Quiz 6

Question 1

What is mRNA?

Answer 1

Messenger RNA

Question 2

Where does mRNA processing occur?

Answer 2

In the nucleus only in eukaryotic organisms

Question 3

The function of mRNA

Answer 3

Use genetic code of mRNA to generate protein

Question 4

What is the five prime cap adding to mRNA?

Answer 4

In addition of seven methyl guanosine to five prime end of mRNA

Question 5

What is the function of a five prime cap?

Answer 5

Stabilize and prevent degradation of mRNA

Question 6

Why do we use a five prime cap?

Answer 6

To help initiate translation in the cytoplasm and facilitate nuclear export of mRNA

Question 7

Steps of mRNA processing

Answer 7

-add a five Prime cap
-Start processing transcription
-capping factors will bind to CTD of RNA polymerase 2
-After about 20 nucleotides of RNA the cat factors, add cap to five prime end of mRNA
-Add a three prime poly a tail
-Splicing will occur

Question 8

What does a three prime poly A tail add to an mRNA

Answer 8

In addition of 200 to 250 adenosines to the three prime mRNA

Question 9

What is the function of a three prime poly A tail

Answer 9

Stabilize and prevent decoration of mRNA. Polyadenylation, elation sequence signals addition of A’s to three prime ends. Use polyadenylation factors on CTD of RNA poll, two and signal termination of transcription.

Question 10

What does Splicing do?

Answer 10

Remove sequences from mRNA

Question 11

When does splicing occur?

Answer 11

Occurs after transcription termination and eukaryotic nucleus

Question 12

What does splicing do?

Answer 12

Cut out intron sequences and join Exxon sequences by ligation

Question 13

For splicing to occur what is needed

Answer 13

SNRNPS: small nuclear ribonucleo protein particles
- U1,U2,U4/U6,U5

Question 14

Steps for splicing

Answer 14

• U1 binds to five prime splice site
  -U2 binds to branch point A
• u4/U6 &U5 will bind to U1& U2 bending the mRNA (making spliceosome)
• Cut at five prime splice sight of Intron
  -U5 will hold Exxon one in position
• Intron forms lariat
• U2 &U6 are holding U5 & mRNA. U1&U4 leave
  -Cut at the three prime splice site using U2,6&5
  -Join or ligate Exxon together
• Three prime of Exxon, one to five prime of Exxon two
  -lariat, released and degraded

Question 15

What is the point of RNA affinity chromatography?

Answer 15

To collect a protein

Question 16

What is the point of RNA foot printing

Answer 16

To see where protein binds on an RNA strand

Question 17

Why do we need spicing?

Answer 17

We can generate multiple mRNA from the same gene joining different introns. But you also can’t take Exxon out of order.

Question 18

What is translation?

Answer 18

RNA →protein

Question 19

mRNA in prokaryotes

Answer 19

• has a shine delgarno sequence
• transcribed from operation with multiple genes
  -multiple start and stop codons
  -Prokaryotes do not process mRNA

Question 20

MRNA in eukaryotes

Answer 20

-One gene, transcribed
-One start and stop codon
-Processed mRNA
-Has a 5’ cap and poly A tail

Question 21

What does the shine delgarno sequence do

Answer 21

Helps initiate translation and small rivals, almost subunits localized to this sequence

Question 22

Tln coding steps

Answer 22

-start with mRNA strand
-find start codon and stop codon
-Read and sets of three
-Generate amino acid sequence

Question 23

Steps for initiation translation

Answer 23

-mRNA w 5’ cap and poly a tail exit nucleus
- In the cytoplasm eIF4E localized to the 5’ cap, and3’ tail of the mRNA
-In the cytoplasm eIF2 bind to first tRNA
- eIF1,3,5 bind to small ribosomal subunit
- eIFs & components combine for initiation complex
-Localized small sub unit to start codon. tRNA in position at the start
-Initiation factors are released in large subunit enters
-First TRA is in the p site