Asexual Reproduction vs. Sexual Reproduction

1. Asexual Reproduction vs. Sexual Reproduction

2. Asexual Reproduction • One Parent Required • Does NOT Require Gametes (sex cells) • Offspring produced by cell division. • Offspring identical to Parent (Identical DNA) • Several Different Types • Binary Fission • Budding • Regeneration/Fragmentation • Vegetative Propagation • Sporulation

3. Binary Fission • Organisms Divide in Half • 2 Identical daughter cells produced. • Daughter cells are half the parent’s size. • Daughter cells grow and then divide into two new identical cells. • This occurs in bacteria.

4. Budding • Small bud grows out of parent cell • Two different sized cells made (with identical DNA) • Bud breaks off and grows • This occurs in yeast and hydra

5. Regeneration • Repair/ grow lost body parts • Left over cells divide to make more cells • Occurs in Lobsters, starfish, lizards

6. Fragmentation • A single parent breaks into parts that regenerate into whole new individuals.

7. Vegetative Propagation • Occurs only in plants (vegetative). • New plants develop from the roots, stems, or leaves of the parent plant.

8. Sporulation • Spore Formation • Spores are produced and each spore develops into offspring which are identical to parent • Spores are surrounded by a tough coat to help them survive harsh environmental conditions. • This occurs in fungi, green algae, molds and non flowering plants (e.g. ferns)

9. Sexual Reproduction • Sexual reproduction is the production of offspring using gametes (sex cells). • Requires two parents that each share ½ of the genetic information. • Offspring share the characteristics of each parent. • The cells of the offspring have two sets of chromosomes (one from each parent), so are diploid. • Haploid = half the number of chromosomes. • Human haploid cells have 23 chromosomes • Diploid= 2 of every chromosome • Human diploid cells have 46 chromosomes. Results in offspring that have a variety of traits that are similar to the parents, but not exact copies!

11. Fertilization • Internally (inside) • The egg is fertilized by sperm inside the female • Mammals, birds, reptiles, insects, spiders • Externally (outside) • The egg is fertilized by sperm outside the female • The female lays the eggs and then the male fertilizes them. • Fish and some amphibians • Plants and fungi (pollen and spores)

12. Pollination pollen grains from the anther are transferred to the stigma by the process of pollination • self pollination (plant pollinates its own eggs) • cross pollination (pollen from one plant pollinates another plants eggs) flowers are designed to lure insects to help with the pollination process • also wind, animals, birds can transport pollen

13. Some Organisms do Both most plants that produce seeds (sexual reproduction) can also reproduce asexually by things like cuttings or runners • this gives them an advantage for survival mosses sponges and hydra

14. Which is Better?It depends! Asexual Reproduction advantages • does not require special cells or a lot of energy • can produce offspring quickly • in a stable environment creates large, thriving population disadvantages • limited ability to adapt • face massive die-off if environment changes Sexual Reproduction advantages • lots of variation within a species • able to live in a variety of environmental settings • able to adapt to changes in the environment disadvantages • needs time & energy • produce small populations