what does anueploidy mean? and what could be the reason
genetic condition where the chromosomes have abnormal number of chromosomes. Incidence and origins. meiotic non-disjunction. Chromosomal dissorders, 3 volnerable stages of oogenesis, materal age effects, environmennal influences.
explain nondisjunction in meiosis.
Chromosome fail to seperate equaly, uccurs in MI or MII.
Produces gamates incorrect number.
Produces zygotes with anueploidy after fertilization
what is monosomic zygote
a zygote with 1 less chromosome 2n-1
what is a trisomic zygote
1 extra chromosome 2n+1
what is trisomy 21
a extra chromosome (trisomic zygote) in the 21st chromosome - autism.
Cognitive impairment, problems in thinking and learining, delayed language and speech.
poor muscle tone
flattened facial profile and nose
upward slanting eyes
small heads, ears, mouth
associated conditions
- heart abnormalities, hearing and vision problems.
whats trisomy 13 and 18
severe efects of CNS
cleft lip and palate
anomalies of extremities most die in a month or 2.
what is klinefelter syndrome and the conditions that come with it
xxy, tall with long limbs, infertile, lack of secondary sexual development, small tests
talk about the conditions in xyy
tall normal aperance, noraml level of sexual developement and fertility, lots of testosterone. may have learing disabilities
xxx
tall, normal sexual developement. nuerodevelopment differences, ususally fertile.
whats turner syndrome
Proshound short strature
webbed neck
lack of prominent female secondary charecteristics
congenital heart defects common
endocrine treatment allows for normal developement.
monosommy of 1 sex chromosome - male y
infertile.
what are the vulnerable stages of oogenesis
- synapsis and recombination
- follicle formation
- Oocyte growth
what is one of the proposed mechanisms contributing to maternal age effect
effects involved with miosis-specific cohesions.
How does cohesion play a role in meiosis
Cohesions are established during S-phase, this tethers homolougus chromosomes together, located at the centromere and distal to the chiasmata
During MI the cohesions distal to the chiasmata are released. allowing homologous chromosomes to sperate during anaphase I
During MII the cohesion protien in the centromere is released allowing for sister chromatids to be seperated at Anaphase II.
genetic quality of the egg may be influenced by events at each of these stages
meiotic initiation in the fetal ovary, follicle formation in the perinatal period, and oocyte growth and maturation in the adult.
at wha phase is the primary oocyte in arrest
Prophase I
waht does high FSH levels say about likelyhood of pregnancies
higher the FSH levels the lower the likelihood of pregnancies, bc them FSH are blocked by progesterone
what is needed for meiotic enrty in females and why men dont have it
retanoic acid signals the meiotic repplication in fetals, in men this part is skiped as it is replicated by testis-specific enzymes that degrade retanoic acid.
when does this meiosis start in terms of weeks in fetal development
11-12 weeks
