIF-1A regulatory factors.

A

nucleolus

103
Q

A DNA sequence found in many eukaryotic genes that is located about 30 bp upstream of the transcription start site.

A

TATA box

104
Q

About ____ of RNA polymerase II genes contain TATA box and/or Inr promoter elements.

A

half

105
Q

The general transcription factors (GTFs) TFIIB and TFIID recruit RNA polymerase II and other GTFs to the promoter, forming a ______ and a transcription bubble.

A

pre-initiation complex (PIC)

106
Q

Genes transcribed by RNA polymerase III are divided into three types, based on their

A

promoter elements

107
Q

During elongation, the CTD of RNA polymerase II is chemically modified to serve as a _________ for other proteins involved in transcription and RNA processing.

A

binding site

108
Q

A model proposing that transcription termination is caused by displacement of RNA polymerase II from DNA by an exonuclease.

A

torpedo termination model

109
Q

A model proposing that transcription termination by RNA pol II is caused by a conformational change within its active site.

A

allosteric termination model

110
Q

RNAs synthesized by RNA polymerase II, including mRNAs and snRNAs, are modified at their 5′ end by addition of a methylated guanine nucleotide, 7-methylguanosine (m7G), more commonly referred to as a

A

cap

111
Q

The ____ end of a eukaryotic mRNA is modified to prevent decay and to serve as a binding site for factors that mediate mRNA processing and export

A

5’

112
Q

______ of mRNAs is programmed to occur early in transcription through the association of capping enzymes with phosphorylated serine 5 on the CTD of RNA polymerase II.

A

Capping

113
Q

The ___ end of mRNAs is modified by addition of a long stretch of adenosine nucleotides, which protects the mRNA from decay and supports translatio

A

3’

114
Q

The _____ is added by a special type of RNA polymerase following mRNA cleavage at a site that is determined by protein factors that bind sequence elements in the mRNA.

A

poly(A) tail

115
Q

A reaction that removes introns and joins together exons in pre-RNA.

A

splicing

116
Q

_____ facilitate splicing by base pairing with conserved sequences in the pre-mRNA.

A

snRNAs

117
Q

The first step is cleavage at the __ splice, and the second step is cleavage at the ___ splice site

A

5’; 3’

118
Q

The joining of exons in different patterns via ____________ greatly expands the number of proteins encoded in the human genome and other eukaryotic genomes.

A

alternative splicing

119
Q

RNAs are subject to ____ and _____

A

editing, modification

120
Q

After removal of the poly(A) tail, mRNA decay by specialized enzymes occurs in

A

both directions

121
Q

Researchers have taken advantage of the endogenous _____ machinery to knock down the expression of a specific gene by introducing into cells dsRNA that is identical in sequence to the target gene. (gene silencing)

A

RNAi

122
Q

How many amino acids are there?

A

20

123
Q

amino acids have which 3 groups

A

amino; carboxyl, R (side chain)

124
Q

A codon of ____ nucleotides specifies an amino acid

A

3

125
Q

The genetic code is _______; more than one codon can specify the same amino acid.

A

degenerate

126
Q

The genetic code is _______; each nucleotide is part of only one codon.

A

nonoverlapping

127
Q

The genetic code is ______; it is read from a fixed starting point and continues uninterrupted to the end of the open reading frame.

A

continuous

128
Q

The genetic code contains how many codons

A

64

Genetics (6 decks)

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