MCP 8 Flashcards
What tissues are most largely affected by mitchondrial mutations?
- broad range of tissues affected, but most notably those tissues that have a high degree of oxidative/phosphorylation.
- most serious in CNS and muscles when these tissue are affected
Define mitochondria
mitochondrai are organelles located in the cytopasm of the cell and contain their own DNA and are thus another source of DNA (circular DNA)
What are the 3 common disorders associated with mitochondrial diseases ?
neuropathies, encephalopathies and myopathies
Is the mitochondrial self sufficient?
NO -mitochondrial function is dependent on nuclear genes, therefore defects in mitochondrial function could be due to autosomal or X-linked mutations of nuclear genome or mutations in mitochondrial DNA itself
how is mitochondrial DNA transmitted ?
matrilineal inheritance -> comes from the cytoplasm of the egg, few if any mitochondria are present in the pronucleus of the sperm but these are essentially null as they are overwhelmed by the number found in the cytoplasm of the egg
Define Matrilineal inheritance
transmitted from mother to children
define homoplasmy
- like homozygosity for one or more cytoplasmic genes
- usually we use this term to refer to mitochondria that all have same genetic composition
Define heteroplasmy
heteroplasmy is when there are two or more different populations of mitochondria present in a cell
-heteroplasmy of cytoplasm is analogous to heterozygosity of nuclear DNA
Explain the idea of phenotypic threshold in relation to mitochondrial DNA?
- in order for any given cell to express dysfunction there must be a high proportion of mutant mitochondria present in that cell -> the rule is greater than 85%
- this is also tissue dependent as stated earlier
- greater the number of copies of mutant DNA, the more severe the disease
Define replicative segregation
as cells divide the relative proportions of mutant mitochondria change over time -> (usually causing increase in the number of mutant copies) - but it is how one who is say heteroplasmic mito DNA can have children affected with a disease more severely and variable expression
-mutations may be lost completely actually
mitochondrial disease arise from either..
new acquired mutation -> because mito DNA has a high mutation rate
or
replicative segregation
Define forensic DNA analysis
use of DNA technologies (PCR, RFLP, sequencing etc) to obtain information on the genetic identity of an individual(s) and how that relates to a criminal, medical or scientific investigation
What is used to ‘DNA fingerprint’ ?
because we want to use most unique sections to identify we -sequence variability with high degree of polymorphisms -> we use hypervariable mini-satellite regions (nuclear DNA) these regions are used bc they are the most variable
Discuss some sources of error in forensic DNA analysis
- poor sample collection
- mislabeling or handling error
- degradation
- contamination
Discuss some important thing(s) to consider when doing statistical analysis for forensic DNA analysis
- one must analyze a sufficient number of polymorphisms with a high degree of variability
- consider the allele frequencies vary between populations
- consider differences in allele frequencies in different racial and ethnic groups - and use the appropriate numbers if the suspect is caucasian etc that kind of idea
