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Bio 181 > gene expression 2 > Flashcards

gene expression 2 Flashcards

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1
Q

Polypeptides are made from mRNA during

A

translation

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2
Q

The genetic code specifies the relationship between the sequence of nucleotides in ______ and the sequence of amino acids in a polypeptide.

A

mRNA

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3
Q

There are __ nucleotide bases in one codon.

A

3

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4
Q

How many amino acids can be specified by a codon?

A

1

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5
Q

Which of the following statements best describes the genetic code?

  • It is universal; no exceptions have been discovered
  • It is not universal; a lot of exceptions have been discovered
  • It is nearly universal; only a few rare exceptions have been discovered
A

It is nearly universal; only a few rare exceptions have been discovered

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6
Q

The synthesis of __ using information within the mRNA is called translation.

A

polypeptides, proteins, polypeptide, or protein

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7
Q

Because the same amino acid can be specified by more than one codon, the genetic code is characterized as ______.

A

degenerate

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8
Q

What is the purpose of the genetic code?

A

It specifies the relationship between mRNA and polypeptide sequences.

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9
Q

Codons that specify the same amino acid typically differ in the base at position number __.

A

3

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10
Q

The genetic code is read in groups of three nucleotide bases known as __.

A

codons

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11
Q

The start codon encodes the amino acid

A

methionine or met

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12
Q

A codon in a messenger RNA molecule consists of ______ nucleotides. Each mRNA codon specifies ______ amino acid(s).

A

three; one

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13
Q

The portion of an mRNA sequence that specifies the amino acid sequence of a polypeptide is called the __ sequence.

A

coding

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14
Q

The genetic code is said to be nearly __ because with few exceptions, all organisms use the same code.

A

universal or identical

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15
Q

The end of translation is signaled by the

A

stop codon

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16
Q

The genetic code is said to be __ because more than one codon can specify the same amino acid.

A

degenerate or redundant

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17
Q

In most cases, codons that specify the same amino acid vary in the ________ base.

A

third

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18
Q

What part of a tRNA binds to the codon of a messenger RNA molecule?

A

Anticodon

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19
Q

What amino acid is specified by the start codon?

A

Methionine

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20
Q

There are __ nucleotides are in an anticodon.

A

3

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21
Q

A coding sequence specifies the amino acid sequence of a(n)

A

polypeptide or protein

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22
Q

Which part of a tRNA molecule binds to a codon on mRNA to determine which amino acid will be added to a growing polypeptide?

A

Anticodon

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23
Q

A stop codon specifies the end of

A

translation.

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24
Q

Which RNA molecule functions as an intermediary between an mRNA codon and an amino acid?

A

The tRNA

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25
Q

Because the same amino acid can be specified by more than one codon, the genetic code is characterized as ______.

A

degenerate

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26
Q

The components mRNA, tRNA, ribosomes, and translation factors must be made by a cell so that __ can be synthesized.

A

polypeptides, proteins, or protein

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27
Q

What is the function of the anticodon of a tRNA molecule?

A

It binds to a codon on an mRNA molecule.

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28
Q

The three major types of RNA are involved in translation. The information to synthesize a polypeptide sequence is contained in __; Amino acids are brought to the ribosome by __; and __ is a major component of the ribosome.

A

Blank 1: mRNA or messengerRNA
Blank 2: tRNA or transferRNA
Blank 3: rRNA or ribosomalRNA

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29
Q

In a tRNA molecule, the anticodon is a ______-base sequence.

A

three

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30
Q

The structural features common to all transfer RNAs include a stem-loop containing a(n) __ that is complementary to the codon on mRNA and an acceptor stem where a(n) __ __ can be attached.

A

Blank 1: anticodon or anti-codon
Blank 2: amino
Blank 3: acid

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31
Q

The __ in tRNA binds to a codon in an mRNA.

A

anticodon

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32
Q

A __-__ structure in a tRNA molecule consists of a region where the RNA is double-stranded due to complementary base pairing, and another region without base pairing.

A

stem-loop or hair-pin

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33
Q

The __ molecule is attached to an amino acid and has an anticodon that can base pair with a codon.

A

tRNA or transferRNA

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34
Q

Which of the following components are necessary for translation?

  • translation factors
  • RNA polymerase
  • ribosomes
  • tRNA
  • spliceosomes
  • mRNA
A

translation factors

ribosomes

tRNA

mRNA

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35
Q

mRNA function

A

contains information needed to synthesize a polypeptide

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36
Q

tRNA function

A

binds to a codon and carries the appropriate amino acid to be added to the polypeptide

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37
Q

ribosome function

A

catalyzes the formation of peptide bonds to synthesize a polypeptide

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38
Q

translation factor function

A

proteins required for translation

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39
Q

What structural features are common to all tRNAs?

  • Acceptor stem for amino acid attachment
  • A, P, and E sites
  • Cloverleaf pattern with three stem-loops
  • Loop that attaches to the spliceosome
A

Acceptor stem for amino acid attachment

Cloverleaf pattern with three stem-loops

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40
Q

What must be attached to the 3’ end of a tRNA molecule in order for translation to proceed properly?

A

An amino acid

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41
Q

A tRNA molecule assumes a stem-loop structure which results from ________ bonds that form between nearby regions.

A

hydrogen

42
Q

What is attached to a charged tRNA molecule?

A

An amino acid

43
Q

The components mRNA, tRNA, ribosomes, and translation factors must be made by a cell so that __ can be synthesized.

A

polypeptides, proteins, or protein

44
Q

The three major types of RNA are involved in translation. The information to synthesize a polypeptide sequence is contained in __; Amino acids are brought to the ribosome by __; and __ is a major component of the ribosome.

A

Blank 1: mRNA or messengerRNA
Blank 2: tRNA or transferRNA
Blank 3: rRNA or ribosomalRNA

45
Q

What is the site of translation?

A

Ribosome

46
Q

In order for translation to be accurate, the appropriate amino acid must be attached to the:

A

3’ end of the correct tRNA

47
Q

What are the two subunits of a ribosome called?

A

Large and small subunits

48
Q

A __-__ structure in a tRNA molecule consists of a region where the RNA is double-stranded due to complementary base pairing, and another region without base pairing.

A

stem loop or hairpin

49
Q

The ribosomal subunits contain two types of macromolecules:

A

Blank 1: protein, proteins, or polypeptides
Blank 2: rRNA, RNA, RNA molecules, ribonucleic acid, ribosomalRNA, RNAs, nucleic acids, nucleic acid, ribonucleicacid, or RNAmolecules

50
Q

A tRNA molecule with its attached amino acid is called a(n) __ tRNA.

A

charged, aminoacyl, or aminoacylated

51
Q

Which of the following components are necessary for translation?

  • translation factors
  • RNA polymerase
  • tRNA
  • spliceosomes
  • mRNA
  • ribosomes
A

translation factors

tRNA

mRNA

ribosomes

52
Q

What are the names of the three sites where tRNA molecules bind to the ribosome?

  • the exit site
  • the peptidyl site
  • the anticodon site
  • the aminoacyl site
  • the codon site
A

the exit site

the peptidyl site

the aminoacyl site

53
Q

Translation occurs on structures called

A

ribosomes

54
Q

Translation occurs in three stages: initiation, __, and __.

A

elongation

termination

55
Q

A(n) __ is composed of structures called the large and small subunits.

A

ribosome

56
Q

Which macromolecules are found in ribosomes?

  • polysaccharides
  • DNA
  • RNA
  • protein
  • phospholipids
A

RNA

protein

57
Q

During the initiation stage of translation, an mRNA molecule, the first (initiator) __ molecule, and the ribosomal subunits associate. During elongation, __ bonds are formed between amino acids. Finally, translation ends when the ribosome reaches a(n) __ codon.

A

Blank 1: tRNA or transferRNA
Blank 2: peptide or covalent
Blank 3: stop, termination, nonsense, or non-sense

58
Q

A ribosome contains three discrete sites where tRNAs may be located. These are known as the A or __ site, the P or __ site, and the E or __ site.

A

Blank 1: aminoacyl
Blank 2: peptidyl
Blank 3: exit

59
Q

What molecules must assemble during the initiation stage of translation?

  • ribosomal subunits
  • the first tRNA
  • mRNA molecule
  • the DNA molecule
A

ribosomal subunits

the first tRNA

mRNA molecule

60
Q

The stages of translation are called:

A

initiation, elongation and termination

61
Q

In most cases, the start codon used for translation is

A

AUG or ATG

62
Q

What are the two subunits of a ribosome called?

A

Large and small subunits

63
Q

During initiation of translation, the initiator tRNA recognizes the __ codon in mRNA and binds to it.

A

start, AUG, starting, initiation, methionine, or starter

64
Q

The ribosomal subunits contain two types of macromolecules:

A

Blank 1: protein, proteins, or polypeptides
Blank 2: rRNA, RNA, RNA molecules, ribonucleic acid, ribosomalRNA, RNAs, nucleic acids, nucleic acid, ribonucleicacid, or RNAmolecules

65
Q

key events that occur during Initiation

A

The mRNA, tRNA, and ribosomal subunits are assembled.

66
Q

key events that occur during Elongation

A

Peptide bonds are formed between amino acids to synthesize a polypeptide.

67
Q

key events that occur during termination

A

A release factor binds to the A site of the ribosome.

68
Q

During the initiation phase of translation, a complex is formed between an mRNA molecule, the first __, and the __ subunits.

A

Blank 1: tRNA, transferRNA, transfer RNA, or tRNA molecule

Blank 2: ribosomal or ribosome

69
Q

In a strand of mRNA, the nucleotide sequence of the start codon is

A

AUG.

70
Q

Which tRNA recognizes and binds to the start codon in mRNA?

A

Initiator tRNA

71
Q

In bacteria, translation is initiated when a(n) __ molecule binds to the small ribosomal subunit.

A

mRNA, messengerRNA, or RNA

72
Q

Which macromolecules are found in ribosomes?

  • phospholipids
  • DNA
  • polysaccharides
  • protein
  • RNA
A

protein

RNA

73
Q

The __ stage of translation involves the covalent bonding of amino acids to each other, one at a time.

A

elongation or second

74
Q

During the initiation stage of translation, an mRNA molecule, the first (initiator) __ molecule, and the ribosomal subunits associate. During elongation, __ bonds are formed between amino acids. Finally, translation ends when the ribosome reaches a(n) __ codon.

A

Blank 1: tRNA or transferRNA
Blank 2: peptide or covalent
Blank 3: stop, termination, nonsense, or non-sense

75
Q

What is attached to a peptidyl tRNA?

A

A short polypeptide

76
Q

What molecules must assemble during the initiation stage of translation?

A

the first tRNA

mRNA molecule

ribosomal subunits

77
Q

Because the anticodon in the tRNA is complementary to the codon in the mRNA, during the elongation phase of translation, a charged tRNA carrying a single amino acid binds to the ______ site.

A

A

78
Q

In most cases, the start codon used for translation is

A

AUG or ATG

79
Q

To obtain the energy required for tRNA to bind to the A site, elongation factors hydrolyze:

A

GTP

80
Q

Identify the stage of translation in which polypeptide synthesis occurs.

A

Elongation

81
Q

The peptidyl transfer reaction involves the removal of the polypeptide from the tRNA in the ______ site and its transfer to the amino acid in the ______ site.

A

P ; A

82
Q

A tRNA with a polypeptide attached to it is called a(n):

A

peptidyl tRNA

83
Q

A charged tRNA molecule carrying a single amino acid binds to the A site because the anticodon in the tRNA has a sequence that is __ to the codon in the mRNA.

A

complementary or corresponding

84
Q

Proteins functioning as elongation factors provide the energy for binding tRNA to the ______ site.

A

A

85
Q

In bacteria, translation is initiated when a(n) __ molecule binds to the small ribosomal subunit.

A

mRNA, messengerRNA, or RNA

86
Q

During the elongation stage of translation, the polypeptide is removed from the tRNA in the P site and added to the tRNA in the A site. This event is termed the ___ ____ reaction.

A

Blank 1: peptidyl

Blank 2: transfer or transferase

87
Q

The peptidyl transferase center, which catalyzes the peptidyl transfer reaction, is composed of several proteins and

A

rRNA

88
Q

What is attached to a peptidyl tRNA?

A

A short polypeptide

89
Q

During the translocation step of protein synthesis, the ribosome moves toward the

A

3’ end of mRNA by exactly one codon

90
Q

Because the anticodon in the tRNA is complementary to the codon in the mRNA, during the elongation phase of translation, a charged tRNA carrying a single amino acid binds to the ______ site.

A

A

91
Q

To obtain the energy required for tRNA to bind to the A site, elongation factors hydrolyze:

A

GTP

92
Q

In the process of protein synthesis, what recognizes the three stop codons?

A

A protein called release factor

93
Q

The three-dimensional structure of a release factor protein mimics the structure of

A

tRNAs

94
Q

The peptidyl transfer reaction that occurs in translation is catalyzed by

A

a region in the 50S subunit

95
Q

What happens as a result of the translocation step of protein synthesis?

  • The next codon moves into the P site
  • The tRNA in the P site moves into E site
  • The tRNA in the A site moves into P site
  • The next codon moves into the A site
  • The tRNA in the P site moves into A site
  • The tRNA in the A site moves into E site
A

The tRNA in the P site moves into E site

The tRNA in the A site moves into P site

The next codon moves into the A site

96
Q

A charged tRNA molecule carrying a single amino acid binds to the A site because the anticodon in the tRNA has a sequence that is __ to the codon in the mRNA.

A

complementary or corresponding

97
Q

During translation, the stop codons are recognized by a protein called a(n) )__ factor.

A

release

98
Q

The translation release factor has a 3-D structure that resembles that of:

A

tRNA

99
Q

During bacterial translation, when a stop codon is encountered, a protein known as a(n) _ factor binds to the A site, which triggers the removal of the _ from the tRNA in the P site.

A

Blank 1: release

Blank 2: polypeptide or protein

100
Q

During the translocation step of protein synthesis, the ribosome moves toward the

A

3’ end of mRNA by exactly one codon

101
Q

Because the anticodon in the tRNA is complementary to the codon in the mRNA, during the elongation phase of translation, a charged tRNA carrying a single amino acid binds to the ______ site.

A

A

102
Q

The three-dimensional structure of a release factor protein mimics the structure of

A

tRNA

Bio 181 (18 decks)

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