Protein Synthesis (to make proteins)

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Protein Synthesis (to make proteins)
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What is Protein Synthesis?

• Flow of Genetic Information
• DNA RNA Protein
• DNA holds the code for protein synthesis but
  cannot leave the nucleus

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• Protein Synthesis is performed at the ribosomes
  in the cytoplasm
• The cell uses RNA to copy the code from DNA and
  bring it to the ribosomes

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RNA Ribonucelic Acid

• Nitrogenous Bases a. Adenine b. Cytosine c.
  Guanine d. Uracil
• Simple Sugar a ribose rather than a deoxyribose
• Phosphate Groups

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II. Structure
a. A nucleic acid backbone b. single strand of
nucleotides c. Sugar is ribose d. Contains
uracil base instead of thymine
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Difference between DNA and RNA

• DNA RNA
• Double strand single strand
• Deoxyribose ribose
• Thymine uracil

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III. Types of RNA

• Three types of RNA are used to make proteins
• a. mRNA messenger RNA
• b. rRNA ribosomal RNA
• c. tRNA transfer RNA

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IV. mRNA Function

• A. transcribe DNA code
• B. take code outside of nucleus to ribosome
• C. give instructions to ribosome on how to
  build protein

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How does DNA transfer info to RNA?
A U G C T A No Ts in RNA
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V. tRNA Function

• To deliver amino acids to the ribosome as it is
  building (synthesizing) protein

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VI. rRNA Function

• where translation of RNA to protein takes place
• Ribosomes are made up of protein and ribosomal
  RNA (rRNA)

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• Remember
• How many different amino acids are there?
• 20
• Look at your notes - What makes each amino acid
  different from one another?
• R groups

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VIII. The CODE!!

• James Watson and Francis Crick, with the help of
  Rosalind Franklins X-ray crystallography images
  unraveled the structure of DNA
• B. The fact that bases paired led directly to a
  theory of how DNA codes for proteins. It took a
  few years to determine that the bases spell
  three-letter words called codons

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mRNA Codons

• 3 letters on mRNA are called codons. These three
  letter codes are used to determine which Amino
  Acid is to be placed on the protein.
• Ex TAC
• AUG Start Codon (Methionine)
• This is where you begin translation of DNAs code
  given to mRNA

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• See the mRNA codon chart (slime green)
• Write the codon for Proline here
• Glycine?
• Which amino acid has the most codons?
• Which amino acid has the fewest?
• Start codon starts each protein
• Three codons tell a ribosome to stop making a
  protein. List them here

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Transcription?

• - Copying the portion of DNA that carries the
  code for a protein.
• http//www.youtube.com/watch?vztPkv7wc3yUfeature
  related
• mRNA Synthesis (Transcription begins with a
  promoter on DNA, site RNA polymerase binds to on
  DNA to begin transcription).
• A mRNA is transcribed (built) using unwound DNAs
  code as a template.
• RNA nucleotides find their compliment.
• RNA Polymerase is the enzyme that brings in the
  nucleotides

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• - Completed when reaches terminator sequence on
  DNA ending transcription
• The original strand is used as the template.

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• Result
• The resulting mRNA looks exactly like the
  template strand of DNA, with one important
  distinction
• each T is replace with a U.
• http//www.youtube.com/watch?vJqx4Y0OjWW4feature
  related
• Where does it go?
• The RNA releases from DNA and is then edited
  before leaving the nucleus

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• Practice Transcription

DNA Strand
3 T A C G A T G C A T C G 5
RNA Strand
5 A U G C U A C G U A G C 3
http//www.youtube.com/watch?vNjczQKjFcksfeature
related
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Translation

• The process of interpreting mRNA to build a chain
  of amino acids that make up a protein.
• http//www.youtube.com/watch?vB6O6uRb1D38feature
  related

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• How does it work?
• i. mRNA leaves the nucleus and heads to the
  cytoplasm where the ribosomes are located.
• Remember Ribosomes are where translation will
  occur
• Each sequence of nucleotides is a codon (mRNA
  codon). Each codon codes for a specific amino
  acid

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• ii. Amino acids are brought to the ribosome by
  tRNA.
• There are 20 different tRNA molecules, one for
  each type of amino acid.
• tRNA anticodon finds their complimentary codon on
  mRNA.

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• Anticodon 3 letters found to match the mRNAs
  codon.
• mRNA codon UAA CGA GGC
• tRNA anticodon AUU GCU CCG

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• iii. Peptide bonds form between the amino acids
  forming a polypeptide.
• iV. Translation stops when a stop codon is
  reached.
• Video http//www.youtube.com/watch?v41_Ne5mS2ls
  featurerelated

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• Video http//www.youtube.com/watch?v983lhh20rGY
  featurerelated