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DNA as Genetic Material Genetics Bio 36404

Transmission Genetics Mendelian Genetics Classical Genetics P:

Round vs Wrinkled Peas RR rr

F1:

All Round Rr 3/4 Round: 1/4 Wrinkled 1/4RR 2/4Rr 1/4rr

F2:

Cytological Genetics Chromosomes and Abnormalities

Molecular Genetics

• Chemistry of the Gene • What are genes made of? • How do they result in traits? • How are they replicated? • How do we manipulate them?

Timeline • 1866 • 1902

Mendel

Sutton - proposed genes on chromosomes

• 1910

Morgan - sex-linked traits, verified genes on chromosomes

• Chromosomes composed of DNA and protein

1928 Griffith Experiment Streptococcus pneumoniae

inject into mouse S form - wild type smooth colonies

mouse dies

1928 Griffith Experiment

inject into mouse R form - rough colonies

mouse lives

1928 Griffith Experiment Heat Killed S inject into mouse

mouse lives

1928 Griffith Experiment

inject into mouse

mouse dies live S forms found in tissue

Mixture of Rough and Heat-Killed S Form

transformation

1944 Avery, MacLeod & McCarty S

Centrifuge

Heat

Blender

1944 Avery, MacLeod & McCarty

protease removes protein carbs proteins fats DNA RNA

RNAase removes RNA carbs fats DNA RNA

DNAase removes DNA carbs fats DNA

carbs fats

1944 Avery, MacLeod & McCarty

protease removes protein

DNAase removes DNA

RNAase removes RNA

Conclusion? DNA causes transformation

R

transformation

R

transformation

R

no transformation

1952 Hershey & Chase

Bacteriophages bacterial viruses Protein DNA

Bacteria

Viruses attach to bacteria

1952 Hershey & Chase

Bacteria inject DNA or protein?

new viruses grow viruses released Bacteria

1952 Hershey & Chase

phage + E. coli with radioactive P

phage with radioactive DNA

phage + E.coli with radioactive S

phage with radioactive protein

1952 Hershey & Chase

radioactive phage + normal E. coli

radioactive phage +normal E.coli

1952 Hershey & Chase

radioactive phage + normal E. coli

? ? ?

radioactive phage +normal E.coli

? ? ? Blender

1952 Hershey & Chase

Conclusion: DNA enters cell radioactive DNA phage + normal E. coli

? ? ?

Blender

radioactive inside

1952 Hershey & Chase

Conclusion: protein does not enter cell

radioactive protein phage +normal E.coli radioactive outside

? ? ?

Blender

DNA Chemistry

• DNA breaks down into 3 components • Phosphate (phosphoric acid) • Deoxyribose (sugar) • Nitrogenous bases (4)

Phosphate PO4 O O-

P

3-

O O-

O

P O

OP

O

Ribose and Deoxyribose H H

5’

H

C

C H

O

4’

O

C H

H

1’

H

H

3’C

C

O

O

H

H

C 2’

O

H H O

H

H

O C H

H

H

C

C

O

H

H

C 2’

O

H

Nitrogenous Base • ring contains N & C H

H H

H

C

N

C

N

C

C N

pyrimidine

H H

C C

N

C

C

C N

N

H purine

H

Bases Pyrimidines

Cytosine

Thymine CH3

NH2 O

O O

Purines

Guanine

Adenine O

NH2

NH2

Nucleotide P 5’

Base

O

sugar

1’

Nucleotide Joining P

Base

O

5’

sugar

1’

3’ P 5’

Base

O

sugar

1’

The End