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

Is cancer a disease transmitted to the individual offspring, How are mutage...

How are mutagenic agents related to cancer incidence in a population? Is cancer a disease transmitted to the individual offspring? The exposition of a population to mutagenic a

Saturated fatty acids, Saturated Fatty Acids - These are solid at ro...

Saturated Fatty Acids - These are solid at room temperature. These are metabolically less active so have a tendency to deposit in the body (synthesized in body) These

Determine the characteristics of soil profile, Characteristics of Soil Prof...

Characteristics of Soil Profile  The profile characteristics studied in the field consist of locating the soil hor izons (based on its colour description that includes the  col

Describe briefly tyndall effect, Tyndall Effect One of the best ways to...

Tyndall Effect One of the best ways to distinguish a solution from a colloidal dispersion is to use a strong beam of intense light. As the beam passes through a colloidal dispe

What do you understand by tegument, What do you understand by tegument? ...

What do you understand by tegument? Outer covering of parasitic flatworms, including tapeworms and flukes, comprising a syncytial outer layer of cytoplasm connected to cell bod

What is the incubation period of an infection, What is the incubation perio...

What is the incubation period of an infection? Incubation period is the time interval among the infection by an agent that causes disease and the first signs or symptoms of th

Photosynthesis, why we add some sodium bicarbonate in water?

why we add some sodium bicarbonate in water?

What is mass transportation across the cell membrane, What is mass transpor...

What is mass transportation across the cell membrane? Mass transportation is the entrance or the exiting of substances in or from the cell engulfed by portions of membrane. The

Mass extinction, Mas s Extinction - Since beginning many species ev...

Mas s Extinction - Since beginning many species evolved and got extinct (in fact only 1 % is living). Sometimes it occured suddenly at large scale, (most recently dinosa

Explain the requirement of nutrition during stress, Explain the requirement...

Explain the requirement of Nutrition during Stress? We all experience stress at some time or the other in life. Stress is the condition or stimulus that threatens the body's ho

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