PROKARYOTICS REPLICATION ENZYEMS

Question 1

Initiator Proteins/DNaA

Answer 1

Function: Binds to ORI & breaks H bonds

Question 2

DNA Helicase/DNaB

Answer 2

Function: Opens/unwinds dsDNA helix and binds primase to form primosome

Question 3

Helicase Inhibitor/DNaC

Answer 3

Function: Delivers helicase to DNA template

Question 4

DNA Primase/RNA Polymerase

Answer 4

Function: Synthesizes RNA primer on lagging strand to enable DNA Pol to synthesize DNA strand

Question 5

DNA Polymerase I

Answer 5

Function: Removes RNA primer and replaces it with DNA

Question 6

DNA Polymerase III

Answer 6

Function: Synthesizes growing strand of DNA in both leading and lagging stands by catalyzing formation of phosphodiester bond between 3’OH group of deoxyribose on previous nucleotide and 5’-phosphate group of dNTP precursor

Question 7

Single-Stranded Binding Proteins (SSBP)

Answer 7

Function: binds to ssDNA in replication bubble and prevents re-annealing/forming 2ndary structure

Question 8

13mers

Answer 8

Function: 13 nucleotide sequences + 9 nucleotide sequences that act as binding sites for DNA proteins

Question 9

Ligase

Answer 9

Function: When DNA Pol I removes RNA primer and replaces with DNA, ligase catalyzes the phosphodiester bonds and joins DNA fragments together

Question 10

Clamp Proteins

Answer 10

Function: tightly hold DNA Pol to template strand and releases it when it stalls at regions of dsDNA

Question 11

Topoisomerase

Answer 11

Function: swivel DNA ahead of replication fork to prevent positive supercoils from forming

Question 12

DNA Gyrase/Topoisomerase II

Answer 12

Function: Introduces negative supercoils into DNA, reducing positive supercoils
Aids in separation of DNA during replication and transcription

Question 13

Telomerase

Answer 13

Function: Fills 5’ gaps at end of newly synthesized DNA by removal of DNA Pol I
Synthesizes DNA using RNA template - carries own RNA primer