• Asexual • Sexual Reproduction Reproduction – involves only one – involves two parent parents – offspring is – offspring has genetically identical genetic mix of both to the parent parents – involves regular – involves specialized body cells sex cells – quick – slow
Asexual Reproduction• Binary Fission – happens in bacteria, amoeba, and some algae – one parent cell splits into two identical daughter cells• Budding – happens in yeast, hydra, corals – parent produces a bud – bud gets detached and develops into offspring which is identical to its parent
Binary Fission Rod-shaped Bacterium, Hemorrhagic E. colitwo daughter cells are identical to its parent
Asexual Reproduction contd.• Spore Formation – happens in fungi, green algae, molds and non-flowering plants (e.g. ferns) – spores are produced and each spore develops into offspring which are identical to its parent• Vegetative Reproduction – does not involve seeds – some offspring can grow from cuttings (e.g. coleus), runners (e.g. strawberries), tubers (e.g. potatoes) or bulbs (e.g. tulips), which are part of the parent plant
Sexual Reproduction in Animals• involves specialized sex cells called gametes• the union of a male and a female gamete results in the formation of a zygote that develops into a new individual
Sexual Reproduction in Plants Female Parts Male Parts (Pistil)pollen (male) + ovule (female) → single-celled zygote → multi-celled embryo (contained in a seed) → new individual
Sexual Reproduction in Plants• stamen is the male part and contains pollen• carpel or pistil is the female part and contains ovule (eggs)• 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 plant’s eggs)
Pollination• flowers are designed to lure insects to help with the pollination process – wind, animals, birds can also transport pollen
Sexual Reproduction Summary Male Female Type of Result of Final Gamete Gamete Union Union ResultPlants pollen ovule pollination single-cell multi-cell (egg) zygote embryo (in seed)Animals sperm egg fertilization single-cell multi-cell zygote embryo
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 sponges and hydrae mosses
Which is Better? It depends! Asexual Reproduction Sexual Reproduction• Advantages • Advantages – does not require special – lots of variations within cells or a lot of energy a species – can produce offspring – able to live in a variety quickly of environmental – creates a large, thriving settings population in a stable – able to adapt to environment changes in the• Disadvantages environment – limited ability to adapt • Disadvantages – face massive die-off if – needs time & energy environment changes – produce small populations
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