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

Dietary considerations oesophagitis, Q. Dietary considerations oesophagitis...

Q. Dietary considerations oesophagitis? The dietary considerations for this condition are the same as in oesophag it is. The patient should be recommended to: • eat smaller

Cloning, there are a restriction map of a plasmid and a human gene of known...

there are a restriction map of a plasmid and a human gene of known sequence. Your task is to clone the human liver cDNA for this gene so that the start codon is closer to the EcoRI

Name two stimulant drugs, Name two stimulant drugs and state the undesirabl...

Name two stimulant drugs and state the undesirable side-effects of each. Amphetamine and cocaine are stimulant drugs. The side-effects of amphetamines are high blood pressure;

Determine the functions of human body system, Determine the function of hum...

Determine the function of human body system Human body has different systems to perform different functions. A system consists of organs to perform a particular set of function

Vaso-constriction, what is a vaso-constriction? what are the effects of vas...

what is a vaso-constriction? what are the effects of vaso-constriction in the skin?

Class of subphylum uniramia - pauropoda, Class of Subphylum Uniramia - Paur...

Class of Subphylum Uniramia - Pauropoda A small group of uniramians, there are 500 species of Pauropoda explained so far. The minute organisms computing about 1.5 mm in length

Explain the reinforcement of patch using fibrin glue, Explain the Reinforce...

Explain the Reinforcement of Patch using Fibrin Glue? Reinforcement of Patch using Fibrin Glue :  In this technique Dacron graft is first sutured to the septum beyond i

Anti-malarial drugs kill the parasites in the blood, (a) Anti-malarial drug...

(a) Anti-malarial drugs kill the parasites in the blood but they do not cure the disease.Why is this? (b) Why was the use of DDT insecticide not successful in eradicating mal

What are the soil-forming factors, What are the soil-forming factors Th...

What are the soil-forming factors There are many degrees or variations of soil-forming factors, and the potential for creating different kinds of soil is enormous. However, whe

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