Lecture 1_Introduction

Lecture 1_Introduction - Lecture 1 Introduction to Genetics...

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Lecture 1: Introduction to Genetics Each organism has its own “ Genetic Blueprint” that leads to an organism that is different from all others. Traits present in the final organism are of two kinds: hereditary and non- hereditary . For humans, having 2 arms and 10 fingers are hereditary traits whereas the language one uses is a non-hereditary trait. Genetics is the study of hereditary traits. These traits are determined by a set of instructions (called genes ) that are present in each cell of an organism. The existence of discrete instructions (genes) for different traits was first inferred by Gregor Mendel, in 1866. F. Miescher, in 1869 discovered the chemical that these genes are composed of. This chemical was later named deoxyribonucleic acid (DNA). Brief History of Genetics. Even though Mendel did his pioneering genetic experiments in 1865, it was not until 1902 that the field of genetics really got going when 3 other people did experiments similar to those of Mendel and rediscovered the earlier neglected study. Between 1902 to1920, many genes in many organisms were identified and it was shown that genes and chromosomes were transmitted in parallel during meiosis and fertilization. From this came the realization that genes were located on the chromosomes. During the same time frame, it was realized that some of the hereditary diseases of humans were due to defects in carrying out metabolic reactions necessary for normal physiology ( “inborn errors of metabolism” ). Groups of genes on the same chromosomes were transmitted together except for occasional separation due to genetic recombination. This led to the ability to create “ Genetic Maps ”. In 1927, it was discovered that X-rays induced new mutations and also fractured chromosomes and led to chromosomal rearrangements. This greatly speeded up the discovery of new mutants. Many new genes were identified and mapped in the 1930s. During the same time period, studies of genes in populations (rather than from individual matings) was begun- “ Population Genetics Starting in 1940, studies using microbes (fungi, bacteria and bacterial viruses) were begun. Due to the smaller genome size, ease and speed of growth and the ability to grow large numbers and carry out biochemical experiments, Microbial Genetics led to the merger of biochemistry and genetics to form the field of Biochemical and Molecular Genetics . With the identification of DNA as the genetic material and the elucidation of the structure of DNA in early 1950s, the field of molecular Genetics really exploded. Mechanisms of DNA duplication, gene expression, genetic coding, regulation of gene expression, etc., were deciphered in the 1960s. Numerous enzymes central to genetic mechanisms (DNA and RNA polymerases, protein synthesis factors, regulatory proteins such as repressors and activators) were also identified during the 1960s. During the 1970s, techniques for DNA manipulation,
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This note was uploaded on 09/29/2011 for the course GENETICS 380 taught by Professor Glodowski during the Spring '08 term at Rutgers.

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Lecture 1_Introduction - Lecture 1 Introduction to Genetics...

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