Sex Determination and Differentiation Flashcards
someone whose gender identity does not match their biological sex
transgender
what is sexual orientation
defines the sex and or gender preferred by an individual as a romantic or sexual partner
prefers the opposite sex or gender
heterosexual
prefers the same sex and or gender
homosexual
prefers members of both sexes and or gender
bisexual
generation of new individuals from existing ones, fundamental characteristics of life
reproduction
creation of offspring from single individual; results in genetic clones
asexual reproduction
creation of offspring through fertilization of gametes, results in genetic combination of parents
sexual reproduction
what are two-fold cost of sex
- cost of meiosis/ fertilizatin
- cost of males
what are other costs of sex
mate searching
mating
sexually-transmitted diseases
genetic recombination
what are benefits of sex
increased genetic variation
why does sex exist
it allows for adaptation to changing environment
what are negative of mate searching
it takes time, energy and predation
why can be mating negative
can cause injury and death
what is negative about sexually transmitted diseases
there can be parasites and pathogens
what is negative about genetic recombination
there can be a loss of beneficial alleles
what dominates multicellular forms of life
sexual production
capable of producing both ‘male’ and ‘female’ gametes
hermaphrodites
example of hermaphrodites
sea slugs or hamlet fish
what can act on gamete production
selection
what is asymmetrical gamete investment
anisogamy
when you have selection on gametes, there are two strategies which are
- maximize fertilization rate
- maximize development, growth, and survival
anisogamy for females means
fewer and larger gametes (eggs)
what is the difference between the sexes in secondary sexual characteristics
sexual dimorphism
anisogamy for males means
many, small, motile gametes (sperm)
natural selection for mating success
sexual selection
competition among individuals of one sex for mates of the opposite sex
intrasexual selection
occurs when individuals of one sex are choosy in selecting their mates
intersexual selection
the process of becoming male or female
sexual differentiation
primary step in sexual differentiation; often occurs at fertilizatioin
sex determination
ovaries produce what
eggs
testes produe
sperm
what contains tissue that can become ovaries or testes
embryo
epididymis, vas deferens, seminal vesicles, etc
wolffian duct
fallopian tubes, uterus, cervis
mullerian duct
gene that codes for TDF
SRY (sex determining region of the Y chromosome)
protein that regulates gene expression for testes development
testis determination factor (TDF)
what connects gonads to external environment
accessory sex organs
what is required for wolffian duct development in males
testosterone
what is secreted by testes; required for regression of mullerian ducts in males
mullerian inhibitory hormone
penis and scrotum in males; clitoris and vaginal labia in females
external genitalia
needed for development of male genitals
5a-dihydrotestosterone (DHT)
enzyme that converts T to DHT
5a-reductase
what is the default sex
female
XO; develop normally as females, but must be treated with sex steroids as teenagers to induce puberty
turner syndrome
females exposed to androgens secreted from ovaries or adrenal glands during development; results in slight to moderate masculinzation
congenital adrenal hyperplasia
XY; complete or partial absence of androgen receptors
androgen insensitivity syndrome or testicular feminized mutant
XY; individuals lack the enzyme needed to reduce T to DHT
5a- reducatase deficiency
extra X or Y chromosome
sex chromosome trisomy
XXY; develop as males, often have learning disabilities and are usually sterile
klinefelter
males are generally taller than average, lower intelligence; used to think represented at higher than average frequencies in prison populations- currently disputed
XYY syndrome
differences in appearance, physiology and behavior between types of males
alternative male morphs
what posses ovotestes and produce both sperm and egg
simultaneous hermaphrodites
what begin life as female and switch to male or begin as male and switch to female
sequential hermphrodites
term for beginning life as a female
protogynous
term for beginning life as a male
protoandrous
if your bigger in fish what does it mean
it can produce more eggs
being bigger in clownfish it means
you can produce more eggs
what is the basis for behavior
the brain
what states that hormones secreted early in development organize the brain for later hormonal activation as adults
organizatinal/ activational hypothesis
who states the organizational/ activationalhypothesis
william c young
mating posture assumed in females
lordosis
mating posture assumed by males
mounting
what is mating behavior regulated by
gonadal hormones as adults
OVX means
ovaries removed
effects of hormones during a critical period of development to determine how the animal responds to hormones in adulthood
organizational effects
acute effects of hormones on behavior during adulthood
activational effects
the time period during which organizational hormones can have their effects
critical period
what is thought to have masculinizing effects in many species, if it reaches the brain
estradiol
what is the aromatization hypothesis
testosterone has its effects by being aromatized to E2
in developing female rodents what is present and binds to E2 and what does it do
alpha-fetoprotein and it prevents E2 from acting on its recepotors and causing masculinzation
what are some factors influencing sex differentiation
- in birds, maternal provisoning of steroids too offspring through egg yolk
- in mammals, placement of developing fetuses in the uterine environment
- paternal care by mothers
- levels of stress
- endocrine-disrupting chemicals
what are compounds found in the environment that mimic steroid hormone function
endocrine-disrupting chemicals
