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Biology 2250 Principles of Genetics. Instructors: Dr. Steven M. Carr  Molecular Genetics Dr. David J. Innes  Mendelian Genetics. Course Web Pages. Dr.Innes: Dr. Carr:

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Biology 2250 Principles of Genetics

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Biology 2250 principles of genetics
Biology 2250Principles of Genetics


Dr. Steven M. CarrMolecular Genetics

Dr. David J. InnesMendelian Genetics

Course web pages
Course Web Pages


Text Web Page:

Virtual Fly:

Tentative lecture dates and topics
Tentative Lecture Dates and Topics

Carr: Sept. 8 – Oct. 4Structure 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)

Weekly online quizzes
Weekly Online Quizzes


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

Webct quizzes
WebCT Quizzes

Log in:

Course goals
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
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

Biology 2250 principles of genetics

Human Genetic


Biology 2250 principles of genetics

DNA Sequence

Molecular Genetic Variation

DNA Fingerprint

Protein variation

Which suspect matches blood stain ?

Subareas of genetics
Subareas of Genetics


molecular genetics

human genetics

population genetics

quantitative genetics

developmental genetics


etc. etc.

Genetic journals
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 (

History of genetics
History of Genetics

Domestication of animals

Cultivation of plants

Historical notes
Historical Notes

1953 J. D.Watson and F. Crick(*)

DNA Structure

Advances in genetics
Advances in Genetics

Human Genome Sequence

Drosophila Genome sequence

Other organsims:

Genetic information
Genetic Information

Online Mendelian Inhertitance in Man (OMIM)

Online Mendelian Inhertiance in Animals (OMIA)

Ethical issues in genetics1
Ethical Issues in Genetics

Genetically modified organisms (GMO)

Gene therapy (Parkinson’s)

Designer genes

Data banks of DNA finger prints (criminals?)

Cloning (Stem cell research)

Biology 2250 principles of genetics


1999 - 2002









“An udder way of making lambs”

“Cc” copy cat




Basic concepts of genetics chapter 1
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

Biology 2250 principles of genetics

Pairs of Chromosomes (maternal, paternal)

Two sets of chromosomes: diploid

One set of chromosomes: haploid

Biology 2250 principles of genetics

Gene Expression

2. Translation of mRNA: triplet codon

Amino acid

1. Transcription of mRNA from DNA

Understanding genetics
Understanding Genetics

Relationship between:


set of genes morphology

inherited physiology


Mendelian genetics
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 genetics1
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
Basic Concepts of Genetics

Cell/nuclear division

Mitosis (somatic tissue):

identical cells

Meiosis (germ tissue):

gametes (variation)

Mendelian genetics chromosomes
Mendelian Genetics:Chromosomes


Transmission of DNA and cell division

- Mitosis and meiosis (Ch. 4)

pp. 92, 100 – 113

Chromosome theory of inheritance ch 4
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
Chromosome and DNA Replication

DNA replication results in

chromosome replication

2. Nuclear and cell division

Biology 2250 principles of genetics


Cell cycle:

S = synthesis

G = “gaps”

n = # of chr. in a set


Haploid (n)


Diploid (2n)

Biology 2250 principles of genetics




Biology 2250 principles of genetics


Polar bodies




Biology 2250 principles of genetics



gp = gametophyte

Cytological observations
Cytological Observations

1. Constancy of the number of chromosomes

Morphologically similar pairs (diploid)

3. Gametes - contain one set (haploid)



Homologous chromosomes

Two processes of nuclear division
Two processes of nuclear division

1. Mitosis (somatic tissue)

2. Meiosis (germ tissue)


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
Four Stages of Mitosis


2. Metaphase

3. Anaphase

4. Telophase

1 prophase



1. Prophase

- chromosomes condense

- 2 chromatids (sister chromatids)

- centromere

- nuclear membrane breaks down

2 metaphase
2. Metaphase

Nuclear spindle

- chromosomes attach to spindle fibers

- chromosomes migrate to plane between poles

- maximum contraction: karyotype

- number

- centromere position

- length

3 anaphase
3. Anaphase

- centromeres divide

- sister chromatids separate

4 telophase
4. Telophase

- nuclear membrane reforms

- spindle disperses

- cytoplasm divides (cytokinesis)

Biology 2250 principles of genetics


Mitosis: Summary

2n = 2



Biology 2250 principles of genetics

Mitosis: Summary

2n = 4



Mitosis animation
Mitosis Animation

Biology 2250 principles of genetics

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 meiosis ii reductional equational
Meiosis I Meiosis II (reductional) (equational)

Prophase I Prophase II

Metaphase I Metaphase II

Anaphase I Anaphase II

Telophase I Telophase II

Meiosis i reductional division
Meiosis I (reductional division)

Pairing of homologous chromosomes

2n = ?

Continued 

Meiosis animation
Meiosis Animation

Biology 2250 principles of genetics

Meiosis: Lily pollen

Fig. 4-22

Prophase I

Metaphase I

Anaphase I

Telophase I

Prophase II

Metaphase II

Anaphase II

Telophase II

Mitosis meiosis

Comparison (Fig. 4-24)

Mitosis Meiosis

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

Mitosis meiosis1

Comparison (continued)

Mitosis Meiosis

# chrs doesn’t change #chrs. halved

No pairing of chr. Synapsis of homologs

Centromeres divide at Not at anaphase I,

anaphase but at anaphase II

Conservative Variation

Genetic terminology
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+

Genes on chromosomes
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


Biology 2250 principles of genetics

Genes on Chromosomes

Fig. 4-17

b+ b+ homozygote

Biology 2250 principles of genetics

Genes on Chromosomes

b b+ heterozygote

Biology 2250 principles of genetics

b bhomozygote

Genetic links
Genetic Links

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