HO-14 - How genes encode proteins: the message and the...

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How genes encode proteins: the message and the genetic code BIO 32O - lecture 14 Problem sets: Question bank A. Text problems ch 8 #1, 2, 4, 5, 11, 13, 21, 31-34. RNA Proteins Transcription Translation DNA DNAreplication base sequence base sequence amino acid sequence The "Central Dogma" : information is transferred from DNA to an RNA "message", to protein. Phenotype Genotype Genes encode the proteins that are the working molecules of the cell. Proteins can be catalytic enzymes, structural building blocks, or switches and regulators that control other proteins or genes. Acting together, they give rise to the shape, metabolism, and behavior of an organism - its phenotype. • Proteins are composed of 20 different amino acids joined by peptide bonds in linear (unbranched) polypeptide chains • The chain is polarized (different at each end); it has an amino (N) end and a carboxy (C) end. • The structure and activity of a particular protein are primarily determined by its linear sequence of amino acids. BASICS OF PROTEIN STRUCTURE THE CODING PROBLEM How is the sequence of amino acids in a protein encoded as a sequence of bases in DNA? - The code is " unpunctuated " and is read in codons of three bases Mutations (in the rII gene of T4 phage) caused by insertion or deletion of a nucleotide changes the reading frame ( frameshift mutation). A deletion downstream of an insertion can cancel the frameshift and revert the phenotype. Two deletions or two insertions will still be mutant, but three deletions or three insertions will return the sequence to its proper reading frame.
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HO-14 - How genes encode proteins: the message and the...

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