Unit 7 - Mitochondrial Genetics and Forensic DNA Analysis Flashcards Preview

Molecular and Cellular Princples of Medicine > Unit 7 - Mitochondrial Genetics and Forensic DNA Analysis > Flashcards

Flashcards in Unit 7 - Mitochondrial Genetics and Forensic DNA Analysis Deck (15):
1

where are mitochondrial diseases most serious?

in CNS and muscle
-usually related to tissues where there's a high degree of oxidative phosphorylation activity
-commonly neuropathies, encephalopathies, and myopathies

2

are mitochondria self sufficient?

no, their full function is linked to nuclear genes
-some processes are governed by mitochondrial genes, others by nuclear genes
-thus, defects in mitochondrial function could be autosomal or X-linked mutations of nuclear genome, or mutations of mitochondrial DNA itself

3

matrilineal inheritance

mitochondria transmitted in egg cytoplasm
-few, if any mitochondria present in pronucleus of sperm

4

homoplasmy

homozygosity for one or more cytoplasmic genes
-usually refers to population of mitochondria that all have same genetic composition

5

heteroplasmy

heterozygosity for one or more cytoplasmic genes
-two or more different populations of mitochondria are present in a cell
-heteroplasmy in cytoplasm is analogous heterozygosity in nucleus

6

how can a mother be heteroplasmic?

mother may be unaffected, but have affected children, or vice versa
-mother must have low frequency of mutated cells, but passes higher frequencies to children who express disease, or vise versa
-require 85% mutant mitochondria in cell for disease to manifest

7

why are mitochondrial disorders often progressive with late onset? how is this explained?

due to increase, over time, in numbers of mutations per cell and numbers of mutant cells
-replicative segregation in oogenesis (relative proportions of mutant mitochondria can increase or decrease) or acquired mutations (that undergo replicative segregation, but not transmitted to progeny)

8

what is MERRF?

myoclonic epilepsy with ragged red fiber disease
-mitochondrial disorder that shows bnormally staining mitochondria

9

what is forensic DNA analysis?

both nuclear and mitochondrial DNA used
-sequence variability with high degree of polymorphism
-nuclear DNA is more robust, for hypervariable minisatellite regions and DNA fingerprinting

10

what are sources of error for DNA analysis?

quality of specimen
-poor sample collection/preparation
-mislabeling/handling error
-degradation or contamination

11

statistical analysis and interpretation

-analyze sufficient number of polymorphisms with high degree of variability
-consider allele frequencies vary between populations
-consider differences in allele frequencies in different racial and ethnic groups

12

what can mitochondrial DNA analysis be used for?

-maternal inheritance
-siblings carry same mDNA
-link individuals by comparing maternal mitochondrial lineages
-family identity (NOT individual identity)

13

paternity and medicine

include or exclude putative father based on biological evidence
-minimum of 2 probes
-frequency of alleles in families differ from population frequencies

14

what is CODIS?

combined DNA information system
-all 50 states, US army, FBI, US Navy, Department of Justice --> all state, local, and federal law enforcement agencies
-enables all crime labs to exchange and compare DNA profiles electronically, to link crimes to each other and to convicted offenders

15

what can be different between identical twins?

-fingerprints
-blood
-hair
-footprints

can have environmental variation