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L31 - Genetic Code

USCSOM: Biochemistry: L31 - Genetic Code

What is a codon? A set of three nucleotides
How many different possible trinucleotides can be formed? 64
Which way, wrt 3' and 5' ends, do codons read? 5' to 3'
What is the second letter for all AAs with a charged side chain? A
Which 2 letters are the most important in a codon? ONLY first 2
Which AAs have the most codons? Arg, Leu, Ser
Which AAs have single codons? Trp and Met
Which codons are stop codons? UGA, UAG, UAA
What is the initiator codon? AUG
Codons with what letter will have a hydrophobic side chain? U
What are anticodons? the codon match on the tRNA during protein synthesis
What is the wobble hypothesis? the first base of the anticodon does not follow stringent pairing with the last base of the codon
What is meant by 5'-UTR? the 5'-untranslated region; usually 30 - 100 nucleotides in before the initiation of translation
What is meant by 3'-UTR? 3'-untranslated region; the region downstream from the stop codon on the mRNA
What is the term reading frame? the nucleotide sequence being translated
How many possible reading frames are there in a given region of DNA? 6
What is ORF? open reading frame; series of codons that lacks a stop codon
What is the frequency of having a stop codon in a random sequence of codons? 1/20
What is a point mutation? What are the two kinds? a single base pair change; transition A to G; transversion purine to pyrimidine
What is a silent mutation? 3rd place change in a codon; typically has no effect on phenotype
Describe a Missense mutation point mutation, changes the meaning of a codon word and thus changes a single AA
Describe a nonsense mutation stop codon in a coding region; generally serious mutations
Insertion mutations lead to frame shift mutations downstream; serious mutations
Created by: jlellerm