CH. 13 Transcription

Question 1

where are RNAs synthesized

Answer 1

nucleus

Question 2

where is mRNA exported to

Answer 2

the cytoplasm- where it is translated

Question 3

What are the building blocks of RNA

Answer 3

ribonucleotide triphosphates (NTPs)

Question 4

When does RNA transcription occur

Answer 4

predominantly in G1 and G2 phases

Question 5

mRNAs are needed for

Answer 5

protein synthesis

Question 6

any DNA sequence that is transcribed into an RNA molecule

Answer 6

Gene

Question 7

The coding strand is the

Answer 7

nontemplate strand

Question 8

Nucleotides are added to the ____ end of the RNA molecule

Answer 8

3’ end

Question 9

In the tree structure of RNA transcription, 3’ (of DNA) is end with the larger or shorter strands of RNA

Answer 9

shorter

Question 10

(RNA christmas trees) The 5’ end of the RNA is closer or farther from the DNA

Answer 10

farther

Question 11

The basal transcription apparatus has

Answer 11

general transcription factors, RNA polymerase

Question 12

RNA poly II consists of 2 sequences called the…

Answer 12

regulatory and core sequences

Question 13

core promoter

Answer 13

bound by basal transcription apparatus

Question 14

is the regulatory promoter upstream or downstream of the core promoter

Answer 14

upstream

Question 15

transcriptional activator proteins

Answer 15

affect the rate of transcription

Question 16

consensus sequences

Answer 16

comprise the most commonly encountered nucleotides at each site

Question 17

What happens in transcription initiation

Answer 17

the transcription apparatus assembles on the promoter and begin the synthesis of RNA

Question 18

What happens in transcription elongation?

Answer 18

TFIIs left on the promoter and RNA polymerase moves along the DNA template

Question 19

What happens in termination

Answer 19

Rat1 is a 5’ to 3’ exonuclease that degrades the RNA starting from the 5’ and going to the 3’ until it reaches the transcription machinery once it does this- transcription terminates

Question 20

What are the different parts of mRNA

Answer 20

5’ methyl cap, 5’ untranslated region, start codon, protein coding region, stop codon, 3’ untraslated region, poly-A-tail

Question 21

What is the protein-coding region

Answer 21

series of nucleotides specificying the amino acids to the added

Question 22

what is the function of of mRNA 5’ UTR

Answer 22

necessary for ribosome binding and intron splicing

Question 23

What is the function of the mRNA 3’ UTR

Answer 23

regulatory role in mRNA stability and translation

Question 24

why do we need the 5’ methyl cap

Answer 24

needed to start translation, increase stability of mRNA, influences intron splicing, added during transcription by an enzyme coupled by Pol II

Question 25

What is the first step in pre-mRNA processing

Answer 25

addition of 5' methyl cap

Question 26

What is the second step in pre-mRNA processing

Answer 26

Polyadenylation

Question 27

is the poly-A-tail coded in the DNA

Answer 27

no- it is a post-transcriptional modification

Question 28

Why is polyadenylation important

Answer 28

increases stability of mRNA, moves mRNA through the cytoplasm, facilitated attachment of the ribosome to the mRNA, is preceded by cleaving of 3' downstream sequences (pre-mRNAs extend many bases 3' of the end of the gene)

Question 29

What is the third step in pre-mRNA processing

Answer 29

intron splicing: stitch together exons and get rid of introns (in nucleus, done by the spliceosome)

Question 30

explain the 2 steps of pre-mRNA splicing

Answer 30

The pre-mRNA is cut at the 5' splice site (frees exon 1 from intron and the 5' end of the intron attached to the branch point forming a lariat); a cut is made at the 3' splice site and simultaneously the 3' end of exon 1 becomes covalently bonded to the 5' end of exon 2

Question 31

Alternative Splicing

Answer 31

the same pre-mRNA can be spliced in more than one way to yield different amino acids and therefore different proteins

Question 32

RNA polymerase I

Answer 32

large rRNAs

Question 33

RNA poly II

Answer 33

mRNA

Question 34

RNA poly III

Answer 34

tRNAs

Question 35

Transcriptional Unit

Answer 35

a stretch of DNA that encodes an RNA molecule and the sequences necessary for its transcription

Question 36

promoter

Answer 36

initial binding site of RNA polymerase; specifies which polymerase is used for the different classes of genes to be transcribed

Question 37

Transcription requires 3 major components

Answer 37

a DNA template, raw materials to build a new RNA molecule (NTPS, and the trancription apparatus

Question 38

The basal transcription apparatus is sufficient to initiate...

Answer 38

minimal levels of transcription