Timeline in Genetics

7/28/2019 Timeline in Genetics

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Timeline in Genetics

MBB 1June 30, 2011


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Early Application & Speculation

Anton van Leeuwenhoek (1632 1723)


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Early Application & Speculation

1676

Anton van Leeuwenhoek (1632 1723)

The first to describe protozoa and bacteria and torecognize that such microorganisms might play arole in fermentation

His treatise on the flea is a classic, proclaiming thatfleas - like fish, dogs, and humans - are sexual beings

Confirmed (1677) the discovery by Louis DominicusHamm of the existence of sperm cells

The Voyager and The Monk

1859 Charles Darwin (1809 - 1882) hypothesized

the "natural selection." He also inferred theprocess of adaptive radiation, wherein

populations spread out into the environment toexploit specialized resources.

Charles Darwin's landmark book, "On the Originof Species," was published in London. Iteffectively drowned out all other scientific voices,including Mendel's, for decades.


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Darwin's theory makes 2 important points relevantto biotechnology:

Every species is ultimately related to every otherthrough common ancestors

The theory implies that a record of theevolutionary past is present inside every living

thing e.g., anatomical remnants


1865

Gregor Mendel (1822 - 1884), an Augustinianmonk, proposed that invisible internal units of

information account for observable traits, andthat these "factors" - which later became knownas genes - are passed from one generation to thenext.


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More Focused Overview

Mendelian genetics

Frederick Griffith's experiment

Avery, MacLeod, and McCarty experiment

Blender experiment

Events leading to discovery of DNA structure

1866: Mendelian Genetics

Gregor Mendel

Austrian monk

Published laws of

inheritance Experiments with pea

plants

Father of Genetics

Timeline of Genetics: GlaxoSmithKline

Website


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Mendel's chosenpea traits:

Terms:Phenotype / genotype

alleles

homozygous

heterozygouspure lines / true-breeding

dominant / recessive

F1, F

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Genetic Terms Introduced

Chromosome - an organized structure of theDNA which contains the genes (packagedDNA)

Gene(from Greek word "genos" "birth") - refers

to a Mendelian hereditary factor- sequence of nucleotides at a specific place

Allelle an alternative form of a gene (onemember of a pair) that is located at a specificposition on a specific chromosome

Genotype - one's genetic make-upPhenotype- one's outward appearance.


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Artificial

cross-pollination

Mendels Results


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Mendels Results

Mendels Model

Mendel heritable factor

1. Alternative versions of genes account forvariations in inherited characters

Allele (purple vs white color)2. For each character, an organism inherits twoalleles, one from each parent


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Mendels Model

3. If the two alleles at a locus differ, then one, thedominant allele, determines the organismsappearance (dominant trait); the other, therecessive allele, has no noticeable effect on theorganisms appearance (recessive trait).

4. Law of segregation: Two alleles for aheritable character segregate (separate) during

gamete formation and end up in different gametes

Law of Segregation


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Mendel's Principles of Genetics

Law of Segregation

Law of Independent Assortment

states that when any individual produces gametes, the copies

of a gene separate so that each gamete receives only one copy

states that alleles of different genes assort independently of

one another during gamete formation

Law of Independent Assortment


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Fred Griffith's Experiment

1928- Frederick Griffith and his transforming principle

Fred Griffith's Experiment

1928- Frederick Griffith and his transforming principle


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1944: DNA Genetic Material

Oswald Avery, Colin MacLeod,and Maclyn McCartyreportevidence that, at least in bacteria, the molecule that carriesgenetic information is deoxyribonucleic acid, DNA

1944: DNA Genetic Material


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1952: Chase and Hershey It is DNA!

Martha Chase andAlfred Hershey: finalproof:

DNA is the substance that transmitsinherited traits.

Hershey receives a Nobel Prize in 1969 for this

work.

Hershey, Chase Blender Experiment


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Erwin Chargaff

Base pairing inDNA

Purine topyrimidineratio = 1:1

Chargaff's Rules, 1949


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Fig 1: Francis Crick &

James Watson at theCavendish Laboratory.

Fig 2: X-raydiffraction image of 'B-

type DNA taken byRosalind Franklin


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James Watson and Francis CrickShared Nobel Prize 1962

Structure of the DNA molecule:

Double helix

4 bases: A, G, C, T

Base pairing: Chargaff's rule

50th Anniversary of Discovery of DNA

Rosalind Franklin in mosaic

Maurice Wilkins SharedNobel prize with Watson & Crick


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References

Barnum SR. (2005). Biotechnology AnIntroduction.

Campbell NA, Reece JB. (2002). Biology.Benjamin-Cummings, CA, USA.

Grace ES. (2006). Biotechnology Unzipped:Promises and Realities, Revised Second Edition.

Monje VD. (2005). MBB 1 Lecture.

Documents

Timeline in Genetics