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L31 - Genetic Code
USCSOM: Biochemistry: L31 - Genetic Code
Question | Answer |
---|---|
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 |