Enzymes in Molecular Biology

Question 1

What do polymerases do

Answer 1

They create polymers of nucleic acids such as DNA & RNA

Question 2

What kind of rxn is involved in forming a phosphodiester bond

Answer 2

Condensation rxn

Question 3

Examples of DNA polymerases in vivo

Answer 3

1. DNA replication
2. DNA repair

Question 4

Example of DNA polymerase in vitro

Answer 4

PCR (polymerase chain rxn)

Question 5

Example of RNA polymerase in vivo

Answer 5

Transcription

Question 6

What are nucleases

Answer 6

Enzymes that cleave the phosphodiester bonds between nucleotide subunits of nucleic acids

Question 7

How do endonucleases work

Answer 7

Endonucleases break the DNA internally (make internal cuts)

Question 8

How do exonucleases work

Answer 8

Exonucleases cut and remove nucleotides from the ends of DNA strand.
They work either in a 5’-3’ direction or a 3’-5’ direction

Question 9

Examples of nucleases in vivo

Answer 9

1. DNA repair: clips out damaged DNA
2. Cell death: 1st step in apoptosis is nucleases breaking down DNA

Question 10

Example of nuclease in vitro

Answer 10

Nucleic acid digests

Question 11

What do DNA ligases do

Answer 11

DNA ligases join DNA strands together by catalysing the formation of a phosphodiester bond.
Can join one end of a DNA molecule to the other end of the same DNA molecule or can join two DNA molecules together.

Question 12

Examples of ligases in vivo

Answer 12

• DNA replication
• DNA repair

Question 13

Example of ligases in vitro

Answer 13

Cloning