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Copyright 2006 Pearson Prentice Hall, Inc.

Chapter 1

Introduction to Genetics

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Mendel to DNA:

Less Than a Century Transmission of Traits

Gregor Mendel Augustinian monk

1860s (published 1866, rediscovered about1900)

Garden peas

Traits controlled by discrete units of inheritance

which followed specific rules

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Uniting Mendel and Meiosis

Chromosomal Theory of Inheritance

Sutton and Boveri independently in

early 1900s

Diploid (2n) vs. haploid (n)

Homologous chromosomes

Mitosis and meiosis

Diploid vs. haploid products

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Human Mitotic Chromosomes

Figure 1-2 Copyright 2006 Pearson Prentice Hall, Inc.

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Human Karyotype

Figure 1-3 Copyright 2006 Pearson Prentice Hall, Inc.

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Genetic Variation

Mutations

Thomas Morgan

Drosophila, red vs. white eyes

Alleles

Phenotype vs. genotype

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Genetic Variation

Figure 1-6 Copyright 2006 Pearson Prentice Hall, Inc.

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Linkage Maps

Figure 1-5 Copyright 2006 Pearson Prentice Hall, Inc.

Alleles of genes located

near each other on the

same chromosome are

more likely to be inheritedas a single group

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Search for the Chemical

Nature of Genes DNA or Protein?

1920s both known to be primaryconstituents of chromosomes

Proteins complex and interesting, DNA

small and boring Work by Griffith, Avery/McCarty/Macleod

and Messelson/Stahl Watson/Crick

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BacteriophageModel for

Genetics Studies

Figure 1-7 Copyright 2006 Pearson Prentice Hall, Inc.

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Structure of DNA and RNA

Nucleic acids made of nucleotides

G, A, T/U, C

Ribose vs. deoxyribose Template-dependent synthesis

Double helix, Watson/Crick 1953

Complementary pairing, A = T, G = C Genetic code

Order of nucleotides specifies amino acids

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DNA Double Helix

Figure 1-8 Copyright 2006 Pearson Prentice Hall, Inc.

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Gene Expression:

DNA to Phenotype Era Transcription

Synthesis of RNA from a DNA template

Messenger RNAs (mRNAs)

Translation

mRNA used by ribosome to synthesize

polypeptide tRNA adapters (transfer RNAs)

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Central Dogma of Genetics

Figure 1-9 Copyright 2006 Pearson Prentice Hall, Inc.

DNA replicates

mRNA is transcribed

from a DNA template

Proteins are made by

translation of an

mRNAGenetic code

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Proteins and Biological Function

Proteins are end products ofgene expression

Limitless variety possible

n20

Conformation determined bylinear order of amino acids

Many functions

EnzymesImmunoglobulins

Structural proteins

Mobility

Many more

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Linking Genotype to Phenotype:

Sickle-Cell Anemia

Hemoglobin

2 each of alpha and beta

chains plus hemes with iron

atomsCarries oxygen in red blood

cells

Sickle cell anemia is a

genetic disease causing therbcs to sickle under certain

conditions, blocking capillaries

Figure 1-10 Copyright 2006 Pearson Prentice Hall, Inc.

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Sickle Cell Red Blood Cells

Figure 1-13 Copyright 2006 Pearson Prentice Hall, Inc.

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Sickle Cell Mutation

Mutation changes GAG codon to GUG,glutamic acid replaced by valine in beta

chain

Figure 1-12 Copyright 2006 Pearson Prentice Hall, Inc.

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Genomics

Field made possible by development of

recombinant DNA technology

Restriction endonucleases

Cloning vectors

DNA sequencing techniques

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Cloning Protocol

Cut cloning vector and

target DNA sample with

restriction endonucleaseCreate recombinant DNA

molecule using DNA ligase

Transform into bacterial

host

Figure 1-14 Copyright 2006 Pearson Prentice Hall, Inc.

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Human Genome Project

Initiated by the same laboratories that

brought you thermonuclear devices

1990 taken over by NIH

Actually involved sequencing many

genomes

First draft sequence in 2001,

completed in 2003 (public effort and

Celera Corp.)

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Haemophilus influenzae

First free-living organism to have its entire genome

sequenced (under 2 Mbp)

Figure 1-15 Copyright 2006 Pearson Prentice Hall, Inc.

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Impact of Biotechnology Is

Growing GMOs

Microorganisms

Pharmaceutical production

Bioremediation

Plants, Animals

Food supply

Bioreactors

Animal cloning

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Table 1-1 Copyright 2006 Pearson Prentice Hall, Inc.

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Cloning Mammals

Initially by embryo

splitting

Dolly the sheep, 1996Nuclear transfer method

Figure 1-16 Copyright 2006 Pearson Prentice Hall, Inc.

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Biotechnology: Legal

Considerations

Who Owns Transgenic Organisms, cell

lines, products produced by rDNAtechnologies?

Patents

Laws and social policies always trailtechnology

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The First GMO

Mice genetically

engineered to be

susceptible for the

development of manyforms of cancer

Rat growth hormone

gene transferred to a

mouse morecontroversial

Figure 1-17 Copyright 2006 Pearson Prentice Hall, Inc.

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Molecular Biotechnology Impacts

on Genetics and Medicine

New pharmaceuticals

Genetic profiles of disease state

Diagnosis, DNA microarrays/chips Rapid screening for infectious disease

Viruses and bacteria

New treatments Gene therapy

Mapping Human Genetic-based

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Mapping Human Genetic-based

Diseases

Thousands

known

Most genesmapped and

sequenced

Figure 1-18 Copyright 2006 Pearson Prentice Hall, Inc.

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Microarrays

Allow for the analysis

of thousands of genes

at a time Mutations

Gene expression

levels

Figure 1-19 Copyright 2006 Pearson Prentice Hall, Inc.

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Model Organisms for Genetic

Studies Model organisms

Chosen to be simpler and/or because they

have specific properties

E.g. short life cycle, easy to grow, simple genetics,

produce many offspring, well studied/characterized,

important

Examples

E. coli, S. cerevisiae, C. elegans, Arabidopsis

thaliana, Drosophila melanogaster, Danio rerio, M.

musculus

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Table 1-2 Copyright 2006 Pearson Prentice Hall, Inc.