Reproduction: key aspects Flashcards
What is reproductions role in homeostasis?
No role
What is dimorphism?
2 sexes of the same species are physically distinct
What do gonads produce?
Gametes - sperm and eggs
What is the chromosome:autosome pair ratio?
1:22
What is the role of the testes and ovaries? (2)
Produce gametes
Secrete sex hormones
What are male and female gametes called?
Male: Spermatozoa
Female: ova
Are gametes haploid or diploid?
Haploid - 22 autosomes, 1 sex chromosome
Are zygotes haploid or diploid?
Diploid - 44 autosomes, 2 sex chromosomes
What are the steps in gametogenesis? (6)
- Mitosis - normal cell division
- DNA replicated once
- Cells undergo division once
- Meiosis - cell division to produce gametes
- DNA replicate once
- Cells undergo division twice
What is the gene that determines sex?
srY - if present testes, if not ovaries
What does the srY gene code for?
Testis-determining factor - foetus develops testes
What are the 2 different male and female ducts that precursor tracts?
Male: Wolffian ducts
Female: Müllerian ducts
What occurs if srY gene is present? (2)
Testes:
- testosterone
- Müllerian-inhibiting substance
What occurs if the srY gene is not present? (2)
- No testosterone - Wolffian duct degenerates
2. Müllerian duct forms vagina
What does adolescence mean and when does is it end?
Inability to produce
10-14 years
What does puberty mean (3) and when does it start?
Sexual maturation
Reproductive organs mature (produce gametes)
Secondary sexual characteristics develop
10-14 years, later in boys
What occurs in the female reproductive cycle? (3)
- Female reproductive system cycle
- Female lose ability to reproduce around 45-50
- Menopause: loss of female reproductive capacity
What are the secondary sexual characteristics? (5)
Males - broad shoulders
Females - curvier hips
Presence/absence of facial hair
Testosterone in males
Oestrogen in females
What are the 3 types of sex?
Genetic sex - determined by XX or XY
Gonadic sex - determined by presence of ovaries/testes
Phenotypic sex - the apparent anatomic sex of an individual
When does genetic sex not = phenotypic sex? (4)
- Testes development fails
- Testicular feminisation syndrome - lack of testosterone receptors
- Genetic deficiency in the conversion of testosterone to DHT
- Adrenal gland secretes weak androgen
