Sex

Question 1

What is the primary determinant of maleness?

Answer 1

A single gene: sex determining region of Y (SRY)

Question 2

How did sex reversal provide evidence implicating SRY?

Answer 2

SRY is always present in XX males
SRY is always nonfunctional in XY females

Question 3

What enables sex chromosomes to pair during meiosis I?

Answer 3

Pseudoautosomal regions (PARs)

Question 4

What is in the MSY region of the Y chromosome?

Answer 4

SRY
3 male fertility genes
8 essential genes shared with X

Question 5

What determines sex in Drosophila?

Answer 5

Ratio of X chromosomes to autosomes

Question 6

What determines sex in humans?

Answer 6

Presence or absence of Y chromosome

Question 7

Differentiate between XXX in drosophila and humans.

Answer 7

D: dies
H: nearly normal female

Question 8

Differentiate between XX in drosophila and humans.

Answer 8

Normal female

Question 9

Differentiate between XXY in drosophila and humans.

Answer 9

D; normal F
H: Klinefelter male

Question 10

What are some characteristics of a Klinefelter male?

Answer 10

Sterile, tall, thin

Question 11

Differentiate between XO in drosophila and humans.

Answer 11

D: sterile male
H: Turner female

Question 12

What are characteristics of Turner females?

Answer 12

sterile, short, webbed neck

Question 13

Differentiate between XY in drosophila and humans.

Answer 13

Normal male

Question 14

Differentiate between XYY in drosophila and humans.

Answer 14

D: normal male
H: Nearly normal male

Question 15

Differentiate between OY in drosophila and humans.

Answer 15

Die

Question 16

What is heterogametic sex?

Answer 16

Sex with two different kinds of gametes

Question 17

What is homogametic sex?

Answer 17

Sex with one type of gamete

Question 18

Is sex always determined by chromosome?

Answer 18

No some species sex is affected by environmental factors, such as environment or age

Question 19

What is a germ line?

Answer 19

Specialized diploid cells set aside during embryogenesis

Question 20

What is gametogenesis?

Answer 20

Gamete formation

Question 21

Describe oogenesis in humans

Answer 21

One ovum produces from each primary oocyte

Question 22

Describe spermatogenesis in humans

Answer 22

four sperm from each primary spermatocyte

Question 23

What are oogonia?

Answer 23

Diploid germ cells in ovaries of female embryos

Question 24

What happens to oogonia before they enter meiosis I?

Answer 24

Divide by mitosis to become primary oocytes and arrest in diplotene of prophase I

Question 25

What happens to oocytes after meiosis I?

Answer 25

Two cells produced; a large secondary oocyte and a smaller sister cell called the first polar body

Question 26

Where does the secondary oocyte arrest in meiosis?

Answer 26

Metaphase II

Question 27

What happens in oogenesis at fertilization?

Answer 27

Meiosis II is completed and produces a mature ovum and second polar body

Question 28

What is produced by the asymmetrical meiosis of oogenesis?

Answer 28

One ovum and 2-3 nonfunctional polar bodies?

Question 29

What eventually happens to the polar bodies produced by oogenesis?

Answer 29

Disintegrate

Question 30

What may contribute to chromosome segregation errors in females?

Answer 30

Long meiotic arrest

Question 31

What are spermatogonia?

Answer 31

Diploid germ cells found only in testes

Question 32

What happens when spermatogonia divide by mitosis?

Answer 32

Form primary spermatocytes

Question 33

What happens to primary spermatocytes in meiosis I

Answer 33

Undergo symmetrical division to produce two haploid secondary spermatocytes

Question 34

What happens to secondary spermatocytes during meiosis II?

Answer 34

Undergo symmetrical division to produce two spermatids

Question 35

What happens when spermatids mature?

Answer 35

Become sperm

Question 36

How long does the entire process of spermatogenesis take?

Answer 36

~48-60 days

Question 37

How many sperm are produced in a male's lifetime?

Answer 37

Billions

Question 38

How did Morgan conclude the white gene in Drosophila was X-lined?

Answer 38

Did a series of crosses that showed daughters inheriting phenotype of fathers and sons of their mothers

Question 39

What is hemizygosity?

Answer 39

Reduced allele number due to sex-linkage and possession of a single sex chromosome rather than through heterozygosity of autosomal alleles.

Question 40

How is red-green colour blindness inherited?

Answer 40

X-linked recessive

Question 41

What pedigree patterns suggest X-linked recessive traits?

Answer 41

Mutation never passes from father to son Daughters of affected males are carriers. Half of sons of carriers will inherit the trait.

Question 42

What pedigree patterns suggest X-linked dominant traits?

Answer 42

Trait seen in every generation Affected male will produce affected daughters and unaffected sons

Question 43

What pedigree patterns suggest Y-linked traits?

Answer 43

Only in males

Question 44

How is hemophilia inherited?

Answer 44

X-linked recessive

Question 45

How is hypophosphatemia inherited?

Answer 45

X-linked dominant

Question 46

What is dosage compensation?

Answer 46

In female cells, one X chromosome is randomly inactivated and condenses into a Barr body

Question 47

What are sex-limited traits?

Answer 47

Affect a structure or process found in only one sex

Question 48

Give an example of a sex-limited trait.

Answer 48

Drosophila stuck mutant males can't separate from female after mating

Question 49

What are sex-influenced traits?

Answer 49

Appear in both sexes but hormonal differences may cause difference

Question 50

Give an example of a sex-influenced trait

Answer 50

Male pattern baldness

Question 51

How many groups of precursor cells do sex organs develop from?

Answer 51

four

Question 52

What are bipotential cells?

Answer 52

Cells that develop as male if SRY is present or female if SRY is absent

Question 53

What are the two types of bipotential cells?

Answer 53

Gonad precursors External sex organ precursors

Question 54

What are the two precursor cells specific to each sex?

Answer 54

Female internal sex organ precursors degenerate in presence of SRY, otherwise develop into female sex organs Male internal sex organ precursors are the opposite

Question 55

What does AMF hormone do?

Answer 55

Inhibits female internal sex organ development

Question 56

What does inheritance of a mutant AMF receptor result in?

Answer 56

Complete male sex organs and internal female sex organs

Question 57

What does inheritance of mutant androgen receptor gene for testosterone result in?

Answer 57

Testis, default external female sex organs, and neither male nor female internal sex organs