HB DNA History, Structure, Replication, and Cell Size

DNA polymerase III

In charge of synthesizing nucleotides onto the leading end in the classic 5' to 3' direction.

Helicase

unwinds DNA

Topoisomerase

Enzyme that functions in DNA replication, helping to relieve strain in the double helix ahead of the replication fork.

Lagging strand of DNA

synthesized discontinuously

leading strand synthesis

synthesized continuously in 5' to 3' direction

Ligase enzyme

Join DNA fragments

RNA primer (primase)

short segment of RNA used to initiate synthesis of a new strand of DNA during replication

semiconservative replication

each new DNA molecule consists of one new strand and one old strand

replication fork

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

SSRBs

single stranded binding proteins- keep the 2 strands open

Griffith Experiment (1928)

Determined "Transformation Principle" using various pneumonia strains with mice

Avery, MacLeod, McCarty

Determined that DNA was Griffith's "Transforming Factor."

Hershey and Chase (1952)

concluded that the genetic material of the bacteriophage was DNA, not protein.

Waston-Crick Model

DNA consists of two long chains of subunits (nucleotides), each twisted around to form a double helix.

Chargaff's Rule

A=T and C=G

Nucleotide

monomer of nucleic acids

5' to 3' direction

the only direction that DNA polymerase can synthesize DNA; it does so by adding nucleotides to the 3' end of a DNA strand.

3' to 5' direction

Direction in which the template DNA is read during DNA replication.

Cell size is limited by

surface to volume ratios

Rosalind Franklin

Used X-ray diffraction to discover the double-helical structure of DNA.

Bonds holding DNA strands together

hydrogen bonds between complementary bases

Proofreader enzymes

Identify and repair incorrect or damaged nucleotides