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BIO 130.01 Genetics, Lecture > Chapter 12: Genetic Code and Transcription > Flashcards

Chapter 12: Genetic Code and Transcription Flashcards

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1
Q

True or False. The code is unambiguous – each triplet specifies only a single amino acid

A

True

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2
Q

Enables the production of synthetic mRNAs.

A

Polynucleotide phosphorylase

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3
Q

Type of RNA that is composed of only one type of ribonucleotides.

A

RNA Homopolymers

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4
Q

Type of RNA with two or more different ribonucleoside diphosphates added in combination to form the synthetic mRNA.

A

RNA Heteropolymers

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5
Q

Almost all amino acids are specified by two, three, or four different codons.

A

Degeneracy

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6
Q

The first two letters of a codon coding for one amino acid are the same, with only the third differing.

A

Wobble hypothesis

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7
Q

Either U or C is often present in the second position of triplets that specify what type of amino acids, including valine and alanine, among others.

A

hydrophobic amino acids

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8
Q

A codon with either G or C in the second position always specifies what kind of amino acid?

A

hydrophilic amino acids

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9
Q

Significance of an “ordered” code?

A

It buffers the potential effect of mutation on protein function.

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10
Q

When the chemical constitution of genes and their encoded proteins, the linear sequence of triplet codons corresponds precisely with the linear sequence of amino acids in each protein. This phenomenon is called?

A

Colinearity

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11
Q

True or False. Codon UGA, normally specifying termination, encodes tryptophan during translation in yeast and human mitochondria.

A

True

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12
Q

True or False. In human mitochondria, AUA, which normally specifies isoleucine, directs the internal insertion of methionine.

A

True

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13
Q

There may be several points of initiation in one mRNA thus, creating several different reading frames within the same mRNA, and specifying more than one polypeptide. These mRNAs are called?

A

Overlapping genes

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14
Q

The process by which RNA molecules are synthesized on a DNA template.

A

Transcription

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15
Q

The enzyme that catalyzes the synthesis of RNA molecule has the same general substrate requirements as does DNA polymerase, the major exception being that the substrate nucleotides contain the ribose rather than the deoxyribose form of the sugar.

A

RNA polymerase

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16
Q

The active form of the RNA polymerase is made of subunits alpha, beta, beta prime, and sigma.

A

holoenzyme

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17
Q

Which subunits provide the catalytic basis and active site for transcription in RNA polymerase?

A

beta and beta prime

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18
Q

What molecule serves as the substrate for the RNA polymerase?

A

nucleoside trisphosphate (NTPs)

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19
Q

RNA polymerase converts nucleoside triphosphate

to what molecule as it is being added to the growing mRNA.

A

nucleoside monophosphate

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20
Q

Nucleotides are linked during synthesis by what kind of bond?

A

3′-to-5′ phosphodiester bonds

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21
Q

Which DNA is being transcribed during transcription?

A

template strand

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22
Q

The DNA strand that is not involved in the transcription

A

Partner strand

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23
Q

The site of this initial binding is established when the RNA polymerase sigma subunit recognizes specific DNA sequences called what?

A

Promoters

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24
Q

Point in the DNA sequence at which transcription actually begins.

A

Transcription Start Site

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25
Q

These sequences are similar (homologous) in different genes of the same organism or in one or more genes of related organisms. They usually exist as promoter sequences or as telomere sequences.

A

Consensus Sequences

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26
Q

This bacterial promoter is located 10 nucleotides (Pribnow Box) upstream from the site of initial transcription.

A

TATAAT sequence

27
Q

This bacterial promoter is located 35 nucleotides upstream (the −35 region).

A

TTGACA sequence

28
Q

Promoter sequence in eukaryotes.

A

TATA box

29
Q

The insertion of the first 5′-ribonucleoside triphosphate, which is complementary to the first nucleotide at the start site of the DNA template strand.

A

Initiation

30
Q

Subsequent ribonucleotide complements are inserted and linked by phosphodiester bonds as RNA polymerization proceeds. This process is called?

A

Elongation

31
Q

The unique sequence of nucleotides in the termination region causes the newly formed transcript to fold back on itself, forming what is called?

A

hairpin secondary structure

32
Q

A large hexameric protein that physically interacts with the growing RNA transcript and serves as termination region.

A

termination factor, R (rho)

33
Q

A large mRNA is produced that encodes more than one protein. Products of genes transcribed in this fashion are usually all needed by the cell at the same time, so this is an efficient way to transcribe and subsequently translate the needed genetic information.

A

Polycistronic mRNA (found in bacteria)

34
Q

What type of mRNA is occurring in eukaryotes?

A

Monocistronic mRNA

35
Q

Alteration of the primary RNA transcript to produce mature eukaryotic mRNA. The initial processing step involves the addition of a 5′ cap and a 3′ tail to most transcripts destined to become mRNAs.

A

RNA processing

36
Q

Such RNA molecules are of variable but large size and are complexed with proteins, forming heterogeneous nuclear ribonucleoprotein particles (hnRNPs). Immature RNA transcript.

A

Pre-RNA

37
Q

Pre-RNA is part of a group of molecules found only in the nucleus referred to as?

A

Heterogeneous nuclear RNA (hnRNA)

38
Q

Initiation of transcription of eukaryotic genes requires
that the compact chromatin fiber, characterized by
nucleosome coiling, must be uncoiled and the DNA made
accessible to RNA polymerase and other regulatory proteins. This tran sition is referred to as?

A

Chromatin Remodeling

39
Q

Responsible for the transcription of a wide range of genes in eukaryotes

A

RNA polymerase II (RNAP II)

40
Q

Determines where RNAP II binds to the DNA and where it begins copying the DNA into RNA.

A

Core-promoter (TATA box in eukaryotes)

41
Q

o Located about 30 nucleotide pairs upstream (−30) from the start point of transcription. It is the cis-acting core-promoter element in Eukaryotic genes.

A

TATA Box (or the Goldberg-Hogness box)

42
Q

Facilitate RNAP II binding and, therefore, the initiation of transcription.

A

Trans-acting factors (transcription factors)

43
Q

This category of transcription factors is absolutely required for all RNAP II-mediated transcription.

A

General transcription factors (GTFs)

44
Q

What general transcription factor (GTFs) is involved with human RNAP II binding?

A

TFIID (binds to TATA box)

45
Q

Once the initial binding of TFIID to DNA occurs, the other general transcription factors, along with RNAP II, bind sequentially to TFIID, forming what structure?

A

Pre-initiation complex

46
Q

These molecules influence the efficiency or the rate of RNAP II transcription initiation.

A

Transcriptional activators and repressors

47
Q

Posttranscriptional modification of eukaryotic RNA transcripts destined to become mRNAs occurs at the 5′-end of these molecules, where a molecule cap is added. What molecule is being described?

A

7-methylguanosine (7-mG)

48
Q

What posttranscriptional molecule is added after the 3′-end of the initial transcript is cleaved enzymatically at a position some 10 to 35 ribonucleotides from a highly conserved AAUAAA sequence?

A

poly-A tail

49
Q

Nucleotide sequences that are not expressed in the amino acid sequence of the proteins they encode. These internal DNA sequences are represented in initial RNA transcripts, but they are removed before the mature mRNA is translated.

A

Intervening sequences (introns)

50
Q

Part of pre-RNA that are retained and expressed.

A

Exons

51
Q

These genes appear to be deprived of introns.

A

Genes coding for histones and interferon

52
Q

True or False. In bacterial tRNA, a specific endonuclease recognizes the intron termini and excises the intervening sequences. Then RNA ligase seals the exon ends to complete each splicing.

A

True

53
Q

Represented by introns that are part of the primary transcript of rRNAs, require no additional components for intron excision; the intron itself is the source of the enzymatic activity necessary for removal.

A

Group I introns

54
Q

Type of RNAs that are capable of catalytic activity

A

Ribozymes

55
Q

Primary RNA and tRNA transcript in mitochondria and chloroplasts where self-excision is also the case.

A

Group II introns

56
Q

Mediates the splicing reactions in nuclear-derived pre-RNA.

A

Spliceosome

57
Q

5’ end of the intron in nuclear-derived pre-RNA

A

Donor sequence

58
Q

3’ end of the intron in nuclear-derived pre-RNA

A

Acceptor sequence

59
Q

Loop of intron produced after spliceosome mediated splicing.

A

Lariat

60
Q

Produced by a group of similar but nonidentical mRNAs resulting from a gene spliced in more than one way.

A

Isoforms

61
Q

The nucleotide sequence of a pre-mRNA is actually changed prior to translation. This process is called?

A

RNA editing

62
Q

An RNA editing process whereby nucleotides are added to or subtracted from the total number of bases.

A

Insertion/Deletion Editing

63
Q

This molecule directs the insertion/deletion editing in Trypanosoma mitochondrial RNA.

A

guide RNA (gRNA)

64
Q

In this editing method, identities of individual nucleotide bases are altered. This is also used in some nuclear-derived eukaryotic RNAs and is prevalent in mitochondrial and chloroplast RNAs transcribed in plants.

A

Substitution Editing

BIO 130.01 Genetics, Lecture (16 decks)

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