UNIT SEVEN GENETICS AND EVOLUTION

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UNIT SEVEN GENETICS AND EVOLUTION

Chapter Five

Chapter Six Evolution

The work of Mendel and others who followed him gave us an idea of inheritance patterns. However, the nature of those 'factors' which determine the phenotype was not very clear. As these `factors' represent the genetic basis of inheritance, understanding the structure of genetic material and the structural basis of genotype and phenotype conversion became the focus of attention in biology for the next century. The entire body of molecular biology was a consequent development with major contributions from Watson, Crick, Nirenberg, Khorana, Kornbergs (father and son), Benzer, Monod, Brenner, etc. A parallel problem being tackled was the mechanism of evolution. Awareness in the areas of molecular genetics, structural biology and bioinformatics have enriched our understanding of the molecular basis of evolution. In this unit the structure and function of DNA and the story and theory of evolution have been examined and explained.

James Dewey Watson was born in Chicago on the sixth of April nineteen twenty-eight. In nineteen forty-seven, he received B.Sc. degree in Zoology. During these years his interest in bird-watching had matured into a serious desire to learn genetics. This became possible when he received a Fellowship for graduate study in Zoology at Indiana University, Bloomington, where he received his Ph.D. degree in nineteen fifty on a study of the effect of hard X-rays on bacteriophage multiplication.

He met Crick and discovered their common interest in solving the DNA structure. Their first serious effort was unsatisfactory. Their second effort based upon more experimental evidence and better appreciation of the nucleic acid literature, resulted, early in March nineteen fifty-three, in the proposal of the complementary double-helical configuration.

Francis Harry Compton Crick was born on the eighth of June nineteen sixteen, at Northampton, England. He studied physics at University College, London and obtained a B.Sc. in nineteen thirty-seven. He completed Ph.D. in nineteen fifty-four on a thesis entitled "X-ray Diffraction: Polypeptides and Proteins".

A critical influence in Crick's career was his friendship with J. D. Watson, then a young man of twenty-three, leading in nineteen fifty-three to the proposal of the double-helical structure for DNA and the replication scheme. Crick was made an F.R.S. in nineteen fifty-nine.

The honors to Watson with Crick include: the John Collins Warren Prize of the Massachusetts General Hospital, in nineteen fifty-nine; the Lasker Award, in nineteen sixty; the Research Corporation Prize, in nineteen sixty-two and above all, the Nobel Prize in nineteen sixty-two.

CHAPTER FOUR

Four point one MENDEL'S LAWS OF INHERITANCE

Four point two INHERITANCE OF ONE GENE

Four point two point one Law of Dominance

Four point two point two Law of Segregation regarde

Four point two point two point one Incomplete Dominance

Four point two point two point two Co-dominance

Four point three INHERITANCE OF TWO GENES

P generation

Four point three point two Chromosomal Theory of Inheritance

Four point three point three Linkage and Recombination

Four point four POLYGENIC INHERITANCE

Four point five PLEIOTROPY

Four point six SEX DETERMINATION

Four point six point one Sex Determination in Humans

Four point six point two Sex Determination in Honey Bee

Four point seven MUTATION

Four point eight GENETIC DISORDERS

Four point eight point two Mendelian Disorders

Four point eight point three Chromosomal Disorders

SUMMARY

EXERCISES

Overview

The document examines genetics and evolution, highlighting the historical development of key concepts, such as Mendel's laws of inheritance and the role of DNA in determining traits. It showcases the advancements made in molecular biology and their implications for our understanding of evolution.

Key Points

1Genetic inheritance patterns were first described by Gregor Mendel through his experiments with pea plants
2The structure of DNA was discovered by Watson and Crick, which underpins modern genetics
3Mendel's laws introduced statistical analysis to biological studies, leading to broader genetic theories
4Evolutionary biology has benefitted from advances in molecular genetics and bioinformatics
5Understanding inheritance is crucial for explaining variation within and between species.

Details

Authors: James Watson, Francis Crick
Category: Biology and Natural Sciences

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