Chapter 47 Flashcards
Asexual reproduction
based on mitosis & results in offspring that are
genetically identical to one another and to their parent equivalent to cloning
ex. budding in hydra, fission in anemones and parthenogenesis in lizards
Sexual reproduction
based on meiosis & gamete fusion
▪Due to genetic recombination during meiosis & fusion of haploid gametes( usually from different parents) during fertilization, on results in offspring that are genetically
different from each other & from their parents!
Binary fission
Major type of asexual reproduction
Single parent cell doubles its DNA, then divides into two cells. Usually occurs in bacteria.
Fragmentation
Organisms break into two or more fragments that develop into a new individual. Occurs in many plants, as well as some animals (like coral, sponges, and starfish).
Benefits of asexual reproduction
- all individuals can reproduce
- requires no mates, travel or competition
Budding
Major type of asexual reproduction
Small growth on surface of parent breaks off, resulting in the formation of two individuals. Occurs in yeast and some animals (like the hydra below).
Parthenogenesis
Type of asexual reproduction
An embryo develops from an unfertilized cell. Occurs in invertebrates, as well as in some fish, amphibians, and reptiles.
Gametogenesis
Consists of spermatogenesis: how the sperm is created and oogenesis or how the egg is created
Oogenesis
1 egg ; 4 sperm
- Primary germ cell
- Oogonium through mitotic divisions
- Primary oocyte forms through mitotic divisions
- arrested n prophase 1 of meiosis - Through meiosis I, secondary oocyte and polar body is formed
- Through meiosis II ootid and another polar body is made
- A mature egg ell (ovum is created)
- arrested at metaphase II of meiosis - Sperm enters and fertilized egg
- Completes meiosis II
Spermatogenesis
Male germ cells undergoes meiosis to produce four gametes
- Primordial germ cell in embryo
- Spermatogonial stem cell through mitotic divisions
- Spermatogonium through mitotic divisions
- Primary spermatocyte from mitotic divisions
- Two secondary spermatocyte through
meiosis 1 - Early 4 spermatid through meiosis II
- Sperm through differentiation (Sertoli cells provide nutrients)
Differences between Oogenesis and spermatogenesis
- Oogenesisceases later in
life; spermatogenesis
continues throughout
adult life - Oogenesishas long
interruptions;
spermatogenesis produces
sperm from precursor cells
in continuous sequence
Ovulation
Sperm entry into matured egg cell and becomes a fertilized egg at completion of meiosis II
Scrotum
Holds testes and penis
Penis
organ of copulation needed for internal fertilization
Where are the accessory fluids formed
seminal vesicles, prostate
gland & bulbourethral gland
Where is sperm produced and stored
Produced by testes and stored in epididymis
Vas deferens
tubes that transport sperm from
epididymis to ejaculatory duct.
Ovary
Where meiosis produces egg cells (ova)
Semen
combination of sperm & accessory fluids
Passes through urethra, that services both reproductive & urinary systems in males
Viviparous
Female retains embryo & provides nourishment during development
Humans are viviparous
What happens during ovulation
Egg is expelled from ovary & enters oviduct (fallopian tube), where fertilization may take place
Uterus
Where embryonic development takes place
During childbirth, the baby passes through
cervix & into the vagina
Where does fertilization take place
Oviduct (fallopian tubes)
How puberty is initiated
- Gonadotropin releasing hormone is released from hypothalamus
- Triggers release of
luteinizing hormone
(LH) & follicle-stimulating
hormone (FSH) from
pituitary gland - LH & FSH trigger increases in testosterone
or estradiol