Intracellular receptors and gene activation
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Flip to reveal answersWhich signals use intracellular receptors?
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Question
Which signals use intracellular receptors?
Answer
**Lipid-soluble** signals — **steroid hormones** and **thyroxine** — because they can diffuse through the plasma membrane.
Question
Where are intracellular receptors located?
Answer
**Inside** the cell — in the **cytoplasm or nucleus** (not on the surface).
Question
How does a lipid-soluble hormone get inside the cell?
Answer
It **diffuses straight through the plasma membrane** (the membrane is lipid, and like dissolves like).
Question
What does the hormone-receptor complex act as?
Answer
A **transcription factor** — it **binds DNA** and **switches specific genes on or off**.
Question
What is the final effect of intracellular signalling?
Answer
It **changes which proteins the cell makes** (gene expression) — a **slower but longer-lasting** effect.
Question
Intracellular vs surface receptors — speed and duration?
Answer
Intracellular = **slow to start, long-lasting** (changes gene expression); surface + second messenger = **fast, short-lived**.
Question
Does a steroid hormone use a second messenger?
Answer
**No** — second messengers belong to the **surface-receptor** route; a steroid acts directly on the cell's DNA.
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Topic 3.4 hub
Chemical signalling
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