Chapter 12 - Chapter 12: From DNA to Protein: Genotype to...

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Chapter 12: From DNA to Protein: Genotype to Phenotype I. One gene, One enzyme hypothesis a. Now: one gene, one polypeptide II. Viruses a. Exception b. Have only RNA c. Retroviruses i. Come in RNA ii. Reverse transcriptase makes temp copies of DNA made from RNA (going backwards) III. RNA a. Ribose b. Single stranded c. Uracil instead of thymine IV.Transcription a. Template strand = copied into mRNA b. RNA polymerase = makes RNA (processive catalysis) c. 3 phases i. Initiation 1. Promoter: special sequence on template DNA letting RNA polymerase to sit on DNA 2. Tells RNA polymerase which way to go and where to start (initiation site) ii. Elongation 1. Reads in 3’ to 5’ direction so that new strand is formed 5’ to 3’ 2. Can only add to 3’ end 3. Antiparallel to template 4. RNA polymerases DO NOT PROOFREAD a. If mistakes are made = not long-lived iii. Termination 1. DNA sequence tells RNA polymerase to stop 2. May need helper proteins a. Help RNA polymerase get off DNA 3. In eukaryotes a. Pre-mRNA that is edited (spliced) V. Genetic Code a. Which amino acids will build a protein (20 in nature) b. 1 nucleotide as code = 4 amino acids c. 2 nucleotides = 16 d. 3 = 64 e. codon = 3 bases of mRNA for a certain amino acid
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Chapter 12 - Chapter 12: From DNA to Protein: Genotype to...

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