dna mutations 2 (unusual inheritance patterns) Flashcards
describe mitochondrial genome? and mutation rate?
Inherited from which parent only?
small- densely packed
higher
Mother
Heteroplasmy? (mt)
How is this visualised?
and what does this make it hard to predict?
Cells have mixed populations of mitochondrial genotypes
by viewing cytochrome c oxidase
the severity of disease in the child inheriting
What is epigenetics?
It is genetic change that is heritable but does not depend on DNA sequence change.
Example of a compound epigenetics is mediated through?
On which base does the compound bind? and what position?
methyl (methylation)
5-methylcytosine
Base pair order of methylation?
CpG
Enzyme responsible for maintaining methylation through cell divisions?
DNMT1
What happens to the methylation pattern in the early embryo? And then what happens to it at implantation?
It is erased then reestablished
X inactivation occurs when? and is the answer to what?
In the early embryo and is the answer to the gene dosage problem (2 X chromosomes)
How and what body does X inactivation form?
And which enzyme maintains it through cell division?
By methylation
Barr body
DNMT1
Which gene initiates X inactivation?
what is the gene product?
where does it go?
XIST gene
non coding rna
coats the chromosome
Where are the genes located that are not silenced by X inactivation?
on the short arm in the pseudoautosomal region.
What is genomic imprinting?
For some genes only the paternal or maternal copy is expressed. the other is silent.
Chrom 15q. deletion on paternal produces what disease? deletion on maternal causes what disease?
paternal- prader willi syndrome
maternal- angelman syndrome
symptoms of prader willi?
symptoms of angelman?
prader- retardation and hyperphagia (over eating)
angelman- developmental delay, seizures and laughter
As well as imprinting angelman syndrome can be caused by a point mutation at which gene?
What is the gene product?
UBE3A
ubiquitin- protein ligase (tags proteins with ubiquitin)
