Module 8 Lec 6 Flashcards
What is the mutation rate of mtDNA compared to nuclear DNA?
mtDNA has a mutation rate about 10 times higher than nuclear DNA.
Why is the high mutation rate in mtDNA important?
It leads to more species differences over time, making mtDNA useful for evolutionary studies
How is mtDNA used in evolutionary studies?
mtDNA helps study evolutionary relationships among closely related organisms.
What can mtDNA trace in human evolution?
mtDNA traces the maternal lineage of humans, back to a few women who lived about 130,000 years ago.
How is mtDNA used in forensic science?
mtDNA is used in Argentina courts for identifying biological relationships and tracing ancestry.
How many mitochondrial genomes are present in each cell?
Cells contain several mitochondria, each with dozens to thousands of mitochondrial genomes.
Do all mitochondrial genomes in a cell have the same sequence?
No, the genomes can differ and do not have to be identical.
How do mitochondria divide?
Mitochondria divide by binary fission, with genomes being distributed randomly
What happens to mutant and wild-type mitochondrial genomes during cell division?
Daughter cells can inherit different proportions of mutant and wild-type mitochondrial genomes.
Is mitochondrial inheritance Mendelian?
No, mitochondrial inheritance is non-Mendelian.
Can we use the terms “heterozygous” or “homozygous” for mitochondrial inheritance?
No, these terms do not apply to mitochondrial inheritance.
What does it mean when all copies of the mitochondrial genome are identical?
It is called homoplasmic.
What does it mean when one or more copies of the mitochondrial genome are different?
It is called heteroplasmic.
What type of inheritance is common for mitochondrial DNA (mtDNA)?
Uniparental and maternal inheritance.
What was observed in the study with Xenopus mtDNA?
In F1 hybrids, the offspring retain only mtDNA from the mother.
How was the maternal inheritance of Xenopus mtDNA tested?
Purified mtDNA from two species was hybridized to probes from the same species, showing maternal inheritance.
What is one possible mechanism of uniparental inheritance?
Differences in gamete size, where the larger female gamete contributes the organelles.
How does the male gamete’s organelles contribute to inheritance in some species?
n some organisms, male gametes’ organelles degrade, preventing paternal mtDNA inheritance.
What happens to paternal organelles in some plants?
Paternal organelles are distributed to cells that will not become part of the embryo.
How does the zygote handle paternal organelles after fertilization in some species?
The zygote destroys paternal organelles shortly after fertilization.
How do some organisms exclude paternal organelles?
In some species, paternal organelles are excluded from the female gamete during fertilization
What is Leber’s hereditary optic neuropathy (LHON)?
LHON is a mitochondrial genetic disorder that causes optic nerve degeneration and blindnes
What causes the severity of LHON?
The severity of LHON can vary due to random distribution of mitochondria, affecting the efficiency of the respiratory chain.
What is the hypothesis regarding mtDNA mutations and aging?
The hypothesis is that accumulation of mutations in mtDNA and biased replication of deleted mtDNA contribute to age-related decline in oxidative phosphorylation.
How does aging affect mitochondrial DNA in heart tissue?
The percentage of heart tissue with mitochondrial deletions increases with age.
How is mitochondrial dysfunction related to Alzheimer’s disease?
Brain cells from Alzheimer’s patients show abnormally low energy metabolism, with 20-35% of mitochondria carrying mutations in cytochrome c oxidase genes.
How does the mutation rate of mtDNA compare to nuclear DNA?
Somatic mutations in mitochondrial DNA are higher than in nuclear DNA.
How does mitochondrial oxidative phosphorylation relate to free radicals?
Mitochondrial oxidative phosphorylation produces more free radicals, which are implicated in aging and cellular damage.
