Molecular Biology Introduction Definitions History Central Dogma
Molecular Biology Definitions Chromosomes DNA Gene Genotype Phenotype
Molecular Biology Chromosomes The structure in cells that carries hereditary information Composed of DNA and protein Prokaryotic - circular Eukaryotic - linear
Molecular Biology DNA Nitrogenous base (4 bases - A,T,G & C Deoxyribose sugar Phosphate Nitrogenous bases are paired AT GC Double helix structure
Molecular Biology Genes Segments of DNA Functional or regulatory Mutability and variation
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
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
Molecular Biology Biochemistry Genetics Meischer Avery & MacLeod Hershey & Chase Watson & Crick Genetics Mendel Sutton Morgan Griffith Delbruck Beadle & Tatum Tatum & Lederberg
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
Molecular Biology
Molecular Biology
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
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
Molecular Biology - Genetics
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
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
Molecular Biology - Genetics
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
Molecular Biology - Genetics Beadle & Tatum developed Neurospora as an experimental organism established one gene one enzyme hypothesis generation time is even shorter with Neurospora
Molecular Biology - Genetics
Molecular Biology - Genetics
Molecular Biology - Genetics
Molecular Biology - Genetics Tatum & Lederburg discovered conjugation in bacteria Led to genetic map of E. coli E. coli became widely used in molecular biology
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
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
Molecular Biology
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
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