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 would be the probability of obtaining result, A plant grown from one o...

A plant grown from one of Mendel's yellow peas is selfed. Five progeny peas are obtained from this self and they are all yellow. If the original selfed plant had been homozygous, w

Simple precautions to prevent injuries, When resheathing needles, simple pr...

When resheathing needles, simple precautions to prevent injuries are to: 1. use only one hand to scoop the cap 2. hold the sheath with a hemostat (suggested but will require

Determine about the microtubules, Determine about the microtubules The...

Determine about the microtubules The microtubules are hollow tubular structures formed by a special arrangement of two proteins called the alpha and beta tubulins. The microtu

How to use atp to make reactions go, What do enzymes do, and how? How is en...

What do enzymes do, and how? How is enzyme activity regulated in cells? How do ATPases u se ATP to make reactions go?

Pathophysiology, Case scenario Mr Kit Lee, a 28-year-old unrestrained dr...

Case scenario Mr Kit Lee, a 28-year-old unrestrained driver of a utility, was travelling on a highway at 100kph and swerved to miss road debris. He lost control and struck a tre

Relate mitochondria organelles with eukaryotic cells, Relate Mitochondria o...

Relate Mitochondria organelles with eukaryotic cells Mitochondria are highly specialised organelles in eukaryotic cells. These perform the energy transducing process, and are o

Light and distribution, Light and Distribution We have mentioned in the...

Light and Distribution We have mentioned in the beginning that the variation in the amount of light generally affects the global and local distribution of plants and animals. L

Biological fixation - nitrogen fixation, Biological fixation - Nitrogen Fix...

Biological fixation - Nitrogen Fixation Approximately 63% of all nitrogen fixed is through biological fixation. Nitrogen fixing organisms are primarily prokaryotes; bacteria a

What are the main endocrine glands of the human body, What are the main end...

What are the main endocrine glands of the human body? The major endocrine glands of the human body are the pineal gland (or pineal body), the hypophysis (or pituitary), the thy

Heat production and respiratory quotient for foodstuff types, Heat producti...

Heat production and respiratory quotient for foodstuff types The heat produced during the metabolic activities of the body helps in maintaining the body temperature. Generally

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