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Flip to reveal answersWhat is an amino acid?
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All 12 Flashcards — Amino acid structure
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Question
What is an amino acid?
Answer
The **monomer (subunit)** that **proteins** are built from.
Question
What four groups are bonded to the central carbon of an amino acid?
Answer
An **amino group (—NH₂)**, a **carboxyl group (—COOH)**, a **hydrogen (—H)** and a **variable R group**.
Question
Which group gives the 'amino' in 'amino acid'?
Answer
The **amino group (—NH₂)** — a nitrogen-containing group.
Question
Which group gives the 'acid' in 'amino acid'?
Answer
The **carboxyl group (—COOH)**.
Question
What is the R group?
Answer
The **variable side chain** of an amino acid — the only part that differs from one amino acid to the next.
Question
How many different amino acids are there, and why?
Answer
**20** — because there are **20 different R groups**; the rest of the structure is identical.
Question
Which parts of an amino acid are the same in all 20 of them?
Answer
The **central carbon**, the **amino group**, the **carboxyl group** and the **hydrogen** — only the R group differs.
Question
Which elements does an amino acid contain?
Answer
**Carbon, hydrogen, oxygen and nitrogen** (some also contain sulfur).
Question
Where does the nitrogen in an amino acid come from?
Answer
From the **amino group (—NH₂)**.
Question
How can you tell a protein from a carbohydrate or lipid by its elements?
Answer
A protein contains **nitrogen**; carbohydrates and lipids contain only **C, H and O**.
Question
Do carbohydrates and lipids contain nitrogen?
Answer
**No** — they contain only carbon, hydrogen and oxygen. Nitrogen is found in proteins / amino acids.
Question
How many central carbons does a single amino acid have?
Answer
**One** — all four groups attach to this single central carbon.
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Topic 2.2 hub
Proteins
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