Chapter 12 - Gene Transcription and RNA Modification

Question 1

What is the first step of gene expression?

Answer 1

It is transcription.

Question 2

What is transcrition?

Answer 2

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

Question 3

What is protein encoding genes?

Answer 3

encodes the amino acid sequences or polypeptides.

Question 4

What does the transcription of gene coding protein?

Answer 4

It produces mRNA.

Question 5

What is promoters?

Answer 5

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

Question 6

Whare is the location of promoters?

Answer 6

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

Question 7

What is the most common promoter sequence is called?

Answer 7

It is called the consensus sequence.

Question 8

What is the function of RNA polymerase?

Answer 8

It is an enzyme that catalyzes the synthesis of RNA.

Question 9

What can RNA polymerase captures?

Answer 9

It can only captures sigma factors.

Question 10

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

Answer 10

It is called helix turn helix structure.

Question 11

What does the sigma factor recognizes?

Answer 11

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

Question 12

Where does sigma factor bind?

Answer 12

It binds at the promoter region.

Question 13

How long is the open complex?

Answer 13

It is about 17 base pair long.

Question 14

what is the rate of RNA synthesis?

Answer 14

It is 43 nucleotide base per second.

Question 15

When does the termination occurs?

Answer 15

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

Question 16

What are the two different mechanism for termination?

Answer 16

1. rho dependent termination

2. rho independent termination

Question 17

What is the recognition site of rho protein?

Answer 17

It is rut recognition site.

Question 18

Where does rho protein bind to ?

Answer 18

It binds at the rut recognition site in the RNA.

Question 19

What does rho independent termination mechanism depends on?

Answer 19

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.

Question 20

Why eukaryotic gene transcription is more complex?

Answer 20

Because there are:

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

Question 21

What does RNA pol I does?

Answer 21

It transcribes all rRNA genes.

Question 22

What does RNA pol II does?

Answer 22

It transcribes all protein encoding genes.

Question 23

What does RNA pol III does?

Answer 23

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

Question 24

How long is the core promoter?

Answer 24

It is relatively short.

Question 25

What does the core promoter consists of?

Answer 25

It consists of TATA box and transcription start site.

Question 26

What is the function of the core promoter?

Answer 26

It determines the precise start point of transcription.

Question 27

What is the basal transcrition?

Answer 27

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

Question 28

What is the regulatory elements?

Answer 28

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

Question 29

What is the transcription factors?

Answer 29

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

Question 30

What are the two different type of regulatory elements?

Answer 30

1. enhancers | 2. silencers.

Question 31

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

Answer 31

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

Question 32

What is the mediator?

Answer 32

It is protein complexes.

Question 33

What are the two models of termination in eukaryotes?

Answer 33

1. Allosteric model | 2. Torpedo model.

Question 34

When does the termination occur in Eukaryote cells?

Answer 34

It occurs 500 to 2000 nucleotide after the polyA tail.

Question 35

How is RNA strands get modified?

Answer 35

1. splicing 2. polyA tail 3. 5 capping

Question 36

To what end the 5 capping is added?

Answer 36

It is added to the 5 prime end.

Question 37

To what end the polyA tail is added?

Answer 37

It is added to the 3 prime end.

Question 38

What is the role of 5 capping?

Answer 38

1. It moves RNA outside the nucleus. | 2. It constitute early stages for translation.

Question 39

What are the three different splicing mechanism?

Answer 39

1. spliceosome 2. group 1 intron splicing 3. group 2 intron splicing

Question 40

What is the function of exonucleases?

Answer 40

cleave a covalent bond between two nucleotide at one end.

Question 41

What is the function of endonuclease?

Answer 41

It cleaves bond within the strand.