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RIBOSOMES

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Eukaryotic Ribosomes Eukaryotic ribosomes are larger than 70S ribosomes. The ribosome consists of two subunits (a large and a small) constructing an 80S particle. – PowerPoint PPT presentation

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Title: RIBOSOMES


1
RIBOSOMES
2
Discovery of Ribosomes
  • Ribosomes first appeared under the electron
    microscope as dense granules.
  • This discovery was made in the mid-1950s by
    Romanian cell biologist George Palade.

3
Ribosome Synthesis
  • Ribosomes are large ribonucleoproteins assembled
    from proteins and ribosomal RNA.
  • In eukaryotic cells the manufacturing of
    ribosomes takes place in the nucleolus.
  • Whereas in prokaryotes ribosomes are synthesised
    in the cytoplasm.

4
Eukaryotic Ribosomes
  • Eukaryotic ribosomes are larger than 70S
    ribosomes.
  • The ribosome consists of two subunits (a large
    and a small) constructing an 80S particle.
  • The larger 60S subunit and the smaller 40S
    subunit.

5
Bacterial Ribosome
  • Bacterial ribosomes have an overall Svedberg unit
    of 70S.
  • Comprised of a large 50S subunit and a small 30S
    subunit.

6
Image displaying translation taken from DNA the
secret of life Watson and Berry (2003) DNA the
secret of life.
7
Translation
  • mRNA template associates with small sub-unit.
  • Ribosomes form peptide bonds between adjacent
    amino acids.
  • The growing polypeptide chain leaves the ribosome
    through an exit tunnel in the body of the large
    subunit.

8
Translation cont.
  • The reaction continues until the ribosome meets a
    STOP codon.

9
References
  • Berg, J.M., Tymoczko, J.L., Stryer, L., 2006.
    Biochemistry. 6th Edition. New York W.H. Freeman
    And Company.
  • Raven, P.H., Johnson, G.B, Mason, K.A, Losos, J.,
    Singer, S., 2008. Biology. 8th edition.
    BostonMcGraw Hill, Higher Education.
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