Regulating Gene Expression Flashcards
(22 cards)
What is gene expression?
Turning genes on or off.
Define a gene.
A segment of a chromosome that produces functional products.
What are the ways to regulate protein control in a cell?
- Synthesis of primary RNA transcript (epigenetic effect, transcription factors)
- Degradation of mRNA
What are transcription factors?
Proteins that bind the promoter of a gene to regulate transcription.
How do transcription factors regulate gene transcription?
By modulating the binding of RNA polymerase to the promoter DNA.
Where is the promoter region located?
Upstream of the gene to be transcribed (5’).
What major target of regulation is RNA polymerase binding associated with?
Promoter sequences near the starting point of the gene (at the 5’ end).
What is the effect of estrogen on gene transcription?
Affects the transcription of over 100 genes.
Which types of cells have estrogen receptors?
Many cells in the body, including the nervous system and bones.
What type of molecule are estrogens?
Small, hydrophobic lipids.
How do estrogens enter the cell?
They pass directly through the plasma membrane and the nuclear membrane.
What happens when estrogens bind to estrogen receptors?
The receptor undergoes a conformational change and detaches from its protein complex.
What is a nucleosome?
A DNA/protein bundle created by wrapping genomic DNA around histones.
What chemical changes can affect histones and DNA?
- Acetylation
- Methylation
What is an epigenome?
The chemical modifications found within an individual.
What is acetylation of histones?
Adding acetyl groups to lysine amino acids on histone proteins.
What effect does acetylation have on histones?
It relaxes chromatin and promotes gene expression.
What happens to DNA when lysine undergoes acetylation?
It loses its positive charge, allowing DNA to bind more easily with transcription factors and RNA polymerase.
What is the outcome of non-acetylated histones?
Condensed chromatin and no RNA transcription.
What is methylation of DNA?
Adding methyl groups to DNA sequences containing multiple cytosine and guanine bases.
What effect does methylation of DNA have on transcription?
It suppresses transcription.
What do methylated bases attract?
Proteins that bind to DNA and inhibit transcription.
