college biology chapter 13

Johann Miescher

discovered DNA, isolated an acid high in phosphorus (pus), called DNA nuclein

Fred Griffith

worked with S (pathogenic) and R (nonpathogenic) strains of a pneumonia causing bacteria, injected in mice, DNA CHANGES

Oswald Avery

showed that the substance was DNA by adding enzymes

bacteriophages

virus that affects bacteria

Hershey and Chase

³⁵S proteins (sulfur) in the bacteriophage coat did not enter the bacteria, the ³²P DNA (phosphorus) in the core did enter the bacteria, proves the hereditary material to be the nucleic acid or DNA

Watson and Crick

published the structure of DNA, double helix

four nucleotides

adenine, cytosine, thymine, guanine

single ring pyrimidines

thymine and cytosine

double ring purines

adenine and guanine

Edwin Chargaff

A=T double bonds, C=G triple bonds

backbone

sugar-phosphate linkages

base pairing, hydrogen bonded

single ringed thymine and double ringed adenine, single ringed cytosine and double ringed guanine

semiconservative

one old strand and one new strand

helicase

unzips the hydrogen bonds causing DNA molecule to unwind

polymerase

attaches nucleotides to the growing strand in 5’ - 3’

ligase

fills gaps and seals on the lagging strands

primase

primes for polymerase on the lagging strand

embryo cloning

can be natural process (identical twins), artificial twinning produced by in vitro fertilization

adult cloning

Dolly, nuclear transfer, shocked to induce replication, fetus is carried by surrogate

therapeutic cloning

undifferentiated cell that can still divide is transplanted, helps with diseases

Rosalind Franklin

used x-ray to produce images of DNA, double helix, Watson and Crick got credit and published it

continuous

leading

discontinuous

lagging

okazaki fragments

pieces on the lagging strand