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OBJECTIVE CYTOGENETICS


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Publishing-in-support-of,

EDUCREATION PUBLISHING

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Printed in India


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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,


(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


(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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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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Srijan and Rakesh (2016)

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6. Chiasma formation occurs in



7. Chiasma terminalization occurs in



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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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


25. The lightly stained regions at interphase

a) Euchromatin b) Heterochromatin



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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


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




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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


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


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


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


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


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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