Eukaryotic Gene Regulation Flashcards
What are three ways chromosomal regions can act as control points?
- Inactivated during development
- Activated by translocation
- Gene deletion
What is an example of chromosomal inactivation?
X chromosomes in female
What is an example of translocation as regulation?
Variable regions of antibody molecules
What is an example of chromosomal material being lost?
Human red blood cell
What is Gene reiteration?
The presence of many identical genes
Allows transcripts to be made at a high rate
How can the initiation of transcription act as a control point?
Through the use of specific transcription factors that are regulated
What are four ways mRNA can be used as a point of regulation?
- alternative splicing
- transportation from the nucleus
- rate of degradation
- masking to an “inactive” form
How does histone acetylation affect gene expression?
Acetylated = favors gene expression
Deacetylation = inactive chromatin
What is the role of scaffolding proteins in gene expression?
Condense regions of the chromatin (inactive)
How does methylation affect gene expression?
DNA methylation favors inactive chromtin
What is the role of promoters?
Bind general transcription factors
What is the role of enhancers?
Bind specific transcription factors
Act in a tissue-specific manner
‘Target for steroid hormones
What is the difference between trans regulators and cis regulators?
Trans regulators – proteins that act on specific DNA sequences
Cis regulators – elements within the DNA that serve regulatory functions (e.g. promoter, enhancer)
What are four ways of activating transcription factors?
- Synthesis
- Ligand binding
- phosphorylation
- addition of second subunit
How do steroid hormones activate transcription factors?
Through ligand binding
What are three common structures of DNA-binding proteins?
- Zinc finger
- Helix-Turn-Helix
- Leucine Zipper
Describe Ferritin and Transferrin Receptor translation in low iron.
A protein is active and binds the mRNA of ferritin and transferrin, this promotes the translation of the receptor and represses ferritin.
In high iron, the protein doesn’t bind and the opposite happens
What is RNA interference?
Small RNA molecules that bind to the 3’ untranslated region of an mRNA molecule to interfere with translation
What is the function of microRNA?
An imperfect match for mRNA, binds and inhibits translation
What is the function of short interfering RNA?
An exact match for the 3’ end of mRNA, binds and causes mRNA degredation due to the presence of double stranded RNA
What is the cause of Prader-Willi Syndrome?
Deletion on chromosome 15 inherited by the father
The maternal copy is methylated at this region, and therefore inactive.
Hypogonadism, small hands and feet, obesity, mental retardation
What is the cause of Angelman syndrome?
Deletion on chromosome 15 inherited by the mother
The paternal copy is methylated at this region, and therefore inactive
seizures, ataxic gait, behavior disorders, mental retardation
