Organismal Biology Reproduction

Sexual and asexual

Sexual vs. Asexual Reproduction Asexual Reproduction: Define Types: Binary Fission and Budding (mostly unicellular organisms) Regeneration and Parthenogenesis (multicellular animals) Advantage: Good for widely dispersed animals (no need to find a mate) Allows for rapid growth in favorable conditions Requires much less energy than sexual reproduction

Sexual vs. Asexual Reproduction Sexual Reproduction: Define Performed by most multicellular plants and animals Ensures genetic diversity and variability through recombination of alleles Allows species to survive better in a changing environment

Prokaryote vs. Eukaryotes Prokaryotes: Binary fission without mitosis Does cytokinesis still occur?

Prokaryote vs. Eukaryotes Besides binary fission, bacteria can also reproduce by transformation (taking in naked, foreign DNA), transduction (new DNA added by a virus), conjugation (exchange of genetic material between bacteria).

Transduction

Conjugation

Prokaryote vs. Eukaryotes Eukaryotes: Mitosis occurs with cytokinesis

Asexual Reproduction: Binary Fission Parent divides into two equal parts The 2 daughter cells are equal in size and grow to normal size Ex: ameba and paramecium

Asexual Reproduction : Budding The parent cell divides into 2 unequal parts Yeast (unicellular) - 2 daughter cells are produced - 1 is larger than the other Hydra (multicellular) - the daughter is a multicellular outgrowth of the parent An important thing to remember is that there is still an equal division of nuclear material in budding even though the cytoplasm is unequally divided

Yeast and Hydra Budding This small hydra bud will eventually separate from the parent Yeast bud

Asexual Reproduction : Parthenogenesis: Development of an unfertilized egg

4. Regeneration The ability of an animal to regrow lost body parts Simple organisms: hydra, planaria, earthworm, and lobster

Regeneration in Planaria

Sexual Reproduction Meiosis produces gametes (sperm and egg). Reduces chromosome number by half. Fertilization restores the diploid chromosome number. It allows for recombination of alleles creating more variability and diversity among the offspring.

Hermaphrodites Organisms that contain both male and female reproductive organs Each earthworm below is placing sperm inside the other Why is this type of existence beneficial for an organism with a lifestyle like the earthworm? Earthworms spend most of their time under the ground and are slow moving. This double fertilization ensures enough offspring

Human Reproduction