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GP 510 PRINCIPLES OF CYTOGENETICS                                                                                 (3L+2P) I

Objective
The aim is to provide insight into chromosomes structure and function, mapping, variations in chromosomal ploidy and structure; its role in crop evolution.

Theory

UNIT I
Chromosome architecture in prokaryotes and eukaryotes; Eukaryotic chromosome structure & organisation Artificial chromosomes- BACS, YACs, construction and its uses; Special types of chromosomes.

UNIT II
Chromosomal theory of inheritance, Cell Cycle and cell division, mitosis and meiosis, Differences, significance and deviations – Synapsis, structure and function of synaptonemal complex and spindle apparatus, anaphase movement of  chromosomes and crossing over-mechanisms and theories of crossing over- recombination models, cytological basis, - Variation in chromosome structure: evolutionary significance – karyotyping techniques; Chromosome banding and painting - in situ hybridization and its applications,

UNIT III
Structural and Numerical variations of chromosomes and their implications - Symbols and terminologies for chromosome numbers - euploidy - haploids, diploids and polyploids; Utilization of aneuploids in gene location - Variation in chromosome behaviour - somatic segregation and chimeras – endomitosis and somatic reduction; Evolutionary significance of chromosomal aberrations - balanced lethals and chromosome complexes

UNIT IV
Inter-varietal chromosome substitutions, Polyploidy and role of polyploids in crop breeding; Evolutionary advantages of autopolyploids vs allopolyploids –- Role of aneuploids in basic and applied aspects of crop breeding; their maintenance and utilization in gene mapping and gene blocks transfer – Alien addition and substitution lines – creation and utilization; Apomixis: Evolutionary and genetic disadvantage.

UNIT V
Reversion of autopolyploids to diploids; genome mapping in polyploids - Interspecific hybridization and allopolyploids; Synthesis of new crops (wheat, triticale and brassica) – Hybrids between species with same chromosome number, alien translocations - Hybrids between species with different chromosome number; Gene transfer using amphidiploids - Bridge species

UNIT VI
Fertilization barriers in crop plants at pre-and postfertilization levels- In vitro techniques to overcome the fertilization barriers in crops, Chromosome manipulations in wide hybridization; case studies – Production and use of haploids, dihaploids and doubled haploids in genetics and breeding;

Practicals
Preparation of tissues for cytogenetical analyses (Fixatives, fixation, dehydration, embedding, staining, cleaning etc.) - Microscopy: various types of  microscopes, Mitosis in wheat, pearl millet,onion, Aloe vera, oilseeds, forage crops and pulses, Measuring pollen grain size in various crops with micrometer, Methods of preparing permanent slides, Pollen germination in vivo and in vitro,  Identification of  polyploids in different crops, Mor phological obser vations on autopolyploids and alloployploids - Morphological observations on aneuploids, Cytogenetic analysis of interspecific and intergeneric crosses, Maintenance of Cytogenetic stocks and their importance in crop breeding;Fluorescent in situ hybridization (FISH), Genome in situ hybridization GISH.

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