Regulation of transcription (transcription factors)
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Flip to reveal answersWhat is the MAIN control point of gene expression?
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Question
What is the MAIN control point of gene expression?
Answer
**Transcription** — whether the gene is copied into **mRNA** at all.
Question
What is a transcription factor?
Answer
A **protein** that binds a specific **regulatory sequence** in the DNA and controls whether a gene is transcribed.
Question
Where do transcription factors bind?
Answer
To **regulatory sequences** in the DNA, such as the **promoter** or an **enhancer**.
Question
What does an ACTIVATOR do?
Answer
It **helps RNA polymerase bind the promoter**, so transcription **starts** — the gene is switched **ON** (mRNA made).
Question
What does a REPRESSOR do?
Answer
It **blocks RNA polymerase / the promoter**, so transcription is **prevented** — the gene is switched **OFF** (no mRNA).
Question
Why do different cell types express different genes from the same DNA?
Answer
Because they contain **different sets of transcription factors**, so different genes are transcribed.
Question
How can a hormone change which genes are expressed?
Answer
It can **act as, or switch on, a transcription factor** that binds specific genes and turns them on in target cells.
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Gene expression
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