Chapter 12 - Gene Transcription and RNA Modification Flashcards

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1
Q

What is the first step of gene expression?

A

It is transcription.

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2
Q

What is transcrition?

A

It refers to the copying of DNA sequence into RNA sequence.

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3
Q

What is protein encoding genes?

A

encodes the amino acid sequences or polypeptides.

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4
Q

What does the transcription of gene coding protein?

A

It produces mRNA.

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5
Q

What is promoters?

A

They are DNA sequence that promote gene expression and direct the exact location for the initiation of transcription.

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6
Q

Whare is the location of promoters?

A

They are typically located upstream of the site where the transcription begins.

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7
Q

What is the most common promoter sequence is called?

A

It is called the consensus sequence.

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8
Q

What is the function of RNA polymerase?

A

It is an enzyme that catalyzes the synthesis of RNA.

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9
Q

What can RNA polymerase captures?

A

It can only captures sigma factors.

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10
Q

What is the region of sigma factor that is tightly bounded to the DNA?

A

It is called helix turn helix structure.

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11
Q

What does the sigma factor recognizes?

A

It recognized the -35 and -10 sequence of the promoter.

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12
Q

Where does sigma factor bind?

A

It binds at the promoter region.

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13
Q

How long is the open complex?

A

It is about 17 base pair long.

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14
Q

what is the rate of RNA synthesis?

A

It is 43 nucleotide base per second.

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15
Q

When does the termination occurs?

A

It occurs when the RNA-DNA hybrid of the open complex is forced to separate.

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16
Q

What are the two different mechanism for termination?

A
  1. rho dependent termination

2. rho independent termination

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17
Q

What is the recognition site of rho protein?

A

It is rut recognition site.

18
Q

Where does rho protein bind to ?

A

It binds at the rut recognition site in the RNA.

19
Q

What does rho independent termination mechanism depends on?

A

It depends on two sequence. 1. the uracil rich region at the 3 prime end of RNA
2. stem loop structure upstream of the uracil rich sequence.

20
Q

Why eukaryotic gene transcription is more complex?

A

Because there are:

  1. larger more complex cells.
  2. more genes
  3. multicellularity which adds higher level of regulation.
21
Q

What does RNA pol I does?

A

It transcribes all rRNA genes.

22
Q

What does RNA pol II does?

A

It transcribes all protein encoding genes.

23
Q

What does RNA pol III does?

A
  1. It transcribes all the tRNA genes.
  2. 5sRNA
  3. Micro RNA genes.
24
Q

How long is the core promoter?

A

It is relatively short.

25
Q

What does the core promoter consists of?

A

It consists of TATA box and transcription start site.

26
Q

What is the function of the core promoter?

A

It determines the precise start point of transcription.

27
Q

What is the basal transcrition?

A

It is the lowest level of transcription in the core promoter.

28
Q

What is the regulatory elements?

A

They are DNA sequences that affect the binding of RNA polymerase to the core promoter.

29
Q

What is the transcription factors?

A

They are protein that bind to the elements and influence the rate of transcription.

30
Q

What are the two different type of regulatory elements?

A
  1. enhancers

2. silencers.

31
Q

What are the three categorize of proteins that must be at the core promoter for transcription to occur?

A
  1. RNA pol II
  2. general transcription factors ( 5 proteins)
  3. Protein complexes called mediator.
32
Q

What is the mediator?

A

It is protein complexes.

33
Q

What are the two models of termination in eukaryotes?

A
  1. Allosteric model

2. Torpedo model.

34
Q

When does the termination occur in Eukaryote cells?

A

It occurs 500 to 2000 nucleotide after the polyA tail.

35
Q

How is RNA strands get modified?

A
  1. splicing
  2. polyA tail
  3. 5 capping
36
Q

To what end the 5 capping is added?

A

It is added to the 5 prime end.

37
Q

To what end the polyA tail is added?

A

It is added to the 3 prime end.

38
Q

What is the role of 5 capping?

A
  1. It moves RNA outside the nucleus.

2. It constitute early stages for translation.

39
Q

What are the three different splicing mechanism?

A
  1. spliceosome
  2. group 1 intron splicing
  3. group 2 intron splicing
40
Q

What is the function of exonucleases?

A

cleave a covalent bond between two nucleotide at one end.

41
Q

What is the function of endonuclease?

A

It cleaves bond within the strand.