UNIT 12 PART A: REPRODUCTION

Question 1

List the 3 set of sturctures of sex organs

Answer 1

1. gonads
2. internal genitalia
3. external genetalia

Question 2

Gonads

Answer 2

Ø Contain germ cells and produce gametes and hormones.

Ø Two main types based on biological sex:

a. Ovaries (XX)
Ø Gamete produced = ova
Ø Hormones produced = estrogen and progesterone

b. Testes (XY)
Ø Gamete produced = sperm
Ø Hormones produced = testosterone

Question 3

Internal genitalia

Answer 3

Accessory glands and ducts that help with development and/or
movement of gametes through the reproductive system

Question 4

List the accessory glands and ducts in XX individuals:

Answer 4

a) Bartholin’s glands

Ducts
b) Fallopian (Uterine) tube
c) Uterus (with cervix)
d) Vagina

Question 5

List the accessory glands and ducts in XY individuals:

Answer 5

a) Seminal Vesicles
b) Prostate
c) Bulbourethral (Cowper’s) glands

Ducts
d) Epididymis
e) Vas Deferens
f) Ejaculatory duct
g) Urethra

Question 6

External genitalia

Answer 6

Ø External reproductive structures

Ø External genitalia in XX individuals:
a) Clitoris – specifically the glans (other parts of the clitoris are internal)
b) Labia minora and majora

Ø External genitalia in XY individuals:
a) Penis
b) Scrotum (contains the testes)

Question 7

autosomes

Answer 7

consists of 22 pairs (44) of chromosomes that carry
genes solely for somatic characteristics,

Question 8

sex chromosomes,

Answer 8

1 pair; 2 chromosomes
usually XX or XY, that carry the genes that help to determine genetic sex

Question 9

What determines biological sex?

Answer 9

Sperm carry an X or Y chromosome, while ova carry only an X chromosome.
Result = biological sex is determined by the sperm

Question 10

What does it mean that the embryonic tissues are considered bipotential?

Answer 10

For the first 6-7 weeks, XY embryos have the potential to develop either typically male or typically female reproductive organs (they are bipotential
during this stage). (have both mullerian and wolffian duct)

This is similar to how stem cells can become any type of
cell depending on which genes get turned on/off during their
development.

Question 11

What directs zygotes to become male or female?

Answer 11

The gene on the Y chromosome responsible for initiating development of reproductive organs for sperm production is the SRY gene.

Ø Activation of the SRY gene stimulates the production of of a protein called testis determining factor (TDF) that controls the development of the testes and associated reproductive structures.

Ø XX (and XO) individuals lack the Y chromosome and therefore lack the SRY gene and the proteins required for development of testes.

Question 12

Reproductive tract develops from

Answer 12

1. Müllerian ducts in XX individuals
2. Wolffian ducts in XY individuals

Question 13

Describe the steps for Steps for XY sex determination:

Answer 13

1. SRY gene codes for protein Testis Determining Factor
   (TDF)
2. TDF causes differentiation of gonads into testes
3. Testes secrete testosterone and Anti-Müllerian Hormone
   a) Testosterone is converted to DHT
   (dihydrotestosterone) which stimulates
   i. development of the external genitalia.
   ii. differentiation of Wolffian ducts into the internal
   parts of the reproductive tract (epididymis, vas
   deferens, ejaculatory duct, seminal vesicles).

b) Anti-Müllerian Hormone causes degeneration of the
Müllerian ducts.

Question 14

Steps for XX sex determination:

Answer 14

1. No SRY gene, so no Testis Determining Factor (TDF)
2. Without TDF, gonads develop into ovaries.
3. Ovaries lack testosterone or Anti-Müllerian Hormone
   production.
   a) Lack of testosterone leads to
   i. development of the external genitalia (clitoris,
   labia)
   ii. Degeneration of the Wolffian duct

b) Lack of Anti-Müllerian Hormone causes development
of Müllerian ducts into the structures of the
reproductive tract (Fallopian tubes and uterus).