Biology 2250 Principles of Genetics

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Biology 2250Principles of Genetics

• Instructors
• Dr. Steven M. Carr ? Molecular Genetics
• Dr. David J. Innes ? Mendelian Genetics

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Course Web Pages

• Dr.Innes www.mun.ca/biology/dinnes/B2250/B2250.ht
  ml
• Dr. Carr www.mun.ca/biology/scarr/Bio2250.html
• Text Web Page http//www.whfreeman.com/mga/
• Virtual Fly http//www.biologylabsonline.com/

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Tentative Lecture Dates and Topics

• Carr Sept. 8 Oct. 4 Structure and function of
  DNA and genes
• Innes Oct. 13 Nov. 15 Mendelian Genetics
• Carr Nov. 22 Dec. 1 Molecular Genomics
• Tests I Oct. 6
  (Thurs)
• II Nov.17
  (Thurs)

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Weekly Online Quizzes

• Marks
• Oct. 14 Example Quiz 2 for logging in
• Oct. 21 Quiz 1 2
• Oct. 28 Quiz 2 2
• Nov. 4 Quiz 3 2
• Nov. 10 Quiz 4 2

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WebCT Quizzes

• Log in http//webct.mun.ca8900/

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Webct quizzes
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Course Goals

• Understanding of basic genetics
• Solve problems
• Think and think critically
• Contribute to a discussion on
• current issues in genetics
• (GMO, gene therapy)

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What is Genetics ?

• - Genetics is the study of heredity and variation
• - Examples of genetic variation (within species)
• 1. Domesticated species
• 2. Human genetics
• 3. Natural Populations
• Genetic variation ?Phenotypic variation
  
• Molecular genetic variation

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Cultivated varieties
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Animal Breeds
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Human Genetic Variation
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Natural Populations
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DNA Sequence
Molecular Genetic Variation
DNA Fingerprint
Protein variation
Which suspect matches blood stain ?
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Subareas of Genetics

• cytogenetics
• molecular genetics
• human genetics
• population genetics
• quantitative genetics
• developmental genetics
• immunogenetics
• etc. etc.

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Genetic Journals

• American Journal of Medical Genetics
  Clinical Genetics
• Developmental Genetics
  Human Molecular Genetics
• Genetics
  European J. of Human Genetics
• Genetics Selection Evolution
  Nature Genetics
• Genetika
  Fungal Genetics and Biology
• Genome
  Cancer Genetics and Cytogenetics
• Genomics
  American J. Human Genetics
• Heredity
  Annals of Human Genetics
• Hereditas
  Opthalmic Genetics
• Japanese Journal of Human Genetics
  Human Genetics
• Journal of Heredity
  Current Genetics
• Molecular Biology and Evolution
  Animal Genetics
• Molecular Ecology
  Brazilian J. Genetics
• Molecular and General Genetics
  Biochemical Genetics
• Theoretical and Applied Genetics
  J. of Medical Genetics
• Trends in Genetics (http//www.trends.com/tig/de
  fault.htm)

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History of Genetics

• Domestication of animals
• Cultivation of plants

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Historical Notes

• 1953 J. D. Watson and F. Crick()
• DNA Structure
• http//www.sil.si.edu/Exhibitions/Science-and-the-
  Artists-Book/bioc.htm

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Advances in Genetics

• Human Genome Sequence
• http//www.hgsc.bcm.tmc.edu/
• Drosophila Genome sequence
• http//flybase.bio.indiana.edu/
• Other organsims
• http//daphnia.cgb.indiana.edu/
• http//www.jgi.doe.gov/

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Genetic Information

• Online Mendelian Inhertitance in Man (OMIM)
• http//www.ncbi.nlm.nih.gov/entrez/query.fcgi?dbO
  MIM
• Online Mendelian Inhertiance in Animals (OMIA)
• http//omia.angis.org.au/

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Ethical Issues in Genetics
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Ethical Issues in Genetics

• Genetically modified organisms (GMO)
• Gene therapy (Parkinsons) http//hdlighthouse.or
  g/research/genetherapy/updates/0053parkinson.phtml
  
• Designer genes
• Data banks of DNA finger prints (criminals?)
• Cloning (Stem cell research)

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Cloning
1999 - 2002
1997
1998
Sheep Mice Pig Goat Cow
Dolly An udder way of making lambs
Cc copy cat
nucleus
foster
egg
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Genetics in the News
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Basic Concepts of Genetics(Chapter 1)

• Nucleus ? contains genetic material
• DNA ? genetic material
• ? 4 bases (nucleotides G,
  C, A, T)
• Gene ? functional unit of heredity
• ? sequence of 4 nucleotides
• Chromosome ? linear DNA molecule

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Pairs of Chromosomes (maternal, paternal)
Two sets of chromosomes diploid One set of
chromosomes haploid
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DNA Replication
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Gene Expression
2. Translation of mRNA triplet codon
Amino acid
1. Transcription of mRNA from DNA
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Understanding Genetics

• Relationship between
• GENOTYPE ENVIRONMENT PHENOTYPE
• set of genes
  morphology
• inherited
  physiology
• 
  behaviour

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Interaction of genes and environment
Phenotype
Genotype
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Mendelian Genetics

• Topics - Transmission of DNA during cell
  division
• Mitosis and Meiosis
  (Ch. 4)
• - Segregation (Ch. 5)
• - Sex linkage (Ch. 5)
• - Inheritance and probability
  (Ch.5)
• - Mendelian genetics in humans
• (pedigrees)
  (Ch.5)
• - Independent Assortment (Ch.
  6)
• - Linkage (Ch. 6)
• - Gene mapping (Ch. 6)

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Mendelian Genetics

• Topics (cont.)
• - Tetrad Analysis (mapping in
  fungi)
• - Extensions to Mendelian
  Genetics
• - Gene mutation
• - Chromosome mutation
• - (Quantitative and
  population genetics)

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Basic Concepts of Genetics

• Cell/nuclear division
• Mitosis (somatic tissue)
• identical cells
• Meiosis (germ tissue)
• gametes (variation)

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Mendelian GeneticsChromosomes

• Readings
• Transmission of DNA and cell division
• - Mitosis and meiosis (Ch. 4)
• pp. 92, 100 113

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Chromosome Theory of Inheritance (Ch. 4)

• - genes organized into chromosomes
• correlation Genetics Cytology
• - theory can explain the behaviour of genes
  (segregation and independent assortment)

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Chromosome and DNA Replication

• DNA replication results in
• chromosome replication
• 2. Nuclear and cell division

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Mitosis
Cell cycle S synthesis G gaps
n of chr. in a set
n
Haploid (n)
2n
Diploid (2n)
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Meiosis
n
2n
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Animal
Polar bodies
n
n
egg
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Plant
n
gp gametophyte
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Fungus
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Cytological Observations

• 1. Constancy of the number of chromosomes
• Morphologically similar pairs (diploid)
• 3. Gametes - contain one set (haploid)

2n
n
Homologous chromosomes
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Two processes of nuclear division

• 1. Mitosis (somatic tissue)
• 2. Meiosis (germ tissue)

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Mitosis

• 1. one parent cell--------gt 2 identical
• 
  daughter cells
• 2. same in all organisms
• 3. simple
• (a) each chromosome
• doubles (identical)
• (b) identical halves separate

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Four Stages of Mitosis

• 1.Prophase
• 2. Metaphase
• 3. Anaphase
• 4. Telophase

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1. Prophase
Chromosome replication

• - chromosomes condense
• - 2 chromatids (sister chromatids)
• - centromere
• - nuclear membrane breaks
  down

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2. Metaphase

• - chromosomes attach to spindle fibers
• - chromosomes migrate to plane between poles
• - maximum contraction karyotype
• -
  number
• -
  centromere position
• -
  length

Nuclear spindle
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3. Anaphase

• - centromeres divide
• - sister chromatids separate

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4. Telophase

• - nuclear membrane reforms
• - spindle disperses
• - cytoplasm divides (cytokinesis)

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Mitosis
Mitosis Summary
2n 2
replication
mitosis
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Mitosis Summary
2n 4
replication
mitosis
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Mitosis Animation
http//www.whfreeman.com/mga/
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Mitosis Lily Fig. 4-21
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Meiosis(overview)

• diploid (2n) ---------------gt haploid (n) gametes
• Chromosome replication once --------gt 2 nuclear
• 
  divisions (meiosis I, II)
• one nucleus -------------------gt 4 nuclei

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Meiosis I Meiosis II
(reductional) (equational)

• Prophase I Prophase II
• Metaphase I Metaphase
  II
• Anaphase I Anaphase
  II
• Telophase I
  Telophase II

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Meiosis I (reductional division)

Pairing of homologous chromosomes
2n ?
Continued ?
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Meiosis II (equational division)

4 products n ?
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Meiosis Animation
http//www.whfreeman.com/mga/
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Meiosis Lily pollen Fig. 4-22
Prophase I Metaphase I Anaphase I Telophase
I Prophase II Metaphase II Anaphase
II Telophase II
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Mitosis Meiosis
Comparison (Fig. 4-24)

• somatic cells
  cells of sexual cycle
• one doubling
  one doubling
• 1 division ? 2 cells 2
  divisions ? 4 cells
• same amount of DNA ½ amount of
  DNA

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Mitosis Meiosis
Comparison (continued)

• chrs doesnt change chrs.
  halved
• No pairing of chr. Synapsis
  of homologs
• Centromeres divide at Not at
  anaphase I,
• anaphase
  but at anaphase II
• Conservative
  Variation

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Mitosis (n) Mitosis (2n) Meiosis
Fig. 4-20
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Genetic Terminology

• Genes hereditary elements
• Alleles forms of a gene A , a
• b,
  b
• Genotypes Gene pairs
• Heterozygote Aa
  bb
• Homozygotes AA aa bb
  b b

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Genes on Chromosomes

• Expect behaviour of genes to correlate with the
  behaviour of chromosomes
• genes
  chromosomes
• Diploid (2n) AA, Aa, aa pairs
• Haploid (n) A one set
• a

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Genes on Chromosomes
Fig. 4-17
b b homozygote
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Genes on Chromosomes
b b heterozygote
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b b homozygote
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Genetic Links

• http//www.biology-online.org/tutorials/2_genetics
  _evolution.htm
• http//www.tokyo-med.ac.jp/genet/mfi-e.htm
• http//www.biology.arizona.edu/mendelian_genetics/
  mendelian_genetics.html
• http//science.nhmccd.edu/biol/genetics.html