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GeneticGeneticssThe Study of BiologicalThe Study of Biological

InformationInformation

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Chapter OutlineChapter Outline

DNA molecules encode the biological DNA molecules encode the biological information fundamental to all life formsinformation fundamental to all life forms

Proteins are the primary unit of biological Proteins are the primary unit of biological functionfunction

Regulatory networks specify the behavior of Regulatory networks specify the behavior of genesgenes

All living forms are closely relatedAll living forms are closely related Genomes are modular, allowing rapid evolutionGenomes are modular, allowing rapid evolution Genetic techniques permit dissection of Genetic techniques permit dissection of

biological complexitybiological complexity Focus of this course is on human geneticsFocus of this course is on human genetics

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Information in DNA Information in DNA generates diversitygenerates diversity

Four bases – G (guanine), A Four bases – G (guanine), A (adenine), T (thymine), and C (adenine), T (thymine), and C (cytosine) are the nucleotide (cytosine) are the nucleotide building block of DNAbuilding block of DNA

DNA is a double stranded DNA is a double stranded helix composed of A-T and G-helix composed of A-T and G-C complementary basesC complementary bases

Order of nucleotide Order of nucleotide sequences determine which sequences determine which proteins are synthesized, as proteins are synthesized, as well as when and where they well as when and where they the synthesis occurs.the synthesis occurs.

Fig. 1.1a

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Genetic Information is Genetic Information is DigitalDigital

The sequence of The sequence of bases in DNA can be bases in DNA can be read by DNA read by DNA sequencers, stored sequencers, stored in computers, and in computers, and synthesized by DNA synthesized by DNA synthesizerssynthesizers

Fig. 1.3

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Genes are sequences of Genes are sequences of DNA that encode proteinsDNA that encode proteins

Fig. 1.2

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DNA resides in within cells DNA resides in within cells packaged as units called packaged as units called

chromosomeschromosomes The entire collection The entire collection

of chromosomes in of chromosomes in each cell of an each cell of an organism is called a organism is called a genomegenome

Human cells have 24 Human cells have 24 distinct kinds of distinct kinds of chromosomeschromosomes

The human genome The human genome has about 3 x 10has about 3 x 1099 base base pairs and 20,000 – pairs and 20,000 – 30,000 genes30,000 genesFig. 1.4

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Biological function emerges Biological function emerges primarily from proteins.primarily from proteins.

Figure 1.5a

Alanine has a relatively simple CH side chain

Tyrosine has a more complex aromatic side chain

Amino acids have a basic amino group (-NH) and an acidic carboxyl group (-COOH)

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A comparison of equivalent A comparison of equivalent chains of two digestive chains of two digestive

proteinsproteins

Figure 1.5b

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The diversity of protein The diversity of protein structure generates structure generates

extraordinary diversityextraordinary diversity

Fig. 1.5b

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Proteins are polymers of Proteins are polymers of amino acids amino acids

Proteins have three dimensional Proteins have three dimensional structuresstructures

Information in DNA dictates the Information in DNA dictates the sequence of its amino acidssequence of its amino acids

There are 20 different amino acidsThere are 20 different amino acids The order of amino acids determines The order of amino acids determines

the type of protein and its structurethe type of protein and its structure

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Proteins interact with DNA Proteins interact with DNA and other proteinsand other proteins

Biological systems function as Biological systems function as complex interactive networks of complex interactive networks of proteins and DNA that interact proteins and DNA that interact with one anotherwith one another

Fig. 1.6

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All living things are closely All living things are closely relatedrelated

RNA was probably the first RNA was probably the first information-processing moleculeinformation-processing molecule

RNA is composed of four bases: RNA is composed of four bases: guanine (g), adenine (a), cytosine guanine (g), adenine (a), cytosine (c), and uracil (u)(c), and uracil (u)

Fig. 1.7a

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All living organisms use the All living organisms use the same arbitrary codes for same arbitrary codes for RNA, DNA, and proteinRNA, DNA, and protein

Fig. 1.7b

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Many genes have similar Many genes have similar functions in very different functions in very different

organismsorganisms

Fig. 1.8

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Relatedness among Relatedness among organisms is important for organisms is important for the study of human genesthe study of human genes

Studies of genetics in model Studies of genetics in model organisms help us understand how organisms help us understand how genes work in humansgenes work in humans

Some model organisms include Some model organisms include bacteria, yeast, roundworms, fruit bacteria, yeast, roundworms, fruit flies, and mice.flies, and mice.

Model organisms may have simpler Model organisms may have simpler biological networks and can be biological networks and can be manipulated experimentally.manipulated experimentally.

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Modular construction of Modular construction of genomes has allowed rapid genomes has allowed rapid

evolution of complexityevolution of complexity

Gene families arise from primordial Gene families arise from primordial genes through duplication and genes through duplication and rearrangementsrearrangements

Duplication followed by mutations Duplication followed by mutations rearrangements can generate new rearrangements can generate new genes with new functionsgenes with new functions

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The process of duplication The process of duplication and divergenceand divergence

Fig. 1.10

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Duplication and divergence Duplication and divergence has made rapid evolution has made rapid evolution

possible.possible.

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Rapid change in regulatory Rapid change in regulatory networks specify how genes networks specify how genes

behavebehave

Fig. 1.9

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Genetic techniques permit the Genetic techniques permit the dissection of complexitydissection of complexity

Genes can be identified and inactivated Genes can be identified and inactivated one at a time using genetic techniquesone at a time using genetic techniques

Dissection of genomes gene-by-gene Dissection of genomes gene-by-gene unravels the complexity of biological unravels the complexity of biological systemssystems

The challenge for modern biology lies The challenge for modern biology lies in understanding how the multitude of in understanding how the multitude of networks of genes and higher level networks of genes and higher level systems interact to produce complex systems interact to produce complex systems.systems.

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Genome sequencing Genome sequencing projects are a step in projects are a step in

understanding the understanding the complexity of genomescomplexity of genomes

Fig.1.12

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New technological tools facilitate the New technological tools facilitate the dissection of genomes and integration dissection of genomes and integration

of informationof information

DNA chips detect the expression of thousands of genes in response to environmental changes

Fig. 1.13c

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Focus on human geneticFocus on human genetic Genetics is a field of science that Genetics is a field of science that

will have an enormous impact on will have an enormous impact on societysociety

Our understanding of biological Our understanding of biological complexity using genetic approaches complexity using genetic approaches is proceeding at a very rapid paceis proceeding at a very rapid pace

Recent technological advances have Recent technological advances have shifted the focus of genetics from shifted the focus of genetics from analysis of single genes and proteins analysis of single genes and proteins to entire networks – the Systems to entire networks – the Systems ApproachApproach

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GeneticsGeneticsPredictive and Preventative Predictive and Preventative

MedicineMedicine Discovery of genes with variations Discovery of genes with variations

that cause or predispose one to that cause or predispose one to disease will continue at a rapid pace. disease will continue at a rapid pace. Gene therapyGene therapy DiagnosticsDiagnostics Therapeutic drugs to block or reverse Therapeutic drugs to block or reverse

effects of mutant geneseffects of mutant genes Detection of disease and treatment Detection of disease and treatment

before onset may increase life span before onset may increase life span significantlysignificantly

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Social issues and Social issues and geneticsgenetics

Should an individual’s genetic profiles Should an individual’s genetic profiles be freely available to insurance be freely available to insurance companies, employers, government?companies, employers, government?

Should our government regulate the Should our government regulate the use of genetic and genomic use of genetic and genomic information to reflect societies social information to reflect societies social values?values?

Is it okay to permanently alter genes Is it okay to permanently alter genes in humans for medical or social in humans for medical or social reasons?reasons?