Chromosomes and their organization, Biology

Assignment Help:

Chromosomes   and Their Organization

During  division  phase , the duplicated  chromatin  fibres  become extremely  shortened (= condensed),  by coiling and folding ,into short think and microscopically   visible  rod like structures  of various  shapes and sizes, It  is necessary to learn about  these  structures before  dealing with  the sequential changes of mitosis. These  structures werer  observed first  by Naegeli 1842 and later by russow 1872 and Balbiani 1876  waldeyer 1888 named these,  chromosomes gr.khroma =coloured + soma =body ) because these take a  dark  stain  when treated  with basis dyes.

Karyotype :Beneden  1888 discovered   that the  chromosomal  pattern  is a specific  character .i.e.   each  species  has  its own chromosomal  complement different  from those  of all  other  species ,This  complement  of a species is called  its karyotype  .It  implies  that in all cells   membrane  of a plant or animals  species,  not only  the number  of chromosomal is the  same  but even  the  shapes  sizes,  and structure  of   the  various chromosomes  in the set are the same .The  chromosomal  number  varies from 10 to 50 in most  of the species,  The smallest  number is however two  found  in a nematode subspecies  ascaris megalocephala  univalence, and the largest  number is 1600 in  aulacantha ( a radiolarian protozoan ) To  quote a few  examples    the chromosomal  number is 46  in man  ( Homo sapiens )  32 in Hydra vulgaris. 12  in housefly (Musca domestica ) 26 in frog  (Rana pipiens )  in rabbit, (Oryctolagus  cuniculus ) 38 in cat (Felish domesticus ) 78 in dog (cains familiaris)  80 in pigeon (Columba  livia)  8 in fruitfly ( Drosophila melanogaster ) in mosquito ( Culex pipiens ) and so on.


Related Discussions:- Chromosomes and their organization

What is etiopathology, Q. What is Etiopathology? Who is likely to devel...

Q. What is Etiopathology? Who is likely to develop gout? What are the risk factors? Let us find out. Gout is caused when there is over production of uric acid in normal purine

What do you mean by the spinal cord, Q. What is the spinal cord? Of which e...

Q. What is the spinal cord? Of which elements is the spinal cord constituted? The spinal cord is the dorsal neural cord of vertebrates it is the part of the central nervous sys

Planning and implementation of nursing care - purpura, Planning of Nursing ...

Planning of Nursing Care   Minimise  trauma  to the child and provide safe environment.  Control bleeding.  Administer drugs.  Implementation of Nursing Care

Explain the irradiation and its implication, Explain the Irradiation and it...

Explain the Irradiation and its Implication The issues are the decreased salivary flow, liability for infection because of the decreased blood supply and the possibility of ost

Define hormonal and receptor proteins, Define Hormonal and Receptor Protein...

Define Hormonal and Receptor Proteins? Hormonal proteins : Hormonal proteins coordinate the bodily activities. Several peptide and protein hormones (like insulin and growth ho

What is biomaterial, What is Biomaterial Biomaterial is defined, in the...

What is Biomaterial Biomaterial is defined, in the broader sense, as any pharmacologically inert material that is capable of interacting with a living organism without causing

Explain in brief about cytokines, Cytokines activate inflammatory cells lik...

Cytokines activate inflammatory cells like neutrophils and eosnophils.IL-5 is important in activation of eosnophils, IL-4 enhances IgE production by B-cells. IL-4, Il-5, IL-6, TNF-

What do you mean by crystalline style, What do you mean by crystalline styl...

What do you mean by crystalline style? A rodlike structure in some mollusc stomachs which is made of enzymatic proteins required for digestion. Cilia lining the stomach rotate

Explain the principle of nelson-somogyi method, Explain the Principle of Ne...

Explain the Principle of Nelson-Somogyi Method? Glucose is estimated by Nelson-Somogyi method. We begin our study of this method by getting to know the principle involved in th

Difference, 1:What is the difference between TERGA and STERNA? 2:What is th...

1:What is the difference between TERGA and STERNA? 2:What is the difference between AMPHID and PHASMID?

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd