exam 3 Flashcards
(201 cards)
advantages of sexual reproduction (2)
- quick evolutionary adaptations to evolutionary changes
- corrects genetic errors and disadvantageous mutations
Mendel’s laws of inheritance (3)
law of dominance
law of segregation
law of independent assortment
(mendel) law of dominance
some alleles are dominant, some are recessive. dominant alleles overcome the recessive
(mendel) law of segregation
each gamete carries only one allele for each gene (because the alleles segregate)
(mendel) law of independent assortment
in the formation of gametes, genes of different traits segregate independently
sex-linked genes
(occurs usually on which chromosome?)
genes located on the sex chromosomes
usually on the x-chromosome
sex-limited genes
examples?
genes present in both sexes, but have a greater effect in only one (occurs due to hormones throughout development)
ex: chest hair, breast size
SRY gene
on which chromosome?
does what?
on the y-chromosome
causes gonads to become testes
what hormones do testes produce
androgenes
testes producing androgens that in turn increase the growth of testes is known as what kind of loop?
positive feedback loop
androgens cause (2):
growth of testes
growth of wolffian ducts
what do wolffian ducts develop into (2)?
seminal vesicles & vas deferens
what hormone (produced by testes) makes the mullerian ducts degenerate?
MIH hormone
what happens if there is no SRY gene (3)?
gonads become ovaries
wolffian ducts degenerate
mullerian ducts develop
what hormone do ovaries produce?
estrogens
what do mullerian ducts develop into?
uterus, oviducts, etc. (female reproductive system)
similarity across all steroids?
same chemical backbone, 4-carbon rings
what is a steroid?
sex hormones (androgens, estrogens, etc)
where are steroids produced?
adrenal glands
organizing effects of hormones
occur when?
determine what?
occur during sensitive periods of development (before birth & puberty)
they determine the development of female or male characteristics
activating effects of hormones
occur when?
do what?
occur at any time of life
they temporarily activate a particular response (pregnancy, menstruation, etc.)
progesterone
what does it do (2)?
prepares uterus for fertilized ovum
promotes maintenance of pregnancy
other word for intersex
hermaphrodite
most common cause of intersex
Congenital adrenal hyperplasia (CAH)