Transcription

Question 1

What determines the primary sequence of a protein?

Answer 1

Its genetic code

Question 2

What does RNA polymerase sigma factor do?

Answer 2

It is responsible for recognizing the beginning of a gene and transcription initiation. It leads the enzyme.

Question 3

What is the beginning of transcription called?

Answer 3

A promoter

Question 4

How does the cell know where transcription begins?

Answer 4

The enzyme( RNA polymerase) scans the DNA molecule and once it recognizes the promoter region it indicates the start

Question 5

Describe the termination segment

Answer 5

It is a G-C rich segment followed by an A-U segment

Question 6

T/F Transcription and translation happen at different times in Prokaryotic cells

Answer 6

False

Question 7

Describe the post-transcriptional modifications done to eukaryotic pre mRNA.

Answer 7

An addition of a 5’ cap
A tail is added to the 3’ end (Polyadenylation)
mRNA splicing

Question 8

T/F prokaryotes don’t have introns

Answer 8

True

Question 9

Name three differences between DNA and RNA

Answer 9

Ribonucleotides have the sugar ribose instead of the sugar deoxyribose

The base uracil replaces the base thymine which is found in DNA

RNA is a single stranded molecule capable of folding into complex structures.

Question 10

What are the three phases of transcription.

Answer 10

initiation, elongation and termination

Question 11

Describe the initiation phase

Answer 11

Transcription factors & RNA polymerase recognize & bind to the promoter

They temporarily separate the two DNA strands, exposing the DNA bases. This region is called the open promoter zone.

Question 12

Describe the elongation phase

Answer 12

RNA polymerase moves along the DNA in synthesizing a RNA transcript. Synthesis is 5’-3’ . Only 1 strand of DNA is read as a template.

Question 13

Describe the termination phase

Answer 13

A termination signal is reached causing RNA polymerase to dissociated from the DNA

Question 14

Compare transcription in eukaryotic cells to prokaryotic cells

Answer 14

Transcription and translation occurs simultaneously within the cell cytoplasm in Prokaryotic cells. In eukaryotes Transcription occurs in the nucleus.

Eukaryotic cells have multiple RNA polymerases (I, II, and III) with distinct roles in transcription, while prokaryotes typically have a single RNA polymerase for all transcription processes.

Prokaryotic genes lack introns and are typically transcribed directly into mature mRNA.

Question 15

What is splicing?

Answer 15

The removal of introns from pre mRNA and simultaneous joining of exons to generate a mature mRNA

Question 16

What is alternative splicing?

Answer 16

Alternative splicing is a mechanism that allows a single gene to produce multiple mRNA variants by selectively including or excluding different parts (exons) of the gene’s transcript, resulting in diverse protein isoforms.

Question 17

Name the three things contained in a prokaryotic promoter.

Answer 17

a conserved consensus sequences, the pribnow box and -35 sequence

Question 18

Transcription occurs along a ____ template forming an mRNA in the ____ direction.

Answer 18

5’ to 3’; 5’ to 3’