Cells need to produce the right proteins at the right time and in the right amounts. This lesson introduces gene expression and explains how cells regulate it, focusing on transcriptional control in prokaryotes and the lac operon in E. coli.
Gene expression is the process of using information in a gene to produce RNA and, often, a protein. Cells regulate gene expression so that a protein is made when it is useful, in an appropriate quantity, and no longer made when it is not needed.
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Gene expression
The use of information in a gene to produce RNA and, when applicable, a protein.
Why do cells regulate gene expression?
To produce useful proteins at appropriate times and amounts, respond to changing conditions, and conserve resources.
Why is transcription a major control point in prokaryotes?
Transcription and translation can occur almost simultaneously, so controlling RNA production quickly affects protein production.
How does allolactose affect the lac repressor?
It binds the repressor and changes its behavior so the repressor can no longer bind effectively to the operator.
Alternative RNA splicing
The production of different mature RNAs by joining different combinations of exons from one transcript.
Quiz questions
In eukaryotic cells, where do transcription and translation primarily occur, respectively?Answer: In the nucleus and in the cytoplasm.
What does epigenetic regulation of gene expression involve?Answer: Changing DNA accessibility through its packaging around nucleosomes.
What is controlled during translational regulation?Answer: Whether and how efficiently an RNA molecule is used to make protein.
Which process is an example of post-translational regulation?Answer: Modifying or transporting a protein after it has been made.
How can abnormal RNA splicing contribute to genetic disease?Answer: Incorrect RNA processing can produce nonfunctional proteins, sometimes without directly changing the DNA sequence.
Based on Concepts of Biology by Samantha Fowler, Rebecca Roush, James Wise (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.