general genetics lec 1

BIO 106

LECTURE 1

CONTENTS

A. Definition of Genetics B. History of Genetics C. Scope of Genetics D. Application of Genetics

the study of HEREDITY and VARIATION

1858: Theory of Natural Selection

Charles Darwin Alfred Russell Wallace

1859

Charles Darwin

1866

Publication of results on inheritance of factors in garden peas

Gregor Mendel

1900: independent discovery and verification of Mendel’s principles

Carl Correns

Hugo de Vries

Erich von Tschermak

1902: noticed relationships of Mendel’s factors with chromosome behavior

Walter S. Sutton

WS Sutton and Theodor Boveri (studying sea urchins) independently propose the

chromosome theory of heredity

1901 Hugo de Vries adopts the term mutation

coined the terms genetics, allele, homozygous, heterozygous

1905: explained how gender is determined by special chromosomes;

William Bateson

: Proposed that some human diseases are due to "inborn errors of metabolism" that result from the lack of a specific enzyme.

Archibald Garrod

independently formulated the Hardy-Weinberg principle

of population genetics

Godfrey Hardy & Wilhelm Weinberg

1908

discovery of how genes are transmitted by chromosomes; sex linkage in Drosophila

1910

1927: X-rays caused artificial gene mutations in Drosophila

Herman J. Muller

1928: Proposed that some unknown "principle" had transformed the harmless R strain of Diplococcus to the virulent S strain.

Frederick Griffith

1931: cytological proof for crossing-over in maize

with Harriet B. Creighton

1941: Irradiated the red bread mold, Neurospora, and proved that the gene produces its effect by regulating particular enzymes; - proposed 1 gene-1 enzyme concept

Reported that they had purified the

transforming principle in Griffith's

experiment and that it was DNA.

Carl Correns

1944 Oswald Avery Colin MacLeod Maclyn McCarty

Developed the hypothesis of transposable elements to explain color variations in corn.

Late 1940s - 1950

1950: Discovered a one-to-one ratio of A to T and G to C in DNA samples from a variety of organisms.

Erwin Chargaff

1951: show by X-ray crystallography that DNA exists as two strands wound together in a spiral or helical shape

Rosalind Franklin Maurice H.F. Wilkins

1952: Used phages in which the protein was labeled with 35S and the DNA with 32P for the final proof that DNA is the molecule of heredity.

Martha Chase Alfred Hershey

1953: Solved the three-dimensional structure of the DNA molecule.

Francis Crick James Watson

1956: showed that the diploid chromosome number for humans is 46

Joe Hin Tijo Albert Levan

1958: Used isotopes of nitrogen to prove the semiconservative replication of DNA.

Matthew Meselson & Frank Stahl

1958: Purified DNA polymerase I from E. coli, the first enzyme that made DNA in a test tube.

Arthur Kornberg

his work in DNA synthesis led to creating recombinant DNA and genetic engineering.

1966: Led teams that cracked the genetic code- that triplet mRNA codons specify each of the twenty amino acids.

H. Gobind Khorana Marshall Nirenberg

1972

Stanley Cohen Herb Boyer

Paul Berg

1973: Led the team at Cold Spring Harbor Laboratory that refined DNA electrophoresis by using agarose gel and staining with ethidium bromide.

Joseph Sambrook

1973: Showed that a recombinant DNA molecule can be maintained and replicated in E. coli.

Stanley Cohen (with Annie Chang)

Developed the chain termination (dideoxy) method for sequencing DNA.

Fred Sanger

1977

The first genetic engineering company (Genentech) is founded, using recombinant DNA methods to make medically important drugs.

1978: Somatostatin became the first human hormone produced using recombinant DNA technology; Walter Gilbert coins the terms INTRON and EXON

1981: Three independent research teams announced the discovery of human oncogenes (cancer genes).

1983: Used blood samples collected by Nancy Wexler and her co-workers to demonstrate that the Huntington's disease gene is on chromosome 4.

James Gusella

1985: Published a paper describing the

polymerase chain reaction (PCR), the

most sensitive assay for DNA yet

devised. Kary B. Mullis

1988: the Human Genome Project began with the goal of determining the entire sequence of DNA composing human chromosomes.

Alec Jeffreys

1989: Coined the term DNA fingerprinting and was the first to use DNA

polymorphisms in paternity, immigration, and murder cases;

-birth of 1st American test tube baby

Identified the gene coding for the cystic fibrosis transmembrane conductance regulator protein (CFTR) on chromosome 7 that, when mutant,

causes cystic fibrosis.

Francis Collins Lap-Chee Tsui

1989

1990: First gene replacement therapy-T cells of a four-year old girl were exposed outside of her body to retroviruses containing an RNA copy of a normal ADA gene. This allowed her immune system to begin functioning.

1993: FlavrSavr tomatoes, genetically engineered for longer shelf life, were marketed.

1997 : Complete Saccharomyces cerevisiae genome is sequenced; complete E. coli genome is sequenced

1998 Caenorhabditis elegans becomes the first animal whose genome is totally sequenced

1999 A human MHC (HLA-DR52) haplotype is totally sequenced (October). Human chromosome 22 becomes the first one to be sequenced completely (November)

2003 Complete sequence of human Y-chromosome was published

3 major fields of Genetics: 1. Transmission genetics 2. Molecular and biochemical

genetics 3. Population and biometrical

genetics

TRANSMISSION GENETICS/CLASSICAL GENETICS

Studies:

- Basic principles of genetics

- transmission of genetic material from one generation to the other

- Focus: individual organism

- emphasis:

Relationship between chromosomes and heredity

Arrangement of genes on the chromosomes

Gene mapping

MOLECULAR AND BIOCHEMICAL GENETICS

- study of the chemical nature (structure and function) of genes

- Emphasis:

How genetic information is encoded, replicated and processed.

The cellular processes of replication, transcription and translation

Gene regulation, the process that controls the expression of genetic information.

POPULATION AND BIOMETRICAL GENETICS - study of the behavior and effects of genes in population, often

using mathematical models

- Focus: the group of genes found in a population.

- emphasis: How the genetic composition of a group changes over time.

- Can include quantitative genetics (predict the response to selection given data on the phenotype and relationships of individuals) and ecological genetics (wild populations of organisms, and attempts to collect data on the ecological aspects of individuals as well as molecular markers from those individuals)

Other Fields:

1. Behavioral genetics

- studies the influence of varying genetics on animal behavior, the effects of human disorders as well as its causes; has yielded some very interesting questions about the evolution of various behaviors, and even some fundamental principles of evolution in general.

2. Clinical genetics

- diagnosis, treatment, and counseling of patients with genetic disorders or syndromes

AGRICULTURE

Selective breeding: cross-breeding of two

parents, each with some good traits, to produce

offspring with the good traits of both parents

BENEFITS OF Selective Breeding

better resistance to pests and diseases

improved nutritional value (superior quality)

fruits with longer shelf life

bigger animal, more meat, more milk production

Increase food production

Disadvantage:

removal of some genes from the gene pool

TRANSGENIC ORGANISMS:

Transgenic plants: resistant to pests, diseases

Transgenic animals: chickens with

HGH to make them grow large and

very fast

Transgenic bacteria: for mass production of insulin, HGH, blood clotting factor

MEDICINE Accurate diagnosis of diseases

Preventing use of medicine or disease prevention

Inherited drug sensitivities

Chromosomal abnormalities

Production of vaccines, antibodies, vitamins, insulin

Gene therapy

Future: personalized medicine

LEGAL (genetic fingerprinting)

Crimes (forensic science)

Parentage

INDUSTRIES - Provide some synthetically produced raw materials

for industries

Brewing industry

INDUSTRIES The pharmaceutical industry has developed strains of

molds, bacteria, and other microorganisms high in antibiotic yield. (examples: Penicillin and cyclosporin from fungi, streptomycin and ampicillin from bacteria)

HUMANS: possibility of making children with only the desirable

traits

Babies who have deficiency could be treated with additions being done to their genetic structure.

Those who cannot reproduce due to medical complications have also seen positive results with surrogate parent's concept becoming available.

Increasing life span (vaccination, medications, vitamins)

ENVIRONMENT

Oil spills

Polluted waterways

BIOREMEDIATION

ENVIRONMENT - Protection of

valuable wild populations (genetic monitoring using genetic markers) thus probably solving problems causing reduction of population

Distribution of elephant in Tanzania