Genetics Flashcards
(19 cards)
What are housekeeping genes?
Genes that are always turned on because their proteins are needed for essential cell functions.
Why is gene regulation important?
It prevents energy waste by ensuring genes are only active when needed and helps cells adapt to changes.
At what stage does most gene regulation occur in prokaryotes?
Transcriptional stage, especially at initiation.
What is an operon?
A group of genes regulated by a single promoter and operator; found in prokaryotes.
What are the parts of an operon?
Promoter, operator, and structural genes.
What does the lac operon do?
Allows E. coli to break down lactose when it’s present.
What happens when lactose is absent in the lac operon?
A repressor binds to the operator and blocks transcription.
What happens when lactose is present in the lac operon?
Lactose (inducer) binds to the repressor, removes it, and allows transcription.
What enzyme breaks down lactose in the lac operon?
β-galactosidase (lacZ).
What does the trp operon control?
Production of the amino acid tryptophan.
What happens when tryptophan levels are high in the trp operon?
Tryptophan (co-repressor) binds to the repressor → transcription is blocked.
What happens when tryptophan levels are low in the trp operon?
The co-repressor detaches, the repressor falls off, and transcription resumes.
What are the five levels of gene regulation in eukaryotic cells?
Pre-transcriptional, Transcriptional, Post-transcriptional, Translational, Post-translational
What happens during pre-transcriptional regulation?
Chromatin structure is altered to allow or block gene access.
What is transcriptional regulation?
Turning genes on/off using transcription factors.
What happens in post-transcriptional regulation?
mRNA is edited (e.g., splicing, 5’ cap, poly-A tail added).
What is translational regulation?
Controls how often and how much mRNA is translated into protein.
What is post-translational regulation?
Modifies proteins after translation to control their activity or lifespan.
Why do humans need multiple levels of gene regulation?
To support cell specialization, development, adaptability, and prevent diseases like cancer.
