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DNA & Translation. Gene : section of DNA that creates a specific protein Approx 25,000 human genes Proteins are used to build cells and tissue Protein synthesis involves two processes: 1) Transcription 2) Translation. DNA and Translation. Transcription Review.
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DNA & Translation
Gene: section of DNA that creates a specific protein Approx 25,000 human genes Proteins are used to build cells and tissue Protein synthesis involves two processes: 1) Transcription 2) Translation DNA and Translation
Transcription Review • Transcription takes place in the nucleus • 1) DNA double helix is broken apart • 2) mRNA nucleotides match up • 3) Finished mRNA detaches, and moves to a ribosome
Codon: Combination of 3 mRNA nucleotides Each mRNA codon matches with 1 of 20 amino acids Codon AAA = Lysine Codon GUU = Valine Codon AUG = Methionine (Start) Codons UAA or UAG or UGA = Stop The Genetic Code
Translation Overview • Defined: Process of making proteins • Step 1: mRNA enters ribosome • Step 2: Ribosome reads one mRNA codon at a time • Step 3: tRNA delivers amino acids until a protein is created
Translation begins when the mRNA codon “AUG” is reached Each mRNA codon matches with a specific amino acid AUG = methionine GCU = alanine tRNA carries over the proper amino acid tRNA anticodon matches with the mRNA codon One by one, amino acids are linked together Translation ends when a “stop” codon is reached End result: Polypeptide (protein) Translation Details
Practice Problem Threonine T G A A C U U G A
Practice Problem Lysine T T C A A G U U C
Quick Review • Every DNA gene codes for a specific protein • Codon/anticodon match guarantees proper amino acid • Many amino acids link to make one protein