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Amino acids, proteins and DNA (A-level only)

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Question 6

Lysine is an amino acid with a basic side chain. Which structure represents the major species of lysine present in a strongly acidic aqueous solution at pH=1\text{pH} = 1pH=1?

A
H3N+−CH−COOH∣(CH2)4NH3+ \begin{array}{c} \text{H}_3\text{N}^+ - \text{CH} - \text{COOH} \\ | \\ (\text{CH}_2)_4\text{NH}_3^+ \end{array} H3​N+−CH−COOH∣(CH2​)4​NH3+​​
B
H3N+−CH−COOH∣(CH2)4NH2 \begin{array}{c} \text{H}_3\text{N}^+ - \text{CH} - \text{COOH} \\ | \\ (\text{CH}_2)_4\text{NH}_2 \end{array} H3​N+−CH−COOH∣(CH2​)4​NH2​​
C
H3N+−CH−COO−∣(CH2)4NH3+ \begin{array}{c} \text{H}_3\text{N}^+ - \text{CH} - \text{COO}^- \\ | \\ (\text{CH}_2)_4\text{NH}_3^+ \end{array} H3​N+−CH−COO−∣(CH2​)4​NH3+​​
D
H2N−CH−COO−∣(CH2)4NH2 \begin{array}{c} \text{H}_2\text{N} - \text{CH} - \text{COO}^- \\ | \\ (\text{CH}_2)_4\text{NH}_2 \end{array} H2​N−CH−COO−∣(CH2​)4​NH2​​
Markscheme

Amino acids, proteins and DNA (A-level only) Questions

  1. A Level
  2. /Chemistry
  3. /Amino acids, proteins and DNA (A-level only)

30 exam-style questions on AQA A Level Chemistry Amino acids, proteins and DNA (A-level only), covering Amino acids (A-level only), Proteins (A-level only), Enzymes (A-level only), DNA (A-level only), and Action of anticancer drugs (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.

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