Lecture 3 & 4 - DNA Replication

Question 1

The ________ is divided into G1, S, G2 and ____phases in that order of progression. DNA replication occurs during S phase and chromosome condensation and cell division occur during M phase.

Answer 1

Cell Cycle

M

Question 2

Watson-Crick base pairing dictates the assembly of a new DNA strand: A pairs only with T, G with C. Thus, DNA “directly directs” its own _________.

Answer 2

Complementarity

Question 3

Nucleoside ________ are substrates for DNA polymerases. The final subunit is a nucleoside monophosphate with the pyrophosphate _______ representing a substantial free energy release that drives the reaction.

Answer 3

Triphisohates

Hydrolyzed

Question 4

DNA strands have a ______, due to the asymmetry of the linkage from one subunit to another. In particular, subunit nucleotides are linked by phosphodiester bonds formed by linking a 5’ phosphate to a free 3’ OH terminal on a growing DNA strand. Complementary DNA strands, composing one DNA molecule, have opposite ________.

Answer 4

Polarity

Polarity

Question 5

DNA synthesis begins at ________ of replication representing specific sequences of nucleotides. The origins initiate as replication bubbles that in turn initiate two replication “forks” proceeding in opposite directions to replicate chromosome DNA.

Answer 5

Origin

Question 6

All DNA _________ synthesize DNA in the 5’ –> 3’ direction. This means that each replication fork is represented by a leading and lagging strand, where the leading strand is synthesized continuously as the fork “opens”. The lagging strand is synthesized “backwards” as Okazaki fragments that must be ligated together.

Answer 6

Polymerases

Question 7

Proteins important for DNA replication are:

Answer 7

Helicase,

single-strand binding protein,

Topoisomerase,

Primase,

DNA polymerase α,

DNA polymerase δ,

DNA Epsilon

RNAse H

DNA ligase

clamp and clamp loader

Question 8

Bloom syndrome is due to a defect in a DNA __________; topo 1 and topo 2 are drug targets in cancer.

Answer 8

Helicase

Question 9

At ___________, replicated DNA is represented by two chromatids that remain attached to one another until anaphase. Both the maternal and paternal homologues are replicated during S phase. Thus, chromosome one in a diploid cell is represented by a total of four chromatids prior to anaphase. This result can be clearly demonstrated by ______________ In Situ hybridization.

Answer 9

Metaphase

Fluorescence

Question 10

__________extends chromosome ends, termed telomeres, providing a “landing site” for the RNA primer required to make use of end of the 5’  3’ parental strand as a template for new DNA.

Answer 10

Telomerase

Question 11

Telomeres protect ends from exonucleolytic degradation and from fusion with other chromosomes.

Answer 11

chromosome

Question 12

The Rb pathway of growth control is just one of many signaling pathways that can effect entry into and cell division.

Answer 12

S Phase

Question 13

The polymerase chain reaction (PCR) amplifies discreet segments of DNA defined on either side by a _____________. The amplification is done in vitro. The primers can be synthesized to represent ANY desired sequence.

Answer 13

Primer

Question 14

____________is highly quantitative, i.e., can represent a comparison of samples with regard to the original amount of original, primer-template.

Answer 14

PCR