Condensation reactions forming dipeptides and polypeptides
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Flip to reveal answersWhat reaction joins two amino acids?
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Question
What reaction joins two amino acids?
Answer
**Condensation** — it forms a **peptide bond** and releases one water molecule.
Question
What is a peptide bond?
Answer
The covalent bond (**CO—NH**) that joins two amino acids; it forms by condensation.
Question
Which two groups react to form a peptide bond?
Answer
The **carboxyl group (—COOH)** of one amino acid and the **amino group (—NH₂)** of the next.
Question
Which atoms are removed when two amino acids join?
Answer
An **—OH** (from the carboxyl group) and an **—H** (from the amino group), leaving together as **one water molecule**.
Question
How much water is released per peptide bond formed?
Answer
**One** molecule of water (H₂O) per peptide bond.
Question
Define a dipeptide.
Answer
**Two amino acids** joined by a single peptide bond.
Question
Define a polypeptide.
Answer
A long chain of **many amino acids** joined by peptide bonds.
Question
What reaction breaks a peptide bond?
Answer
**Hydrolysis** — one water molecule is **added** across the bond, splitting the chain into amino acids.
Question
When does hydrolysis of peptide bonds happen in the body?
Answer
During **digestion**, when dietary protein is broken back down into amino acids.
Question
How many peptide bonds are in a single chain of n amino acids?
Answer
**n − 1** — each bond links a pair, so there is one fewer bond than amino acids.
Question
How do you count peptide bonds across several chains?
Answer
**Total amino acids − number of chains** (each chain has one fewer bond than its amino acids).
Question
How many peptide bonds are in a chain of 5 amino acids?
Answer
**4** (5 − 1).
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