Question

An alanine residue exists at position 180 of a certain plant protein. If the codon specifying alanine is GCU, how many singlebase substitutions will result in an amino acid substitution at position \(180,\) and what are they?

Short answer

Answer: There are 5 single base substitutions that will result in an amino acid substitution at position 180. The resulting amino acids are Aspartic acid, Glutamic acid, Glycine, and Valine.

Step-by-step solution

Identify the codon and its constituent bases

The given codon for alanine is GCU, which consists of three bases: Guanine (G), Cytosine (C), and Uracil (U).

Determine possible single base substitutions

For each base in the codon, there are three possible substitutions as there are four nucleotide bases (A, U, C, and G) in total. We will list down the possible substitutions for each base in the GCU codon: - First base (G): GAU, GAA, GGU - Second base (C): GAU, GUU, GCA - Third base (U): GCA, GCC, GCG, GCU

Identify which substitutions result in amino acid changes

Now, we will identify which of these codons code for a different amino acid than alanine. To determine this, we can refer to the genetic code table: - First base (G): GAU (Aspartic acid), GAA (Glutamic acid), GGU (Glycine) - Second base (C): GAU (Aspartic acid), GUU (Valine), GCA (Alanine - not a substitution) - Third base (U): GCA (Alanine - not a substitution), GCC (Alanine - not a substitution), GCG (Alanine - not a substitution)

Count the base substitutions and list the resulting amino acids

There are a total of 5 single base substitutions that result in an amino acid substitution at position 180, and they are: 1. GAU (Aspartic acid) 2. GAA (Glutamic acid) 3. GGU (Glycine) 4. GAU (Aspartic acid) 5. GUU (Valine) Therefore, 5 single base substitutions will result in an amino acid substitution at position 180, and the resulting amino acids are Aspartic acid, Glutamic acid, Glycine, and Valine.