The Genetic Code and Protein Synthesis

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The Genetic Code and Protein Synthesis
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Genes and the Genetic Code

• Gene a segment of DNA on a chromosomes that
  codes for a specific trait
• Genetic Code formed by the order of nitrogen
  bases along a gene that specifies what type of
  protein will be produced

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How cells make proteins

• A cell uses information from a segment of DNA
  (gene) on a chromosome to produce a specific
  protein
• Why make proteins?
• Proteins determine your traits, hair color, eye
  color, tongue rolling ability, etc.

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What Protein Synthesis involves

• DNA found in the nucleus
• Ribosome
• RNA
• Amino acids these are the building blocks of
  proteins

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RNA

• Similar to DNA
• Structure of RNA
• Sugar is different
• Single-stranded
• Uracil replaces thymine
• Still has cytosine (C), guanine (G), and adenine
  (A)

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Draw me under DNA
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Draw me under RNA
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2 Types of RNA

• mRNA messenger RNA
• Copies the coded message from the DNA in the
  nucleus and carries the message to the ribosome
  in the cytoplasm
• tRNA transfer RNA
• Carries amino acids to the ribosome and adds them
  to the growing proteins

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Concept Map
Section 12-3
RNA
can be
also called
which functions to
also called
also called
which functions to
which functions to
from
to
to make up
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The Steps of Protein Synthesis

• In the nucleus, DNA serves as a pattern for
  making mRNA

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• The DNA molecule unzips and RNA bases match up
  along one strand of the DNA.
• This transfers the information from the DNA to
  the mRNA strand
• Each group of 3 bases on the mRNA codes for one
  amino acid

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 Steps 1 and 2
Section 12-3
Adenine (DNA and RNA) Cystosine (DNA and
RNA) Guanine(DNA and RNA) Thymine (DNA
only) Uracil (RNA only)
RNApolymerase
DNA
RNA
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• The mRNA moves out of the nucleus and attaches
  to the ribosome, where protein chain production
  begins
• tRNA attaches to the mRNA, and reads the mRNA
  code

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• If the tRNA matches the code on the mRNA, it
  drops off its amino acid
• The amino acids are joined to make a protein

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