Chapter 6 pt 1 (sex det)

Question 1

“Sexual reproduction is the masterpiece of nature”

Answer 1

Erasmus Darwin

Question 2

I tis quatrain to notice that that the number of speculations connected with the nature of sex have well-nigh doubled since drelincourt, in the 18th century brought together 262 groundless hypothesis

Answer 2

JA Thomsom

Question 3

_______ claimed sex was determined by the heat of the male partner during intercourse. The more heated the passion, the greater the probability of producing male offspring. Elderly men should try to conceive in the summer if they wish to have sons

Answer 3

Aristotle

Question 4

When were the X and Y chromosomes identified in humans?

Answer 4

early 1900’s

Question 5

In _______, the presence of a second X and or presence of Y determines sex

Answer 5

Mammals
-XX = female
-XY = male

Question 6

In _______, males have two similar sex chromosomes (ZZ) while females have unmatched sex chromosomes (ZW)

Answer 6

birds

Question 7

In _______, Y chromosome does not appear to play a major role. Sex is determined by the number of X chromosomes

Answer 7

Drosophilia
- XX = female
- X_ = Male

Question 8

In _______, fertlized diploid eggs will develop as female, while unfertilized haploid eggs become male

Answer 8

many insects
- hymenopterans (bees, ants, wasps)

Question 9

What is primary sex determination in mammals?

Answer 9

determination of the gonads

Question 10

The Y chromosome is critically important in mammals because it produces _______, which organizes the gonad into testes

Answer 10

Testes determination factor

Question 11

What is secondary sex determination in mammals?

Answer 11

development of sexual phenotype
- male female duct system and genetalia

Question 12

Mammalian gonads originally are formed indifferent with no sex chosen this is an example of _______

Answer 12

bipotential gonad
(indifferent gonad)

Question 13

in male mammals:
_____ cells secrete _______ that block the formation of the female duct system from the _______ duct. The _______ duct differentiates into the vas deferens

Answer 13

1) sertoli
2) anti-mullerian factor
3) mullerian duct
4) wolffian duct

Question 14

In female mammals:
in the absence of testosterone, the _______ duct degenerates while the _______ duct differentiates into the oviducts, uterus, cervix, and upper vagina

Answer 14

1) wolffian
2) Mullerian

Question 15

In mammals, maleness is determined by the presence or absence of _______

Answer 15

testis (phenotypic)
- y chromosome (genotypic)

Question 16

_______: sex determining region of the Y chromosome

Answer 16

SRY gene

Question 17

_______ cell of the testis secretes testosterone

Answer 17

Leydig

Question 18

Testosterone is _______ meaning it is a male determining hormone

Answer 18

androgenic

Question 19

In males (XY), _______ gene on the Y chromosome is activated by a series of factors in the early stages of genital ridge formation

Answer 19

SRY

Question 20

SRY protein binds to _______ promotor, increasing its expression

Answer 20

SOX9
- Sry is only active for a few hours

Question 21

In males, _______ and _______ both act to block the ovary forming pathway by blocking the function of β-catenin

Answer 21

Sox9 and Fgf9

Question 22

In females (XX) ________ is critical in activating further ovary development and blocks the synthesis of Sox 9

Answer 22

β-catenin

Question 23

β-catenin is activated through a _______ pathway

Answer 23

Wnt4/Rspo1

Question 24

β-catenin can stimulate the production of _______ and other genes that lead to ovary formation

Answer 24

Follistatin

Question 25

In lab experimental situations, a delay of Sry expression by as little as __-hours caused testis to fail to develop nad the gonads instead to become ovaries

Answer 25

6

Question 26

_______ the development of male and female phenotypes in response to hormones secreted by the ovaries and testis

Answer 26

Secondary sex determination

Question 27

What are the 2 major phases of secondary sex determination?

Answer 27

1) embryogenesis 2) puberty

Question 28

_______ stimulates the mullerian ducts to differentiate into the uterus, cervix, oviducts, and upper vagina

Answer 28

Estrogen

Question 29

In females, the ______ differentiates into clitoris, while in males it differentiates into the penis

Answer 29

genital tubercle

Question 30

In females, the labio-scrotal folds become the _______, while in males they become the _______

Answer 30

labia majora scrotum

Question 31

The androgen insensitivity syndrome results in __ individuals that have the SRY gene with testis and testosterone. However, they develop externally as _______

Answer 31

XY female - sterile women that lack uterus, oviducts, and have testes in abdomen

Question 32

_______: male and female traits seen in the same individual

Answer 32

intersex

Question 33

_______: only one type of gonad, but the secondary sexual characteristics **depart** from what is expected when carrying that type of gonad

Answer 33

pseudo-hermaphroditism - androgen insensitivity - mutation in testosterone synthesis

Question 34

What is a cause of pseudo-hermaphroditism? (2)

Answer 34

1) androgen insensitivity syndrome 2) mutation in testosterone synthesis

Question 35

_______: when gonadal sex is female but externally shows male phenotypes.

Answer 35

female pseudo-hermaphroditism - can be caused by overproduction of androgens from adrenal glands or ovaries

Question 36

What is a cause of female pseudo-hermaphroditism

Answer 36

overproduction androgen in adrenal glands or ovaries

Question 37

_______: A genetic deficiency of an enzyme responsible for metabolizing cortisol steroids in the adrenal gland. In the absence of this enzyme, testosterone-like steroids accumulate masculinizing the fetus.

Answer 37

congenital adrenal hyperplasia

Question 38

In drosophila, examination of _______ (mosaic individuals with both male and female cells in the same body) suggests that in insects, each individual cell makes its own decision about sex

Answer 38

gynandromorphs

Question 39

the critical gene in drosophila sex determination is the _______ gene that encodes the _______ protein

Answer 39

Sxl gene sex-lethal

Question 40

Transcription of the Sxl gene is controlled by what two promoters?

Answer 40

1) PE (early) - only activated in XX female cells 2) PL (late) - activated in both XX and XY cells

Question 41

What are the 4 transcription factors responsible for stimulating sxl transcription?

Answer 41

1) SisA 2) Scute 3) Runt 4) unpaired

Question 42

In drosophila XY cells, transcription of Sxl from PE (is/isnt) sufficiently stimulated

Answer 42

isnt - haploinsufficient - XX has double the amount of TF which allows for XX PE transcription

Question 43

The SXL protein is an RNA-binding protein that directs the splicing of sxl mRNA molecules produced from the _______ promoter

Answer 43

PL

Question 44

In the absence of the SXL protein, sxl mRNA's produced from the PL promoter are spliced in a manner that **maintains** a _______ present in exon 3 resulting in _______ additional functional SXL protein being produced

Answer 44

- in males stop codon no

Question 45

In the presence of the SXL protein, sxl mRNA's produced from the PL promoter are alternatively spliced in a manner that **removes** a _______ present in exon 3 resulting in _______ functional SXL protein being produced

Answer 45

- in females stop codon additional

Question 46

Females have _______ and _______ Sxl protein while males have _______ sxl protein

Answer 46

early and late non-functional

Question 47

The pre-mRNA of the _______ gene is produced in both male and female cells and is a target of Sex-lethal

Answer 47

transformer (tra) - produces another splicing factor

Question 48

In female cells the presence of SXL protein directs the splicing apparatus to an alternate splice site producing the female-specific _______ protein. In male cells, the premature stop codon is not spliced out and no functional _______ protein is produced

Answer 48

TRA TRA

Question 49

TRA works to alternatively splice the pre-mRNA of the _______ gene to produce both male and female specific versions

Answer 49

double-sex (dsx) - transcription factor

Question 50

In females the _______ protein acts as a TF to activate female-specific genes and repress male-specific genes

Answer 50

DSXf

Question 51

In males the _______ protein acts as a TF to activate male-specific genes and repress female-specific genes

Answer 51

DSXm

Question 52

briefly explain sex-specific RNA splicing in drosophila

Answer 52

4 mRNA (sex-lethal, transformer, doublesex, fruitless) are spliced differently - sex lethal affects sex lethal and transformer - transformer affects doublesex, and fruitless

Question 53

The dsx gene is processed in a sex-specific manner by _______ and _______

Answer 53

tra and tra2

Question 54

DsxF in association with the _______ protein creates a TF complex that activates female-specific genes

Answer 54

intersex (Ix)

Question 55

_______ is an enzyme that converts testosterone into estrogen

Answer 55

aromatase

Question 56

In turtles, @ 25°C aromatase activity is _______

Answer 56

very low Hot chicks, cool dudes

Question 57

In turtles, @ 30°C aromatase activity _______

Answer 57

increases Hot chicks, cool dudes

Question 58

Aromatase control happens via what two mechanisms?

Answer 58

1) temp-dependent transcription 2) temp-dependent enzyme activity

Question 59

Work done by _______ and colleagues has shown a link between _______ and sex determination

Answer 59

tyrone hayes atrazine

Question 60

atrazine produced sexual anomalies in males frogs like _______ and _______

Answer 60

testicular dysgenesis and conversion to ovaries