1. Molecular Biology
Introduction
Definitions
History
Central Dogma

2. Molecular Biology
Definitions
Chromosomes
DNA
Gene
Genotype
Phenotype

3. Molecular Biology Chromosomes
The structure in cells that carries hereditary information
Composed of DNA and protein
Prokaryotic - circular
Eukaryotic - linear

4. Molecular Biology DNA Nitrogenous base (4 bases - A,T,G & C
Deoxyribose sugar
Phosphate
Nitrogenous bases are paired AT GC
Double helix structure

6. Molecular Biology Genes Segments of DNA Functional or regulatory
Mutability and variation

7. Molecular Biology Genotype Phenotype
The genetic make-up of an organism; the information that codes for all the characteristics of an organism
Phenotype
The expression or physical manifestation of a gene; how it appears

8. Molecular Biology
Molecular biology seeks to understand the molecular or chemical basis of genetics
History of molecular biology is a melding of biochemistry, especially nucleic acid biochemistry and genetics

9. Molecular Biology Biochemistry Genetics Meischer Avery & MacLeod
Hershey & Chase
Watson & Crick
Genetics
Mendel
Sutton
Morgan
Griffith
Delbruck
Beadle & Tatum
Tatum & Lederberg

10. Molecular Biology - Genetics
Mendel (1865)
Fluid vs. particulate inheritance
Studied pure breeding pea plants
Law of Segregation
Law of Independent Assortment
Rediscovered by de Vries & others

11. Molecular Biology

12. Molecular Biology

13. Molecular Biology - Genetics
Cross of pure breeding purple flowers with
pure breeding white flowers produces all purple
plants with genotype Pp; crossing Pp plants
produces following distribution: P p PP
purple Pp pp
white

14. Molecular Biology - Genetics
Walter Sutton (1902)
Studied meiosis in grasshoppers (insects have large readily observable chomosomes)
Observed that chromosomes behave in manner similar to segregation of hereditary material
Found that chromosomes occur in morphologically similar pairs
Pairs separate during meiosis

15. Molecular Biology - Genetics

16. Molecular Biology - Genetics
Morgan
Developed modern science of genetics
Used fruit flies because they had a shorter generation time than peas
Discovered sex-linkage
Students developed techniques of mapping genes on chromosomes

17. Molecular Biology - Genetics
Griffith
discovered transformation in 1927
is a means of genetic transfer in microorganisms
a process by which a nonpathogenic strain is transformed into a pathogenic strain

18. Molecular Biology - Genetics

19. Molecular Biology - Genetics
Delbruck
developed quantitative methods for analysis of bacteriophage; viruses of bacteria
organized course to teach biologists methods at Cold Spring Harbor resulting in a large number of biologists trained in molecular techniques

20. Molecular Biology - Genetics
Beadle & Tatum
developed Neurospora as an experimental organism
established one gene one enzyme hypothesis
generation time is even shorter with Neurospora

21. Molecular Biology - Genetics

22. Molecular Biology - Genetics

23. Molecular Biology - Genetics

24. Molecular Biology - Genetics
Tatum & Lederburg
discovered conjugation in bacteria
Led to genetic map of E. coli
E. coli became widely used in molecular biology

25. Molecular Biology - Biochemistry
Meischer (1869)
Austrian doctor
isolated a substance called “nuclein” from the nuclei of cells obtained from the pus of surgical bandages
found to contain nitrogenous chemicals, sugar and phosphate

26. Molecular Biology - Biochemistry
Avery & MacLeod (1944)
isolated Griffith’s transforming factor to a high degree of purity
characterized transforming factor using highly purified enzymes
found transforming factor to be DNA

27. Molecular Biology

28. Molecular Biology - Biochemistry
Hershey & Chase (1952)
used newly developed radioisotopes
35S for protein
32P for nucleic acid
labeled bacteriophage (a virus of bacteria)
found 32P went into cells but 35S did not implying that nucleic acid transfer information to cell for new bacteriophages

29. Molecular Biology - Biochemistry
Watson & Crick (1953)
used X-ray crystallography to study structure of DNA
by combining chemical data and X-ray data were able to construct a model of DNA
structure inferred function leading to Central Dogma