DLA 10

Question 1

What is the function of mRNA?

Answer 1

This RNA encodes the genetic information which will be used to translate into AA

Question 2

What is the function of tRNA?

Answer 2

brings AA to the ribosome complex

Question 3

What is the function of rRNA?

Answer 3

combines with ribosomal proteins to form the ribosome

Question 4

What is the function of snRNA?

Answer 4

combines with certain proteins and is involved in RNA processing and gene regulation in eukaryotes

Question 5

What is the function of miRNA?

Answer 5

involved in the inhibition of mRNA transcription

Ex: miRNA or siRNA

Question 6

What is the basic transcription process?

Answer 6

1. RNA polymerase will recognize a particular sequence of DNA called the promoter region
2. RNA polymerase has helicase activity that will generate a transcription bubble
3. RNA polymerase catalyzes the synthesis of an RNA molecule in the 5’ to 3’ direction along the 3’ to 5’ template strand of the DNA

Question 7

RNA polymerase in prokaryotes?

Answer 7

In bacteria, there is only one single RNA poly.

it is composed of the core polymerase plus sigma factor

Question 8

What is the role of the sigma factor in a prokaryote RNA poly?

Answer 8

enables the recognition of promoters

Question 9

What are the three polymerases in eukaryotes?

Answer 9

1. RNA poly I
2. RNA poly II
3. RNA poly III

Question 10

What are the functions of the three eukaryotic RNA polys?

Answer 10

RNA poly I - 5.8S, 18S, 28S rRNA genes

RNA poly II - all mRNAs and some snRNA and miRNA

RNA poly III - tRNA genes and some snRNA

Question 11

3 regions of the prokaryotic gene?

Answer 11

1. promoter
2. RNA coding sequence
3. terminator

Question 12

What does + 1 mean?

Answer 12

That is where transcription starts

Question 13

Where is the prokaryotic promoter region found in respect to the coding region?

Answer 13

-35 and -10 from the start of the coding strand

Question 14

What is important about -10 in prokaryotes?

Answer 14

It is where the TATA box is located (pribnow box)

Question 15

What are the trans elements of eukaryotic transcription?

transcription factors

Answer 15

1. TBP
2. TFIIA- Facilitates the binding of TBP to the TATA box
3. TFIIB- recognizes the initiation site BRE element
4. TFIID- Will recognize the TATA box sequence
5. TFIIH- contains DNA helicase and activates RNA poly
6. TFIIE- will associate with the growing assembly of factors and attracts TFIIH
7. TFIIF- stabilizes RNA poly (attracts TFIIH)

Question 16

main components of DNA synthesis?

Answer 16

1. DNA polymerase
2. dNTP precursor
3. primer required
4. A and T

Question 17

Main components of RNA synthesis?

Answer 17

1. RNA polymerase
2. NTP precursor
3. no primer needed
4. A and U

Question 18

What are the two types of termination in prokaryotes?

Answer 18

1. Intrinsic termination

2. extrinsic termination

Question 19

How is intrinsic termination done?

Answer 19

The palindromic region of the DNA (terminator sequence) a stem loop structure will form. The stem loop structure destabilizes transcription and the transcription proteins will dissociate.

Question 20

How is extrinsic termination done?

Answer 20

1. Rho protein attaches to the recognition site on the RNA
2. Rho moves along the RNA following RNA poly
3. RNA poly pauses at the terminator and Rho catches up
4. Rho unwinds the DNA/RNA hybrid ans separates the RNA from the RNA poly
5. RNA poly, Rho, and RNA are released

Question 21

What kind of protein is Rho?

Answer 21

RNA/DNA helicase

Question 22

How does termination occur in Eukaryotes?

Answer 22

Termination of the mRNA sequence is directly linked directly with the process of poly-adenylation (poly A tail)

The 3 prime end of the mRNA is cleaved by cleaving factors. This separates the RNA from the RNA/DNA hybrid. this leads to termination

poly A tail is added to the 3 prime end

Question 23

Explain rifampin/ rifampicin?

Answer 23

an antibiotic from streptomyces

inhibits the start of transcription

blocks formation of first phosphodiester bond by binding to RNA poly

Eukaryote poly not impacted

used to treat tuberculosis

Question 24

alpha- amanitin?

Answer 24

found in the death cap mushroom and is an inhibitor of RNA poly II (transcribes mRNAs)

Question 25

Explain Actinomycin D?

Answer 25

binds tightly to double stranded DNA inhibits both transcription and replication in both eukaryotes and prokaryotes normally used as an anti-cancer drug not an antibiotic

Question 26

What do courmarins and quinolones do?

Answer 26

They inhibit bacterial gyrase, thus supercoiling cannot be corrected. antibiotic that is effective