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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 the coded information from a segment of DNA (gene) to make a specific protein Why make proteins? – Proteins determine your traits, hair color, eye color, tongue rolling ability, etc. Things that are not traits: athletic ability
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What Protein Synthesis involves: – DNA found in the nucleus – Ribosome: where the proteins are made – RNA (see below) – Amino acids: these are the building blocks of proteins
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RNA Similar to DNA Structure of RNA: 1. Sugar is different 2. Single-stranded 3. Uracil replaces thymine 4. Still has cytosine (C), guanine (G), and adenine (A)
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Draw me under DNA Draw me under RNA
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2 Types of RNA 1. mRNA: messenger RNA – Copies the coded message from the DNA in the nucleus and carries the message to the ribosome in the cytoplasm 2. tRNA: transfer RNA – Picks up and transfers amino acids in the cytoplasm to the ribosome and adds them to the growing proteins
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DNA RNA
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The Steps of Protein Synthesis 1. In the nucleus, DNA serves as a pattern for making mRNA
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2. 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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RNA DNA RNA polymerase 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)
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3. The mRNA moves out of the nucleus and attaches to the ribosome, where protein chain production begins 4. tRNA attaches to the mRNA, and reads the mRNA code
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5. If the tRNA matches the code on the mRNA, it drops off its amino acid 6. The amino acids are joined to make a protein
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http://www.PHSchool.com – cep-3034
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