Genetics_ an Overview

Document Sample
Genetics_ an Overview Powered By Docstoc
					Genetics, an Overview
Ahad Baghery
Ahad_Baghery@UManitoba.Ca

PhD Student, The University of Manitoba Wednesday, Oct. 26, 2005
Grant Park High School, Winnipeg, MB, Canada

Outline
• • • • • • • • Introduction Model organisms Cell division: Mitosis, Meiosis Mendelian principles of genetics Key experiments DNA, RNA, Transcription, Translation PCR: A revolution Genetic engineering: Recombinant DNA technology • Applications of genetics • Branches of Genetics
2

Introduction
A Paradox: Genetics is Hard Because it is Simple.

•Genetics: the scientific study of inheritance and its underlying mechanisms. •Genetics: The study of the structure and function of genes and the transmission of genes from parents to offspring.

3

Model organisms
Pea

Corn

Yeast
Fruit fly

Rapid Cycling Brassica

Arabidopsis

4

Cell division: Mitosis, Meiosis
Zygote
Mitosis

♀ Egg
♂ Sperm Gametes

Growth

Meiosis

5

Mendelian principles of genetics
Gregor Mendel, 1822-1864

•Monohybrid cross: Law of Segregation •Dihybrid cross: Law of Independence

6

Monohybrid cross

7

Monohybrid cross

3 Spherical:1Wrinkled
8

Monohybrid cross
Mendel’s first law:

The Principle of Segregation:
The two members of a heredity factor pair segregate from each other in the formation of gametes.
Now: Two members = alleles Hereditary factor = gene
9

Dihybrid cross

F2 generation ratio:

10

Dihybrid cross
Mendel’s second law: The Principle of independence: During gamete formation, members of one heredity factor pair segregate into gametes independently from other heredity factor pairs.
Now: Two members = alleles Hereditary factor = gene

11

Key experiments
•Morgan: 1866-1945 •Avery 1877-1955

•Griffith: 1881-1941

•Watson & Crick

12

Morgan’s experiment

♀

♂

♀

♂

♀

♂

♀

♂
13

Conclusion: “Genes” are located on chromosomes.

Griffith’s experiment
Conclusion:
Living harmful strain

Some “principles” should be transferred from the dead harmful strain into living harmless strain making transformation.

Living harmless strain

×× ××
Heat-killed harmful strain

×× + ××
Living harmless strain Heat-killed harmful strain
14

Avery’s experiment harmful strain
Isolate and purify macromolecules

Proteins

RNA

DNA

Carbohydrates

Lipids

Treat living harmless strain with the purified chemicals

harmful strain

Only DNA changed the heredity of the living harmless strain

Conclusion: “DNA” is the “principle of transformation”

15

Watson & Crick
The double helix structure of DNA, the giant molecule of life.

One nucleotide
16

17

DNA, RNA, Transcription, Translation
• DNA replication: the process by which new DNA molecules (and thus new copies of genetic information) are synthesized. • Transcription: the templating process that results in synthesis of a strand of RNA containing a copy of specific genetic information found in DNA. • Translation: synthesis of a polypeptide whose amino acid sequence is determined by the nucleotide sequence of RNA.
18

DNA, RNA, Transcription, Translation
DNA replication

19

PCR: A revolution
Polymerase Chain Reaction: A technique for replicating a specific piece of DNA in-vitro , even in the presence of excess non-specific DNA.

Nobel Prize: Kary Mullis 1993 "DNA Xeroxing": in vitro (cell-free) DNA "cloning"

20

Genetic engineering: Recombinant DNA technology
• select the desired gene (or genes) to be inserted into the organism • cut two DNA molecules into fragments with special (restriction) enzymes • splice the fragments together in the desired combination • introduce the new DNA into a living cell for replication

21

Genetic engineering: Recombinant DNA technology

22

Applications of genetics
• Medicine, hereditary diseases gene therapy strategies against:
– – – – – – – – – – – – – cancer, Alzheimer's disease, Parkinson's disease, heart disease, diabetes, multiple sclerosis, and AIDS. Disease resistance, Pest resistance, High production yield, High quality, Stress resistance, and Livestock and pets.

• Agriculture, Breeding for:

• Industry, • Crime Scene Investigation, • Paleontology, species evolution, etc.
23

Branches of Genetics
• • • • • • • Classical or Mendelian genetics Cytogenetics Molecular genetics Genetic engineering Population genetics Quantitative genetics Genomics: study of large-scale genetic patterns across the genome for (and in principle, all the DNA in) a given species. • genetics of bacteria, viruses, insects, animals and plants, as well as humans
24

The End
• Questions?

25