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

Explain terms of osmosis, A red blood cell has an internal salt concentrati...

A red blood cell has an internal salt concentration of 150mM. The cell is placed in a beaker of 500mM salt. (a) Assuming that the cell membrane is permeable to water but not to

Biotic potential of a bacterial population, Q. How different is the growth ...

Q. How different is the growth according to the biotic potential of a viral population from the growth according to the biotic potential of a bacterial population? The growth c

5 kingdom system, what r the demerits of 5 kingdom classification?

what r the demerits of 5 kingdom classification?

Explain the functionality of carboxymethyl cellulose, Functionality of CMC ...

Functionality of CMC CMC is soluble in cold water and mainly used for controlling viscosity without gelling. As its viscosity drops during heating, it may be used to improve t

What type of bonds is susceptible to hydrolysis, What type of bonds is susc...

What type of bonds is susceptible to hydrolysis? Book examples are C-N and C-OH.

Are there ribosomes in a plant cell, Are there ribosomes in a plant cell? ...

Are there ribosomes in a plant cell? Yes, in fact there are ribosomes in both plant and animal cells. That is right. Ribosomes are the site of synthesis of polypeptide chain

Explain the identification of fungi and yeasts, Explain the Identification ...

Explain the Identification of Fungi and Yeasts? In this we learnt about different staining techniques used to visualize bacterial cell morphology. What about identification tec

Systems of human body, Systems of Human Body Many organs work in a coo...

Systems of Human Body Many organs work in a coordinated'manner to form a system. For example in our-body the nose, the trachea and the lungs form the respiratory system. Table

What is the bio-medical waste, What is the Bio-medical waste The Bio-m...

What is the Bio-medical waste The Bio-medical waste (Management & Handling Rules), 1998 is applicable to all persons, who generate, collect, receive, store, transport, treat,

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