Patterns of inheritance Flashcards
What is epigenetics?
Something that effects gene expression and is inherited by daughter cells but not the result of changes to the DNA sequences
Controlled by the chromatin structure rather than by nucleotide sequence
What is X inactivation?
Heterochomatin formation that occurs in female mammals which one X is randomly inactivated and only one is expressed
What is a barr body?
A darkly staining, heterochromatic inactive X chromosome
When does X inactivation occur?
During early embryogenesis - maintained colonaly in every subsequent cell division
What happens to Tsix when Xist in increased when and X is picked to be active?
It spreads a coat over the DNA because it can no longer bind with Xist
Why is the PAR area on the X and Y not inactivated?
So they can locate each other for appropriate segregation
If an X chromosome lacks the XIC locus:
It cannot be inactivated because it does not have the Xist
Necessary
If a XIC is translocated onto to an autosome:
The autosome is inactivated
Sufficiency
What is dependent for phenotype in calico cats?
Epigenetic
What is the naming convention for Klinefelers syndrome?
47, XXY
How can a male escape X inactivation?
By having an extra X
What is Retts syndrome?
Carry one normal and one defective MeCP2 (inactive) where the target is brain development, learning and memory (BDLM) in girls and boys die
Recessive X-linked disorder
What does paternal imprinting mean?
An allele inherited from the father is not expressed in the offspring
What does maternal imprinting mean?
An allele inherited from the mother is not expressed in offspring
What does it mean when a locus is imprinted?
One allele is expressed and on allele is silenced in a parent-of-origin manner
On the maternal chromosome, the ICR is bound to the CTCF protein and the H19 area is unmethylated. How does the enhancer do and what does it cause?
The enhancer binds to H19 leaving IgF2 inactive
On the paternal chromosome the ICR and H19 are methylated. What does the enhancer do and what does it cause?
The enhancer binds to IgF2 making it active
What is the father’s goal in breeding?
Get as many genes out in the world as possible regardless of the mother’s well being, growing strong babies
The mother’s goal is:
To conserve her resources equally in its offspring while still being able to manage caring for them so growth should be limited
If a mutated IgF2 is inherited from the father:
There is stunted growth
If a mutated IgF2 is inherited from the mother:
Growth is normal
What is Beckworth-Wiedmann’s syndrome?
Overgrowth and increased susceptibility to kid cancer
Disrupted genes of chromosome 11
Biallelic expression of IgF2 and no H19 expression
Pareternal uniparental disomy
Paternal inheritance of a deletion of the specific region in Prader-Willi syndrome is also known as:
Maternal uniparental disomy
Maternal inheritance of a deletion of the specific region in Angelman syndrome is also known as:
Paternal uniparental disomy
Autosomal dominant:
Each effected individual has an affected parent
Males and females are equally affected
1/2 offspring of affected individual are also affected
Normal siblings develop normal babies
Autosomal recessive:
Non-affected parents have a an affected babeh
