BCHM 10000 Lecture Notes - Lecture 5: Base Pair, Phenylpyruvic Acid, Missense Mutation
3 Jul 2018
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Nucleic acids
• RNAs in the cell belong to several different classes
– Messenger RNA (mRNA)
●5 to 10% of cellular RNA
●carries the genetic information for the synthesis of proteins
– Transfer RNA (tRNA)
●10 to 15% of cellular RNA
●decodes mRNA during protein synthesis
– Ribosomal RNA (rRNA)
●75 to 80% of cellular RNA
●major structural feature of ribosomes
●complexed with proteins
Translation, mutations and the genetic code
●in mRNA (and DNA), 1 amino acid is specified by a group of three bases called a codon
●the genetic code is redundant (degenerate)
– most amino acids have more than one codon
Within open reading frames, mutations alter the sequence of mRNA
Document Summary
Nucleic acids: rnas in the cell belong to several different classes. Carries the genetic information for the synthesis of proteins. In mrna (and dna), 1 amino acid is specified by a group of three bases called a codon. Most amino acids have more than one codon. Within open reading frames, mutations alter the sequence of mrna. Base pair substitutions can lead to amino acid changes in proteins (missense mutations), premature stop codons (nonsense mutations) or can be silent. Much of this sequence difference contributes to allelic variation among populations: frame shift mutations are caused by deletion or insertion of nucleotides in numbers not divisible by 3. Alters the reading frame of the encoded protein. Changes the protein sequence encoded downstream of the change. Often results in a premature stop codon. Phenylketonuria (pku) first described first in 1934 by ivar asbj rn f lling: symptoms. Name of disease gives clear indication of disease symptoms.
