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Chapter 1 - A brief history. This chapter introduce to a brief history of molecular biology. Molecular biology grew out of the disciplines of genetics and biochemistry. In this chapter we will review the major early developments in the history of this hybrid discipline, beginning with the earliest genetic experiments performed by Gregor Mendel in the mid-nineteenth century. | Molecular Biology Fifth Edition Chapter 1 A Brief History Lecture PowerPoint to accompany Robert F. Weaver Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. A Brief History What is molecular biology? The attempt to understand biological phenomena in molecular terms The study of gene structure and function at the molecular level Molecular biology is a melding of aspects of genetics and biochemistry 1- 1.1 Transmission Genetics Transmission genetics deals with the transmission of traits from parental organisms to their offspring The chemical composition of genes was not known until 1944 Gene - genetic units Phenotype - observable characteristics 1- Mendel’s Laws of Inheritance A gene can exist in different forms called alleles One allele can be dominant over the other, recessive, allele The first filial generation (F1) contains offspring of the original parents If each parent carries two copies of a gene, the parents are diploid for . | Molecular Biology Fifth Edition Chapter 1 A Brief History Lecture PowerPoint to accompany Robert F. Weaver Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. A Brief History What is molecular biology? The attempt to understand biological phenomena in molecular terms The study of gene structure and function at the molecular level Molecular biology is a melding of aspects of genetics and biochemistry 1- 1.1 Transmission Genetics Transmission genetics deals with the transmission of traits from parental organisms to their offspring The chemical composition of genes was not known until 1944 Gene - genetic units Phenotype - observable characteristics 1- Mendel’s Laws of Inheritance A gene can exist in different forms called alleles One allele can be dominant over the other, recessive, allele The first filial generation (F1) contains offspring of the original parents If each parent carries two copies of a gene, the parents are diploid for that gene 1- Mendel’s Laws of Inheritance Homoozygotes have two copies of the same allele Heterozygotes have one copy of each allele Parents in 1st mating are homozygotes, having 2 copies of one allele Sex cells, or gametes, are haploid, containing only 1 copy of each gene Heterozygotes produce gametes having either allele Homozygotes produce gametes having only one allele 1- Summary Genes can exist in several different forms or alleles One allele can be dominant over the other, so heterozygotes having two different alleles of one gene will generally exhibit the characteristic dictated by the dominant allele The recessive allele is not lost; it can still exert its influence when paired with another recessive allele in a homozygote 1- The Chromosome Theory of Inheritance Chromosomes are discrete physical entities that carry genes Thomas Hunt Morgan used the fruit fly, Drosophila melanogaster, to study genetics Autosomes occur in pairs in a given individual (not the X or the Y .
