Lecture 22- Asexual and sexual reproduction Flashcards
What are the three types of asexual reproduction?
Budding, regeneration, reparthenogenesis
How does budding and regeneration produce new individuals?
Mitosis
How does budding work?
A bud grows by mitosis, cells differentiate before the bud breaks away
What is regeneration?
- Usually replacement of damaged tissues
- Sometimes pieces of an organism can regenerate complete organisms
In what organisms can regeneration be seen?
Echinoderms- each piece including central disk can regenerate
Colonial cnidarians such as corals- pieces broken off in a storm start new colonies
Segmented marine worms break apart
What is parthenogenesis?
The development of offspring from unfertilized eggs
When is parthenogenesis common?
Arthropods, fish, amphibians and reptiles
What can parthenogenesis determine?
Sex- for example, bees:
- Male are haploid
- Females are diploid
What happens in some species where the parthenogentic reproduction requires sexual behavior?
Females may act as males depending on cyclical hormonal states (estrogen and progesterone)
The sexual activity stimulates the release of the egg
What process produces haploid gametes through meiotic cell division?
Gametogenesis
What are the three fundamental steps of sexual reproduction in animals?
Gametogenesis (making gametes)
Mating (bringing gametes together)
Fertilization (fusing gametes)
What are the disadvantages of sexual reproduction?
- Time and energy
- Exposes to predators/damage
- Detracts from other behaviors
What does sexual reproduction require?
Joining of two haploid cells to form a diploid individual
Where does gametogenesis occur?
In the gonads- the testes and ovaries
What are the different gametes?
- Small, motile sperm
- Nonmotile ova (eggs)
What are gametes produced from?
Germ cells
Where do germ cells come from?
They are produced early in the development of the embryo and remain distinct from the rest of the cells
Other than germ cells, what are other embryonic cells called?
Somatic cells
What happens to the germ cells when gonads begin to form?
They migrate to the gonads
Once germ cells are within male gonads, what happens?
They undergo mitosis to produce spermatogonia