3/9/17 sex and gender - sex ratio, gender/sex selection Flashcards Preview

BIOL 1003 > 3/9/17 sex and gender - sex ratio, gender/sex selection > Flashcards

Flashcards in 3/9/17 sex and gender - sex ratio, gender/sex selection Deck (23):
1

individuals are _______, but have _____

chromosomally female, but have male phenotype due to insertion of SRY gene into genome

2

X chromosome inactivation

in female mammals, males defcient or females overproducing - acoounted for in females

3

Barr Body

covered with RNA - encase so gene cant function - in half cells paternal turns off, other half maternal turns off, X chromosome inactivated, this is bcause dosage is unequal in Males and Females

4

the one chromosome that is deactivated, does it get passed on

no, which one turns off is random but it doesnt get passed on. cells can be traced back in a lineage

5

calico cat

all cats females- heterozygous

6

dosage compensation

M/F need to express same amount so F turn off chromosome

7

environemntal sex determination

temperature sex determination, parasite mediated sex determination, context dependent sex determination

8

temperatrue sex determination

tortoises, turtles, lizards, alligators, crocodiles, snap turtles- adjust m/f ratio in population on enviornment

9

parasite mediated sex determination

cytoplasm comes from mom- insects, wolbachia parasite- want to produce females

10

how does wolbachia infect

feminization, parthogenesis, male killing, cytoplasmic incompatibility

11

context dependent sex determination

features of population in which youre leaving; hermaphroditism- in greek mthology offspring of Hermes (father), Aphrodite (mom)

12

wors practice what

simultaneous hermaphroditism - both give and recieve sperm, outcorssing

13

advantages to simultaneous hermaphroditism

population increases, for individual - lots of possible mates, worm density- find worms

14

sequential hermaphroditism

slipper snail- cement above each other- where you are in sequence determines sex- starting ones are F, later ones/turn into males

15

protogyny

female first, then male

16

protandry

being male first, then female

17

why are there usually only two sexes

motility, nutrient, disruptive selection

18

sperm is

motility

19

egg is

nutrients

20

introgenomic cnflict

prokaryotes v eurkayotic

21

sex ratios

within group of organism, ratio of osns and daughters

22

Fisher's principle

1. suppose M births are less common than F
2. Newborn M then has better mating prospects than Newborn F, and therefore can expect to have more offspring
3. Therefore parents genetically disposed to produce M tend to hav emore than average number of grandchildren born to them
4. therefore the genes for male production tendencies spread and male births become more common
5. as the 1:1 sex ratio is approached, advantage w/producing males dies away
6. the same reasoning holds if F are substituted for males --- sex ratio 1:1 equilibrium validated

23

at birth, do we expect sex ratio to be 1:1

produce more M bc M die quicker so they need to be replenished, sons die at a higher rate, by reproductive age we will have more duaghters than sons= male biased production in humans

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