Ch. 10 - Reproductive Behaviours

Question 1

SRY gene

Answer 1

• The sex-determining region on the y chromosome
• Sex-determining gene on the male’s Y chromosome that causes those undifferentiated gonads to develop into TESTES, the sperm-producing organs
• These testes produce ANDROGENS (hormones that are more abundant in males) that increase the growth of the testes, causing them to produce more androgens and so forth
• Androgens also cause the Wolffian ducts to develop into seminal vesicles (saclike structures that store semen) and the vas deferens (a duct from the testes into the penis)
• The testes also produce Mullerian-inhibiting hormone (MIH) that causes the Mullerian ducts to degenerate

Question 2

Mullerian ducts

Answer 2

• Precursors to female internal structures

- Turns into the female’s uterus, oviducts, and the upper part of the vagina

Question 3

Wolffian ducts

Answer 3

• Precursors to male internal structures

- Turns into the seminal vesicles (which store semen) and vas deferens (a duct from the testis into the penis) in males

Question 4

The development of female structures…

Answer 4

• Females do not have the SRY gene, so their gonads develop into OVARIES instead of testes, and their Wolffian ducts degenerate
• Because their ovaries do not produce MIH, females’ Mullerian ducts develop and mature into oviducts, uterus, and the upper vagina

Question 5

Steroids exert their effects in 3 ways…

Answer 5

1. First, they bind to membrane receptors, like neurotransmitters, exerting rapid effects
2. Second, they enter cells and activate certain kinds of proteins in the cytoplasm
3. Third, they bind to receptors that bind to chromosomes, where they activate certain genes

Question 6

Organizing effects of sex hormones

Answer 6

-Produce LONG-LASTING structural effects

Question 7

Activating effects of sex hormones

Answer 7

-Are more TEMPORARY, continuing only while a hormone is present or shortly beyond

Question 8

Estradiol

Answer 8

-The most prominent type of estrogen

Question 9

Testosterone

Answer 9

-The most prominent type of androgen

Question 10

What determines whether an embryo will develop male or female anatomy?

Answer 10

• Differentiation of the external gonads depends mainly on TESTOSTERONE.
• A high level of T = becomes male
• A lower level of T = becomes female