Biochemistry 7: Genetics Flashcards
At what stage in cell cycle will you have arrest with vincristine? Why would this make sense?
M phase (mitosis)
Centrioles are constructed of microtubules, and connect via microtubules to the centromeres of the dividing chromosomes → pull chromosome pairs apart. Vincas/taxanes inhibit microtubule function → prevent the separation of chromosomes in mitosis.
How can you use the mechanisms of creating seedless bananas to understand the classic gonadal finding in Turner’s syndrome?
Seedless bananas have gametes with uneven numbers of chromosomes (e.g. one ovule may have 2 copies of one chromosome, but none of another). It is exceedingly unlikely that two such gametes would combine to form a seed with a complete set of chromosomes
More detailed explanation:
What is one possible mechanism for streak ovaries in Turner’s? (NOTE: a brief reading through medical journals demonstrated a TON of theories, so it’s best to pick out one that makes sense and know that they will never test you on this particular mechanism on your exam)
One proposed mechanism: germ cells less likely to have a full complement of chromosomes → germ cell death → insufficient germ cells for ovarian development → ovarian dysgenesis
In other words, a 45, XO germ cell, when it divides during embryogenesis → 45, XO progeny, which are non-viable. To form viable you would need to have an (unlikely) non-disjunction event to develop a germ cell with a 46, XX genotype
How are the mechanisms of lack of ovarian germ cells in Turner patients, and the lack of seeds in bananas similar?
In both cases, cells are unable to have a full complement of chromosomes. In the case of Turner, germ cells are unable to have a full complement of chromosomes, while in bananas, the pollen/ovule combination are unable to have a full complement of chromosomes
What is the height of someone with Klinefelter’s? Mechanism?
Ultimately very tall
Testicular atrophy → testosterone release ↓ → lack of closing of epiphyseal growth plates during puberty → continue to grow through adult lif
What is the ultimate height of someone with precocious puberty? Mechanism?
Ultimately short, following an early growth spurt (tallest kid in elementary school, but shortest kid in high school).
Testosterone/estrogen ↑ → GH ↑ / epiphyseal growth plate closure
