8.4 Polypeptide synthesis - transcription and splicing

Question 1

What is transcription?

Answer 1

The production of mRNA from DNA.

Question 2

What is the strand that is used for transcription called?

Answer 2

Template strand

Question 3

What is the strand that is not used for transcription called?

Answer 3

Coding strand

Question 4

What is the enzyme called that breaks hydrogen bonds between bases?

Answer 4

DNA helicase

Question 5

What is the enzyme called that joins free nucleotides together to form a pre-mRNA?

Answer 5

RNA polymerase

Question 6

What are the stages of transcription?

Answer 6

1. DNA helicase (enzyme) binds to DNA
2. hydrogen bonds between the DNA bases break, and the two strands of the double helix separate
3. the template strand pairs with free RNA nucleotides through complementary base pairing
4. in RNA molecule, A pairs with U and C pairs with G
5. RNA polymerase (enzyme) joins free nucleotides together to form a pre-mRNA
6. as RNA polymerase joins free nucleotides together, the DNA strand rejoins behind it
7. when RNA polymerase reaches a particular sequence of bases on the DNA called terminator sequence, it detaches (分離) from the DNA and the production of pre-mRNA is complete

Question 7

What is the function of DNA helicase?

Answer 7

Breaking hydrogen bonds that link the bases together

Question 8

What is the function of RNA polymerase?

Answer 8

Joining nucleotides together to form a pre-mRNA molecule