Transcription

Question 1

What is the aim of transcription?

Answer 1

Making an mRNA strand for DNA

Question 2

Where does transcription take place in eukaryotes?

Answer 2

Nucleus

Question 3

Where does transcription take place in prokaryotes?

Answer 3

Cytoplasm (no nucleus)

Question 4

In prokaryotes, mRNA is made directly from DNA. Why?

Answer 4

No introns in DNA of prokaryotes

No pre-mRNA

Question 5

Before mRNA is made in eukaryotes, pre-mRNA is made. What is pre-mRNA?

Answer 5

mRNA containing both introns and exons

Question 6

How is pre-mRNA turned into mRNA?

Answer 6

Splicing (removing introns and joining exons)

Question 7

What enzyme is involved in transcription?

Answer 7

RNA polymerase

Question 8

Describe the process of transcription

Answer 8

RNA polymerase attaches to DNA
Breaks hydrogen bonds, exposes bases
Template strand- free nucleotides joined by RNA polymerase forming phosphodiester bonds
RNA polymerase moves along DNA- separating and reassembling mRNA
After RNA polymerase passes, H bonds reform and recoil
Reaches stop signal, RNA polymerase stops making mRNA and detached from DNA
mRNA moves out of nucleus to ribosomes

Question 9

What is splicing?

Answer 9

Removing introns form pre-mRNA to form mRNA

Question 10

What is a stop signal?

Answer 10

Particular sequence of DNA

Tells RNA polymerase to stop making mRNA and detach from DNA

Question 11

Once free nucleotides are lined up, RNA polymerase forms what bonds to make the mRNA strand?

Answer 11

Phosphodiester