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 – 422222, India 1

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

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 arunmesh@hotmail.com 3 3

© 2007, YCMOU. All Rights Reserved. Dec 18, 2007 Dec 18, 2007 How to Use This Resource Counselor at each study center should use this presentation to deliver lecture of 40-60 minutes during Face-To-Face counseling. Discussion about students difficulties or tutorial with assignments should follow the lecture for about 40-60 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. © 2007, YCMOU. All Rights Reserved. 4 4

© 2007, YCMOU. All Rights Reserved. Dec 18, 2007 Dec 18, 2007 Learning Objectives After studying this module, you should be able to: Define chromosomal variations. Describe various types of chromosomal variations and the underlined mechanisms. © 2007, YCMOU. All Rights Reserved. 5 5

© 2007, YCMOU. All Rights Reserved. Dec 18, 2007 Dec 18, 2007 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. © 2007, YCMOU. All Rights Reserved. 6 6

© 2007, YCMOU. All Rights Reserved. Dec 18, 2007 Dec 18, 2007 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. © 2007, YCMOU. All Rights Reserved. 7 7

© 2007, YCMOU. All Rights Reserved. Dec 18, 2007 Dec 18, 2007 Chromosomal Variations-2 Euploidy and Aneuploidy:- © 2007, YCMOU. All Rights Reserved. 8 8

© 2007, YCMOU. All Rights Reserved. Dec 18, 2007 Dec 18, 2007 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. © 2007, YCMOU. All Rights Reserved. 9 9

© 2007, YCMOU. All Rights Reserved. Dec 18, 2007 Dec 18, 2007 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. © 2007, YCMOU. All Rights Reserved. 10 10

© 2007, YCMOU. All Rights Reserved. Dec 18, 2007 Dec 18, 2007 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. © 2007, YCMOU. All Rights Reserved. 11 11

© 2007, YCMOU. All Rights Reserved. Dec 18, 2007 Dec 18, 2007 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. © 2007, YCMOU. All Rights Reserved. 12 12

© 2007, YCMOU. All Rights Reserved. Dec 18, 2007 Dec 18, 2007 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. © 2007, YCMOU. All Rights Reserved. 13 13

© 2007, YCMOU. All Rights Reserved. Dec 18, 2007 Dec 18, 2007 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. © 2007, YCMOU. All Rights Reserved. 14 14

© 2007, YCMOU. All Rights Reserved. Dec 18, 2007 Dec 18, 2007 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. © 2007, YCMOU. All Rights Reserved. 15 15

© 2007, YCMOU. All Rights Reserved. Dec 18, 2007 Dec 18, 2007 Autopolyploidy -4 Generation of autotriploidy:- For example in banana plant © 2007, YCMOU. All Rights Reserved. 16 16

© 2007, YCMOU. All Rights Reserved. Dec 18, 2007 Dec 18, 2007 Autopolyploidy-5 Production of triploidy Defective meiosis produce diploid gamete which fertilizes with the normal haploid gamete producing triploid zygote. © 2007, YCMOU. All Rights Reserved. 17 17

© 2007, YCMOU. All Rights Reserved. Dec 18, 2007 Dec 18, 2007 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. © 2007, YCMOU. All Rights Reserved. 18 18

Dec 18, 2007 Allopolyploidy-7 Generation of allopolyploidy:-

© 2007, YCMOU. All Rights Reserved. Dec 18, 2007 Dec 18, 2007 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. © 2007, YCMOU. All Rights Reserved. 20 20

© 2007, YCMOU. All Rights Reserved. Dec 18, 2007 Dec 18, 2007 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. © 2007, YCMOU. All Rights Reserved. 21 21

© 2007, YCMOU. All Rights Reserved. Dec 18, 2007 Dec 18, 2007 Aneuploidy-3 Mechanism:- Non disjunction of chromatids- result due faulty alignment of chromatids at meiotic plate. © 2007, YCMOU. All Rights Reserved. 22 22

© 2007, YCMOU. All Rights Reserved. Dec 18, 2007 Dec 18, 2007 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 © 2007, YCMOU. All Rights Reserved. 23 23

© 2007, YCMOU. All Rights Reserved. Dec 18, 2007 Dec 18, 2007 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. © 2007, YCMOU. All Rights Reserved. 24 24

Dec 18, 2007 Dec 18, 2007 What We Learn….. Different mechanisms of generation of chromosomal variations. Polyploidy: advantages and disadvantages. Aneuploidy: diseases. 25

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

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

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

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