Question 1

Which of the following amino acid 1-letter symbols is of phonetic origin?

Accepted Answer

E

Question 2

Which amino acid has a 1-letter code that is neither the first letter of its name nor phonetic in origin?

Accepted Answer

K (Lysine)

Question 3

Why was the letter 'K' chosen as the 1-letter code for lysine?

Accepted Answer

Because 'L' was already assigned to leucine, and 'K' is the next closest available letter in the alphabet.

Question 4

Given the following amino acids, which one has a 1-letter code that is the same as the first letter of its name?

Accepted Answer

Alanine

Question 5

Which of the following is the correct 1-letter code for glutamic acid?

Accepted Answer

E

Question 6

A mutation changes a codon from coding for leucine to coding for lysine. Which 1-letter code change would you expect in the protein sequence?

Accepted Answer

L to K

Question 7

Which amino acid is represented by the 1-letter code 'W'?

Accepted Answer

Tryptophan

Question 8

If a protein sequence contains the 1-letter code 'F', which amino acid is present?

Accepted Answer

Phenylalanine

Question 9

Which of the following statements best explains why some amino acids do not use the first letter of their name as their 1-letter code?

Accepted Answer

Because there are more amino acids than unique letters, so some letters are assigned based on frequency or phonetic similarity.

Question 10

Which 1-letter code is used for asparagine?

Accepted Answer

N

Question 11

A patient’s protein sequence is analyzed and found to have a substitution from 'Q' to 'E'. Which amino acids are involved in this mutation?

Accepted Answer

Glutamine to Glutamic Acid

Question 12

Which of the following amino acids has a 1-letter code that is not unique but is used because it is more common in proteins?

Accepted Answer

Leucine

Question 13

Which of the following is the correct 1-letter code for threonine?

Accepted Answer

T

Question 14

If a protein sequence is written as 'ARND', which amino acids are present in order?

Accepted Answer

Alanine, Arginine, Asparagine, Aspartic Acid

Question 15

Which amino acid is represented by the 1-letter code 'Y'?

Accepted Answer

Tyrosine

Question 16

A researcher is analyzing a protein and finds the sequence 'QKLE'. Which amino acids are present in this segment?

Accepted Answer

Glutamine, Lysine, Leucine, Glutamic Acid

Question 17

Which of the following is the correct 1-letter code for glycine?

Accepted Answer

G

Question 18

Which amino acid is represented by the 1-letter code 'C'?

Accepted Answer

Cysteine

Question 19

Which of the following 1-letter codes is used for aspartic acid?

Accepted Answer

D

Question 20

A protein sequence contains the segment 'WYT'. Which amino acids are present in this order?

Accepted Answer

Tryptophan, Tyrosine, Threonine

Amino Acid 1-Letter Codes: Origins, Usage, and Practice

Study Guide - Practice Questions