meiosis Flashcards
does meiosis produce diploid gametes?
no, produces haploid gametes
when do male and female haploid gametes fuse?
during fertilization - to form a zygote
what is the product of meiosis?
haploid gametes
what is meiosis also referred to as?
reproductive and reductive division
which stage does recombination take place?
prophase I
which meiosis stage is most similar to mitosis?
meiosis 2
what is crossing over?
formation of chiasmata, then the small sections of chromosomes can be exchanged between non homologous sister chromatids
what is bivalent?
pair of homologous chromosomes
what allows for greater diversity of genotypes in the population?
recombination and independent assortment
which stage dominates meiosis?
prophase I
what happens during meiosis I?
maternal and paternal homologues segregate independently and reduce the number of chromosomes to half
what happens during meiosis II?
sister chromatids seperate and move to opposite oles
what is nondisjunction?
when the seperation of chromosomes is not normal
what does nondisjunction result in?
gametes which have either more or less of the usual number of chromosomes - common mechanism of trisomy or monosomy
nondisjunction is the cause of several medical conditions in humans including:
down syndrome, klinefelter (xxy) syndrome, turner syndorme and XYY syndrome
where is spermatogonia found?
in the outer cortex of the seminiferous tubules of the testicles
is all sperm produced functional?
no, sperm are made continously but most are malformed
smoking reduces the chances of concieving by …
10 to 40%
smoking can age a womans body clock by ….
10 years
how does smoking affect males in terms of fertility?
lower sperm count and more malformed sperm than non smokers
can genetic defects in sperm affect the children?
yes, genetic defects in sperm accumulate and can be carried over into children.
do nicotine patches help with fertility?
no, the effect on fertility is down to nicotine
