Centrioles, Biology

Assignment Help:

Centrioles

  • Centrioles is also called cell centre.
  • Centrosome discovered by Benden. T. Boveri called it centrosome.
  • Centrosome is present in all animal eukaryotic cells but absent in higher plants.
  • H. Fol discovered spindle fibres.
  • Two centrioles located just outside nucleus, lie at right angle to each other.
  • Surrounding cytoplasm is clear called "Centrosphere" or "Kinoplasm".
  • Centrioles + centrosphere = Centrosome or Microcentrum or Diplosome.
  • Due to clear and shining centrosphere, centrioles are previously thought as light artifact. One end of centriole is open and other end is closed.
  • Centrioles are membraneless elongated structure.
  • Centrioles exhibit "Cart Wheel Structure" (Just like Basal body of Cilia). Basal body is also a type of centriole.

 

1208_centrioles.png

  • Each centriole consists of 9 peripheral microtubules and each microtubule made up of three sub tubules which are called A, B and C. So centriole is made up of peripheral triplet.
  • Each subtubule is made up of 13 protofilaments.
  • Each protofilament is a dimer of a and b tubulin protein.
  • Microtubules of centriole are made up of tubulin protein.
  • Central microtubules are completely absent in centriole but in central part Hub protein is present.
  • Each peripheral microtubule connects with hub protein with the help of radial spoke.
  • Terminal end of radial spoke (towards peripheri) forms a dense structure called X-body, which is present near the A-subtubule.
  • Between two X bodies, a Y-body is also present.
  • Each Y-body connected to X-bodies on its both sides.
  • A-C linker connects C- sub tubule of a microtubules with A-subtubule of another microtubule.
  • Randell and Disprey discovered DNA in centriole, which is called centriolar DNA. It has not been isolated till now but its presence is confirmed. Centriolar DNA is probably circular, naked and double stranded. Centriolar DNA helps in duplication of centriole during G phase of cell division but recently it is beleived that Massules or Pericentriolar Satellites help in duplication of centriole.
  • Around each peripheral microtubule a spherical structure is present, which is called Pericentriolar Satellites or Massules. These are 9 in number.
  • Centrioles are self duplicating units, contain DNA and RNA and are capable of protein synthesis.

Related Discussions:- Centrioles

Spiral cleavage - metazoa, Spiral Cleavage - Metazoa In Spiral Cleavag...

Spiral Cleavage - Metazoa In Spiral Cleavage, however, the third and fourth cleavage planes are oblique to the polar axis and the resulting blastomeres do not lie on top of on

Explain ketoconazole, Explain Ketoconazole It is now seldom used. The ...

Explain Ketoconazole It is now seldom used. The other azoles have fewer adverse effects and are usually preferred. Ketoconazole remains an option for treatment of infections w

Dissimmilarity between an ecosystem and a biome, What is the difference bet...

What is the difference between an ecosystem and a biome?

Define metabolic effects of thyroid hormones, Define Metabolic Effects of T...

Define Metabolic Effects of Thyroid Hormones? Although (T 4 ) is quantitatively predominant, (T 3 ) is the more active form. The mechanism of action of thyroid hormones appears

Hemoglobin binds o2 cooperatively, Which of the following statements is cor...

Which of the following statements is correct? A. Hemoglobin binds O2 cooperatively, while myoglobin does not. B. Myoglobin binds O2 cooperatively, while hemoglobin does not.

Describe the factors of maintenance of implants, What are the special consi...

What are the special considerations required to be taken in maintenance of implants? The procedures for maintenance of patients with implants are similar to those with natural

Acclimation and acclimatisation, Normal 0 false false false...

Normal 0 false false false EN-IN X-NONE X-NONE MicrosoftInternetExplorer4

Radiation cataract and steroid induced cataract of the eye, Explain the rad...

Explain the radiation cataract and steroid induced cataract of the eye. Radiation Cataract Exposure to radiation causes discoid posterior sub-capsular opacities. Mechanism o

Explain the classification of malignant tumors, Explain the Classification ...

Explain the Classification of Malignant Tumors Malignant tumors can be classified as: Carcinomas: These tumors arise from the epithelial lining (the squamous cells) e.g. ski

What are integral membrane proteins, Membrane proteins are classify as eith...

Membrane proteins are classify as either integral (intrinsic) or peripheral (extrinsic) depending on how tightly they are linked with membrane. The Integral membrane proteins are s

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