CALM 5

Question 1

During the ____ , all embryos develop two unspecialized gonads, which are organs that will develop as either testes or ovaries. Each such “indifferent” gonad forms near two sets

Answer 1

fifth week

Question 2

one set of tube

Answer 2

Müllerian ducts

Question 3

sexual structures characteristic of a female.

Answer 3

Müllerian ducts

Question 4

If a gene on the Y chromosome called SRY (for “sex-determining region of the Y”) is activated,

Answer 4

hormones steer development along a male route.

Question 5

In the absence of SRY activation,

Answer 5

a female develops.

Question 6

Human males and females have equal numbers of autosomes

Answer 6

(44 or 22 pairs

Question 7

two different sex chromosomes

Answer 7

heterogametic sex

Question 8

two of the same sex chromosome

Answer 8

homogametic sex.

Question 9

This symmetry in a DNA sequence, described by researchers as ___destabilizes DNA replication.

Answer 9

“a hall of mirrors”

Question 10

The ___has a distinctive overall structure with a short arm and a long arm.

Answer 10

Y chromosome

Question 11

At both tips of the Y chromosome are___ , termed PAR1 and PAR2.

Answer 11

pseudoautosomal regions

Question 12

means that the DNA sequences have counterparts on the X chromosome and can cross over with them.

Answer 12

pseudoautosomal

Question 13

lies between the two pseudoautosomal regions. It consists of three classes of DNA sequences.

Answer 13

male-specific region, or MSY

Question 14

Many of the genes in the MSY are essential to fertility, including

Answer 14

SRY

Question 15

The SRY gene encodes a very important type of protein called a ___, which controls the expression of other genes.

Answer 15

transcription factor

Question 16

___cells in the developing testis secrete anti-Müllerian hormone, which destroys potential female structures (uterus, uterine tubes, and upper vagina).

Answer 16

sustentacular (Sertoli)

Question 17

____ cells in the testes secrete testosterone, which stimulates the development of male structures (the epididymis, ductus deferentia, seminal vesicles, and ejaculatory ducts).

Answer 17

interstitial (Leydig)

Question 18

embryos don’t have SRY, so they develop as females.

Answer 18

XX

Question 19

embryos do have SRY, so they develop as male.

Answer 19

XY

Question 20

caused by a mutation in a gene on the X chromosome, the absence of receptors for androgens (the male sex hormones testosterone and DHT) stops cells in early reproductive structures from receiving the signal to develop as male. The person looks female, but is XY.

Answer 20

androgen insensitivity syndrome (MIM 300068)

Question 21

Is an older and more general term for an individual with both male and female sexual structures.

Answer 21

Hermaphroditism

Question 22

Refers to individuals whose internal structures are inconsistent with external structures, or whose genitals are ambiguous. It is the preferred term outside of medical circles.

Answer 22

Intersex

Question 23

Refers to the presence of both types of structures but at different stages of life.

Answer 23

Pseudohermaphroditism

Question 24

Affected individuals have a normal Y chromosome, a wild type SRY gene, and testes.

Answer 24

5-alpha reductase deficiency

Question 25

lack of__ causes the fetus to develop externally as female—that is, without DHT, a penis cannot form.

Answer 25

DHT

Question 26

due to 21- hydroxylase deficiency (MIM 201910),

Answer 26

congenital adrenal hyperplasia (CAH)

Question 27

a person’s phenotype & genotype are consistent, and physical attraction is toward members of the same sex.

Answer 27

homosexuality

Question 28

Undifferentiated structure begins to develop as testis or ovary

Answer 28

Gonadal Sex

Question 29

Development of external & internal reproductive structures continues as male or female in response to hormones

Answer 29

Phenotypic Sex

Question 30

Strong feelings of being male or female develop

Answer 30

Gender Identity

Question 31

Attraction to same or opposite sex

Answer 31

Sexual Orientation

Question 32

predicts that populations should have approximately equal numbers of male and female newborns.

Answer 32

Mendel’s law of segregation

Question 33

proportion of males to females in a human population

Answer 33

sex ratio

Question 34

calculated as the number of males divided by the number of females multiplied by 1,000, for people of a particular age

Answer 34

sex ratio

Question 35

The sex ratio at conception is called the

Answer 35

primary sex ratio.

Question 36

Sex ratio at birth is termed

Answer 36

secondary

Question 37

and at maturity is called

Answer 37

tertiary.

Question 38

The human male is considered ))))for X-linked traits, because he has only one set of X-linked genes.

Answer 38

hemizygous

Question 39

An enzyme deficiency blocks removal of cholesterol from skin cells, the upper skin layer cannot peel off as it normally does, appearing brown and scaly. It is transmitted as an X-linked recessive trait.

Answer 39

Ichthyosis

Question 40

Is another X-linked recessive trait that does not hamper the ability of a man to have children

Answer 40

Color Blindness

Question 41

Blood-clotting disorder.

Answer 41

Hemophilia A

Question 42

In affected females, swirls of skin pigment arise when melanin penetrates the deeper skin layers.

Answer 42

Incontinentia Pigmenti

Question 43

This condition produces many extra hair follicles, and hence denser and more abundant upper body hair.

Answer 43

Congenital generalized hypertrichosis

Question 44

X-linked recessive trait generally is more prevalent in

Answer 44

males than females

Question 45

affects a structure or function of the body that is present in only males or only females. Such a gene may be X-linked or autosomal.

Answer 45

sex-limited trait

Question 46

sudden rise in blood pressure late in pregnancy.

Answer 46

preeclampsia

Question 47

An allele is dominant in one sex but recessive in the other.

Answer 47

sex-influenced trait

Question 48

balances this apparent inequality in the expression of genes on the X chromosome.

Answer 48

X inactivation

Question 49

a random process that happens separately in individual cells during embryonic development.

Answer 49

X-inactivation

Question 50

gene called ___controls X inactivation.

Answer 50

XIST

Question 51

can alter the phenotype (gene expression), but not the genotype.

Answer 51

X inactivation

Question 52

a ___does not have an inactivated X chromosome.

Answer 52

fertilized ovum

Question 53

X inactivation is an example of an .____ one that is passed from one cell generation to the next but that does not alter the DNA base sequence.

Answer 53

epigenetic change i

Question 54

The nucleus of a cell of a female, during interphase, has one dark-staining X chromosome

Answer 54

Barr body (a small, dense structure).

Question 55

A female who is ___can express the associated condition if the normal allele is inactivated in the tissues that the illness affects.

Answer 55

heterozygous for an X-linked recessive gene

Question 56

carrier of an X-linked trait who expresses the phenotype is called a

Answer 56

manifesting heterozygote.

Question 57

Cells that make the enzyme readily send it to neighboring cells that do not, essentially correcting the defect in cells that can’t make the enzyme.

Answer 57

Hunter syndrome (mucopolysaccharidosis II),

Question 58

Affected boys are deaf, mentally retarded, have dwarfism and abnormal facial features, heart damage, and enlarged liver and spleen.

Answer 58

Hunter syndrome (mucopolysaccharidosis II),

Question 59

may develop mild symptoms of this disorder that causes skin lesions, abdominal pain, and kidney failure in boys.

Answer 59

Fabry disease (alpha-galactosidase A deficiency)

Question 60

methyl (CH 3) groups cover a gene or several linked genes and prevent them from being accessed to synthesize protein

Answer 60

genomic imprinting

Question 61

epigenetic alteration.

Answer 61

Imprinting

Question 62

passed from cell to cell in mitosis, but not from individual to individual through meiosis.

Answer 62

Imprinting

Question 63

controls placenta development

Answer 63

male genome

Question 64

controls embryo development.

Answer 64

female genome

Question 65

When two sperm fertilize an oocyte and the female pronucleus degenerates, an abnormal growth of placenta-like tissue called a ___forms

Answer 65

hydatidiform mole

Question 66

due to a deletion in the copy of the chromosome he inherited from his father. Note his small hands.

Answer 66

Prader-Willi syndrome

Question 67

caused by a deletion in the chromosome 15 that he inherited from his mother. He is mentally retarded.

Answer 67

Angelman syndrome