Lecture 17: DNA replication

Question 1

the percentage of adenine in the DNA of an organism is approximately 30%. what is the percentage of cytosine?

Answer 1

20%

Question 2

Chromosome

Answer 2

product of DNA replication

Question 3

what is replicated by a semi-conservative process

Answer 3

DNA only

Question 4

Replication

Answer 4

begins only at the ORI (origin of replication)

Question 5

Additions of nucleotides

Answer 5

only to the 3’ end of the newly synthesized strand

Question 6

what powers the synthesis of DNA

Answer 6

the breaking of phosphoanydride bonds

Question 7

what occurs during DNA replication

Answer 7

DNA helices separates the two DNA strands

Question 8

Primase

Answer 8

RNA polymerase that “primes” the synthesis of the new DNA strand with a short segment of RNA

• Attaches apprx 10 RNA nucleotides that allow DNA polymerase to attach to the growing strand
• RNA came 1st in the world (need RNA to replicate DNA)

Question 9

leading and lagging strands

Answer 9

are a matter of perspective to the ORI

Question 10

Lagging strand synthesis

Answer 10

1. initiation of replication by primate/RNA primer
2. DNA polymerase adds dNTPs at 3’ end
3. a different DNA polymerase removes RNA primer and replaces with dNTPs
4. DNA ligase seals phosphodiester bond

Question 11

which enzyme maintains the separation of the strands of DNA during replication

Answer 11

single stranded binding proteins

Question 12

DNA polymerase

Answer 12

family of proteins that catalyze DNA SYNTHESIS

• catalyzes addition of about 50 nucleotides per second in eukaryotes
• about 15 major DNA POLs in eukaryotes

Question 13

Ligase

Answer 13

seals together DNA fragments