PROTEIN SYNTHESIS

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PROTEIN SYNTHESIS Powered By Docstoc
					         Quiz on DNA & RNA
• Actual link to quiz in case hyperlink doesn’t
  work:
• http://www.biologyjunction.com/qz_DNA.html
     PROTEIN SYNTHESIS
• Genes: small sections of DNA
  – Controls production of proteins
  – Nucleotide: base unit for strand of DNA (made
    of sugar, phosphate and nitrogenous base
       PROTEIN SYNTHESIS
• Proteins are used to build cells and control
  chemical reactions so they do most of the work
  – Ex: breaking down glucose in cellular respiration,
    digesting food, making spindle fibers in mitosis
     PROTEIN SYNTHESIS
• Proteins are polymers of amino acids
  – Amino acid chains are call polypeptides
• Nucleotides in each gene has info for
  assembling string of amino acids that make
  up a single protein
     PROTEIN SYNTHESIS
• Enzymes control all chemical reactions of
  organisms

• DNA has instructions for making proteins,
  therefore, DNA controls cells
  – Provides workers with instructions


• Workers for protein synthesis take
  instructions, the workers are RNA
  Replication Fork Annimation
• http://highered.mcgraw-
  hill.com/olcweb/cgi/pluginpop.cgi?it=swf::
  535::535::/sites/dl/free/0072437316/120076
  /micro04.swf::DNA Replication Fork
    PROTEIN SYNTHESIS
• RNA:
 – Nucleic acid
 – DNA = double helix (zipper);
 – RNA = single helix (one side of zipper)
     PROTEIN SYNTHESIS
• RNA: workers for protein synthesis
  – Take instructions for how proteins are
    assembled
  – RNA assembles protein
     PROTEIN SYNTHESIS
3 Types of RNA that build proteins:
    1. Messenger RNA (mRNA)
    2. Ribosomal RNA (rRNA)
    3. Transfer RNA (tRNA)
      PROTEIN SYNTHESIS
1. Messenger RNA (mRNA):
  •   Brings instructions from DNA to cytoplasm
  •   In cytoplasm, moves to ribosome
  •   The ribosome is made up of ribosomal RNA
      (rRNA)
      PROTEIN SYNTHESIS
2. Ribosomal RNA (rRNA):
  –   Makes up ribosome
  –   Binds to mRNA
  –   Uses instructions to assemble amino acids in
      correct order
      PROTEIN SYNTHESIS
3. Transfer RNA (tRNA):
  •    the “supplier”
  •   Delivers amino acids to ribosome to be
      assembled into a protein




                  Click image to view movie
      PROTEIN SYNTHESIS
• Transcription:
  – In nucleus, enzymes make an “RNA copy” of piece
    of DNA strand
  – Result: formation of 1 RNA molecule (1/2 zipper)




                   Click image to view movie
PROTEIN SYNTHESIS
     PROTEIN SYNTHESIS
• Genetic Code:
  – Genetic message of info for building protein
  – Proteins contain chains of amino acids
     • Language of proteins = alphabet of amino acids
  – In DNA, nitrogen bases are: A T C G
  – In RNA, nitrogen bases are: A U C G
PROTEIN SYNTHESIS
     PROTEIN SYNTHESIS
• Genetic Code:
  – Codon: group of three bases in mRNA
  – All organisms use same genetic code
     PROTEIN SYNTHESIS
• Translation:
  – Converting info in sequence of mRNA bases
    into sequence of amino acids in protein
  – Takes place at ribosomes in cytoplasm
     PROTEIN SYNTHESIS
• Translation: From mRNA to Protein
  – mRNA made in nucleus travels to cytoplasm
  – In cytoplasm, ribosome attaches to strand of
    mRNA like clothespin clamped onto clothesline
     PROTEIN SYNTHESIS
• Function of tRNA
  – Transfers RNA to ribosomes
  – Each tRNA attaches to one type of amino acid
     PROTEIN SYNTHESIS
• Function of tRNA:
  – Pairs with mRNA codon, two molecules join
    together
  – Ribosome slides along mRNA to next codon
  – Chain of amino acids is formed until a “stop”
    codon is reached on mRNA strand
PROTEIN SYNTHESIS
         PROTEIN SYNTHESIS
•    5 Steps of Translation:
    1. Ribosome attaches to mRNA strand; tRNA
       approaches ribosome
    2. AUG codon signals “start” of protein synthesis
    3. New tRNA molecule attaches to ribosome; amino
       acids on tRNA molecules join
    4. Ribosome slides along mRNA to next codon; new
       tRNA carrying amino acid attaches to ribosome
       and mRNA
    5. Chain of amino acids is formed until “stop” codon
   DNAi animation of protein
synthesis process from beginning
    (Watson & Crick) to end

• http://www.dnai.org/a/index.html
             Annimations
• http://www.biostudio.com/demo_freeman_p
  rotein_synthesis.htm
• http://www.wisc-
  online.com/objects/index_tj.asp?objID=AP
  1302
• http://www.lewport.wnyric.org/JWANAM
  AKER/animations/Protein%20Synthesis%2
  0-%20long.html

				
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posted:6/12/2012
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