Molecular genetics. People and Structures

Bacteriophages

 viruses that infect bacteria by injecting genetic material into host cells.

Griffith

Found out that the transforming agent is DNA (even tho later on it was actually protein)because of the Living S cells in the blood sample from a dead mouse

Bacterial transformation demonstrated

Bacterial transformation

cells are able to absorb some non-living chemical factor from the environment and gain new traits; transfer of genetic information between bacteria

Living Rough cells and Heat killed smooth cells

Healthy Mouse

Living smooth cellsHeat-killed S+Living R (Living S cells inside mouse and he put living R in the mouse)

Mouse dies

Avery

discovering the transformation agent is DNA; and bacteriophages

Add proteinase

deletes proteins

-DNA and RNA left

-Add R cells(bacteria) and transformation occurs

Add ribonuclease

deletes RNA

Dna and protein left

Add R cells and transformation occurs

Add deoxyribonuclease

deletes DNA

-Protein and RNA left

-Add R cells and no transformation occurs

Hershey-Chase

Considered convincing evidence that DNA (nucleic acids) is the hereditary material, NOT proteins

Chargaff

found the number of purines equals the number of pyrimidines (AT, GC)

Franklin-Wilkin

X ray diffraction, discovered that DNA is a double Helix and that nucleotides are stacked on top of each other like the rungs of ladder

Watson-Crick

Used Franklin and Wilkin’s diffraction to build scale models of DNA. They found that there was a constant diameter for DNA (0.2nm), that purines are paired with pyrimidines, nitrogenous bases are complementary to each other, Antiparallel 5’-3’

Nucleotide

the monomer of which DNA and RNA(nucleic acids) are composed of; consists of a phosphate group, pentose sugar and nitrogenous base

Nucleic acids

a type of macromolecule which stores or transmits genetic information

Phosphate groups attach at

5’ and 3’

Hydrogen on Deoxyribose and OH on ribose

is on 2’

Purines

 the type of nitrogenous base consisting of two attached nitrogen and carbon rings; includes Adenine and Guanine. (one 5 sided, one 6 sided), bigger

Pyrimidine

cytosine and thymine (one 6 sided ring); smaller

Phosphodiester bonds

type of bond which holds the sides of a DNA ladder together; connects with the phosphate groups and hydroxyls

Sides of the ladder

 have the sugar phosphate backbone and the phosphodiester bonds

Hydrogen bonds

 the weak bonds that holds the base pairs together

Anti-parallel

Parallel but backwards to each other; describes the orientation of the two sides to the DNA ladder with respect to each other

Hydrogen bonding sites

 are on the base pairs when the pairs align when they are upside down with respect to each other