Transcription

Question 1

Helicase and topoisomerase:

Answer 1

unwind the DNA double helix

Question 2

RNA polymerase 2

Answer 2

binds to the TATA box within the promoter region of the gene (25 base pairs upstream from first transcribed base)

Question 3

hnRNA

Answer 3

synthesized from the DNA template (antisense) strand

Question 4

Posttranscritional modifications include:

Answer 4

• a 7 - methylguanylate triphosphate cap is aded to the 5’ end
• a polyadenosyl (PolyA) tail is added to the 3’ end

Question 5

Splicing

Answer 5

is done by snRNA and snRNPs in the spliceosome; introns are removed in a lariat structure, and eons are ligated together

Question 6

Prokaryotic cells can increase WHAT?

Answer 6

the variability of gene products from one transcript through POLYCISTRONIC GENES (starting transcription in different sites within the gene leads to different gene products)

Question 7

Eukaryotic cells can increase WHAT?

Answer 7

the variability of gene products through alternative splicing (combining different eons in a modular fashion to acquire different gene products)

Question 8

generating a protein is done where?

Answer 8

in the cytoplasm

Question 9

transcription

Answer 9

the creation of mRNA from a DNA template

Question 10

RNA polymerase I

Answer 10

located in the nucleus and synthesizes rRNA

Question 11

RNA polymerase II

Answer 11

located in the nucleus and synthesizes horn (preprocessed mRNA) and some small nuclear RNA (snRNA)

Question 12

RNA polymerase III

Answer 12

located in the nucleus and synthesizes tRNA and some rRNA

Question 13

In what direction does the RNA polymerase travel?

Answer 13

3’ –> 5’

Question 14

RNA polymerase

Answer 14

does not proofread its work

Question 15

coding strand (sense strand)

Answer 15

not used as a template during transcription

complementary to the template strand

Question 16

Where does the RNA polymerase II bind?

Answer 16

the TATA box

Question 17

heterogenous nuclear RNA (hnRNA)

Answer 17

The primary transcript that is formed when the DNA double helix reforms.
mRNA is derived from horn via post transcriptional modifications

Question 18

Maturation of the horn includes:

Answer 18

splicing of the transcript to remove noncoding sequences (introns) and ligate coding sequences (exons) together

Question 19

Splicing is accomplished by the

Answer 19

spliceosome

Question 20

In the spliceosome,

Answer 20

small nuclear RNA (snRNA) molecules couple with proteins known as small nuclear ribonucleoprotines (snRNPS or “snurps”). The snRNP/snRNA complex recognizes both he 5’ and 3’ splice sits of the introns. These noncoding sequences are excised in the form of a lariat (lasso - shaped structure) and then degraded

Question 21

7 - methylguanylate triphosphate cap

Answer 21

this is added at the 5’ end of the hnRNA molecule.
This cap is added during the process of transcription and is recognized by the ribosome as the binding site. It also protects the mRNA from degradation in the cytoplasm

Question 22

3’ Poly - A Tail

Answer 22

A poly A tail is added to the 3’ end of the mRNA transcript and protects the message against rapid degradation.

Question 23

alternative splicing

Answer 23

occurs in eukaryotic cells
the primary transcript of hnRNA may be spliced together in different ways to produce multiple variants of proteins encoded by the same original gene.

the function in the regulation of gene expression, in addition to generating protein diversity.