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BIOL 1105 > 12: Gene Expression > Flashcards

12: Gene Expression Flashcards

Module 3, Lesson 1

1
Q

An organism’s genome encodes…

A

Functional molecules

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2
Q

____ and ____ are functional molecules.

A

RNA and proteins

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3
Q

True or false:

The proportion of the genome that codes for functional molecules is constant across all species.

A

False

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4
Q

Approximately ____ of the human genome codes for functional molecules.

A

1-2%

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5
Q

A discrete nucleotide that codes for RNA or protein is called a…

A

Gene

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6
Q

____ is the process by which DNA is converted into RNA.

A

Transcription

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7
Q

____ is the process by which RNA is converted into polypeptides.

A

Translation

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8
Q

The central dogma of biology states that…

A

The output of gene expression is proteins.

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9
Q

The central dogma of biology describes the process by which…

A

DNA is converted into RNA, which is then converted into proteins.

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10
Q

The enzyme that synthesizes an RNA copy of DNA template strands is…

A

RNA polymerase

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11
Q

Like DNA polymerase, RNA polymerase catalyzes…

A

Phosphodiester bond formation

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12
Q

RNA polymerase synthesizes RNA from the ____ end to the ____ end.

A

5’ to 3’

(the same as DNA polymerase)

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13
Q

RNA polymerase uses ____ strand(s) of DNA as a template.

A

1

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14
Q

True or false:

RNA polymerase requires a primer to begin synthesis.

A

False

Unlike DNA polymerase, RNA polymerase can begin synthesis without a primer.

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15
Q

To transcribe RNA, RNA polymerase must be located at the…

A

Promoter

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16
Q

What is the promoter?

A

A sequence of nucleotide that serves as the binding site upstream (in front of) the gene to be transcribed.

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17
Q

Transcription begins at the ____, which is the nucleotide designated…

A

Start site ; +1

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18
Q

List the five main types of RNA.

A
  1. Messenger RNA (mRNA)
  2. Ribosomal RNA (rRNA)
  3. Transfer RNA (tRNA)
  4. Small-nuclear RNA (snRNA)
  5. Micro RNA (miRNA)
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19
Q

What are the functions of messenger RNA?

(two)

A
  1. Acts as an intermediate in the flow of genetic information
  2. Codes for proteins
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20
Q

What are the functions of ribosomal RNA?

(two)

A
  1. Interacts with proteins to form the ribosome
  2. Some catalyze protein synthesis
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21
Q

What is the function of transfer RNA?

A

Uses information from mRNA to deliver the correct amino acid during translation

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22
Q

What is the function of small-nuclear RNA?

A

Involved in pre-mRNA splicing (removing non-coding sequences from the mRNA)

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23
Q

What is the function of micro RNA?

A

Regulates the expression of some genes

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24
Q

Which types of RNA are not involved in translation?

A

snRNA
miRNA

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25
Q

List the main steps of the initiation phase of transcription.

A
  1. RNA polymerase binds to the promoter, along with the sigma subunit
  2. RNA polymerase reaches the transcription start site
  3. RNA polymerase unwinds the DNA helix
  4. The first complementary RNA nucleotide is incorporated
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26
Q

The strand of DNA from which RNA is synthesized is termed the…

A

Template strand

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27
Q

The strand of DNA which the completed RNA strand is nearly identical to is the…

A

Coding strand

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28
Q

The new RNA molecule is synthesized antiparallel to the…

A

Template strand

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29
Q

During transcription, the complementary base for adenine becomes…

A

Uracil

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30
Q

The elongation phase of transcription begins after about ____ nucleotide(s) are synthesized.

A

10

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31
Q

List the 3 major components of the transcription bubble.

A
  1. RNA polymerase
  2. Part of the exposed template DNA strand
  3. Part of the new RNA base-paired to the template DNA
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32
Q

Transcription continues until…

A

A terminator sequence is encountered and transcribed.

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33
Q

The terminator sequence codes for RNA that…

A

Pairs to itself, creating a hairpin structure

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34
Q

The hairpin structure formed by the terminator sequence disrupts…

A

The interactions between DNA, RNA, and RNA polymerase

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35
Q

In eukaryotes, transcription occurs in the…

A

Nucleus

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36
Q

True or false:

Both eukaryotes and prokaryotes have only one kind of RNA polymerase.

A

False

Eukaryotes have three different RNA polymerases.

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37
Q

In eukaryotes, mRNA is synthesized by…

A

RNA polymerase II

(also the best understood of the three RNA polymerases)

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38
Q

List the major differences between eukaryotic and prokaryotic transcription.

(four)

A
  1. Eukaryotes have 3 RNA polymerases
  2. The promoter’s position and sequence is different
  3. Eukaryotic transcription is initiated by transcription factors
  4. The initial mRNA molecule is modified in eukaryotes
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39
Q

Compared to prokaryotes, the mechanism for binding RNA to the promoter is ____ complicated in eukaryotes.

A

More

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40
Q

In eukaryotes, RNA polymerase II is recruited to the promoter and activated by a series of proteins called…

A

Transcription factors

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41
Q

True or false:

In eukaryotes, the intial mRNA molecule must undergo additional processing to become a mature molecule.

A

True

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42
Q

The initial molecule of mRNA synthesized is called the…

A

Primary transcript

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43
Q

List the three ways in which eukaryotes modify mRNA.

A
  1. A cap is added to the 5’ end
  2. A 3’ poly-A tail is added to the 3’ end
  3. Non-coding regions are removed
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44
Q

What is the purpose of the 5’ cap?

A

Protects the mRNA from degradation and helps to align it during translation

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45
Q

What is the purpose of the 3’ poly-A tail?

A

Protects the mRNA from degradation

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46
Q

Regions of mRNA that specify amino acids are called…

A

Exons

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47
Q

Regions of mRNA that do not specify amino acids and are not translated are called…

A

Introns

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48
Q

Introns are removed from the mRNA by the…

A

Spliceosome

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49
Q

During splicing, introns are ____ and exons are ____.

A

Removed ; spliced together

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50
Q

True or false:

Different genes have different numbers of introns and exons.

A

True

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51
Q

True or false:

Only eukaryotes have introns.

A

True

52
Q

The output of splicing is…

A

Mature mRNA

53
Q

True or false:

A single primary transcript can code for multiple proteins, depending on how it is spliced.

A

True

54
Q

How can a single primary transcript code for multiple different proteins?

A

Different exons are included when it is spliced.

55
Q

The second step in gene expression is…

A

Translation

56
Q

Translation is the process of…

A

Protein synthesis

57
Q

During translation…

A

The nucleotide sequence of mRNA is converted to a polypeptide sequence and eventually a functional protein

58
Q

List the three main components involved in translation.

A
  1. mRNA
  2. tRNA
  3. rRNA
59
Q

Protein synthesis proceeds from the ____-terminus to the ____-terminus

A

N to C

60
Q

The mRNA sequence is always read in a ____ to ____ direction.

A

5’ to 3’

61
Q

In prokaryotes, mRNA contains ____ coding sequence(s).

A

Multiple

62
Q

Prokaryotic genes are organized into…

A

Operons

63
Q

True or false:

Some regions of prokaryotic mRNA do not code for proteins.

A

True

64
Q

____ are located at the beginning and end of prokaryotic RNA.

A

Untranslated regions
(UTRs)

65
Q

Untranslated regions are regions that do not…

A

Code for any proteins

66
Q

Eukaryotic mRNA contains ____ coding sequence(s).

A

One

67
Q

True or false:

Eukaryotic genes may be organized into operons.

A

False

Operons are only found in prokaryotes.

68
Q

In prokaryotic mRNA, each coding region begins with a…

A

Translation start site

69
Q

An amino acid is specified by a sequence of three nucleotides called a…

A

Codon

70
Q

Each codon specifies ____ amino acid(s).

A

One

71
Q

The codon AUG, which does for methionine, is termed the…

A

“Start codon”

72
Q

The first codon in a coding sequence is almost always…

A

AUG

73
Q

There are a total of ____ possible codons.

A

64

74
Q

True or false:

More than one codon can specify the same amino acid.

A

True

75
Q

____ codons specify an amino acid.

A

61

76
Q

____ codons code for “stop codons”.

A

3

77
Q

The genetic code is…

A

Redundant (degenerate)

78
Q

True or false:

The genetic code is practically universal.

A

True

79
Q

There are ____ possible reading frames for any mRNA.

A

3

80
Q

The reading frame used for an mRNA depends on…

A

The nucleotide at which reading starts.

81
Q

During translation, what is the function of tRNA?

A

Carries amino acids to the ribosomes, where they are assembled into polypeptides.

82
Q

tRNA self-folds into a ____ shape.

A

Cloverleaf

83
Q

What creates the 3D stucture of tRNA?

A

Internal complementary base pairing

84
Q

List the two important regions found on opposite ends of the tRNA molecule.

A
  1. 3’ acceptor end
  2. Anticodon loop
85
Q

What is the function of the 3’ acceptor end?

A

Amino acids are loaded onto it

86
Q

What is the anticodon loop and what is its function?

A

A 3-nucleotide sequence that recognizes and binds to a complementary codon in the mRNA.

87
Q

tRNA and the amino acids it transports are able to interact with the correct codon due to the…

A

Anticodon loop

88
Q

Interactions between tRNA and mRNA are based on…

A

Base pairing using hydrogen bonds

89
Q

True or false:

tRNA–mRNA base pairing is fundamentally the same as nucleotide base pairing in DNA strands.

A

False

90
Q

True or false:

Some tRNA molecules can recognize more than one codon.

A

True

91
Q

The less stringent interactions between the 3’ end of the codon and the 5’ end of the anticodon are called…

A

“Wobble” or “wobble pairing”

92
Q

“Wobble pairing” is also called…

A

Relaxed base pairing

93
Q

True or false:

It is possible for the codon UUU to pair with the anticodon AAG.

A

True

Due to relaxed base pairing, G is able to pair with U.

94
Q

List the two main subunits of the ribosome.

A
  1. Large subunit
  2. Small subunit

wow biologists are so creative

95
Q

What is the function of the large subunit?

A

Catalyzes peptide bond formation

96
Q

What is the function of the small subunit?

A

Decodes the mRNA sequence

97
Q

List the three tRNA binding sites found in the ribosome.

A
  1. Exit site (E-site)
  2. Peptidyl site (P-site)
  3. Aminoacyl site (A-site)
98
Q

What tRNA molecule does the E-site bind to?

A

The tRNA molecule from the previous amino acid

(the amino acid that was just added to the c-terminus)

99
Q

Which tRNA molecule does the P-site bind to?

A

The tRNA currently attached to the growing peptide chain.

100
Q

Which tRNA molecule does the A-site bind to?

A

The tRNA for the next amino acid to be added to the chain.

101
Q

List the steps of the initiation phase of translation.

A
  1. The small subunit binds to the mRNA to determine the translation start site
  2. Initiator tRNA binds to the start codon at the P-site
  3. The large subunit binds
  4. The A-site and E-site are empty
102
Q

In prokaryotes, the small subunit binds to the…

A

Ribosome binding site
(RBS)

103
Q

In eukaryotes, the small subunit binds to the…

A

5’ cap

104
Q

True or false:

The methionine involved in prokaryotic initiation is modified.

A

True

(the eukaryotic version is unmodified)

105
Q

During the elongation phase of translation…

A

Successive amino acids are added

106
Q

List the major steps of the elongation phase of translation.

A
  1. The ribosome catalyzes peptide bond formation
  2. The A-site receives an amino acid
  3. A peptide bond forms between the A-site amino acid and the P-site amino acid
  4. The P-site amino acid shifts to the E-site, and the A-site amino acid shifts to the P-site
107
Q

The elongation phase of translation begins when…

A

The A-site is occupied for the first time

108
Q

Translation continues until…

A

A stop codon is encountered and enters the A-site

109
Q

Instead of being recognized by a tRNA molecule, the stop codon is recognized by the…

A

Release factor

110
Q

What happens after the completed polypeptide is released?

A

The ribosome shifts one “codon”, then disassembles.

111
Q

Proteins are important to a cell’s…

A

Structure and function

112
Q

Mutations alter ____ and ____ sequences.

A

Gene and protein

113
Q

A ____ does not alter the resulting amino acid, because the modified codon still specifies the same amino acid.

A

Silent mutation

114
Q

A ____ is a change to the nucleotide that also changes the encoded amino acid.

A

Missense mutation

115
Q

A ____ is a change in a nucleotide that results in a stop codon.

A

Nonsense mutation

116
Q

What happens as a result of a nonsense mutation?

A

Translation is terminated prematurely, resulting in a nonfunctional protein.

117
Q

A ____ is a mutation that occurs when one nucleotide base is swapped with another.

A

Base substitution

118
Q

List the three types of base subsititution mutations.

A
  1. Silent
  2. Missense
  3. Nonsense
119
Q

A ____ occurs when a base is either added to or deleted from a DNA sequence.

A

Frameshift mutation

120
Q

What happens as a result of a frameshift mutation?

A

The downstream reading frame is altered, which almost always affects protein function.

121
Q

List the four main types of chromsome mutations.

A
  1. Deletion
  2. Duplication
  3. Inversion
  4. Translocation
122
Q

Deletion occurs when part of a chromsome is…

A

Lost / deleted
(1 or more genes are lost)

123
Q

Duplication occurs when part of a chromosome is…

A

Copied
(1 or more genes are copied)

124
Q

Inversion occurs when part of a chromosome is…

A

In reverse order
(affects gene function or may combine genes)

125
Q

Translocation occurs when part of a chromosome is…

A

Moved onto another chromosome
(can combine genes)

126
Q

Mutations are the starting point for…

A

Evolution

127
Q

A balance must exist between the ____ and the ____.

A

Variance of new mutations and the health of the species

BIOL 1105 (22 decks)

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