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Chapter 1 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 Fourth 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 Chemical composition of genes not known until 1944 Gene Phenotype 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 Gene Transmission . | Molecular Biology Fourth 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 Chemical composition of genes not known until 1944 Gene Phenotype 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 Gene Transmission 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- The Chromosome Theory of Inheritance Chromosomes are discrete physical entities that carry the genes Thomas Hunt Morgan used the fruit fly, Drosophila melanogaster, to study genetics Autosomes occur in pairs in a given individual Sex chromosomes are identified as X and Y Female has two X chromosomes Male has one X and one Y chromosome 1- Hypothetical Chromosomes Every gene has its place, or locus, on a chromosome Genotype is the combination of alleles found in an organism Phenotype is the visible expression of the genotype Wild-type phenotype is the most common or generally accepted standard Mutant alleles are usually recessive 1- Genetic Recombination and Mapping In early experiments genes on .
