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OBJECTIVE CYTOGENETICS
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OBJECTIVE CYTOGENETICS A competitive book for ICAR-JRF, SRF, Civil services, UGC- NET,
ICAR- NET, CSIR-NET, ASRB and all SAUs examinations
Srijan Ambati Ph. D Scholar (DST- INSPIRE Fellow)
Genetics & Plant Breeding,
Professor Jayashankar Telangana State Agricultural University
(Formerly ANGRAU)
Hyderabad - 500030
Rakesh Alle Ph. D Scholar
Genetics & Plant Breeding,
Professor Jayashankar Telangana State Agricultural University
(Formerly ANGRAU)
Hyderabad - 500030
EDUCREATION PUBLISHING (Since 2011)
www.educreation.in
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About The Authors
Srijan Ambati completed his B.Sc. Ag. Degree
from Acharya N.G. Ranga Agricultural
University in 2013 with first class and
distinction. He secured State third rank in M.Sc.
Ag. entrance test conducted by ANGRAU and
opted Genetics & Plant Breeding. He completed
his M.Sc. Ag in 2015 with highest OGPA in the
discipline of Genetics & Plant Breeding from
Professor Jayashankar Telangana State Agricultural University
(Formerly ANGRAU). He also cleared ICAR- SRF examination in
2015 and ASRB - NET in 2016. Currently he is pursuing his Ph.D.
at PJTSAU, Hyderabad. He was also awarded with DST- INSPIRE
fellowship for his Ph. D. program from Ministry of Science &
Technology, Government of India. He has publications in NAAS
rated peer reviewed international journals as well as book chapters
to his credit. He has participated in many national and international
conferences, presented papers and posters. His popular articles
have been published in about ten different telugu agricultural
monthly magazines.
Rakesh Alle is a Ph. D. Scholar in the
department of Genetics and Plant Breeding,
College of Agriculture, PJTSAU, Hyderabad. He
has completed his B.Sc. (Ag) degree in 2012 in
Agricultural College, Aswaraopet (ANGRAU)
with first class and distinction. He has completed
post-graduation (M.Sc. Ag) in the department of
Genetics and Plant Breeding from College of
Agriculture, ANGRAU, Hyderabad, in the year 2014 in first
division. He has a very good academic record. He has published
research articles in leading agricultural journals and published
many popular articles in different Telugu agricultural magazines.
The author also has the experience in wheat breeding in ITC Ltd.
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and also in hybrid rice breeding, worked with the project “CRP-on
Hybrid Rice Technology” in ICAR-IIRR. He has also qualified
National Eligibility Test (ASRB), during 2014.
*****
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Dedicated To Our Beloved Parents Mr. & Mrs. Ambati Susheela Sreedhar Raju
And
Mr. & Mrs. Alle Suguna Rajaveeru
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viii
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Preface ______________________________________________________
The present book entitled “Objective Cytogenetics” is the first
book of Cytogenetics that is written in objective point of view.
This book is prepared as per the syllabus of ICAR and ASRB in
particular to suit the student community of Plant Science
disciplines. The most classical topics of Cytogenetics such as
structural chromosomal aberrations viz., Duplications,
Deficiencies, Inversions and Interchanges; Auto polyploidy;
Allopolyploidy; Aneuploidy (Hyperploids and Hypoploids); Alien
addition and Substitution lines are thoroughly covered. The critical
interventions that are most necessary to understand in Cytogenetics
which any student, should be clear about were discussed in the
form of objective type questions to facilitate in their preparation
for any competitive examinations. Not only the topics quoted
above but the most common basics starting from designations,
symbols, formulae and characteristics were framed in the form of
objective type questions. This book can be an asset to any aspiring
student in achieving their goals of cracking competitive
examinations. As this is the first edition we have tried our level
best to provide the things with the maximum accuracy and
sufficient proof reading. However if any kind of mistakes or
controversies if found may be brought to our notice so that we can
make necessary changes if needed. We also welcome your
suggestions to improve this book further in the upcoming editions.
Finally we wish the student community, exploit this book to the
extent possible to make their dreams come true.
SRIJAN AMBATI
RAKESH ALLE
*****
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Acknowledgements ______________________________________________________
We are highly thankful to our teachers for their efforts in teaching,
for our better understanding of the subject. We thank our Gurus`
Dr. S. Sudheer Kumar, Hon`ble Registrar, PJTSAU and Dr.
Kuldeep Singh Dangi, Hon`ble Dean of Agriculture, PJTSAU for
their constant moral support that acted as a driving force in
bringing this book into reality. We are also likely to acknowledge
our Cytogenetics teacher, Dr. M. Bharathi (Professor Rtd.) whose
teaching has cleared many of misconceptions that were obstructing
our understanding of this subject. We are highly grateful for the
support from the senior faculty members Dr. C. Cheralu and Dr.
K.V. Radha Krishna who are always guiding us in a right way. We
also acknowledge the entire Department of Genetics and Plant
Breeding, PJTSAU both scientists and teachers who directly or
indirectly supported us. We are also grateful to our typists who
have been supportive in providing their timely service. Finally we
also appreciate the efforts and the support from educreation in
publishing this book in time with great quality and precision.
SRIJAN AMBATI
RAKESH ALLE
*****
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Syllabus of Cytogenetics ______________________________________________________
Architecture of chromosomes in prokaryotes and eukaryotes -
Terminology, euchromatin and heterochromatin karyotype and
techniques for karyotyping. Banding patterns for identification of
chromosomes - C value paradox - DNA content (genome size) and
adoptability - split gene. Special type of chromosomes - lamp
brush chromosomes polytene chromosomes B chromosomes and
sex chromosomes. Mitosis cell cycle - significance of mitosis.
Meiosis cell cycle - significance of meiosis - differences between
mitosis and meiosis - significance. Crossing over - mechanisms
and theories of crossing over. Recombination models and
cytological basis of crossing over. Structural chromosomal
aberrations Deletions - types of deletions, origin and occurrence -
meiosis and breeding behaviour of deletion heterozygote, genetics
of deletions. Duplications - origin, types of duplications -
chromosome pairing and crossing over at meiosis in duplicate
heterozygotes, phenotypic effects of duplications. Bridge -
breakage - fusion cycle in corn. Role of duplications in plant
breeding and evolution. Inversions: origin, types of inversions -
meiotic pairing in inversions - detection and uses pericentric and
paracentric inversions. Breeding behaviour of inversion
heterozygotes - Role of inversions in evolution and karyotype.
Breeding behaviour of translocation heterozygote permanent
hybrids in Oenothera - Robertsonian translocations and uses.
Numerical chromosomal aberrations: classification. Euploidy:
Haploidy Terminology and classification of haploids - Origin,
occurrence and production of haploids - Detection of haploids -
Phenotypic effects of haploids Meiosis and breeding behaviour of
haploids use of haploids in plant breeding.
Polyploidy - autopolyploidy Origin and types of autopolyploids
Meiotic behaviour in autopolyploids - Autotriploids and
autopolyploids. Allopolyploidy - segmental allopolyploidy -
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Genome analysis of allopolyploids - Evolution of important
polyploid crops - wheat - Tobacco. Bajra, Brassica and Cotton.
Aneuploidy - hyperploids - trisomics and tetrasomics - primary
trisomics and secondary trisomics - Meiotic behavior in trisomics
and uses. Balanced tertiary trisomics in hybrid seed production -
Trisomics in polyploids - tetrasomics. Aneuploidy - hypoploidy:
Monosomics and nullisomics - method of production of
monosomics - Meiotic behaviour of monosomics - monosomics in
maize. Production of nullisomics - meiotic behaviour of
nullisomics - nullisomic analysis - use of nullisomics in locating
genes on chromosomes. Alien gene transfer through chromosome
manipulations - transfer of genome to 4x and 6x wheat - transfer of
genome in the genus Arachis. Transfer of individual whole
chromosomes - alien addition lines - alien substitution lines.
Apomixis - Evolutionary and genetic problems in crops with
apomixes. Chromosome painting, chromosome walking and
chromosome jumping. Artificial chromosome construction and its
uses. Reversion of autopolyploids to diploids: Genome mapping in
polyploids. Fertilization barriers in crop plants at pre and post
fertilization levels. In vitro techniques to overcome the fertilization
barriers in crops. Chromosome manipulations in wide
hybridization; case studies - Production and use of haploids
diploids and doubled haploids in genetics and breeding.
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Content List
S.no. Chapter Page
1. Introduction to Cytogenetics and Chromosomes 1
2. Structural Chromosomal Aberrations
Part-I: Duplications and Duplications 11
Part-II: Inversions 22
Part-III: Translocations (or) Interchanges 35
3. Haploidy 50
4. Polyploidy-Autopolyploidy 60
5. Polyploidy-Allopolyploidy 71
6. Anueploidy 80
Hyperploidy (Trisomics and Tetrasomics)
7. Anueploidy 91
Hypoploidy (Monosomics and Nullisomics)
8. Alien Addition and Substitution Lines 97
9. Matchings 103
Appendices
I. Anueploid Terminology 116
II. Important Tables 119
III. Previous objective bits asked in ASRB –
NET and ICAR-SRF examinations from
Cytogenetics (Memory Based)
125
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IV. Previous questions asked in ARS Mains
examinations from Cytogenetics (Memory
Based)
131
Glossary 133
References 175
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Introduction to
Cytogenetics and Chromosomes
______________________________________________________
1. The science of relationship, of specific genes with specific
chromosomes is
a) Cytology b) Cytogenetics
c) Genetics d) Molecular genetics
2. Cytogenetics was natural outcome of
a) Chromosomal theory of inheritance
b) Cytoplasmic theory of inheritance
c) Multiple factor hypothesis
d) Genic balance theory
3. A diploid nucleus consists of two chromosomes of each type
called
a) Hetero chromosomes b) Homologous chromosomes
c) Non- sister chromosomes d) Heterologous chromosomes
3. Pairing of homologous chromosomes, length-wise occur during
a) Pachytene b) Diplotene
c) Zygotene d) Diakinesis
4. Exchanges of segments due to crossing over occur during
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a) Pachytene b) Diplotene
c) Zygotene d) Diakinesis
6. Chiasma formation occurs in
a) Pachytene b) Diplotene
c) Zygotene d) Diakinesis
7. Chiasma terminalization occurs in
a) Pachytene b) Diplotene
c) Zygotene d) Diakinesis
8. The paired chromosomes arranges at equatorial plate separate
out to form dyads
a) Anaphase I b) Metaphase I
c) Prophase I d) Metaphase II
9. The book “Cytology and Cytogenetics” was written by
a) Stebbins b) Swanson
c) P K Gupta d) Sturtevant
10. The term which is given to a group of characteristics that
identifies a particular chromosome set is called as
a) Indiogram b) Haploid set
c) Karyotype d) Genotype
11. Diagrammatic representation of karyotype is called as
a) Phenotype b) Idiogram
c) Ideotype d) Genotype
12. In case of Idiogram haploid set of chromosomes are arranged
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based on size in-
a) Increasing order b) Decreasing order
c) Based on shape d) None of the above
13. Karyotype with large difference between smallest and largest
chromosomes of the set is called
a) Symmetric karyotype b) Isokaryotype
c) Anisokaryotype d) Asymmetric Karyotype
14. Karyotype asymmetry was extensively studied by Lewitsky in
a) Crepis b) Oryza
c) Triticum d) Brassica
15. In several cases, increased karyotype asymmetry was
associated with specialized
a) Actinomorphic flowers b) Incomplete flowers
c) Zygomorphic flowers d) Complete flowers
16. Linear differentiation of chromosomes with basic stains which
then shows dark and light regions is called
a) Heteropycnosis b) Eupycnosis
c) Chromosome banding d) Chromosome fading
17. The darkly stained regions during chromosome staining at
prophase is
a) Heterochromatin b) Euchromatin
c) Both a & b d) None of the above
18. The lightly stained regions during chromosome staining at
prophase is
a) Heterochromatin b) Euchromatin
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c) Both a & b d) None of the above
19. Heterochromatic regions consists of
a) Chromomeres b) Chromocentres
c) Knobs d) All the above
20. One of the following can act as valuable chromosome markers
for distinguishing related species
a) Chromomeres b) Chromocentres
c) Knobs d) None of the above
21. Very distinct chromosome knobs can be observed in maize at
a) Zygotene b) Pachytene
c) Diplotene d) Diakinesis
22. The banding techniques are based on identification of
chromosome segments which consists of
a) GC rich regions b) AT rich regions
c) Constitutive heterochromatin d) All the above
23. Q-banding technique was given by
a) T. Caspersson b) Landsteiner
c) Swanson d) Stebbins
24. The darkly stained regions at interphase
a) Euchromatin b) Hetero chromatin
c) Both a & b d) None of the above
25. The lightly stained regions at interphase
a) Euchromatin b) Heterochromatin
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c) Both a & b d) None of the above
26. The flourochrome used in case of Q-banding is
a) Acetocarmine b) Feulgen
c) Fuchsin d) Quinacrin mustard
27. Staining of constitute heterochromatin using Giemsa dye was
first observed in chromosomes of-
a) Human b) Mouse
c) Monkey d) Rabbit
28. C and N banding uses
a) Giemsa b) Quinacrin
c) Acetocarmine d) Feulgen
29. C-banding not all the chromosomes were identified, was first
recognized in
a) Pulses b) Cereals
c) Millets d) Oil seeds
30. The banding technique which was originally developed for
location of nucleolar organizers (NORS)
a) Q- banding b) C- banding
c) N- banding d) G- banding
31. Improved N-banding technique (Giemsa) was developed by
combining C-banding and N- banding for studying the
chromosomes of
a) Rice b) Wheat
c) Barley d) Sugarcane
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32. N- banding stains more intensively a specialized
heterochromatin within the
a) C-banding b) Q- banding
c) R- banding d) G- banding
33. G-banding corresponds roughly with
a) R-banding b) Q- banding
c) C-banding d) N-banding
34. R-banding show a pattern which is reverse of
a) C- banding b) N-banding
c) Q-banding d) G-banding
35. The technique used to locate the physical position of known
DNA sequence on a chromosome is called
a) In-situ hybridization b) Ex-situ hybridization
c) Chromosome banding d) None of the above
36. In-situ hybridization technique where specific DNA sequences
are located on chromosomes using radioactive isotopes (or) non-
radioactive labeling followed by staining is
a) FISH b) GISH
c) Chromosome banding d) None of the above
37. In-situ hybridization in which total genomic DNA derived from
alien species used as probe
a) GISH b) FISH
c) ISH d) None of the above
38. GISH is also sometimes called as
a) Alien hybridization b) Genome hybridization
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c) Genome blocking d) Alien blocking
39. Giant chromosomes were observed in salivary gland cells of
dipteran species for the first time in 1881 by
a) Stebbins b) Jenkins
c) Balbiani d) Flemming
40. For studying dipterans giant chromosomes the stage of larva
selected for squashing
a) 1st instar b) 2
nd instar
c) 3rd
instar d) 4th
instar
41. Giant chromosomes are also called as
a) Polytene chromosomes b) Lamp brush chromosomes
c) B-chromosome d) None of the above
42.Giant chromosomes are also called as “Polytene chromosomes”
because of
a) Duplication b) Deletion
c) Endoreduplication d) Endoduplication
43. Differential gene activation in case of giant chromosomes
corresponds to
a) Chromosomes puffs b) Balbiani rings
c) Both a & b d) None of the above
44. A particular kind of supernumerary chromosomes that may be
missing (or) extra chromosomes over and above the standard
diploid or polyploid is
a) Accessory chromosomes b) B- chromosomes
c) Both a & b d) None of the above
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45. Through B-A interchanges in maize, the type of chromosomes
used for chromosome mapping
a) B- chromosomes b) A- chromosomes
c) Both a & b d) None of the above
46. The following are the characteristics of B-chromosomes
a) Not homologous with A-chromosomes
b) Non-mendelian inheritance
c) Dispensable
d) All of the above
47. The chromosomes when present in high number suppress
vigour & fertility are
a) B-chromosomes b) A-Chromosomes
c) Both a & b d) None of the above
48. B-chromosomes are mostly found in
a) Inbreeders b) Outbreeders
c) Partial outbreeders d) None of the above
49. The most significant effect of B-chromosomes in on
a) Pollen fertility b) Seed set
c) Both a & b d) None of the above
50. The book “B-chromosomes” was written by
a) Jones and Rees (1982) b) Carlson (1963)
c) Mounting (1963) d) None of the above
51. Lack of pairing among the chromosomes is called
a) Desynapsis b) Asynapsis
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c) Synapsis d) None of the above
52. Initial pairing which is not followed by effective chiasma
formation resulting in no bivalent and multivalent is
a) Desynapsis b) Asynapsis
c) Synapsis d) None of the above
53. The process which force polyploidy to behave as diploid is
a) Poly polarization b) Diploidization
c) Haploidization d) None of the above
54. Suppression of chromosomes pairing among partially
homologous (or) homeologous chromosomes to behave as diploid
a) Polyploidization b) Haploidization
c) Diploidization d) None of the above
55. The formation of apomictic seed is usually associated with
a) Irregular meiosis b) Polyploidy
c) Both a & b d) None of the above
56. At higher recombination values, mapping function is given by
a) x = logn {( 1+2y)/(1-2y)} b) x = 25 logn {( 1+2y)/( 1-2y)}
c) x = 25 logn {(1-2y)/(1+2y)} d) x = 25 logn {(1+2y)/(1-2y)}
57. Apomictic mode of reproduction was reported in a number of
genera from the families
a) Compositae b) Gramineae
c) Both a & b d) None of the above
58. Apomixis can be studied only at
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a) Vegetative Stage b) Embryonic Stage
c) Reproductive Stage d) None of the Above
59. Apomixis involves
a) Production of unreduced gametophytes
b) Failure of Fertilization
c) Parthenogenesis development of whole plant from unreduced
gametes
d) All the above
60. When chromosome maps are compared with physical maps
a) Distances differs b) Linear order remains same
c) Both a & b d) Linear order differs
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