Identifying a biopolymer by its monomers: A polymer composed of alanine, tyrosine, and lysine would be classified as what type of molecule?
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ADNA
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BStrong base
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CPhospholipid
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DProtein
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EPolysaccharide
Answer
Correct Answer: Protein
Explanation
Introduction / Context:Biopolymers are recognized by their repeating monomer units. Correctly identifying the polymer class from its monomers is a core skill in biochemistry and cell biology.
Given Data / Assumptions:
- Monomers listed: alanine, tyrosine, lysine.
- These are standard alpha-amino acids.
- No other chemical classes are implied.
Concept / Approach:Proteins are polymers of amino acids linked by peptide bonds. Nucleic acids (DNA/RNA) are polymers of nucleotides; phospholipids are built from glycerol, fatty acids, and phosphate-containing headgroups; polysaccharides are polymers of monosaccharides. Therefore, a chain of amino acids defines a protein or peptide.
Step-by-Step Solution:Recognize alanine, tyrosine, lysine as amino acids.Recall that amino acids form polypeptide chains via peptide bonds.Classify the polymer as a protein.
Verification / Alternative check:Tyrosine brings an aromatic phenolic side chain; lysine contributes a basic side chain; alanine is nonpolar—typical amino acid diversity seen in proteins.
Why Other Options Are Wrong:
- DNA: Built from nucleotides (A, T, G, C), not amino acids.
- Phospholipid: Not a polymer of amino acids.
- Strong base: A property, not a macromolecule class.
- Polysaccharide: Built from sugars.
Common Pitfalls:Confusing amino acid names with nucleotides or fatty acids; learn characteristic functional groups.
Final Answer:Protein.