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49 Cards in this Set
- Front
- Back
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what is chromosome theory? |
inheritance can be explained by transmission of chromosomes during meiosis |
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what are 5 defining characteristics of chromosomes? |
contain genetic material replicated and passed along nuclei contain chromosomes that are found in homologous pairs during formation of haploid cells, segregate independently each parent contributes one set of chromosomes in offspring |
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who first observed sex chromosomes? |
1901Clarence Mcclung in grasshoppers |
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who proposed the chromosome and based on what? |
1902-1903 Bovari and Sutton based on concordances between observations between Mendel and meiosis and observations of fertilization |
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what are Mendel's 4 postulates? |
unit factors in pairs dominance/recessiveness segregation independent assortment |
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who first observed chromosome theory? |
1910 Thomas Hunt |
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explain the experiment and the conclusions |
could assign a trait to a chromosome in sex chromosomes-1/2 males had red eyes, 1/2 had white in F2 generation trait has to be on X chromosome proof chromosomes hold genetic material |
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what are secondary sexual differentiation characteristics? |
what you look like (hair, muscles, etc.) |
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what are primary sexual differentiation characteristics? |
gonads |
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what is an organism with 1 sex? |
unisexual, dioecious |
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what is an organism with 2 sexes? |
bisexual, monecious, hermaphroditic |
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what is an example of a monecious organism? |
corn-sex parts on same plant, different parts |
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what is a hermaphroditic plant? |
flower has male and female parts |
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heterogametic |
XY (males) |
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homogametic |
XX (females) |
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what causes the sexes to be different? |
females have 2 X's males have Y |
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how do we know? |
rare sex chromosome mutations |
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Turner syndrome XO |
have 1X, female |
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Triple X syndrome XXX |
no symptoms because barr bodies
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Klinefelter Syndrome XXY |
are male |
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XXY syndrome |
"very" male |
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what causes these syndromes? |
disjungtion |
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disjungtion |
don't pull apart correctly at anaphase |
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when can this occur? |
during meiosis I or II |
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describe how sex determination development happens |
5th week of gestation-gonadal ridges arise, primordial germ cells migrate 7th week-testes develop if XY from testosterone 12th week-oogonia begins meiosis |
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Mullerian ducts in presence of testosterone
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shut down |
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Wolffian ducts with no testosterone |
shut down |
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what is external male genitalia caused by? |
dihydrotestosterone |
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describe Y chromosome |
PAR-pseudo-autosomal region sex determining region-SRY transcription factor-turns on and off expression on other chromosomes |
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what does the presence of SRY do? |
determines male sex |
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5-alpha reductase deficiency |
testes (caused by testosterone) female external genitalia-didn't produce dihydrogentestosterone becomes male during puberty |
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Androgen insensitivity |
XY individuals X linked mutation-cells don't respond to androgens testes form no female gonads puberty-develop secondary female characteristics estrogen goes up as testosterone does |
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androgen |
hormones that make you male |
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hermaphroditism |
both kind of gametes both don't function-only 1 can function external genitalia intermediate |
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what is hermaphroditism caused by? |
usually XX mutation moving SRY to X division of ovum-each fertilized and then merged (1 egg-2 sperm) |
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congenital adrenal hyperplasia |
adrenal glands produce too much hormones too much androgens produced external genitalia intermediate too much testosterone XX |
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X-0 Sex determination |
males X0-matters how many X chromosomes female-XX |
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how is sex determined in fruit flies? |
males XY |
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caenohabditis elegans |
5 autosomes, 1 pair of sex chromosomes hermaphrodites XX-produce both sperm and egg males XO |
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bird sex determination |
males ZZ females ZW-heterogametic |
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social insect sex determination |
haplodiploid males haploid-descend from unfertilized cells females diploid |
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gyandromorphy |
bilateral differences in sex half female/half male |
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what can cause environmental sex determination and in what animals? |
temperature in turtles and crocodiles |
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what do warm temperatures produce in reptiles? |
females |
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what do all clownfish start off as and mature to? |
start as males, mature to females |
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who gets to reproduce in clownfish? |
dominant male and female |
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how are female sea worms produced? |
if larvae falls on open floor |
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how are male sea worms produced? |
if larvae lands on top of female |
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what sex are whip tailed lizards? |
all female, clones |
