sex determination Flashcards
without recombination, how many different gametes can you produce
(formula)
where n is _
2^n
of different chromosome pairs
a self cross dihydrid will produce gametes in a ::: ratio for 2 different traits
with a ::: ratio
1:1:1:1
9:3:3:1
if two events are not related _____
if two probabilities are mutually exclusive, you ____
multiply
add
what is an example of something being mutually exclusive
being homozygous
if you are yy you can’t be YY, and their probabilities add because they are both homozygous
what is it called when an organism doesn’t have sex chromosomes
how do they do instead
genic determination
allelic differences in a small number of loci
what is an environmental way to determine sex
temperature changes
how is sex determined in haplodiploid determination
males are from haploids, unfertilized eggs
females are diploid, fertilized eggs
In slipper limpet, what determines sex
their position in the mollusk pyramid so they switch
imn genotypic determination, how is sex determined
sex chromosomes
the XX/X0 mode depends on the _____ distribution of the X chromosomes into ____ of the ___ gametes
when are there females in this case
random distribution
half of the male gametes
when they have 2 X chromosome4s
what is homogametous pair in humans
what is heterogamous
what example is this switched and what are the variables
XX, female
XY, males
birds; ZZ: males, ZW: females
What is missing in turner syndrome
what is X0 in this case
what does this prove
an X chromosomes
female
determined by the presence of a Y chromosome, not the number of X chromosomes
what is wrong in Klinefelter syndrome
what are you when you have this
what does this prove
XXY chromosome (47 tot)
male
its the presence of Y, not the number of X
the Y chromosome is ____ and ____ for human male development
necessary and sufficient
what does SRY stand for
sex determining region of Y
what does PAR stand for
pseudoautosomal region
what essentially is the pseudoautosomal region
where the X and Y chromosomes overlap
what sex is someone who is XY but missing the SRY on the Y chromosome
female
what sex is someone who is XX but has SRY on the X chromosome
male
SRY is both ____ and ____ for male development
necessary and sufficient
fruit fly use XY but what determines sex
ratio X chromosomes to autosomes
1/2 is male
1/1 is female
what is cross where you switch the sex of alleles on sex chromosomes
a reciprocal cross
what is dosage compensation
what are 3 ways to do this and their example organisms
compensating gene dosage so that x-linked females will not double the expression of x linked genes
double the male expression - fruit flies
half both x chromosomes - c. elegans
inactivate one x - humans
when one X chromosome is expressed, is it different per cell
yes. half may have one x expression, half may have the other half. They are quantized for changes, either one way or the other
