Nucleic%20Acids%20and%20Protein%20Synthesis

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Nucleic Acids and Protein Synthesis
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I. DNA deoxyribonucleic acid

• A. Contains Genes specific locations on DNA.
• Genes specify proteins and traits (eye color,
  disease, etc)

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DNA is bundled into structures called chromosomes.

• If the DNA in a person was stretched out it would
  reach to the sun and back 600 times. It is an
  extremely long molecule that coils really tight.

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• B. The Structure of DNA
• Rosalind Franklin and Maurice Wilkins
• Produced X-ray diffraction photograph of DNA.
• Showed that DNA is a double helix.

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• James Watson and Francis Crick (1953)
• Used Franklins info to build DNA model
• Model double helix of repeating nucleotide
  monomers

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1953
2003
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• c. Nucleotides have three parts
• Deoxyribose Sugar
• Phosphate Group
• Nitrogen Base (4 kinds)
• Purines Adenine (A) Guanine (G)
• Pyrimidines Thymine (T) Cytosine (C)

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How do the nitrogen bases bind?
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• d.Sugar-phosphate molecules on outside of ladder
  paired bases on inside.
• e.Purines paired to pyrimidines.
• A is hydrogen-bonded to T
• G is hydrogen-bonded to C
• f. Watson and Crick
• - Nobel Prize in 1954 for their model of DNA.

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• Stop
• End of day 1

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II. DNA Replication process of duplicating a
molecule of DNA

• Begins at a specific sequence of nucleotides
• DNA is unzipped by DNA Helicase enzyme.
• Helicase breaks the hydrogen bonds between
  nitrogen bases.
• Free floating nucleotides bind with complementary
  bases.

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II. DNA Replication process of duplicating a
molecule of DNA

• E. DNA polymerase enzyme
• catalyzes the bonding of sugar and phosphates
• F. Results in 2 new strands of DNA
• G. Each new DNA molecule has one old and one new
  strand (semi-conservative replication)
• H. Special Enzymes (DNA polymerase) proofread
  and repair any mistakes
• I. If repairs are not made, the mutations may
  cause cancer.

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• I. Replication Errors Do Occur
• Ability to mutate is requirement for genetic
  material.
• Only one error per billion nucleotides.

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• J. The newly synthesized strand always forms
  from 5 to 3.

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Animation of DNA Replication

• http//207.207.4.198/pub/flash/24/menu.swf
• 15 minutes

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STOP

• End of day 2

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III. Ribonucleic Acid (RNA) makes proteins

• DNA ultimately determines amino acid sequence of
  proteins.
• DNA molecule cannot directly control the sequence
  of amino acids.
• DNA is restricted to nucleus.
• Go-between is ribonucleic acid (RNA).

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• The Structure of RNA
• Polymer of nucleotides
• (ribose sugar, Nitrogen base, PO 4 group
• 2. Unlike DNA, RNA
• a) Single-stranded
• b) Contains the sugar ribose
• c) Contains the nitrogen base uracil instead of
  thymine.

No T in RNA A-U
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• There are three major classes of RNA.
• Messenger RNA (mRNA)- takes a message from DNA in
  nucleus to ribosomes in cytoplasm.
• Ribosomal RNA (rRNA)- and proteins make up
  ribosomes where proteins are synthesized.
• Transfer RNA (tRNA)- transfers a particular amino
  acid to a ribosome.

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IV. Central Dogma of Molecular Biology

• DNA undergoes transcription to mRNA
• mRNA undergoes translation to a protein.

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V. Transcription process in which mRNA is made
according to the sequence of bases in DNA

• Occurs in the nucleus.
• Begins when RNA polymerase (enzyme) binds to a
  DNA molecule. (Unzips the DNA)
• Complementary RNA nucleotides pair with DNA
  nucleotides.
• RNA polymerase joins the RNA nucleotides
  together.
• Terminator sequence causes RNA polymerase to
  stop.
• DNA strands rejoin.

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VI. Translation

• assembling proteins from info encoded in mRNA

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• Takes place in cytoplasm.
• One language (nucleic acids) is translated into
  another language (protein).
• How Genes Code for Amino Acids
• DNA serves as a template to build RNA
• mRNA contains the genetic code in the form of
  codons.

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• Codons
• 3 sequential nucleotide bases of mRNA. (4364)
• Each codes for an amino acid.
• There are 64 triplets to code for 20 amino acids.
• The Code Is Universal
• AUG is universal start codon.
• There are three stop codons.

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• Ribosome attaches to a start codon(AUG).
• tRNA transfers Amino Acids to the ribosome.
• tRNA is a single-stranded ribonucleic acid that
  doubles back on itself to create a cloverleaf
  structure.
• At one end it binds to amino acid at other end
  it has an anticodon that binds to mRNA codon.
• Brings the correct amino acid to the codon.

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• Ribosome moves to next codon and a new tRNA
  brings next amino acid.
• A peptide bond is formed between amino acids.
• Process continues until ribosomes hits a stop
  codon.
• Polypeptide (protein) is formed.

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