DNA Replication

Question 1

DNA synthesis

Answer 1

G1 - growth
S - growth and DNA synthesis
G2 - growth and final preparations for division
Mitosis - prophase, metaphase, anaphase, telophase
cytokinesis

Question 2

DNA replication

Answer 2

goal to make an exact copy of DNA
done quickly and accurately

Question 3

DNA replication steps

Answer 3

begins at origins of replication where two DNA strands are separated opening a replication bubble
1. topoisomerase relieves the twisting strain of the double helix
2. helicase separatets double stranded DNA into single strands
3. primase synthesize a short RNA strand called a primer used by the polymerase to initiate the new nucleotide strand
4. DNA polymerase III adds dNTPs at the 3’ end of newly synthesized strand
5. new strand can only elongate in the 5’ to 3’ direction

Question 4

dNTPs - deoxyribonucleottide triphosphates

Answer 4

dATP, dGTP, dCTP, dTTP

Question 5

DNA polymerase function

Answer 5

Use dNTPs with three phosphate groups attached to the 5’ carbon
3’ - OH on previous nucleotide reacts with phosphate group attached to incoming 5’ carbon
exergonic reaction provides energy for new covalent bond and strand grow in the 5’ to 3’ direction

Question 6

eukaryotic chromosomes telomeres

Answer 6

postpone the erosion of genes near the ends of DNA molecule and have telomerase enzyme which has the RNA template used to maintain length of telomeres