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

Define use of isotopically labelled nutrients, Define Use of Isotopically L...

Define Use of Isotopically Labelled Nutrients? Nutrient Turnover Radioactive labelled nutrients are used to know the total body pool and the compartment in which it is stored.

Processing grains and oil seeds for animal feeding, Processing grains and o...

Processing grains and oil seeds for animal feeding Simple processing of grains such as grinding facilitates the digestion particularly in cattle and buffaloes. Fine grinding of

Describe the morphological characteristics, Q. Describe the Morphological C...

Q. Describe the Morphological Characteristics? One of the first steps in the identification of bacteria in food is microscopic examination to ascertain the shape, size, aggreg

Nutritional management in inflammatory bowel disease, Q. Nutritional Manage...

Q. Nutritional Management in Inflammatory Bowel Disease? Adequacy of nutritional needs and minimizing stress on the inflamed or narrowed segment of the bowel are the main princ

Define biomaterial and an implant, Define biomaterial and an implant and st...

Define biomaterial and an implant and state their role in general Biomaterial : A pharmacologically inert material that is capable of interacting with a living organism witho

Hydrarch - kinds of succession, Hydrarch - Kinds of Succession When su...

Hydrarch - Kinds of Succession When succession takes place in a wet area, that is, succession progresses from hydric to mesic conditions. This can be further subdivided as:

Hydrology, Hydrology Background: Hydrology is the study of the move...

Hydrology Background: Hydrology is the study of the movement and distribution of water resources. This is an important field of study in a dry climate like Utah. Although c

Explain prophylaxis - fungal infection, Prophylaxis   High-risk neutrope...

Prophylaxis   High-risk neutropenic patients, such as those undergoing allogeneic and certain autologous stem cell transplants, and those with hematologic malignancy who are exp

Classification of living beings, Q. What is the Biology field that studies ...

Q. What is the Biology field that studies the classification of living beings? The Biology field that studies the classification of living beings is termed as Taxonomy. Q.

Explain indications for surgery of total anomalous, Explain Indications for...

Explain Indications for Surgery of Total Anomalous pulmonary Venous Connection ? Once TAPVC is diagnosed in a neonate with symptoms, operation should be undertaken immediately.

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