Topic 22 DNA ain't just in the nucleus

maternal inheritance

organelles almost always from mom

• AKA extranuclear inheritance, cytoplasmic inheritance, uniparental inheritance

mtDNA and cpDNA

mitochondria and chloroplasts have their own DNA and ribosomes

organelle nucleoids

organelles can have multiple nucleoids with multiple chromosomes per nucleoid

ex. tobacco chloroplast gene

circular, very dense

• cpDNA contains photosynthesis genes and genes for txn/tln

• chloroplasts have 70S ribosomes (like proks) while plants have 80S ribsosomes (like euks)

• rep, txn, tln all inside chloroplast

ex. human mitochondrial genome

contains genes for oxidative phosphorylation (making ATP) and txn/tln

• mitochondria have 70S ribosome

• rep, txn, tln all in mitochondria

• mtDNA has altered genetic code

phenotypic inheritance by mutant cp/mt genes

almost always inherited from mom

• mitochondrial disorders in pedigree → mom/daughters all have affected kids

mt disorders typically affect

tissues that require lots of ATP

homoplasmy vs heteroplasmy

• homoplasmy is all mutant mtDNAs

• heteroplasmy is mix of normal and mutated mtDNAs

• more defective mt leads to more severe disorder

wear and tear theory (aging)

mtDNA acquires mutations faster than nuclear DNA

• repair sys not as good

• ROS → lots of e- transfer

mt sequences can be used to study origin of humans

microplastics impact of mt fxn

• disrupt membrane potential

• depolarization

• mtDNA + mt damage

• oxidative stress