Transcription and Post Transcription 2B part 2

Question 1

5’ cap (4)

Answer 1

a modified guanosine triphosphate added to the 5’ UTR end of the mRNA

acts as the binding site for ribosomes

protect from 5’-3’ exonuclease

5’-5’ triphosphate bridge forms by the addition of 7-methylgaunosine triphosphate to the 5’ carbon of the first nucleotide of mRNA.

Question 2

Poly A tail

Answer 2

a long string go adenine nucleotides added to the 3’ end of the mRNA by Pol-A polymerase to protect the mRNA from being degraded (from 3’-5’ exonuclease) and incense translational efficient (influence how ribosomes get docked onto 5’UTR)

Question 3

5’UTR and 3’ UTR

what they do

Answer 3

regulate mRNA stability and translational efficiency

Question 4

5’ UTR (3)

what it has

+ in prokaryotes/ eukaryotes

Answer 4

contain a ribosome binding site that function in translational initiation

Shine Dalgarno sequence in prokaryotes

Kozak box sequence in eukaryotes

Question 5

The open reading frame

includes

Answer 5

the region of mRNA that is translated and includes the start and stop codons at the borders and utr

Question 6

UTRs are

Answer 6

not translated

Question 7

3’ UTR cleavage (2)
+what is after cleavage on 3’ side?

Answer 7

polyadenylation signal in DNA gets translated into RNA in the 3’UTR which tells CPSF to cleave. Poly A then comes to add tail

Question 8

3 steps of mRNA maturation that happens in nucleus

Answer 8

5’ cap

Poly A tail

intron splicing

Question 9

removal of introns generate an….

Answer 9

open reading frame consist of a continuous stretch of codons and UTRs

Question 10

If introns are not spliced out then….

Answer 10

ribosome make wrong amino acid and produce non functional proteins

Question 11

so what is going out of nucleus to cytoplasm for translation?

Answer 11

5’ cap-5’UTR-protein coding sequence all exons-3’UTR-Poly A tail

Question 12

splicesome (2)

Answer 12

made up of 5 noncoding RNAs (SnRNA) complied to several proteins to form a ribonucleoprotein

need ATP to function (hydrolysis)

Question 13

How are intron spliced? (4)

Answer 13

1. splice some binds to intron-exon junctions
2. Loop intron out of the pre-mRNA bringing axons closer together (use to be far away)
3. Clip the intron at each exon boundary releasing the lariat structure
4. join the adjacent axons together by ligating them

Question 14

Alternative splicing (4)

Answer 14

generating different proteins/mrna from one gene

dramatically increases the number and variety of proteins that can be encoded by the genome.

In eukaryotes, we are able to generate a maximum number of protein from minimum number of genes

different isoforms are made in different tissues from the same gene producing tissue specific phenotypes

Question 15

isoforms

Answer 15

proteins that are similar to each other and perform similar roles within cells

Question 16

Transcriptional regulation

Answer 16

control of mRNA synthesis

Question 17

Transcriptional rate depends on

Answer 17

the speed of transcriptional initiation (Everything assembled on promotor)

Question 18

Posttranscriptional regulation

Answer 18

processing of mRNA which affect its stability and translational efficiency

Question 19

stronger promotor strength+outcome (2)

Answer 19

more mRNA been made, everything get on promotor a lot faster

pale blue eyes vs dark blue eye

Question 20

longer poly A tail

Answer 20

more stable

Question 21

stability of mRNA depends on

Answer 21

presence of 5’ cap and length of poly A tail

Question 22

the expression level of a specific gene depends on (3)

Answer 22

abundance of mRNA, nucleotide sequence and its eventual translation

Question 23

abundance of RNA depends on rate of (2)

Answer 23

synthesis (transcription) and degradation of mRNA (posttranscritptional)

Question 24

Deletion of enhancer causes

Gene expression…bc…

Answer 24

decreased gene expression as RNA polymerase cannot initiate transcription

Question 25

Removal of 5’cap causes

Gene expression…bc…

Answer 25

Decreased gene expression as mRNA degradation accelerated and less efficient in translation initiation

Question 26

Deletion of TATA box causes

Gene expression…bc…

Answer 26

decreased gene expression because formation of transcriptional initial complex is hindered

Question 27

inhibition of siRNA synthesis causes

Gene expression…bc…

Answer 27

increased gene expression as less mRNA degradation