Biology 2250
Principles of Genetics
Instructors:
Dr. Steven M. Carr  Molecular Genetics
Dr. David J. Innes

Mendelian Genetics
Course Web Pages
Dr.Innes:
www.mun.ca/biology/dinnes/B2250/B2250.html
Dr. Carr: www.mun.ca/biology/scarr/Bio2250.html
Text Web Page: http://www.whfreeman.com/mga/
Virtual Fly: http://www.biologylabsonline.com/
Tentative Lecture Dates
and Topics
Carr: Sept. 8 – Oct. 4 Structure and function of
Innes: Oct. 13 – Nov. 15 Mendelian Genetics
Carr: Nov. 22 – Dec. 1 Molecular Genomics
Tests: I Oct. 6 (Thurs)
II Nov.17 (Thurs)
DNA and genes
Weekly Online Quizzes
Oct. 14
Oct. 21
Oct. 28
Nov. 4
Nov. 10
Marks
Example Quiz 2** for logging in
Quiz 1
2
Quiz 2
2
Quiz 3
2
Quiz 4
2
WebCT Quizzes
Log in: http://webct.mun.ca:8900/
Webct
quizzes
Course Goals
•
•
•
•
Understanding of basic genetics
Solve problems
Think and think critically
Contribute to a discussion on
current issues in genetics
(GMO, gene therapy…)
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
Cultivated varieties
Animal Breeds
Human Genetic
Variation
Natural
Populations
DNA Sequence
Molecular Genetic Variation
DNA Fingerprint
Protein variation
Which
suspect
matches
blood stain ?
Subareas of Genetics
cytogenetics
molecular genetics
human genetics
population genetics
quantitative genetics
developmental genetics
immunogenetics
etc. etc.
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/default.htm)
History of Genetics
• Domestication of animals
• Cultivation of plants
Historical Notes
1953 J. D. Watson and F. Crick(*)
DNA Structure
http://www.sil.si.edu/Exhibitions/Science-and-theArtists-Book/bioc.htm
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/
Genetic Information
Online Mendelian Inhertitance in Man (OMIM)
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db
=OMIM
Online Mendelian Inhertiance in Animals (OMIA)
http://omia.angis.org.au/
Ethical Issues in Genetics
Ethical Issues in Genetics
• Genetically modified organisms (GMO)
• Gene therapy (Parkinson’s)
http://hdlighthouse.org/research/genetherapy/upd
ates/0053parkinson.phtml
• Designer genes
• Data banks of DNA finger prints (criminals?)
• Cloning (Stem cell research)
1997
Cloning
1999 - 2002
1998
Sheep
Mice
Pig
Dolly
“An udder way of
making lambs”
Goat
Cow
nucleus foster egg
“Cc”
copy cat
Genetics in the News
Basic Concepts of Genetics
(Chapter 1)
 contains genetic material
 genetic material
 4 bases (nucleotides G, C, A, T)
Gene
 functional unit of heredity
 sequence of 4 nucleotides
Chromosome  linear DNA molecule
Nucleus
DNA
Pairs of Chromosomes
(maternal, paternal)
Two sets of chromosomes: diploid
One set of chromosomes: haploid
DNA Replication
Gene Expression
2. Translation of mRNA: triplet codon
Amino acid
1. Transcription of mRNA from DNA
Understanding Genetics
Relationship between:
GENOTYPE
set of genes
inherited
ENVIRONMENT PHENOTYPE
morphology
physiology
behaviour
Interaction of genes and environment
Genotype
Phenotype
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)
Mendelian Genetics
Topics (cont.):
- Tetrad Analysis (mapping in fungi)
- Extensions to Mendelian Genetics
- Gene mutation
- Chromosome mutation
- (Quantitative and population genetics)
Basic Concepts of Genetics
Cell/nuclear division
Mitosis (somatic tissue):
identical cells
Meiosis (germ tissue):
gametes (variation)
Mendelian Genetics:
Chromosomes
Readings:
Transmission of DNA and cell division
- Mitosis and meiosis (Ch. 4)
pp. 92, 100 – 113
Chromosome Theory of
Inheritance (Ch. 4)
- genes organized into chromosomes
- correlation: Genetics & Cytology
- theory can explain the behaviour
of genes (segregation and
independent assortment)
Chromosome and DNA
Replication
1. DNA replication results in
chromosome replication
2. Nuclear and cell division
Cell cycle:
S = synthesis
Mitosis
G = “gaps”
n = # of chr.
in a set
Haploid (n)
Diploid (2n)
n
2n
Meiosis
2n
n
Animal
Polar bodies
n
n
egg
Plant
n
gp = gametophyte
Fungus
Cytological Observations
1. Constancy of the number of chromosomes
2. Morphologically similar pairs (diploid)
3. Gametes - contain one set (haploid)
2n
Homologous chromosomes
n
Two processes of nuclear
division
1. Mitosis (somatic tissue)
2. Meiosis (germ tissue)
Mitosis
1. one parent cell--------> 2 identical
daughter cells
2. same in all organisms
3. simple:
(a) each chromosome
doubles (identical)
(b) identical halves separate
Four Stages of Mitosis
1.Prophase
2. Metaphase
3. Anaphase
4. Telophase
Chromosome
replication
1. Prophase
- chromosomes condense
- 2 chromatids (sister chromatids)
- centromere
- nuclear membrane breaks down
2. Metaphase
- chromosomes attach to spindle fibers
- chromosomes migrate to plane between poles
- maximum contraction: karyotype
- number
Nuclear spindle
- centromere position
- length
3. Anaphase
- centromeres divide
- sister chromatids separate
4. Telophase
- nuclear membrane reforms
- spindle disperses
- cytoplasm divides (cytokinesis)
Mitosis:
Mitosis: Summary
2n = 2
replication
mitosis
2n = 4
Mitosis: Summary
replication
mitosis
Mitosis Animation
http://www.whfreeman.com/mga/
Mitosis:
Lily
Fig. 4-21
Meiosis
(overview)
diploid (2n) ---------------> haploid (n) gametes
Chromosome replication once --------> 2 nuclear
divisions (meiosis I, II)
one nucleus -------------------> 4 nuclei
Meiosis I
(reductional)
Prophase I
Metaphase I
Anaphase I
Telophase I
Meiosis II
(equational)
Prophase II
Metaphase II
Anaphase II
Telophase II
Meiosis I (reductional division)
2n = ?
Pairing of homologous
chromosomes
Continued 
Meiosis II (equational division)
4 products
n=?
Meiosis Animation
http://www.whfreeman.com/mga/
Meiosis:
Lily
pollen
Fig. 4-22
Prophase I
Metaphase I
Anaphase I
Telophase I
Prophase II
Metaphase II
Anaphase II
Telophase II
Comparison (Fig. 4-24)
Mitosis
somatic cells
one doubling
Meiosis
cells of sexual cycle
one doubling
1 division  2 cells
2 divisions  4 cells
same amount of DNA
½ amount of DNA
Comparison (continued)
Mitosis
Meiosis
# chrs doesn’t change
#chrs. halved
No pairing of chr.
Synapsis of homologs
Centromeres divide at
anaphase
Conservative
Not at anaphase I,
but at anaphase II
Variation
Mitosis (n)
Fig. 4-20
Mitosis (2n)
Meiosis
Genetic Terminology
Genes: hereditary elements
Alleles: forms of a gene: A , a
b, b+
Genotypes
Heterozygote:
Homozygotes:
Gene pairs
Aa
AA
aa
bb+
bb b+ b+
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
a
one set
Genes on Chromosomes
Fig. 4-17
b+ b+ homozygote
Genes on Chromosomes
b b+ heterozygote
b b homozygote
Genetic Links
http://www.biologyonline.org/tutorials/2_genetics_evolution.htm
http://www.tokyo-med.ac.jp/genet/mfi-e.htm
http://www.biology.arizona.edu/mendelian_gen
etics/mendelian_genetics.html
http://science.nhmccd.edu/biol/genetics.html