BIOCHEM FINAL - Genetic code

Three bases (a codon) with no overlaps or gaps

how many bases code for one amino acid?

61 codons

How many codons code for amino acids?

Three stop codons

how many stop codons are there?

AUG (Methionine)

What codon starts translation?

The start codon (AUG) followed by codons until a stop codon

What determines the reading frame of a protein?

Three

How many reading frames does each DNA strand have?

The non-template (coding) strand

Which DNA stand directly corresponds to the protein sequence?

Methionine (Met) and Tryptophan (Trp)

Which two amino acids have only one codon

What molecule physically links codons to amino acids during translation

tRNA

Flexible pairing between the 3rd codon base and the 1st anticodon base

What is “wobble pairing”?

Inosine (I)

Which anticodon base can pair with A, U, or C?

Reduces the number of tRNAs needed and speeds up translation

How does wobble pairing benefit translation?

-redundancy in the 3rd codon position

-most changes in the 1st/2nd positions gives similar amino acids

Why is the genetic code resistant to mutation?

When it changes the protein sequence

When does a DNA mutation actually affect phenotype?