RNA: Transcription, Processing and Decay

Question 1

Does DNA actually do work in a cell?

Answer 1

No

Question 2

In eukaryotes, where is the DNA and where is the protein?

Answer 2

DNA is in the nucleus
Protein is predominately in the cytoplasm

Question 3

In ~1957, Elliot Volkin and Lawrence Astrachan made an important insight suggesting that _ was the intermediate

Answer 3

RNA was the intermediate

Question 4

What did Volkin and Astrachan find?

Answer 4

A striking burst of RNA synthesis following the phage infection of E. coli

Question 5

What did Volkin and Astrachan’s finding suggest?

Answer 5

RNA might play an important role in enabling the phage genome to act

Question 6

Does uracil exist in RNA or DNA

Answer 6

Uracil only exists in RNA

Question 7

What was the experiement and what did we find out radioactive uracil was pulsed in?

Answer 7

Radioactive uracil was pulsed then chased with regular uracil. The newly synthesized RNA was found to be exported into the cytoplasm.
Suggesting RNA was the intermediate

Question 8

What is the ribose difference between RNA and DNA

Answer 8

DNA- deoxyribose
RNA - ribose

Question 9

How do ribose and deoxyribose differ at the 2’ position?

Answer 9

Ribose has an OH group at the 2’ position and Deoxyribose has an H at the 2’ position

Question 10

Is RNA double or single stranded?

Answer 10

RNA - single stranded
DNA - double stranded

Question 11

What amino acid does RNA have insead of Thymine?

Answer 11

Uracil

Question 12

What does uracil exhibit that thymine doesnt?

Answer 12

Exhibits wobble, can pair with both Adenine and Guanine

Question 13

What does uracils wobble help form?

Answer 13

Complex secondary structures

Question 14

Unlike DNA, RNA can catalyze some _ reactions

Answer 14

Biochemical reactions

Question 15

What RNAs can catalyze biochemical reactions?

Answer 15

Ribozymes

Question 16

Which type of RNAs are intermediates between DNA and protein?

Answer 16

Messenger - mRNAs

Question 17

What are the RNA bases
ACGU

Answer 17

Adenine
Cytosine
Guanine
Uracil

Question 18

What is a nucleoside? What are the 4?

Answer 18

Base+ribose
Adenosine
Cytidine
Guanosine
Uridine

Question 19

What is a nucleotide?
What are the 4?

Answer 19

Base + ribose + triphosphate
Adenosine triphosphate
Cytidine triphosphate
Guanosine triphosphate
Uridine triphosphate

Question 20

What is transcription?

Answer 20

The process of generating RNA transcripts from a DNA template

Question 21

What direction does RNA transcription proceed?

Answer 21

5’-to-3’: the transcription’s 3’ end will terminate at the template’s 5’ end.

Can occur on either of DNAs two strands.

Question 22

In what direction does RNA polymerase read the template strand?

Answer 22

Reads 3’-to-5’ of template so new RNA is synthesized 5’ to 3’

Question 23

the _ end of an entering ribonucleotide attaches to the _ end of the growing RNA

Answer 23

5’ end attaches to the 3’ end

Question 24

RNA polymerase catalyzes the formation of _ bonds

Answer 24

phosphodiester bonds

Question 25

Many RNAs can be _ transcribed from the same gene

Answer 25

simultaneously

Question 26

An RNA will be the _ _ of its DNA template? meaning?

Answer 26

Reverse complement Meaning the coding strand will have the same sequence at the non-template strand except with Us replacing Ts

Question 27

What are the three steps of transcription?

Answer 27

Initiation Elongation Termination

Question 28

Initiation occurs when RNA polymerase binds specific sequences called _

Answer 28

Promoters

Question 29

Where are promoters located?

Answer 29

Upstream of coding regions

Question 30

What happens to the space between the promoter and coding region

Answer 30

The space is transcribed but not translated

Question 31

Transcripts _ and are extended from promoters

Answer 31

Initiate

Question 32

Each gene or operon has its own promoter and these promoters have _ sequences

Answer 32

Different

Question 33

In E.coli what do sigma factors do?

Answer 33

Sigma factors position RNA polymerase to the right motifs prior to transcription

Question 34

After transcription initiates, what happens to the sigma factor.

Answer 34

It dissociates

Question 35

E. Coli has a number of different sigma factors that facilitate transcription of different _

Answer 35

genes

Question 36

As RNA polymerase slides along its template, DNA is _ in front and _ behind

Answer 36

DNA is unwound in front and rewound behind

Question 37

What eventually stops transcription at most genes in E.coli?

Answer 37

Hairpin formation

Question 38

What mechanism stops transcriptions in prokaryotes?

Answer 38

Rho protein

Question 39

Degradation of mRNAs promotes rapid turnover of the _

Answer 39

Transcriptome

Question 40

What is the range of half life of RNAs in E.coli

Answer 40

30 seconds to 20 minutes

Question 41

What does pyrophosphohydrolase cleavage do?

Answer 41

Initiate degradation

Question 42

what is Rnase E and what does it do?

Answer 42

It is an endouclease that binds and cleaves RNA at the A- and U- rich regions

Question 43

How do you further break down mRNA fragments?

Answer 43

Additional rounds of cleavage and enzymes