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Flip to reveal answersWhat is a protein's 'conformation'?
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All 13 Flashcards — Protein structure and conformation
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Question
What is a protein's 'conformation'?
Answer
Its specific **folded 3D shape**. The protein only works correctly in its normal conformation.
Question
What determines a protein's conformation (folded shape)?
Answer
The **sequence (order) of its amino acids** — the primary structure.
Question
What is the primary structure of a protein?
Answer
The **sequence (order) of amino acids** in the chain, joined by peptide bonds.
Question
What is the secondary structure of a protein?
Answer
Local folding into **α-helices** (coils) and **β-pleated sheets**, held by **hydrogen bonds**.
Question
What is the tertiary structure of a protein?
Answer
The way the **whole single chain folds** into one overall **3D shape**, held by bonds between the R-groups.
Question
What is the quaternary structure of a protein?
Answer
The way **two or more folded chains (subunits)** join together to make one functional protein (e.g. haemoglobin).
Question
Name the four levels of protein structure in order.
Answer
**Primary → secondary → tertiary → quaternary.**
Question
Which proteins do NOT have quaternary structure?
Answer
**Single-chain** proteins — quaternary structure needs **two or more** chains.
Question
What holds the secondary structure together?
Answer
**Hydrogen bonds** between parts of the polypeptide backbone.
Question
What is denaturation?
Answer
The **loss of a protein's folded 3D shape**, so it can no longer do its job.
Question
What two conditions commonly cause denaturation?
Answer
**High temperature** and **extreme pH** (very acidic or alkaline).
Question
When a protein denatures, what is preserved and what is lost?
Answer
The **amino acid sequence (peptide bonds) is preserved**; the **folded 3D shape (conformation) is lost**.
Question
Why does a denatured enzyme stop working?
Answer
Its **active site changes shape**, so the **substrate no longer fits** and the reaction is not catalysed.
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Proteins
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