Gregory Mendel
Explain his peas
First described heredity
Why does Mendel use peas
Both sexes
Easily pollinated
No sex chromosomes
Fast growing
Simple inheritance
Nuclein
DNA initially called nuclein
T H Morgan
Called Mendels” factor” genes which are found in chromosomes
Contributed:
Chromosomal theory of hereditary
Genetic linkage
Crossing over/ non-disjunction
Griffith Experiment
Shows something that can transfer traits between organisms
- injected mice with pneumonia
Mice experiment
Control 1
Control 2
Control 3
Experiment
What are the criteria for genetic material
1) storage of info- produce unique traits
2) capable of replication
- pass on to future generations
3) ability to change
- needed to allow for mutations
Protein vs DNA in
20 vs 4
Avery, McLeod, and McCarty
Added treatments to lysed S cells to see what the genetic criteria was
Transformation
Ability to take up DNA from external environment and change
Hershey and Chase
Used (T2 phages) and bacteria
Tracked DNA and protein with radioactive substances
Sulfer in protein- supernatant
Phosphorus in DNA- cell pellet
Chargaffs rule
Purines= pyramadines
A=T
C=G
1) all DNA is made of 4 boxes
2) each species has a specific and unique amount of each base
3) a species base composition is neither random nor 1:1:1:1
Rosalind Franklin
Important in DNA structure
X- Ray crystallography
Watson and Crick
DNA is double helix
Strands are anti parallel
Fixed width
Sugar/ phosphate backbone
Bases inside due to hydrophobic interaction and hydrogen bonds
Allele
Gene that produces a specific characteristic
Diploid
2 alleles of a gene
Dominant vs Recessive
