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 is the goal of risk assessment, What  is  the  goal  of  risk ass...

What  is  the  goal  of  risk assessment? The goal of risk assessment is to provide risk managers, who might be, for example, government regulatory officials, industry health a

What is megalobastic anemia, Question 1) What is megalobastic anemia? Disc...

Question 1) What is megalobastic anemia? Discuss briefly its lab diagnosis. How would you differentiate megaloblastic anemia from other anemias? Question 2) What is hem

Explain the meaning of a repression lag, Which of the following most accura...

Which of the following most accurately explains the meaning of a repression lag? A. A repression lag refers to the time that it takes for the last full-length mRNA transcript t

The seven levels of taxonomy, how are the listed from largest group to smal...

how are the listed from largest group to smallest group

Explain iron and zinc, Give information as asked about the following minera...

Give information as asked about the following mineral nutrients in plants: a. Iron: i. it is a constituent of-, ii. it's one typical deficiency symptom. b. Zinc:

Reasons for increasing popularity of dental implants, Q. Reasons for increa...

Q. Reasons for increasing popularity of dental implants? There are various reasons for increased popularity of dental implants. With the rapid development and evolution of impl

What are rna polymerase subunits, Each of the three eukaryotic RNA polymera...

Each of the three eukaryotic RNA polymerases has more subunits or 12 and so these are big complex enzymes. The genes encoding some of the subunits of each  eukaryotic  enzyme  show

How we can do karyotype analysis, Why in the preparation of a karyotype ana...

Why in the preparation of a karyotype analysis is the use of a substance like colchicine interesting? Colchicine is a substance that disallows the formation of microtubules and

What is the function of lymph nodes, Explain function of lymph nodes? L...

Explain function of lymph nodes? Lymph nodes have white blood cells which ingest bacteria and prevent them from reaching the circulation.

Explain atrial pressure, Q. Explain Atrial Pressure? The RA pressure wa...

Q. Explain Atrial Pressure? The RA pressure wave form has three positive deflections - "a", "c", and "v" waves. The "a" wave is due to atrial systole and follows the P-wave on

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