1. Online Counseling Resource YCMOU ELearning Drive…
Dec 18, 2007
Dec 18, 2007
Online Counseling Resource YCMOU ELearning Drive…
School of Architecture, Science and Technology
Yashwantrao Chavan Maharashtra Open University, Nashik – , India 1

2. Programmes and Courses SEP – SBT083–Unit 01
Dec 18, 2007
Dec 18, 2007
OC-SBT083-CP1-03 Introduction
Programmes and Courses
SEP – SBT083–Unit 01 2

3. Credits Academic Inputs by Arun Punaji More. M.Sc. (Microbiology)‏
Dec 18, 2007
Dec 18, 2007
Dec 18, 2007
Credits
Academic Inputs by
Arun Punaji More.
M.Sc. (Microbiology)‏
Experience: 11 Years 3 3

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How to Use This Resource
Counselor at each study center should use this presentation to deliver lecture of minutes during Face-To-Face counseling.
Discussion about students difficulties or tutorial with assignments should follow the lecture for about minutes.
Handouts (with 6 slides on each A4 size page) of this presentation should be provided to each student.
Each student should discuss on the discussion forum all the terms which could not be understood. This will improve his writing skills and enhance knowledge level about topics, which shall be immensely useful for end exam.
Appear several times, for all the Self-Tests, available for this course.
Student can use handouts for last minutes preparation just before end exam.
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Learning Objectives
After studying this module, you should be able to:
Define chromosomal variations.
Describe various types of chromosomal variations and the underlined mechanisms.
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Introduction - 1
Genetic variations are caused either of abrupt change in nucleotide sequences or change in structure and number of chromosomes.
Both these types of variations are also called as mutations.
However the degree of effects of both these types of variation are different at phenotypes and vary in animals and plants.
In this module, chromosomal variations are discussed.
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Chromosomal Variations-1
Normal cells of members of a species all have same number of chromosomes.
However some times this number of chromosomes change abnormally.
Chromosomal variations involving change in number:-
Euploidy :-
Euploidy refer to change in entire sets of chromosomes.
Aneuploidy :-
Refer to change in number of a single chromosome within a set of chromosomes.
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Chromosomal Variations-2
Euploidy and Aneuploidy:-
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Chromosomal Variations-3
Euploidy:- on the basis of number of set of chromosomes affected euploidy is described as
Haploid – refer to only a single set of chromosomes.
Diploid – refer to two set of chromosomes.
Polyploidy – refer to more than one set of chromosomes.
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Chromosomal Variations-4
Haploid or monoploidy:-
Normally the animal cells are diploid however sometimes haploid cell arises abnormally.
In animal sex cells which are called as gametes are haploid so that after fertilization of male and female gametes diploidy which is normal in animals is restored when zygote is formed.
Meiosis in animals produces haploid sex cells necessary for normal fertilization in which normal diploidy is restored.
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Polyploidy
There are two types of polyploidy
Autopolyploidy:-
Is refer to duplication of chromosomes set in a single species.
Allopolyploidy:-
Refer to duplication of chromosomes set arised due to combining of chromosomes from different species.
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Polyploidy
Polyploidy occur when
An egg is fertilized by more than one sperm leading to production of zygote with three or more set of chromosomes.
Defective meiosis producing diploid sex cell instead of haploid sex cell.
Defective mitosis which produce multiple chromosome copies causing increasing in chromosome number leading polyploidy.
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Autopolyploidy-1
Autopolyploidy refers to polyploidy arised when individual members of the same species breed.
Triploid, tetraploid pentaploid are some of the examples of polyploidy.
Triploid usually produce gametes with uneven number of chromosome sets; some gametes containing three chromosome sets and some containing zero set of chromosome.
Sterility is the result of triploidy in sexually producing organisms.
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Autopolyploidy-2
However the autopolyploidy is common among number of plant species.
The few examples of plant species among which polyploidy is common are tomatoes, banana, corn, plums, Datura and rye.
potato,coffee and peanuts are some examples of tetraploid plants.
Though the polyploidy lead to sterility in sexual reproduction of plant species, propagation of plant is not affected because plant can propagate by asexual means or by vegetative mode.
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Autopolyploidy-3
Autotriploidy arises when normal meiosis fails producing diploid gametes which when is fertilized by normal haploid gamete, triploid zygote is formed.
Triploid always produce defective gamete due to absence of third homologous pairing during meiosis.
Because of this reason the polyploid organism with odd number of chromosomes are always sterile.
In polyploidy with even number of chromosomes, equal separation of chromosomes occur during meiosis.
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Autopolyploidy -4
Generation of autotriploidy:-
For example in banana plant
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Autopolyploidy-5
Production of triploidy
Defective meiosis produce diploid
gamete which fertilizes with the
normal haploid gamete producing
triploid zygote.
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Allopolyploidy-6
Allopolyploidy occurs when there is interspecies breeding.
Allopolyploid thus generated is completely new species because they can breed with each other but not with other species.
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Allopolyploidy-7
Generation of allopolyploidy:-

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Aneuploidy-1
Aneuploidy can occur in meiosis as well as in mitosis.
Down syndrome, a genetic disease, is example of meiotic aneuploidy caused due to extra chromosome no. 21.
Mitotic aneuploidy lead to cancer of that cell line in which it occur.
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Aneuploidy-2
Different forms of aneuploidy:-
Monosomy-referred to lack on chromosome from its pair.
Disomy- referred to two copies of a chromosome.
Trisomy – referred to three copies a chromosome
Tetrasomy- referred to four copies a chromosome.
Pentasomy-referred to five copies of a chromosome.
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Aneuploidy-3
Mechanism:-
Non disjunction of chromatids- result due faulty alignment of chromatids at meiotic plate.
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Aneuploidy-4
Detection of aneuploidy:-
Karyotyping
Fluorescence in situ hybridization
Quantitative polymerase chain reaction of short tandem repeat.
Comparative genomic hybridization
By amniocentesis
Chorionic villus sampling
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Aneuploidy-5
Trisomy of chromosome number 21:-
The karyotype of human genome
show one extra copy of chromosome
number 21 referred to as trisomy of
chromosome number 21.
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25. Dec 18, 2007
Dec 18, 2007
What We Learn…..
Different mechanisms of generation of chromosomal variations.
Polyploidy: advantages and disadvantages.
Aneuploidy: diseases. 25

26. Critical Thinking Questions
Dec 18, 2007
Dec 18, 2007
Critical Thinking Questions
Why polyploidy is common in plants kingdom?
Why polyploidy is rare in animals?
Why aneuploidy is almost always lethal? 26

27. Hint for Critical Thinking Question
Dec 18, 2007
Dec 18, 2007
Hint for Critical Thinking Question
Mode of reproduction
Defective gamete formation do not affect the survival of plants. 27

28. Study Tips Book Title: Principles of Genetics Title: Genetics
Dec 18, 2007
Dec 18, 2007
Study Tips
Book
Title: Genetics
Author: Monroe W. Strickberger
Publication: prentice-Hall of India private Limited
Title: Principles of Genetics
Author: Tamarin
Publication: Tata Mcgrawhills 28

29. End of the Presentation
Dec 18, 2007
Dec 18, 2007
End of the Presentation
Thank You ! 29