Let

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Lets Review

• Who discovered the structure of DNA?
• They declared it as a ________ _______
• When DNA copies itself, it is called ___________.
• Make the complementary strand
• ATTCGCTACGAAT

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Protein Synthesis
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Central Dogma

• The central dogma of molecular biology states
• DNA RNA Protein

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I. How do chromosomes lead to specific traits?

• A. Chromosomes are made of DNA
• Segments of DNA code for a protein (genes)
• A protein in turn, relates to a trait (examples
  eye color, hair color, enzymes, hormones)
• Movie Review

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Structure and Function of RNA

• Why is RNA needed?
• Proteins are made by ribosomes outside the
  nucleus and DNA cannot leave the nucleus (its
  stuck) 
• RNA is needed so that it can carry the genetic
  code needed for making proteins to the ribosomes

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Structure and Function of RNA

• What is RNA?
• 1) RNA - Ribonucleic Acid
• a) the sugar in RNA is ribose
•  

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Structure and Function of RNA

• b) RNA is single stranded
• c) Uracil replaces Thymine as a nitrogenous base
  in RNA

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Structure and Function of RNA

• 2) There are 3 kinds of RNA
• a) r RNA - Ribosomal RNA
• - makes up ribosomes
•  
• b) mRNA- messenger RNA
• -carries the genetic code out of the nucleus
  to the ribosomes

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Structure and Function of RNA

• c) tRNA- Transfer RNA
• - transfers amino acids to the ribosome in
  order to make proteins

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Lets Review

• Shoulder Partner
• Selector
• Face Partner
• Selector

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The RNA Code

• II. RNA Code
• a) mRNA carries the code for an amino acid in a
  series of 3 nucleotides (like DNA triplet)
•  b) A group of 3 mRNA nucleotides is called a
  codon.

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The RNA Code

•   c) A group of 3 tRNA nucleotides is called an
  anti-codon (opposite of the codon)
• ex. mRNA codon UAG
• tRNA anti-codon AUC
• d) The genetic code is universal - codons code
  for the same amino acids in all known life forms

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Protein Synthesis

• Protein Synthesis is a two part process
• 1) Transcription (in the nucleus)
• 2) Translation (in the cytoplasm)

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Lets Review

• Selector

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Central Dogma

• DNA RNA Protein

Transcription
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Transcription

• III. Transcription - mRNA is copied from DNA
• Steps
• 1) RNA polymerase binds to DNA at a promoter
  sequence separates the strands
• 2) RNA nucleotides bond to the exposed bases
  on the DNA strand
• 3) Transcription continues until it reaches a
  termination sequence

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Transcription
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Transcription

• Lets Practice
• Write this at the bottom of the second page of
  your notes. Transcribe the DNA
• DNA TATAGCCGATAGCTCCGTA
• mRNA - AUAUCGGCUAUCGAGGCAU

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Central Dogma

• DNA RNA Protein

Translation
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Translation

• Translation - mRNA is used to make protein
• Steps
• 1) mRNA leaves the DNA in the nucleus and
  travels to a ribosome
• 2) the ribosome begin translating the mRNA
  into protein when it reaches a start codon

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Translation

•   3) the ribosometranslates the mRNA into a
  sequence of amino acids that make up a specific
  protein
• 4) Translation continues until a stop codon
  is reached.

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Translation
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tRNA

• V. How do the Ribosome do their job?
• tRNA is the key
• 2) What is tRNA?
• tRNA carries an amino
• acid on one end. The
• other end contains the
• anti- codon (three
• nitrogen bases) that will
• match up with the mRNA
• codon.
•  

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tRNA

• 3) tRNA molecules match their anti-codon to
  the mRNA codon
• 4)A protein is formed as tRNAs release their
  amino acids which bond together to make a
  protein
• (peptide bond)

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tRNA
Protein (amino acid chain)
Ribosome
mRNA
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Amino Acids

• All of the proteins in your body are made up of
  combinations of only 20 different amino acids
  linked together in different ways.
• Movie Review

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How do we get proteins from genes (coding
DNA)? Lets find out http//www.wisc-online.com/
objects/index_tj.asp?objIDAP1302
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Amino Acids
Third Letter
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Let's Practice
Third Letter
Write the mRNA sequence on to the bottom of the
third page of the notes. Translate the mRNA into
an amino acid sequence, usingthe chart above!
AUGCUAAAGCGUGGUUCUUUGGCG
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• AUG/CUA/AAG/CGU/GGU/UCU/UUG/GCG
• Met Leu Lys Arg Gly Ser Leu - Ala

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Review

• TRANSCRIPTION
• (in the nucleus)
• 1. DNA helix opens
• 2. mRNA chain is copied from DNA

• TRANSLATION
• (in the cytoplasm)
• 1. mRNA attaches to a ribosome in the cytoplasm
• 2. tRNA molecules carrying amino acids match
  anti-codon to mRNA codon
• 3. Amino acids are released and bonded together
  to make a protein.