LS4-1_SPRING_2008_01

LS4-1_SPRING_2008_01 - Genetics The Study of Biological...

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Unformatted text preview: Genetics The Study of Biological Information 1 Hershey and Chase Waring blender experiment Fig. 6.5 a,b 2 Information 3 Proteins interact with DNA and other proteins. Biological systems function as complex interactive networks of proteins and DNA that interact with one another. 4 Fig. 1.6 All living things are closely related. RNA was probably the first informationprocessing molecule. RNA is composed of four bases: guanine (g), adenine (a), cytosine (c), and uracil (u). 5' Fig. 1.7a 5 Amino-acid sequences determine the three-dimensional shape of a protein. Fig. 1.5c 6 A comparison of equivalent chains of two digestive proteins Figure 1.5b 7 The process of duplication and divergence Fig. 1.10 8 Modular construction of genomes has allowed rapid evolution of complexity. Gene families arise from primordial genes through duplication and rearrangements. Duplication and divergence of new genes can generate genes with new functions. 9 Genome sequencing projects are a step in understanding the complexity of genomes. Fig.1.12 10 DNA resides within cells packaged as units called chromosomes. The entire collection of chromosomes in each cell of an organism is called a genome. Humans have 23 pairs of chromosomes. The human genome has about 3 x 109 base pairs and 20,000 30,000 genes. Fig. 1.4 11 Duplication and divergence has made rapid evolution possible. 12 Many genes have similar functions in very different organisms. Fig. 1.8 13 New technological tools facilitate the dissection of genomes and integration of information. DNA chips detect the expression of thousands of genes in response to environmental changes Fig. 1.13c 14 Genetic Information is Digital The sequence of bases in DNA can be read by DNA sequencers, stored in computers, and synthesized by DNA synthesizers. 15 Fig. 1.3 Inheritance-work with mutant copy! Determine the importance or function of a single gene by deleting or inactivating it and see what the consequence is. Alternatively: Identify single gene mutant and follow its inheritance to see what phenotype (consequence) goes with it. Alternatively: Identify (rare) traits (phenotype changes), follow their inheritance and work to locate which gene is mutated for each trait. 16 Proteins interact with DNA and other proteins. Biological systems function as complex interactive networks of proteins and DNA that interact with one another. 17 Fig. 1.6 18 How does genetic diversity contribute to phenotypic diversity? Broad (information): how do genes specify biological processes, functions, etc? Narrow (inheritance): what are the mechanisms by which variant genes give rise to variant traits? Of medical interest, etc. 19 Focus on human genetics Genetics is a field of science that will have an enormous impact on society. Our understanding of biological complexity using genetic approaches is proceeding at a very rapid pace. Recent technological advances have shifted the focus of genetics from analysis of single genes and proteins to entire networks the Systems Approach. 20 Nature-nurture No trait is completely genetic. No trait is completely environmental. Both are important. 21 Ethics (patient's rights) has replaced eugenics as the goal of medical genetics 22 Social issues and genetics Should an individual's genetic profiles be freely available to insurance companies, employers, government? Should our government regulate the use of genetic and genomic information to reflect societies social values? Is it okay to permanently alter genes in humans for medical or social reasons? 23 ...
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