Sex Chromosomes & Sex Linkage Flashcards Preview

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Flashcards in Sex Chromosomes & Sex Linkage Deck (45)
1

not every organism has ____

sex chromosomes or even separate sexes

2

monoecious

in many plants and animals, every individual is both male and female

1 individual makes both male and female gametes

3

dioecious

organisms where there are separate males and females

4

all vertebrates are ...

dioecious

in lower vertebrates however, males and females are not high differentiated

5

if sexes are not highly differentiated, then

there may be no special sex chromosomes

6

species with highly differentiated sexes also have differentiated _____

sex chromosomes

7

sex in humans is typical of ...

placental mammals, in its biology, genetics, and cytogenetics

8

XX makes

females

9

XY makes

males

10

nonsex chromosomes are called

autosomes

11

humans have __ pairs of autosomes and __ pair of

autosomes, sex chromosomes (either XX or XY)

12

the X is ...

big and metacentric

centromere near the middle

13

the Y is ...

small and acrocentric

centromere very close to the end

14

X and Y act as a ...

pair of homologs

even though they look different

15

what happens to X and Y in meiosis?

form a bivalent but only at the tips

16

psuedo-autosomal regions

Y pairs with X only in these regions on the tips

17

non-recombining region

male-specific region

located between the tips of the Y chromosome

18

do X chromosomes in the female recombine with each other?

yes, just like a normal pair of autosomes

they make a "normal" bivalent where recombination can happen anywhere along the length

19

chromosomal sex determination ensures..

equal numbers of males and females

20

SRY gene

found only on the Y chromosome on the short arm

near the end of the non-recombining region of Y

responsible for initiating male development

21

TDF

testis-determining factor

22

SRY makes

TDF protein

23

in the presence of TDF....

the testis-determining facror turns gonads into testes instead of ovaries

24

is SRY a dominant gene?

yes, only one copy makes you male

25

is SRY a pleitropic gene?

yes, it has multiple effects

26

testes make...

testosterone and other androgens

all are male sec hormones

27

male sec hormones cause...

the body's organs to develop male characteristics

28

androgen insensitivity syndrome

AIS

no receptors for androgens

29

sex-limited traits

secondary sex characteristics

30

sex-limited traits include all...

of the typical physical differences between men and women

31

sec limited traits can be produced...

in either sex, just by male or female hormones acting during development

32

the signal for sex-limited traits to develop comes from...

steroid hormone balances

33

the genes that control the growth of sex-limited traits are ...

distributed all over the chromosomes

34

sex-linked traits are caused...

by genes of the sex chromosomes

35

genes on the X chromosome

more than 1000

random set of genes for varied functions

similar to a typical autosome

36

the human Y has...

150-200 transcription units (majority not protein-coding)

codes for 30 different proteins

11 function in the testes (all in male-specific region)

37

hemizygous

situations where a diploid has only one allele for a gene

due to a deletion of one homolog, for example

38

males are hemizygous for ...

most of the genes of the X chromosome

they only have 1 copy

39

exceptions to hemizygous males

small number of genes in psudo-autosomal regions have 2 copies

40

males get ...

all the recessive genetic disorders on the X is they inherit only one recessive allele

41

sex linked genetic disorders

about 100 X-linked diseases

most are recessive due to alleles on X-chromosome genes

almost all occur in males

42

males can only get an X from...

their mothers

43

males can only pass an X to their...

daughters

44

sons cannot get an x-linked disease from...

their fathers

45

sons can only get an x-linked disease from...

their mothers