Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Genetics > Lesson 7 Transcription > Flashcards

Lesson 7 Transcription Flashcards

You may prefer our related Brainscape-certified flashcards:
Biology 101 flashcards
1
Q

What is the difference between a template strand and a coding strand in transcription?

A

The template strand is the DNA strand from which RNA is transcribed. RNA is complementary to the template strand but identical to the coding strand, which is the DNA strand opposite to the template strand.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the difference between the promoter, the terminator, and regulatory sequences?

A

The promoter is a sequence that provides a signal to begin transcription. The terminator signals the end of transcription. Regulatory sequences are involved in the regulation of gene expression.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

In bacteria, what is the ribosomal binding site, AKA Shine-Dalgarno sequence?

A

This sequence provides a location for the ribosomes to recognize and begin the process of translation.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are codons? What are the start and stop codon?

A

A codon is a sequence of three nucleotides. A start codon is the first codon, and it is very close to the initiation site of translation. A stop codon signals the end of translation.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the three stages of transcription?

A

Initiation, elongation, in which the RNA transcript is synthesized, and termination.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What happens during transcription initiation?

A

The promoter functions as a recognition site for transcription factors. The transcription factors enable RNA polymerase to bind to the promoter. Following binding, the DNA is dentures into a bubble known as the open complex.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the DNA open complex?

A

A bubble into which DNA is dentures once RNA polymerase has bound to the promoter.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What happens during transcription elongation?

A

RNA polymerase slides along the DNA in an open complex to synthesize RNA.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What happens during termination?

A

A termination signal is reached that causes RNA polymerase and the RNA transcript to dissociate from the DNA.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What recognizes the sequences of bases within the promoter region?

A

Proteins known as transcription factors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are structural genes?

A

Genes that encode an RNA transcript known as mRNA.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is tRNA?

A

Transfer RNA. It is necessary for the translation of mRNA.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is rRNA?

A

Ribosomal RNA. It is necessary for the translation of mRNA. rRNAs are components of ribosomes that are composed of both rRNAs and protein subunits.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is 7S RNA?

A

Found in eukaryotes. Necessary in the targeting of proteins to the endoplasmic reticulum. It is a component of a complex known as signal recognition particle (SRP), which is composed of 7S RNA and six different protein subunits.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is scRNA?

A

Small cytoplasmic RNA. Found in bacteria. Its sequence is similar to 7S RNA found in eukaryotes. ScRNA is needed for protein secretion.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is RNA of RNaseP?

A

RNaseP is an enzyme that is necessary in the processing of all bacterial tRNA molecules. The RNA is the catalytic component of this enzyme.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is snRNA?

A

Small nuclear RNA (snRNA) is necessary in the splicing of eukaryotic pre-mRNA. SnRNAs are components of a spliceosome, which is composed of both snRNAs and protein subunits.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is snoRNA?

A

Small nucleolar RNA is necessary in the processing of eukaryotic rRNA transcripts. SnoRNAs are also associated with protein subunits. In eukaryotes, snoRNAs are found in the nucleolus where rRNA processing and ribosomes assembly occur.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are viral RNAs?

A

Some types of viruses use RNA as their genome, which is packaged within the viral capsid.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

In bacteria, what is the -35 sequence? The -10 sequence?

A

The -35 sequence is a recognition sequence and the -10 sequence is the site where the two DNA strands will separate when transcription begins. Both sequences are in the promoter region.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is the consensus sequence?

A

The most common promoter sequence.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

When is bacterial transcription initiated?

A

Bacterial transcription is initiated when RNA polymerase holoenzyme binds at a promoter sequence.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is bacterial RNA polymerase composed of?

A

Bacterial RNA polymerase is composed of a core enzyme plus a subunit called sigma factor.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is the role of sigma factor in bacterial RNA polymerase?

A

Sigma factor recognizes the promoter and initiates transcription.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What is the role of the core enzyme in bacterial RNA polymerase?

A

The core enzyme catalyzes the synthesis of an RNA strand.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What happens to sigma factor once the -10 region has been unwound during transcription initiation?

A

The sigma factor dissociate from the holoenzyme.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

In what direction is RNA synthesized during transcription? What is used as a precursor?

A

The RNA is synthesized in a 5’ to 3’ direction using ribonucleoside triphosphate as precursors.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What substance is released by ribosome during transcription?

A

Pyrophosphate is released by the ribosomes during transcription.

29
Q

How do nucleotides enter ribosome to elongate RNA? Where are the nucleotides added?

A

Nucleotides diffuse through a pore in the enzyme and are attached at the 3’ end of the growing RNA transcript.

30
Q

What are the two common mechanisms for transcriptional termination?

A

The two common mechanisms for transcription termination are rho-dependant termination and rho-independent termination.

31
Q

How are rho-dependent and rho-independent termination different?

A

In rho-dependent termination, the synthesis of an RNA sequence near the end of the RNA transcript causes RNA polymerase to pause. In rho-independent termination pausing also occurs. During the pausing, RNA polymerase spontaneously dissociates from the DNA because an AT-rich region in the open complex is unable to keep the RNA strand and the DNA template strand together.

32
Q

What is the rut site in rho-dependent termination?

A

The rut site is a rho recognition site in RNA. Rho protein binds the rut site in RNA and moves toward the 3’ end.

33
Q

What does rho protein do once RNA polymerase has paused due to its interaction with the stem loop?

A

Rho protein catches up to the open complex and separates the RNA-DNA hybrid.

34
Q

In rho-independent or intrinsic termination, what does RNA polymerase do when it reaches the end of the gene?

A

RNA polymerase transcribes a uracil-rich sequence. Soon after this uracil-rich sequence is complete, a stem-loop forms just upstream of the open complex.

35
Q

In intrinsic termination, what does stem-loop cause RNA polymerase to do?

A

The stem-loop causes RNA polymerase to pause in its synthesis of the transcript.

36
Q

What stabilizes RNA polymerase pausing due to stem-loop in intrinsic termination?

A

The pausing is stabilized by NusA, which binds near the region where RNA exits the open complex.

37
Q

Why do the transcript (RNA) and RNA polymerase dissociate from the DNA while RNA polymerase is pausing during intrinsic termination?

A

They dissociate because the RNA-DNA hybrid region is a uracil-rich sequence. UA hydrogen bonds are relatively weak interactions, so the transcript and RNA polymerase dissociate.

38
Q

What does the core promoter in eukaryotes contain?

A

The promoter contains a TATA box and a transcriptional start site. These elements are recognized by general transcription factors and RNA polymerase.

39
Q

When is transcription of eukaryotic structural genes initiated?

A

Transcription of eukaryotic structural genes are initiated when RNA polymerase II and general transcription factors bind to a promoter sequence.

40
Q

What steps lead to the formation of the open complex in eukaryotes?

A
  1. TFIID binds to the TATA box. A subset of the TFIID, known as the TATA-binding protein, recognizes the TATA box sequence.
  2. TFIIB then binds to TFIID. TFIIB promotes the binding of RNA polymerase II/TFIIF.
  3. TFIIE and TFIIH bind to RNA polymerase II and form closed complex.
  4. To open complex, TFIIH hydrolyzes ATP and phosphorylates a region in RNA polymerase II known as the carboxyl terminal domain. This phosphorylation leads to RNA poly II release from TFIIB.
  5. TFIIH functions as helicase and promotes formation of open complex.
  6. After complex is formed, TFIIB, TFIIE and TFIIH dissociate, and RNA polymerase II proceeds to elongation.
41
Q

What does a. helicase do?

A

A helicase breaks the hydrogen bonding between the double-stranded DNA.

42
Q

What is the role of TFIID?

A

TFIID recognizes the TATA-binding sequence of eukaryotic structural gene promoters.

43
Q

What is the role of TFIIB?

A

Binds to TFIID and then enables RNA polymerase II to bind to the core promoter.

44
Q

What is the role of TFIIF?

A

TFIIF binds to RNA polymerase II and plays a role in its ability to bind to TFIIB and the core promoter. Also plays a role in the ability of TFIIE and TFIIH to bind to RNA polymerase II.

45
Q

What is the role of TFIIE?

A

TFIIE plays a role in the formation and/or the maintenance of the open complex. It may exert its effects by facilitating the binding of TFIIH to RNA polymerase II and regulating the activity of TFIIH.

46
Q

What is the role of TFIIH?

A

TFIIH has multiple roles. Its helicase activity can promote the formation of the open complex. Other of its subunits phosphorylates CTD of RNA polymerase II, which releases its interaction with TFIIB and thereby allows RNA polymerase II to proceed to the elongation phase.

47
Q

When might DNA be inaccessible to general transcription factors and RNA polymerase?

A

If the DNA is highly compacted.

48
Q

What must happen to DNA before it undergoes transcription?

A

DNA must have its promoter region decondensed.

49
Q

What enzymes serve to decondense DNA before transcription?

A

Enzymes such as histone acetyltransferases and ATP-dependent-remodeling proteins serve to decondense the chromatin.

50
Q

What is the colinearity of gene expression?

A

Colinearity of gene expression is the correspondence between the sequence of codon in the DNA coding strand and the amino acid sequence of the polypeptide.

51
Q

Are all eukaryotic genes colinear?

A

No.

52
Q

What are exons? Intros?

A

Exons are the coding sequences. Intros are the sequences that interrupt exons.

53
Q

What is RNA splicing?

A

RNA splicing happens when intros are cut out and the exons are connected together.

54
Q

What modifications may occur to RNAs?

A

Trimming, 5’ capping, 3’ polyA tailing, splicing, RNA editing, base modification.

55
Q

What is trimming?

A

The cleavage of a large DNA transcript into smaller pieces. One or more of the smaller pieces becomes a functional RNA molecule. Trimming occurs for rRNA and tRNA transcripts.

56
Q

What is 5’ capping?

A

The attachment of a 7-methylguanosine cap to the 5’ end of mRNA. This occurs in eukaryotic mRNAs. The cap plays a role in translational initiation.

57
Q

What is 3’ polyA tailing?

A

The attachment of a string of adenine-containing nucleoti8des to the 3’ end of mRNA at a site where the mRNA is cleaved. This occurs in eukaryotic mRNAs. It is important for RNA stability and translation.

58
Q

What is RNA editing?

A

The change of the base sequence of an RNA after it has been transcribed.

59
Q

What is base modification?

A

The covalent modification of a base within an RNA molecule. Base modification commonly occurs in tRNA molecules.

60
Q

Intron experiment: what is an R loop?

A

When RNA has displaced one of the DNA strands.

61
Q

Intron experiment: what was the hypothesis?

A

The mouse beta-globin gene contains one or more intros.

62
Q

Intron experiment: How were the data interpreted?

A

The mRNA hybridized to the DNA, which caused a formation of two R loops separated by a double-stranded DNA region.

63
Q

Intros experiment: how does the electron micrograph indicate that globin genes contain introns.

A

The micrograph showed the formation of two R loops where mRNA had hybridized to DNA.

64
Q

What three different splicing mechanisms remove intros?

A

The chemistry of splicing among Group I and Group II intros is called self-splicing. Pre-mRNA requires the spliceosome.

65
Q

What is self-splicing?

A

When splicing does not require the aid of other enzymes. The RNA itself functions as its own ribozyme.

66
Q

What is pre-mRNA?

A

A long transcript produced by the transcription of structural genes. It is located within the nucleus. Also known as heterogeneous nuclear RNA or hnRNA.

67
Q

How is pre-mRNA spliced?

A

Pre-mRNA splicing requires the aid of a multicomponent structure known as the spliceosome.

68
Q

What is the spliceosome?

A

A large multimeric complex that splices pre-mRNA.

69
Q

How are introns spliced out in pre-mRNA?

A

A lariat is spliced out and the exons are connected together.

Genetics (12 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions