BIO 151 1nd Edition Lecture 18 Outline of Last Lecture - Gene to trait- Overview of Transcriptiono Why Transcribe DNA- DNA vs RNA- mRNA processing- Alternative splicingOutline of Current Lecture - Proteino Monomers of amino acids- RNA codingo tRNAo CodonCurrent Lecture- Protein: chain of monomerso Monomer: amino acids; 20 different amino acids; amino on 5’ side, carboxyl on 3’ side R on side chain, unique to each amino acid, give individuality; more amino acids than Nitrogenous Baseso Peptide Bonds: bonds between amino acids; N-terminus and C-terminus- How can RNA code for 20 amino acids with 4 nucleotideso Code has to contain at least 3 bases per amino acids to get 20 amino acids from 4nucleotides- Genetic code: figured out in the 60’so 3 RNA nucleotides = 1 codonThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.o 1+ codon per amino acids (1-6)o 1 codon=START (AUG)o 3 codons= STOP (UAA, UAG, UGU)o Code is redundant: several codons= same amino acid (except for methionine, which is the start codon)o Code is unambiguous: each codon only has one amino acido Code is universal: all life forms use the same genetic code- How to use code to build protein?o Need: Code: mRNA Adaptors to match codon to amino acid: Transfer RNA (tRNA) Assembler: ribosomeo Transfer RNA (tRNA): the adapter; can only bond to one amino acid Role: translate mRNA codon to amion acid at ribosome Came from: transcribed from DNA in nucleus; goes to cytoplasm to work; used repeatedly Structure: single strand of RNA, 80 nucleotides long; forms H bonds with itself- Anticodon: complements mRNA; carries codon specific amino acidat 3’ end; goes from 3’ 5’ in order to code- Codon-Anticodon-Amino acido Codon mRNA tripleto Anticodon: complementary to mRNA tripleto Amino acid: linked to 3’ of tRNA- Amino acid-tRNA synthase: a tRNA to amino acid matchmakero 20 aminoacyl-tRNA synthases: 1 for each amino acidso Tyrosl – tRNA Synthetase: only fits tRNA with AUA and tyrosine (no other amino acid) o Anticodon for tyrosino Catalytic domain: bond forms between tRNA and amino acid energy source; converts ATP to AMP + 2P, process requires energy - Matching tRNA’s to codons: 61 codons require 45 tRNAs o 3’ 5’ anticodon U at wobble can pair with A or G at 3’ of codon if U is at 5’ most sideo 61 codons – 45 tRNAs -20 Amino acids -20 aminoacyl-tRNA
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