Types of ribosomes, Biology

Assignment Help:

TYPES OF RIBOSOMES

Ribosomes are of two types:-

1. Procaryotic Ribosomes -

70 s = Occur in cytoplasm of prokaryotes, and also in mitochondria, and Chloroplast of eukaryotes

2. Eukaryotic Ribosomes -

80 s = Occur in cytoplasm of eukaryotic cells.

  • Each ribosome composed of two subunits i.e. larger and smaller subunits.
  • Larger subunit is dome-shaped and smaller is ovoid. Smaller subunit has a platform, a cleft, a head and a base.
  • The larger subunit has a protuberance a ridge and a stalk. Larger subunit also contains a tunnel which opens in cavity of E.R.
  • 40s + 60s = 80s
  • 30s + 50s = 70s
  • Two subunits are held together by Mg+2. Mg+2 form ionic bond with phosphate groups of rRNA of two subunits.
  • Minimum 0.001M Mg+2 concentrations required for structural formation of ribosomes. If Mg+2 concentration increased 10 times then ribosome DIMER are formed.

583_ribosomes.png

 

  • In prokaryotes 100s type of dimers are formed, whereas in eukaryotes 120s dimers are formed.

1036_ribosomes1.png

52_ribosomes2.png

  • At the time of proteins synthesis, several ribosomes become attached to m-RNA with the help of smaller subunits.
  • This structure is called polyribosome or polysome or Ergosome.
  • The ribosomes move along the m- RNA like beads on a string. Larger subunit contains peptidyl transferase enzyme which catalyses synthesis of peptide bond bet amino acids. Larger subunit has two sites.

(i) A-site - Acceptor site for t-RNA

(ii) P-site - site for growing polypeptide chain

  • After synthesis on ribosomes protein are transported in cytoplasm and organelles.
  • The proper folding of proteins following synthesis is assisted by specific proteins called chaperons which also assist in transport of proteins.

Related Discussions:- Types of ribosomes

Air movements at tropical latitudes, Air movements at tropical latitudes ...

Air movements at tropical latitudes Let us now explain air movements at tropical latitudes. The surface air that rushes to fill the equatorial void from the north is deflected

Cell surface junctions, CELL SURFACE JUNCTIONS (1 )      Desmosomes (...

CELL SURFACE JUNCTIONS (1 )      Desmosomes (Maculae adherence) - Thickened circular areas on P.M. of adjacent cells with radiating fibrils in cytoplasm. These fibrils calle

What is brown algae, What is Brown Algae ? Phaeophyta are commonly know...

What is Brown Algae ? Phaeophyta are commonly known as brown algae; precisely because they are - guess what? - brown in color! They are brown because they contain brown colored

Aschelminthes, in what part of the human body aschelminthes found?

in what part of the human body aschelminthes found?

How is the respiratory system of insects, Q. How is the respiratory system ...

Q. How is the respiratory system of insects with its independence between respiration and circulation related to the motor agility of some species of this arthropod class? Even

Short-day plants (sdp) - plant responses to light-dark cycle, Short-Day Pla...

Short-Day Plants (SDP) - Plant Responses to Light-Dark Cycles These plants only flower or flower more profusely and rapidly when given less than a certain (critical) number of

What is chromosome mapping in phenotypic trait, What is Chromosome Mapping ...

What is Chromosome Mapping in phenotypic trait? Chromosome Mapping : By noting how often a gene segment associated with a specific phenotypic trait crossed over during meios

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