Showing posts with label 30S. Show all posts
Showing posts with label 30S. Show all posts

Tuesday, 25 February 2014

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How do prokaryotes produce ribosomes without a nucleus?

Prokaryotes have 70S(it is measure in centrifuge) ribosomes, each consisting of a small (30S) and a large (50S) subunit and each sub-units have different proteins and RNA's in too groups
In the nuclear region they contain their own circular shaped DNA and RNA segments called "bacterial chromosomes". This contains instructions on how to make essential ribosomes. The ribosomes float freely in the cytoplasm of the prokaryotic cell.
They  reproduce by a process that is called binary fission. The  DNA in such cells is contained in a single circular chromosome called a plasmid within the cytoplasm. The reproductive process starts with the replication of the chromosome. The new chromosome attaches itself to the plasma membrane and the two chromosomes migrate to opposite ends of the cell. The plasma membrane in the middle of the cell grows inward until it closes to separate the cell into two compartments, each with a full complement of genetic material. The cell then "fission" at the center, forming two new daughter cells.
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Monday, 23 December 2013

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In bacteria, a 70S initiation complex is assembled from the two ribosomal subunits, mRNA, and initiator tRNA with the assistance of three initiation factors and energy from GTP.

The sequence of event in which this process takes place in a very brief manner 

please list the following in order
A. IF3 binds to the 30S subunit and prevents its association with the 50S subunit.
B. Initiation factors are released from the complex
C. The 50S subunit joins the complex
D. tRNAfMet, with the IF2 and GTP bound, binds to the start codon. IF1 then binds to the A site of the 30S subunit.
E. A 70S iniation complex is formed
F. The 16S rRNA base-pairs with the Shine - Dalgarno sequence.

  1. IF3 binds to the 30S subunit and prevents its association with the 50S subunit.
  2. The 16S rRNA base-pairs with the Shine - Dalgarno sequence.
  3. tRNAfMet, with the IF2 and GTP bound, binds to the start codon. IF1 then binds to the A site of the 30S subunit.
  4. The 50S subunit joins the complex
  5. Initiation factors are released from the complex
  6. A 70S initiation complex is formed
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