Chapter 11: DNA/Gene Synthesis and Repair

Erwin Chargaff

The scientist who discovered that there are equal proportions of base pairs AT and GC

secondary structure

Early data provided clues to DNA secondary structure

sugar-phosphate

Early chemists knew the structure of nucleotides and that DNA has a _________-__________ backbone.

Chargoff's Base Pair Rule

The base pair rule that %A=%T and %G=%C

Rosalin Franklin, Maurice Wilkins

______ ______ obtained images of DNA using X-ray crystallography, an idea first broached by ______ ______.

True

(T/F) Scientists build on eachother's ideas

hydrogen bonds

two strands of the DNA is held together by ______ bonds between pyrimidines and purines

True

(T/F) DNA is antiparallel. Meaning one strand runs 3 to 5 while te other 5 to 3.

exterior

The sugar phosphate backbone faces: interior or exterior?

interior

The nitrogenous base pairs face the: interior or exterior?

nucleotide

A building block of DNA, consisting of a five-carbon sugar covalently bonded to a nitrogenous base and a phosphate group.

phosphate, hydroxyl

DNA strands are directional. One end has an unlinked 5' ____________ (P) group, while the other ends has an unlinked 3' ___________ (OH) group.

Pyrimdines

thymine, cytosine, uracil

Purines

Adenine, Guanine

Thymine

Adenine binds with _____

Cytosine

Guanine binds with _____

Conservative

DNA replication is semi-_________ because one strand is from the parent while the other is daughter strand

Origin of replication

In DNA replication, a bubble forms when DNA synthesizes, this area is known as the "________ __ _____________"

1) Unwinding

2) Priming the leading strand

3) Building the leading strand

4) Priming and building the lagging strand.

There are 4 stages of DNA Replication

1) Un________

2) Priming the _________ strand

3) Building the _________ strand

4) Priming and building the _________ strand

DNA Helicase

An enzyme that unwinds the DNA double helix during DNA replication

Topoisomerase

corrects "overwinding" ahead of replication forks by breaking, swiveling, and rejoining DNA strands

RNA Primase

An enzyme that creates an RNA primer for initiation of DNA replication.

DNA polymerase III

synthesizes new DNA only in the 5' to 3' direction

Lagging strand

A discontinuously synthesized DNA strand that elongates by means of Okazaki fragments, each synthesized in a 5' to 3' direction away from the replication fork.

single-strand DNA-binding proteins

SSBPs: attach to separated strands to prevent them from closing

Leading strand

The new continuous complementary DNA strand synthesized along the template strand in the mandatory 5' to 3' direction.

Okazaki fragment

Small fragments of DNA produced on the lagging strand during DNA replication, joined later by DNA ligase to form a complete strand.

Ligase

final binding of sugar-phosphate backbone in DNA during synthesis and repair

Replication fork

A Y-shaped region on a replicating DNA molecule where new strands are growing.

TACGTA

What's the matching strand?

ATGCAT