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

Nervous tissue and its components, NE R V OU S TISSUE The nervous...

NE R V OU S TISSUE The nervous tissue in general develops from the ectoderm of the embryo, but the microgliocytes. It does not have a matrix. The special properti

Describe u - waves, Q. Describe U - Waves? The U-wave is usually uprigh...

Q. Describe U - Waves? The U-wave is usually upright if the T is also upright and is highest at low rates. When the heart rate increases to more than 90, the U-wave is rarely v

Anaphase of karyokinesis, There is no splitting of the centromere. The ...

There is no splitting of the centromere. The kinetochore fibers contract and the spindle or pole fibers elongate , As a result homologous chromosomes of each pair rather than

Explain adverse effects of fosamprenavir calcium, Explain adverse effects o...

Explain adverse effects of fosamprenavir calcium   Adverse effects are similar to those with amprenavir, but in clinical studies the incidence of nausea, vomiting and severe ra

Explain beginning and the end of the third interphase period, Q. What are t...

Q. What are the events that mark the beginning and the end of the third interphase period? What happens in the cell in this period? The third interphase period is the G2, It be

What occurs to transcription at the lac operon, What happens to transcripti...

What happens to transcription at the lac operon when lactose is absent and why? What happens to transcription at the lac operon when lactose is present and why? What happens

What are the main biological functions of water, What are the main biologic...

What are the main biological functions of water? Water is the basic solvent for chemical reactions of living beings; it is the major means of substance transportation in the ce

Disadvantages of m - mode echocardiography, Various structures are seen in...

Various structures are seen in two-dimensional planes; hence mental conceptualization is still required because the heart is three-dimensional. Now, newer technology has evolved

Chlamydiosis-epidemiology, Epidemiology The organism does not appear t...

Epidemiology The organism does not appear to be very host or tissue specific and can infect naturally a large number of avian and mammalian species. Chlamydiosis has been reco

Define physiology cohesion and adhesion theory, Define Physiology: Cohesion...

Define Physiology: Cohesion & Adhesion Theory? Transport in Plants :  Transport of water, minerals and nutrients within vascular plants is dramatically different from animals

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