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Biotechnology - Mid > Lec2 | The Central Dogma > Flashcards

Lec2 | The Central Dogma Flashcards

1
Q

The Central Dogma describes…

A

how genetic information flows from DNA to a protein product.

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2
Q

Gene expression is the process of…

A

genetic information flowing from DNA to RNA to protein.

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3
Q

The process of DNA to RNA is…

A

transcription.

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4
Q

The process of RNA to protein is…

A

translation.

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5
Q

What is it called when DNA makes more DNA?

A

Replication.

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6
Q

In the very rare cases when RNA is used to make DNA it’s called…

A

Reverse transcription.

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7
Q

Transcription copies…

A

a segment of DNA into RNA.

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8
Q

DNA segments transcribed into RNA that encode proteins are…

A

messenger RNA (mRNA).

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9
Q

DNA segments copied into RNA that do not encode proteins are…

A

non-coding RNAs.

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10
Q

mRNA comprises how much of total RNA?

A

1-3%.

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11
Q

The three steps of transcription are…

A

Initiation, Elongation, Termination.

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12
Q

The region of DNA where RNA polymerase binds to initiate transcription is the…

A

Promoter.

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13
Q

The segment of DNA that is transcribed into RNA is called the…

A

Coding sequence.

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14
Q

The region of DNA that signals the end of transcription is the…

A

Terminator.

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15
Q

In a gene, the region where RNA polymerase first binds is the…

A

Promoter.

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16
Q

The +1 site on a gene designates…

A

the transcription initiation site.

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17
Q

The region of DNA that is transcribed into an RNA molecule is the…

A

RNA-coding sequence.

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18
Q

The region of a gene that signals the end of transcription is the…

A

Terminator.

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19
Q

The DNA strand that is used as a guide to make mRNA during transcription is the…

A

Template strand.

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20
Q

The DNA strand that is not used during transcription and has a nearly identical sequence to the newly made mRNA is the…

A

Non-template strand.

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21
Q

The region towards the 5’ end of the gene relative to the coding sequence is considered…

A

upstream.

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22
Q

The region towards the 3’ end of the gene relative to the coding sequence is considered…

A

downstream.

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23
Q

During transcription, the enzyme that synthesizes RNA is…

A

RNA polymerase.

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24
Q

The DNA strand used by RNA polymerase to make mRNA is the…

A

template strand.

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25
Q

Other names for the template strand include the…

A

on-coding, or anti-sense strand

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26
Q

The newly synthesized RNA molecule is also called…

A

Nascent mRNA.

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27
Q

The DNA strand not used during transcription is called the…

A

non-template strand.

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28
Q

Other names for the non-template strand include the…

A

coding or sense strand.

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29
Q

RNA polymerase adds nucleotides to which end of the growing RNA molecule?

A

3’ end.

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30
Q

The region where RNA is temporarily bound to DNA during transcription is called the…

A

RNA-DNA hybrid.

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31
Q

During transcription, the RNA molecule is synthesized in which direction?

A

5’ to 3’ direction.

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32
Q

What is the direction of the movement of RNA polymerase along the template strand?

A

3’ to 5’ direction

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33
Q

Transcription in eukaryotes begins at which end of the gene?

A

3’ end (upstream) in the promoter region.

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34
Q

The TATA box is located how many base pairs upstream of the transcription start site?

A

Approximately 25-35 base pairs.

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35
Q

What protein binds to the TATA box?

A

TATA-binding protein (TBP).

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36
Q

TBP recruits what to the promoter?

A

Transcription factors and RNA polymerase II.

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37
Q

The complex formed at the promoter that initiates transcription is called the…

A

transcription initiation complex.

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38
Q

Why is the TATA box a common site for DNA unwinding?

A

Because it is rich in A and T bases, which have fewer hydrogen bonds than G and C, making them easier to separate.

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39
Q

In eukaryotes, the main RNA polymerase enzyme that is involved in transcribing most genes is…

A

RNA polymerase II

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40
Q

In a eukaryotic promoter, what’s the start point?

A

Where the actual transcription of the gene begins, designated as +1 on the DNA sequence.

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41
Q

After the transcription initiation complex forms then…

A

RNA synthesis begins.

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42
Q

During elongation, the template DNA strand is read in which direction?

A

3’ to 5’ direction.

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43
Q

RNA synthesis during elongation occurs in which direction?

A

5’ to 3’ direction.

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44
Q

The DNA strand that has a sequence nearly identical to the new mRNA (except for T’s replaced with U’s) is the…

A

coding strand.

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45
Q

What enzyme catalyzes the formation of phosphodiester bonds between adjacent ribonucleotides in the growing RNA molecule?

A

RNA polymerase.

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46
Q

What are the differences between the sequences in the mRNA and coding strand?

A

The base sequences are identical except T in DNA is replaced by U in RNA.

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47
Q

The region of DNA that signals the end of transcription is the…

A

terminator.

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48
Q

During termination, what happens when RNA polymerase recognizes the termination sequence?

A

It changes conformation, releasing itself from the template strand, and stops transcription.

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49
Q

What happens to the DNA template during termination?

A

It rewinds back into a double helix.

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50
Q

The RNA molecule released at the end of transcription is called…

A

Pre-mRNA.

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51
Q

During transcription, which DNA strand is read to synthesize RNA?

A

The template strand.

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52
Q

What is the corresponding RNA base for Adenine (A) in DNA during transcription?

A

Uracil (U).

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53
Q

What is the corresponding RNA base for Thymine (T) in DNA?

A

Adenine (A).

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54
Q

What is the corresponding RNA base for Cytosine (C) in DNA?

A

Guanine (G).

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55
Q

What is the corresponding RNA base for Guanine (G) in DNA?

A

Cytosine (C).

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56
Q

In what direction is the template DNA strand read?

A

3’ to 5’ direction.

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57
Q

In what direction is the RNA molecule synthesized?

A

5’ to 3’ direction.

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58
Q

Where is pre-mRNA produced?

A

In the nucleus.

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59
Q

Pre-mRNA is transcribed from what type of chromosome?

A

Linear.

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60
Q

What three processing steps must pre-mRNA undergo to become mature mRNA?

A

5’ capping, poly-A tail addition, and splicing.

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61
Q

The addition of a methylated guanine to the 5’ end of pre-mRNA is called…

A

5’ capping.

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62
Q

The addition of a string of adenine nucleotides to the 3’ end of pre-mRNA is called…

A

poly-A tail addition.

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63
Q

The process of removing introns from pre-mRNA is called…

A

Splicing.

64
Q

What are the regions of pre-mRNA that are removed during splicing?

A

Introns.

65
Q

What are the regions of pre-mRNA that are retained and joined together during splicing?

A

Exons.

66
Q

What region in mRNA is translated to a protein?

A

The protein-coding region.

67
Q

What regions are present in pre-mRNA that are not translated into the final protein sequence?

A

5’ and 3’ UTR.

68
Q

One function of the 5’ cap and poly-A tail is to facilitate…

A

nucleocytoplasmic transport of mRNA.

69
Q

The 5’ cap and poly-A tail protect mRNA from degradation by…

A

exonucleases.

70
Q

How does the poly-A tail length affect mRNA stability and translation?

A

Shortening can trigger degradation; lengthening can enhance stability and translation.

71
Q

The 5’ cap helps in the recognition of mRNA by…

A

translational machinery (ribosomes).

72
Q

What do the 5’ cap and poly-A tail ensure during translation?

A

They distinguish between immature and mature mRNA, ensuring that only mature mRNA is translated.

73
Q

Alternative splicing is a process where…

A

exons from the same gene are joined in different combinations.

74
Q

Alternative splicing leads to the production of…

A

different, but related, mRNA transcripts.

75
Q

Different mRNAs produced by alternative splicing can be translated into proteins with…

A

distinct structures and functions.

76
Q

The main function of alternative splicing is to…

A

increase the diversity of mRNAs and proteins expressed from a single gene.

77
Q

Alternative splicing increases the transcriptome size from approximately 21,000 genes to…

A

around 200,000 transcripts.

78
Q

In a eukaryotic gene, the region where RNA polymerase binds to initiate transcription is the…

A

Promoter.

79
Q

The initial RNA molecule transcribed from DNA, which includes both introns and exons, is called the…

A

Primary transcript (or pre-mRNA).

80
Q

The non-coding sequences within the primary transcript that are removed during RNA processing are…

A

Introns.

81
Q

The coding sequences within the primary transcript that are retained and joined together to form mature mRNA are…

A

Exons.

82
Q

What are the three main processing steps that convert a primary transcript into mature mRNA?

A

Capping, splicing, and polyadenylation.

83
Q

What is added to the 5’ end of the mRNA during capping?

A

A 7-methylguanosine (7-mG) cap.

84
Q

What is added to the 3’ end of the mRNA during polyadenylation?

A

A poly-A tail (100-200 adenine nucleotides).

85
Q

The regions at the beginning and end of the mRNA that are not translated into protein are called…

A

5’ UTR and 3’ UTR (untranslated regions).

86
Q

The genetic code defines how the four-letter DNA code is translated into…

A

the 20-letter amino acid code.

87
Q

A unit of three adjacent nucleotides in mRNA that codes for an amino acid is called a…

A

codon.

88
Q

How many possible codons are there?

A

64 (4 bases ^ 3 positions = 64).

89
Q

Why is the genetic code described as degenerate or redundant?

A

Because a single amino acid can be coded for by more than one codon.

90
Q

What is the start codon and what amino acid does it code for?

A

AUG, Methionine.

91
Q

What are the three stop codons?

A

UAA, UAG, UGA.

92
Q

How do you determine the amino acid sequence from an mRNA sequence?

A

Divide the mRNA into codons (3 nucleotides each), then use the genetic code table to find the corresponding amino acid for each codon.

93
Q

If an mRNA sequence is 5’-AUGCCUAGU-3’, what is the first codon?

A

5’-AUG-3’

94
Q

Using the genetic code table, what amino acid does the codon 5’-AUG-3’ code for?

A

Methionine.

95
Q

How do you find the number of amino acids a given mRNA will make?

A

Divide the number of nucleotides by 3 since every codon is 3 nucleotides long, but remember to not count the stop codon since it does not make an amino acid.

96
Q

Using the genetic code table, what amino acid does the codon 5’-CAU-3’ code for?

A

Histidine (His).

97
Q

Using the genetic code table, what amino acid does the codon 5’-GGG-3’ code for?

A

Glycine (Gly).

98
Q

Using the genetic code table, what amino acid does the codon 5’-UCA-3’ code for?

A

Serine (Ser).

99
Q

Using the genetic code table, what does the codon 5’-UAG-3’ code for?

A

Stop codon.

100
Q

What are the possible codons for the amino acid Leucine (Leu), according to the genetic code table?

A

UUA, UUG, CUU, CUC, CUA, CUG.

101
Q

What are the possible codons for the amino acid Alanine (Ala)?

A

GCU, GCC, GCA, GCG.

102
Q

If a codon is mutated from 5’-UUU-3’ to 5’-UUC-3’, what is the effect on the amino acid sequence?

A

No effect, both code for Phenylalanine (Phe). This demonstrates the redundancy of the genetic code.

103
Q

Translation is the process where information in mRNA directs…

A

the addition of amino acids during protein synthesis.

104
Q

What are the three types of RNA involved in translation?

A

mRNA (messenger RNA), tRNA (transfer RNA), and rRNA (ribosomal RNA).

105
Q

What is the role of mRNA in translation?

A

Carries the genetic code from DNA that specifies the amino acid sequence.

106
Q

What is the role of tRNA in translation?

A

Brings specific amino acids to the ribosome, matching its anticodon to the mRNA codon.

107
Q

What is the role of rRNA in translation?

A

Forms part of the ribosome, the machinery that synthesizes proteins.

108
Q

The region on tRNA that is complementary to the mRNA codon is the…

A

anticodon.

109
Q

What is the function of the ribosome in translation?

A

It provides the site for protein synthesis, where mRNA and tRNA interact and amino acids are linked together.

110
Q

What is the growing chain of amino acids called during translation?

A

A polypeptide.

111
Q

What type of bond is formed between amino acids during translation?

A

A peptide bond.

112
Q

If a codon in mRNA is 5’-AUG-3’, what would be the anticodon sequence on the tRNA?

A

3’-UAC-5’. (Remember, the anticodon is complementary and antiparallel to the codon)

113
Q

What does it mean that tRNA and mRNA interact in an antiparallel manner?

A

The 5’ end of the mRNA codon pairs with the 3’ end of the tRNA anticodon, and vice-versa.

114
Q

Ribosomes are made of…

A

both RNA (rRNA) and protein.

115
Q

What is the main function of ribosomes in the cell?

A

They are the site of protein synthesis.

116
Q

What are the two main functions of rRNA in the ribosome?

A

1) Ensure proper alignment of mRNA and ribosome.
2) Catalyze peptide bond formation.

117
Q

What are the two subunits of a ribosome?

A

The large subunit and the small subunit.

118
Q

What are the three binding sites on the ribosome for tRNA molecules?

A

A site, P site, and E site.

119
Q

What does the A site on the ribosome stand for and what is its function?

A

Aminoacyl-tRNA binding site; holds the tRNA carrying the next amino acid to be added.

120
Q

What does the P site on the ribosome stand for and what is its function?

A

Peptidyl-tRNA binding site; holds the tRNA carrying the growing polypeptide chain.

121
Q

What does the E site on the ribosome stand for and what is its function?

A

Exit site; where discharged tRNAs leave the ribosome.

122
Q

In what order does an mRNA molecule move through the ribosome binding sites?

A

A site, then P site, then E site.

123
Q

Where does the very first tRNA carrying Methionine bind on the ribosome?

A

It binds directly to the P site, subsequent tRNAs first bind to the A site.

124
Q

When does the polypeptide exit from the ribosome?

A

It exits from the P site after a new peptide bond is formed and the ribosome has moved along the mRNA, transferring the polypeptide to the tRNA in the A site.

125
Q

What is the main function of tRNA?

A

To carry amino acids to the ribosome during translation.

126
Q

The characteristic shape of a tRNA molecule is described as…

A

a cloverleaf.

127
Q

What is the name of the three-base sequence on tRNA that is complementary to the mRNA codon?

A

Anticodon.

128
Q

To which end of the tRNA molecule does the amino acid attach?

A

The 3’ end.

129
Q

What is the name of the enzyme that attaches the correct amino acid to a tRNA molecule?

A

Aminoacyl-tRNA synthetase.

130
Q

A tRNA molecule that has an amino acid attached is said to be…

A

charged.

131
Q

How does the tRNA anticodon interact with the mRNA codon?

A

Through complementary base pairing (A with U, G with C).

132
Q

What is the first step in the initiation of translation?

A

The small ribosomal subunit binds to the 5’ cap of the mRNA.

133
Q

What is the start codon that the ribosome scans for in the mRNA?

A

AUG.

134
Q

In what direction does the ribosome scan the mRNA to find the start codon?

A

5’ to 3’ direction.

135
Q

What is the initiator tRNA in eukaryotes and what amino acid does it carry?

A

Initiator tRNA is tRNA that carries methionine (Met).

136
Q

To which site on the ribosome does the initiator tRNA (Met) bind?

A

The P site.

137
Q

Once the initiator tRNA is bound to the start codon, what happens next?

A

The large ribosomal subunit joins the complex.

138
Q

How is the translational reading frame established?

A

By the position of the start codon (AUG), which dictates that subsequent codons are read as groups of three nucleotides.

139
Q

Which part of the ribosome initially binds to the mRNA to hold it in place?

A

Small ribosomal subunit.

140
Q

Where is the initiator tRNA located in the fully assembled ribosome?

A

P site

141
Q

Elongation in translation refers to…

A

the addition of amino acids to the growing polypeptide chain.

142
Q

During elongation, which tRNA binding site on the ribosome holds the growing polypeptide chain?

A

The P site.

143
Q

During elongation, where does a new tRNA carrying an amino acid bind?

A

To the A site.

144
Q

What happens to the polypeptide chain when a new tRNA binds to the A site?

A

The polypeptide chain is transferred from the tRNA in the P site to the amino acid on the tRNA in the A site.

145
Q

What is the movement of the ribosome along the mRNA during elongation called?

A

Translocation.

146
Q

During translocation, the ribosome moves down by how many codons?

A

One codon.

147
Q

What happens to the tRNA that was in the P site after the polypeptide chain is transferred?

A

It moves to the E site and then exits the ribosome.

148
Q

What happens to the tRNA in the A site after translocation?

A

It moves to the P site, carrying the polypeptide chain.

149
Q

The state in which an incoming tRNA brings a new amino acid to the A site is known as…

A

the pre-translocation state.

150
Q

The state after which the ribosome moves one codon down the mRNA, the empty tRNA leaves the E site, the tRNA carrying the polypeptide moves from the A site to the P site is known as…

A

the post-translocation state.

151
Q

What marks the termination of translation?

A

The presence of a stop codon in the mRNA.

152
Q

What are the three stop codons?

A

UAA, UAG, UGA.

153
Q

Do stop codons code for any amino acid?

A

No.

154
Q

What binds to the ribosome when a stop codon is in the A site?

A

A release factor protein.

155
Q

What is the effect of the release factor binding to the ribosome?

A

It causes the ribosome, mRNA, and the newly synthesized polypeptide to dissociate.

156
Q

What happens to the ribosomal subunits after termination?

A

They can be recycled and used for another round of translation.

157
Q

What happens to the mRNA after termination?

A

The mRNA can be reused for another round of translation, or be degraded.

Biotechnology - Mid (11 decks)

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