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

Compute the amount of nacl need, A saline drip is to be prepared for a lab ...

A saline drip is to be prepared for a lab experiment that is looking at hydration in lab rats. Calculate the amount of NaCl need to make 4 liters of a 0.9% solution.

Explain the meaning of anthropometric measures, Explain the Meaning of anth...

Explain the Meaning of anthropometric measures Anthropometric Measures mean and its uses. The term Anthropometric refers comparative measurement relating to the body structure.

Define the recommended dietary allowances of vitamin k, Define the Recommen...

Define the Recommended Dietary Allowances of Vitamin K? Recommended dietary intakes have not been suggested for different age groups or gentler. The safe levels of intake have

Shock, S h o c k It is defined as a generalized acute reduction in ...

S h o c k It is defined as a generalized acute reduction in the perfusion of tissues by which there is oxygen deficiency in the cells. It is characterized by reduction in e

Tissue, Ask ques different tipe tissue and ideas minimum 100 words accepted...

Ask ques different tipe tissue and ideas minimum 100 words accepted#

Drawbacks of nutritional status that assessed traditionally, Define drawbac...

Define drawbacks of Nutritional status that assessed traditionally? Nutritional status assessed traditionally with the use of anthropometric, biochemical clinical and dietary a

Characteristics of river systems, Characteristics of River Systems Th...

Characteristics of River Systems The basic function of the rivers is to convey surplus rain water from land to sea. Annually the rivers carry fresh water, equivalent to 25 cm

Zoonoses disease-monkey b virus disease, Monkey B virus disease The di...

Monkey B virus disease The disease is caused by Herpesvirus simiae or B virus, a member of the herpes group of viruses. The infection occurs naturally among primates of the ge

What are cytokines, What are Cytokines? Cytokines are polypeptides, whi...

What are Cytokines? Cytokines are polypeptides, which influence the proliferation, differentiation, metabolism and activation of cells. There are three areas in cancer that hav

How are roots affected by water, How are roots affected by water? Grow ...

How are roots affected by water? Grow some seedlings in single end of a glass dish or pan. When they are about 5 cm tall start watering them on one side only and a little dista

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