PROTEIN SYNTHESIS - 123SeminarsOnly.ppt

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PROTEIN SYNTHESIS - 123SeminarsOnly.ppt Powered By Docstoc
					PROTEIN SYNTHESIS


   PRESENTATION


   Adenine
   Uracil
   Guanine
   Cytosine
There are two processes
involved:

• Transcription-Copying of DNA code to
  form mRNA.



• Translation-Conversion of RNA code into a
  sequence of amino acids.
Transcription-RNA polymerase binds to double helix at
promoter region


RNA POLYMERASE




                           DNA DOUBLE HELIX
Bonds between bases are broken and DNA double helix unwinds


                                          Sense strand




                                         Anti-sense strand
Free nucleotides from inside nucleus bind onto exposed DNA
bases forming a molecule of mRNA


                     Sense strand

                                                 Free
                                                 Nucleotides




                    Anti-sense strand
When mRNA has formed, it moves away and the DNA reforms




                        +            DNA double helix rewinds




                                      mRNA
•The 5` end of the polynucleotide mRNA is modified by a
guanine cap which is thought to be a translation promoter.
•About 100 adenines (POLY A) are added to the 3` end
which is thought to:
   >to be a signal for the exit of mRNA from the nucleus.
   >Protect mRNA from enzyme action.

                                                   5` end
  3` end
 Poly-A
                                                      Guanine
                                                      “CAP”
                                          mRNA
       Translation- Diagram of an anti-codon
                        Anti Codon bases




tRNA




                                      Amino acid
2 codons enter the information processing region of ribosome.
An anti-codon attaches to the bottom of ribosome and codes the
amino acid with corresponding bases.
                                   2 Codons


                                                      mRNA




         5` end
                                                          3` end

                                                    Ribosome
    Anti Codon.
A second anti-codon comes along and after it has coded
its amino acid, a peptide bond is formed between the 2
amino acids



                                                  mRNA




     5` end
                                                         3` end

                                                Ribosome
Anti Codon.

                              Peptide bond
The first anti-codon detaches leaving its amino acid behind.
The mRNA moves along ribosome and a third tRNA binds onto the
third codon.
                                2nd and 3rd codons



5` end



                                                  3` end




                          Peptide bond
         The End
By Sahira, Kulsoom and Sarah.

				
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posted:2/24/2014
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Lingjuan Ma Lingjuan Ma
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