Chapter 15 Eukaryotic Transcription

Question 1

•THREE major differences from prokaryotic transcription:

(Eukaryotic Transcription)

Answer 1

–1) Three types of RNA polymerase as opposed to just one— RNA polymerase I, II, & III

–2) Initiation requires a host of transcription factors

–3) Eukaryotic transcripts are MODIFIED!!

Question 2

RNA polymerase I in Eukaryotic Transcription

Answer 2

transcribes rRNA.

Question 3

RNA polymerase II in Eukaryotic Transcription

Answer 3

transcribes mRNA and some small nuclear RNA.

Question 4

RNA Polymeras III in Eukaryotic Transcription

Answer 4

transcribes tRNA and some other small RNAs.

Question 5

–proteins that act to bind RNA polymerase to the promoter and initiate transcription

Answer 5

transcription factors

Question 6

mRNA is not formed

until AFTER processing in eukaryotes

Answer 6

Processing of RNA
after transcription

Question 7

In eukaryotes, the primary transcript is modified in three different ways:

Answer 7

1) addition of a 5’ methyl G cap to the 5’ end

–2) addition of a 3’ poly-A tail

3) Splicing

Question 8

•the 5’ methyl G cap has at least two important functions:

Answer 8

–It helps protect mRNA from being degraded by hydrolytic enzymes.

–It also functions as an “attach here” signal for ribosomes.

Question 9

•At the 3’ end of the mRNA transcript, the enzyme ________ adds ~200 adenine nucleotides, the poly(A) tail.

Answer 9

poly-A polymerase

Question 10

–are the noncoding segments, between coding regions (“intra”=between).

Answer 10

Introns

Question 11

–are the coding segments separated by the introns

Answer 11

Exons

Question 12

is the organelle responsible for removing introns and splicing exons together.

Answer 12

Spliceosome

Question 13

Small ribonucleoprotein particles within the spliceosome recognize the intron-exon boundaries

Answer 13

(snRNPs— “snurps”)

Question 14

YIELDS DIFFERENT PROTEINS FROM SAME GENE

Answer 14

ALTERNATIVE SPLICING