7/29/2019 Chapter 1_2012 V

1/36

Chapter 1

The Science of Genetics

7/29/2019 Chapter 1_2012 V

2/36

7/29/2019 Chapter 1_2012 V

3/36

7/29/2019 Chapter 1_2012 V

4/36

Pit Bull Tree

Scientists make a pit bull tree that can defend itself in

the rain forest.

7/29/2019 Chapter 1_2012 V

5/36

Ugly Flower Pollination

Pretty flower worries that shell be pollinated by anugly flower.

7/29/2019 Chapter 1_2012 V

6/36

7/29/2019 Chapter 1_2012 V

7/36

Babys Mickey Mouse Ears

Baby mouses round ears reveal mothersrelationship with Mickey Mouse.

7/29/2019 Chapter 1_2012 V

8/36

Chapter Outline

Three Great Milestones in Genetics

DNA as the Genetic Material

Genetics and Evolution

Levels of Genetic AnalysisGenetics in the World: Applications of

Genetics to Human Endeavors

7/29/2019 Chapter 1_2012 V

9/36

Three Great Milestones in

GeneticsGregor Mendel: the rules of inheritance

James Watson and Francis Crick: the

structure of DNAThe Human Genome Project: the detailed

analysis of human DNA

7/29/2019 Chapter 1_2012 V

10/36

Mendel: Genes and the

Rules of Inheritance (1866)Geneshereditary

factors responsible fortraits

Allelesdifferent formsof genes

Rules of Inheritance Alleles of the same gene

separate during gamete

formation Alleles of different genes

are inheritedindependently

7/29/2019 Chapter 1_2012 V

11/36

What is a Gene?

Genes are made of nucleic acids

Nucleic acids are made of buildingblocks called nucleotides

Nucleotides have threecomponents

Sugar molecule (ribose ordeoxyribose)

Phosphate molecule

Nitrogen-containing molecule

(adenine, guanine, cytosine,thymine, uracil)

RNA is ribonucleic acid

DNA is deoxyribonucleic acid

7/29/2019 Chapter 1_2012 V

12/36

Watson and Crick:

The Structure of DNA (1953)Nucleotides are linked

in a chain throughsugar-phosphate

interactionsDNA molecules are

made of two chains ofnucleotides woundaround each other in a

helixBase pairs hold the

chains together A pairs with T

G pairs with C

7/29/2019 Chapter 1_2012 V

13/36

The Human Genome Project:Sequencing DNA and

Cataloguing Genes

Genomethe collection ofDNA molecules that ischaracteristic of an organism

Genomics is the analysis ofDNA sequences that make upa genome

Genomics involves DNAsequencing technology,

robotics, and computer science The Human Genome Project

determined the sequence ofnucleotides in the DNA of thehuman genome

7/29/2019 Chapter 1_2012 V

14/36

A Milestone in Genetics:X174, the First DNA Genome

SequencedX174 is a virus that

has single-stranded

DNA as its geneticmaterial.

Frederick Sangersequenced the

genome of X174 in1977

7/29/2019 Chapter 1_2012 V

15/36

Key Points

Gregor Mendel postulated the existence ofparticular factorsnow called genesto

explain how traits are inherited.Alleles, the alternate forms of genes, account

for heritable differences among individuals.

James Watson and Francis Crick elucidatedthe structure of DNA, a macromoleculecomposed of two complementary chains ofnucleotides.

7/29/2019 Chapter 1_2012 V

16/36

Key Points

DNA is the hereditary material of all life formsexcept some types of viruses, in which RNA

is the hereditary material.The Human Genome Project determined the

sequence of nucleotides in the DNA of thehuman genome.

Sequencing the DNA of a genome providesthe data to identify and catalogue all thegenes of an organism.

7/29/2019 Chapter 1_2012 V

17/36

DNA as the Genetic Material

Information flows from DNA to RNA toprotein.

In all cellular organisms, the geneticmaterial is DNA.

The genetic material

Must be able to replicate Must contain information

Must be able to change

7/29/2019 Chapter 1_2012 V

18/36

DNA Replication

7/29/2019 Chapter 1_2012 V

19/36

7/29/2019 Chapter 1_2012 V

20/36

Gene Expression:

Using Genetic Information

7/29/2019 Chapter 1_2012 V

21/36

Gene Expression

During transcription, an RNA molecule issynthesized from a DNA template.

This messenger RNA (mRNA) moleculescontains the information needed tosynthesize a polypeptide.

During translation, the triplet codons in the

RNA specify the incorporation of particularamino acids into a polypeptide chain.

7/29/2019 Chapter 1_2012 V

22/36

The Proteome

Proteomethe collection of all thedifferent proteins in an organism.

Humans have between 20,000 and25,000 genes in the genome andhundreds of thousands of proteins in theproteome.

Proteomicsthe study of all theproteins in cells.

7/29/2019 Chapter 1_2012 V

23/36

The Central Dogma of

Molecular Biology

The flow of information is DNA RNA protein.

Some viruses can use RNA as a template for thesynthesis of DNA in reverse transcription.

Many genes do not encode polypeptides; their end-products are RNA molecules.

7/29/2019 Chapter 1_2012 V

24/36

Mutation:

Changing Genetic Information

7/29/2019 Chapter 1_2012 V

25/36

Key Points

When DNA replicates, each strand of a duplexmolecule serves as the template for thesynthesis of a complementary strand.

When genetic information is expressed, onestrand of a genes DNA duplex is used as atemplate for the synthesis of a complementarystrand of DNA.

For most genes, RNA synthesis (transcription)generates a molecule (the RNA transcript) thatbecomes a messenger RNA (mRNA).

7/29/2019 Chapter 1_2012 V

26/36

Key Points

Coded information in an mRNA istranslated into a sequence of amino

acids in a polypeptide.Mutations can alter the DNA sequence

of a gene.

The genetic variability created bymutation is the basis for biologicalevolution.

7/29/2019 Chapter 1_2012 V

27/36

Genetics and Evolution

Variation in the DNAsequence makes it

possible for speciesto evolve over time.

Organisms withsimilar DNA

sequences aredescended from acommon ancestor.

7/29/2019 Chapter 1_2012 V

28/36

A phylogenetic tree

A phylogenetictree, or phylogeny,

represents thehistoricalrelationships amongorganisms.

7/29/2019 Chapter 1_2012 V

29/36

Key Points

Evolution depends on the occurrence,transmission, and spread of mutant

genes in groups of organisms.DNA sequence data provide a way of

studying the historical process of

evolution.

7/29/2019 Chapter 1_2012 V

30/36

Still Not Convinced About Evolution?

7/29/2019 Chapter 1_2012 V

31/36

Genetics in the World:Applications of Genetics to

Human Endeavors

Genetics is relevant in manyvenues outside the research

laboratory.

7/29/2019 Chapter 1_2012 V

32/36

Genetics in Agriculture:

Selective Breeding

7/29/2019 Chapter 1_2012 V

33/36

Genetics in Agriculture:

Genetically Modified OrganismsGenetically

Modified

Organisms (GMOs)are have beenaltered by theintroduction of

foreign genes.

7/29/2019 Chapter 1_2012 V

34/36

Genetics in Medicine

Inborn Errors ofMetabolism aremetabolic abnormalities

caused to mutant alleles.Genetic Counselors

advise people aboutinheritance of geneticdiseases.

Molecular genetics new ways to detect mutant

alleles.

new ways to treatdiseases.

7/29/2019 Chapter 1_2012 V

35/36

Genetics in Society

Economic impactbiotechnologyindustry, pharmaceutical industry.

Legal impactpaternity testing,forensics, identification

Philosophical impact

7/29/2019 Chapter 1_2012 V

36/36

Key Points

Discoveries in genetics are changingprocedures and practices in agriculture

and medicine.Advances in genetics are raising

ethical, legal, political, social, and

philosophical questions.