Chapter 15, Test 4 Flashcards
what organelles contain their own genome
mitochondria and chloroplasts
what do the chromosomes look like in mitochondria and chloroplast
circular DNA
whats significant about the mito and chloroplast genome
encode their own rRNA and tRNA and have their own translation apparatus
can the genes that mito and chloro encode for all development and function
no, need some from nucleus
what mtDNA diseases affect
electron transport chain
what specifically in ETC of mtDNA do diseases affect
ATP synthesis
what is one hypothesis to aging
accumulation of mtDNA mutations
what certain proteins are needed for mitochondria
for oxidative phosphorylation
what certain proteins are needed for chloroplasts
photosynthesis
how many bp would you see in cpDNA
120-200
what RNA is most abundant in mtDNA
tRNA
how are genes in mtDNA
tightly packed, no introns and no useless nucleotides
what is RNA editing like in mitochondria
make premRNA into mature mRNA
delete or add uracils
what are the exceptions for mitochondria to the universal code
carry own rRNA and tRNA,
N-formyl methionine and tRNA(met) initiate translation,
5 triplets are different than nucleus DNA, UGA not stop and AUA= met
are there more genes in mito or chloro
chloroplasts
does cpDNA contain introns
yes
what is the endosymbiont theory
organelles represent remnants of free-living organism that est symbiotic relationship with proto-eukaryots
what are examples of the endosymbiont theory
mito have double membranes, have bacterialike protein synthetic machinery, divide by binary fission
what is biparental inheritance
obtain organelles from both parents
what is uniparental inheritance
obtain organelles from one parents, mainly mom
what is non mendelian inheritance
uniparental inheritance
usually through egg cytoplasm
what is MERRF
high levels of lactate in blood, seizures, muscle atrophy, brain and cognitive degenration over time
what causes MERRF
mutation in tRNA-lys in mito genome
translation of mito proteins affected and ATP production
how is MERRF inherited
maternal
why does MERRF show great variability in severity of expression
genetic heteroplasty
what is heteroplasmy
contain both wildtype and mutant allele
expressivity based on number of mutant in cell
how does threshold effect work with heteroplasmy
depends on fraction of wildtype and mutant genome copies
how does heteroplasmy affect daughter cells
distributed randomly
mutant number in daughter cell and not every cell undergoes replication
why are rates of mutation higher in mitochondria
high conc of free radicals due to oxidative phosphorylation, preferential replication of mtDNA carrying deletions, lower selection against new mutations
if maternal genes contributing mRNA to oocyte are mutant then what happens to progeny
progeny may be affected by mutation
what is the generation lag for maternal effect
one generation lag between genotype and phenotype
does cytoplasmic inheritance follow mendelian rules
no
what is the direct effect like in cytoplasmic inheritance
long term
