Transcription

Question 1

What is transcription, simply?

Answer 1

The first step of protein synthesis

Question 2

What enzyme is used to unzip DNA in the first stage?

Answer 2

RNA helicase

Question 3

How do you describe the two strands of DNA once it has been unzipped?

Answer 3

Anti-parrallel

Question 4

What is a sense strand?

Answer 4

• Contains the correct coding for an amino acid sequence
• Runs from 5’ end to 3’ end

Question 5

What is the template-antisense strand, and what will happen when it is transcribed?

Answer 5

• Runs from 3’ end to 5’ end (sense is 5’ to 3’)
• Complementary to sense strand
• When transcribed, it will make an mRNA strand which has the same base sequence as the sense strand
• So coding for the correct amino acid sequence

Question 6

In the free RNA nucleotides, instead of thymine, what base is complementary to adenine?

Answer 6

Uracil

Question 7

What enzyme joins the nucleotides to the bases?

Answer 7

RNA polymerase

Question 8

After all the RNA nucleotides have been joined up, a single strand of mRNA forms, what does mRNA contain?

Answer 8

• Contains the correct sequence of bases/codons for the correct amino acid sequence

Question 9

Once the remaining template strand rejoins the sense strand to form a double helix again, what happens to the mRNA?

Answer 9

• It leaves the nucleus through the nuclear pore
• Goes to the ribosome for translation

Question 10

Why does mRNA need to be made, instead of directly using the DNA?

Answer 10

DNA is too big to pass through the nuclear pore