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cell bio > chapter 7 > Flashcards

chapter 7 Flashcards

1
Q

The segments of DNA that are transcribed into RNA are called

A

genes

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2
Q

RNA is made of nucleotides that are linked by

A

phosphodiester
bonds

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3
Q

Same phosphodiester bond that links nucleotides in RNA…

A

is same as DNA

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4
Q

the structure of
RNA differs from that of DNA
in __ ways

A

3

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5
Q

RNA and DNA differences

A

1.RNA contains ribose not deoxyribose, has an additional -OH group.
2. RNA contains uracil instead of thymine in DNA
3. RNA is single stranded, no double helix

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6
Q

The nucleotides in RNA are

A

ribonucleotides

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7
Q

Uracil differs from thymine by the

A

absence of methyl group

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8
Q

Uracil, like thymine, can form

A

base-pairs with adenine (A)

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9
Q

How does RNA fold into a variety of shapes…

A

forming base-pairs between
nucleotides within the same strand

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10
Q

Base pairing always occurs between

A

anti-parallel strands

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11
Q

The ability to fold into shapes allows RNA to perform…

A

structural, regulatory, or catalytic roles in cells

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12
Q

__ produces an RNA molecule that is
complementary to one strand of DNA

A

Transcription

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13
Q

One of the two strands of DNA serves as a __ for RNA synthesis

A

template

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14
Q

Ribonucleotides are added

A

1 by 1 to rna molecule

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15
Q

The nucleotide sequence of the RNA chain is determined by

A

complementary base pairing with the DNA template strand

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16
Q

RNA is transcribed in what direction….
Nucleotides are added to what end…

A

5’-to-3’ direction (nucleotides are added to the 3’ end)

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17
Q

The DNA template strand is read in the

A

3’-to’5’ direction

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18
Q

same base sequence as RNA transcript

A

Non-template strand = coding strand

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19
Q

complementary to RNA transcript

A

Template strand

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20
Q

Write the sequence of the RNA transcript that is generated using the bottom strand of the following DNA sequence as the template:

5’-TTTTT-3’
3’-AAAAA-5’

A

3’-AAAAA-5” (template)
5’- UUUUU-3’ (rna transcript sequence)

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21
Q

Write the sequence of the RNA transcript that is generated using the top strand of the following DNA sequence as the template:
5’-CGGAATC-3’
3’-GCCTTAG-5’

A

5’-CGGAATC-3’ (template)
3’- GCCUUAG-5’ rna transcript sequence)

read 5’-GAUUCCG-3’

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22
Q

Using the DNA sequence below, identify the coding strand for the following RNA
transcript: 5’-AUCGA-3’

DNA sequence:5’-ATCGA-3’
3’-TAGCT-5’

A

5’-ATCGA-3’

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23
Q

is an enzyme that catalyzes the formation of phosphodiester
bonds that link ribonucleotides together

A

RNA polymerase

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24
Q

RNA polymerase unwinds the DNA helix to expose a region of the..

A

template strand for complementary base pairing

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25
Q

The RNA strand elongates one nucleotide at a time in the

A

5’-to-3’ direction

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26
Q

used to direct the synthesis of proteins In eukaryotes

A

mRNA

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27
Q

each mRNA carries information transcribed from a

A

single gene

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28
Q

What kind of rna play regulatory,
structural and catalytic roles in cells

A

Noncoding RNAs (e.g. rRNA, tRNA, miRNA)

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29
Q

The promoter is located

A

upstream (a.k.a. before) of the starting point for RNA synthesis

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30
Q

binds the promoter and begins transcription

A

RNA polymerase

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31
Q

Transcription proceeds until RNA polymerase encounters a

A

terminator

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32
Q

Every promoter has a

A

polarity

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33
Q

Bacterial promoters contain __ different nucleotide sequences that are laid out in a specific __ order

A

2, 5’-to’3’

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34
Q

RNA polymerase always moves in the __ direction on the template DNA strand

A

3’-to-5’

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35
Q

what determines which strand will serve as the
template?

A

The polarity (orientation) of the promoter sequence at the
beginning of each gene

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36
Q

Terminators have specific…

A

nucleotide sequences

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37
Q

Terminator sequences are

A

palindromic

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38
Q

cause a stem-loop structure to form in the RNA
transcript

A

terminator sequences

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39
Q

What causes the transcipt to dissociate from the DNA template

A

stem loop stricture in the RNA transcript

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40
Q

Transcription in bacteria: Bacterial RNA polymerase contains a subunit called a

A

sigma factor

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41
Q

recognizes and binds the promoter of a gene

A

sigma factor

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42
Q

in bacterial transcription, once transcription begins what is released

A

sigma factor

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43
Q

In bacterial transcription, RNA polymerase opens the double
helix immediately in

A

front of the promotoer

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44
Q

synthesizes a chain of RNA by base pairing with the template strand

A

RNA polymerase

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45
Q

When RNA polymerase reaches the terminator…

A

It stops and releases the DNA template and the
RNA transcript

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46
Q

Bacteria use a __ RNA polymerase for transcription, while eukaryotic cells use __

A

single, 3 (RNA poly 1, 11, 111)

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47
Q

Which polymerase transcribe genes encoding tRNA, rRNA and other small RNAs (regulatory RNA)

A

RNA polymerase I and III

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48
Q

which polymerase transcribes mRNA and other RNAs

A

RNA polymerase II

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49
Q

Bacterial RNA polymerase (with its sigma factor) initiates transcription on its own, while eukaryotic RNA polymerases require a…

A

large set of
accessory proteins

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50
Q

Accessory proteins can include

A

general transcription factors

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51
Q

assemble at
each promoter along with the polymerase before transcription can
begin

A

general transcription factors

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52
Q

Transcription in eukaryotes requires the

A

General Transcription Factors

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53
Q

Step 1 in transcription factors of eukaryotes

A

TFIID binds a short sequence
of DNA that is rich in T and A nucleotides à called the “TATA box

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54
Q

TFIID binding to the TATA box…

A

distorts DNA double helix

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55
Q

Step 2 in transcription factors of eukaryotes

A

TFIID recruits RNA
polymerase II and others to form a transcription initiation complex

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56
Q

Step 3 in transcription factors of eukaryotes

A

TFIIH pulls apart the double
helix at the transcription start point and phosphorylates RNA
polymerase II

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57
Q

Step 4 in transcription factors of eukaryotes

A

Transcription begins

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58
Q

Eukaryotic transcription occurs in the

A

nucleus

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59
Q

Translation occurs on ribosomes in the

A

cytosol

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60
Q

Before a eukaryotic mRNA can be translated into protein, it must be transported

A

out of the nucleus

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61
Q

Before RNA is exported, it must go through

A

RNA processing

62
Q

What is involved in RNA processing

A

capping, splicing and polyadenylation

63
Q

Processing occurs ___ transcription

A

during and after

64
Q

RNA-processing proteins bind
to the phosphorylated tail of __, it gives them access to the

A

RNA polymerase II, RNA transcript as it emerges from the polymerase

65
Q

modifies the 5’ end of the transcript by adding an
atypical guanine nucleotide with a methyl group

A

RNA capping

66
Q

addition of a series of repeated adenine (A) nucleotides to the 3’ end

A

Polyadenylation

67
Q

Capping and polyadenylation promote the

A

stability, export and
translation of mRNAs

68
Q

RNA capping and polyadenylation occur on all
RNA transcripts that become

A

mRNA molecules

69
Q

contain single stretches of nucleotides that encode
the amino acid sequence of proteins

A

Bacterial genes

70
Q

The coding sequences of most eukaryotic genes are interrupted by noncoding “intervening sequences” called

A

introns

71
Q

The protein-coding sequences are called “expressed sequences” or

A

exons

72
Q

Most of the nucleotide sequences
of introns are

A

unimportant

73
Q

involves the precise removal of introns

A

splicing

74
Q

The intron is removed as a __
structure, which is degraded in the __

A

lariat, nucleus

75
Q

Once an intro is removed, the two exons are joined together…

A

covalently

76
Q

allows increased genetic diversity and complexity

A

Alternative splicing

77
Q

Fully processed mRNAs are recognized as

A

mature transcripts
that are allowed to leave the nucleus

78
Q

Proteins bind to __ cap, splice junctions and poly-A tail and promote:

A

5’, transport out of the nucleus, mRNA stability, translation

79
Q

Prokaryotes don’t have a nucleus, so transcription and translation happen in the

A

cytosol

80
Q

Prokaryotes don’t need

A

RNA processing

81
Q

In eukaryotes, transcription happens in the

A

nucleus

82
Q

In eukaryotes, mRNA must be processed via

A

5’ capping, 3’ polyadenylation, and splicing before it is exported into the
cytosol and translated

83
Q

mitochondria and chloroplasts
have their own

A

RNA polymerases

84
Q

The process of transcription begins with RNA polymerase binding to a region of the gene called a

A

promotor

85
Q

TFIID contains a subunit called __ that binds to a sequence in the promotor known as __

A

TATA binding protein, TATA box

86
Q

TFIIH has two important functions:

A
  1. it partially unwinds the DNA to expose the
    template strand at the promoter
  2. it phosphorylates RNA polymerase II to release it from the general transcription factors
87
Q

cap is added to the 5’ end of the mRNA

A

Capping

88
Q

poly-A-tail pf 100 or more repeated adenine nucleotides is added to the 3’ end of the mRNA

A

Polyadenylation

89
Q

Splicing is performed by a molecular machine known as the

A

splicesome

90
Q

deflects in splicing are the cause of

A

some human disease

91
Q

Nucleotides are read in groups of three called

A

codons

92
Q

__ possible codons used to specify 20 amino acids

A

64

93
Q

Most amino acids are specified by

A

2 or more codons

94
Q

__ codons are used as a translation stop signal

A

3

95
Q

Genetic code can be described as

A

redundant

96
Q

Each mRNA has 3 possible __, only __ encodes the correct protein sequence

A

reading frames, 1

97
Q

Small adaptor molecules known as __ are responsible for matching the
proper amino acid to the correct mRNA codon.

A

tRNAa

98
Q

site of protein synthesis

A

ribosomes

99
Q

There are __ different nucleotides in mRNA but __ different amino
acids in proteins

A

4, 20

100
Q

The nucleotide sequence of an mRNA is translated into amino acids
using

A

codons

101
Q

Each codon consists of nucleotides

A

3

102
Q

Codons are translated sequentially in the _ direction, without overlaps or spacers

A

5’ to 3’

103
Q

The genetic code is

A

redundant

104
Q

In the genetic code, __ codons are used to specific 20 amino acids

A

64

105
Q

what RNA translate the code

A

tRNAs

106
Q

Transfer RNAs (tRNAs) fold into a

A

cloverleaf structure

107
Q

The cloverleaf structure from tRNA folds further into a

A

L shaped structure

108
Q

set of three nucleotides that bind the complementary
codon in an mRNA molecule

A

anticodon

109
Q

in the tRNA, the amino acid that matches the codon is __ attached to the single stranded region at the __ end of the tRNA

A

covalently, 3’

110
Q

Two regions of the tRNA are crucial for translation

A

amino acid and anticodon

111
Q

In the genetic code, multiple codons…

A

encode the same amino acid

112
Q

Codons are most variable at the __ position

A

3rd

113
Q

Some tRNAs require accurate base-pairing only at the

A

first 2 positions

114
Q

tRNA base pairing can tolerate a mismatch at the __ position

A

(wobble), 3rd

115
Q

__ tRNAs for __ total codons in humans

A

48, 61

116
Q

establish the tRNA code

A

tRNA synthetases

117
Q

covalently attach each amino acid to the appropriate tRNAs

A

tRNA synthetases

118
Q

There are __ tRNA synthetases

A

20

119
Q

a key link between the nucleotide and amino acid
languages

A

tRNA synthetases

120
Q

The same mRNA sequence can specify __ different amino acid sequences, depending on the nucleotide at which translation begins

A

3

121
Q

Translation begins at the initiation codon __

A

AUG

122
Q

AUG encodes a

A

methionine

123
Q

The position of the initiation codon sets the translation __

A

reading frame

124
Q

catalyzes protein synthesis

A

ribosome

125
Q

Ribosomes are composed of

A

one large subunit and one small subunit

126
Q

Eukaryotic ribosomes are made from __ ribosomal RNAs (rRNAs) and more than 80 proteins

A

4

127
Q

Each ribosome has how many binding sites for mRNA and rRNAs

A

mRNA- 1
tRNA- 3

128
Q

The ribosome’s 3 tRNA binding sites are called

A

the A site, the P site and the E site

129
Q

Four step cycle of translation…

A

step 1: growing polypeptide chain is linked to the tRNA in the P site
step 2: new peptide bond is catalyzed by RNA in large ribosomal subunit
step 3: large ribosomal subunit shifts forward to move 2 tRNAs into E and P sites
step 4: small subunit moves forward 2 nucleotides along the mRNA to rejoin large subunit; movement ejects the spent tRNA from E site and resets the ribosome with an empty A site so next tRNA can bind

130
Q

In the first step of translation, to add an amino acid to a growing peptide chain, a

A

tRNA enters A site, w base pairing on complimentary mRNA

131
Q

In eukaryotes, translation of mRNA begins with __ and requires __

A

AUG codon, initiator tRNA

132
Q

In eukaryotes. the initiator codon always carries the amino acid

A

methionine

133
Q

In translation in eukaryotes, Newly made proteins all have methionine as the first amino acid at their

A

N-terminal end

134
Q

In translation in eukaryotes, __ is loaded into the __ site of the __ ribosomal subunit along with __

A

initiator tRNA, P, small, translation initiation factors

135
Q

In translation in eukaryotes, the small ribosomal subunit then binds to the __ end of the mRNA

A

5’

136
Q

After the small ribosomal subunit binds to the mRNA in translation, the small ribosomal subunit then scans the mRNA in the

A

5’-to-3’ direction until it encounters the first AUG codon

137
Q

In translation in eukaryotes, when the AUG is recognized by the initiator tRNA, several initiation factors dissociate, allowing….

A

the large ribosomal
subunit to bind

138
Q

in translation in eukaryotes, Because the initiator tRNA is
bound to the P site, protein
synthesis is ready to begin
with the addition of the next

A

tRNA to the A site

139
Q

to initiate translation in prokaryotes, there’s no __ for the small ribosomal subunit to bind on bacterial mRNAs/ Instead ribosomes…

A

5’ cap, bind directly to specific sequences adjacent to coding
regions

140
Q

Most bacteria mRNAs are

A

polycistronic

141
Q

a single mRNA encodes several different proteins, usually with related functions

A

polycistronic

142
Q

in translation in prokaryotes each ribosome has…

A

its own ribosome-binding site instead of scanning for aug

143
Q

How to terminate translation

A

Stop codons; release factors bind to stop codon in the A-site; peptide chain is transferred to a water molecule, ending synthesis

144
Q

what are the stop codons

A

UAA, UAG, UGA

145
Q

can be translated by multiple
ribosomes at the same time

A

A single mRNA

146
Q

simultaneously translate the same mRNA

A

Polyribosomes

147
Q

A single gene can be transcribed by multiple RNA polymerases at the same time T or F

A

True

148
Q

Misfolded or damaged proteins and proteins that are meant to be short-lived are degraded by the

A

proteasome

149
Q

large protein complex that contains enzymes
called proteases

A

proteasome

150
Q

cut proteins into short peptides

A

proteases

151
Q

Proteins are marked for degradation by the covalent attachment of
a small protein called

A

ubiquitin

cell bio (15 decks)

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