Chapter 49 - Reproduction Flashcards
What is the difference between sexual and asexual reproduction?
asexual reproduction creates genetically identical offspring to the single parent. sexual reproduction creates genetically different offspring where male and female gametes come together
What is another name for asexual reproduction?
clonal reproduction
What are the 3 advantages of asexual reproduction?
1) Preserves genetic uniformity – advantageous in environments that remain stable and uniform
2) No energy expended in producing gametes
3) No energy expended in finding a mate, especially in sparsely populated areas or in sessile organisms
What type of environment does asexual reproduction usually occur in?
aqueous
What are the 3 different types of asexual reproduction?
fission, budding, fragmentation, parthenogenesis
What is fission? example?
the parent separates into two or more offspring of approximately equal size (e.g., planarians)
What is budding? example?
a new individual develops while attached to the parent (specialized region) – offspring may break free from the parent, or remain attached to form a colony (e.g., Hydra)
What is fragmentation? examples?
pieces separate from the body of a parent and develop (regenerate) into new individuals (e.g., flatworms, annelids, and some echinoderms)
What is pathogenesis? how does it work? offspring haploid or diploid?
no fertilization takes place, offspring can be haploid or diploid and are genetically different than the parent as the egg is still produced by meiosis
What are the advantages and disadvantages of sexual reproduction?
advantages: genetic diversity improves survival rate in a changing environment
disadvantages: use energy to create gametes and find mates
What are the 3 ways sexual reproduction creates genetic varaibility?
genetic recombination, independent assortment, and random fusion of gametes
What is the ultimate sources of variability for both sexual and asexual reproduction?
random DNA mutations
What is the formation of male and female gametes called?
gametogenesis
What is a zygote?
fusion of haploid sperm and egg
What are germ cells? location?
where gametes are formed, located in testes and ovaries
What do mitotic division of germ cells produce?
spermatogonia and oogonia
What does spermatogenesis produce?
4 mature haploid spermatozoa (sperm)
What is the structure of sperm?
motile cells driven through a watery medium by a flagellum
What is spermatid? what occurs here?
immature sperm, cytoplasm is lost – except for mitochondria, which produce the ATP that drive the flagellum this creates mature sperm
What is an acrosome?
A specialized secretory vesicle containing enzymes and other proteins that help the sperm penetrate the egg forms a cap over the nucleus in the head of the sperm
What does oogensis produce?
one mature, haploid ovum (egg) – a large cell containing most of the cytoplasm of the parent cell and 3 nonfunctional polar bodies
What stage does the oocytes in the ovary remain in?
1st prophase in meiosis
What stage are the oocytes in during ovulation?
2nd metaphase
When do oocytes complete meiosis?
fertilization