Angiosperm Reproduction and Biotechnology

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Angiosperm Reproduction and Biotechnology
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Angiosperm Reproduction and Biotechnology

• Angiosperms may reproduce sexually or asexually.

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Angiosperm Reproduction and Biotechnology

• Plants show alternation of generations.

gametes
mitosis
n gametophyte
2n sporophyte
spores
meiosis
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Angiosperm Reproduction and Biotechnology

• In angiosperms, the sporophyte is dominant.

2n sporophyte
n gametophyte
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Angiosperm Reproduction and Biotechnology
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Angiosperm Reproduction and Biotechnology

• Pollen (male gametophytes)
• 1. In the anther there are diploid microsporocytes
  (also called microspore mother cells)
• 2. These divide by meiosis to make four haploid
  microspores.

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Angiosperm Reproduction and Biotechnology

• 3. Each microspore becomes a pollen grain, and
  each pollen grain can make two sperm
• 4. The pollen grain doesnt mature and make
  sperm until it has landed on the stigma of a
  carpel and the pollen tube begins to grow.

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Angiosperm Reproduction and Biotechnology

• Embryo sac (female gametophyte)
• 1. In the ovule there is a diploid megasporocyte
  (megaspore mother cell)
• 2. It divides by meiosis to make four haploid
  megaspores, but only one survives.

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Angiosperm Reproduction and Biotechnology

• 3. Mitosis of the megaspore forms the embryo sac
• 4. Ovule now consists of embryo sac and
  integuments.

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Angiosperm Reproduction and Biotechnology

• Preventing self-fertilization
• carpellate vs. staminate
• pin vs. thrum
• floral organs mature at different times
• self-incompatibility.

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Angiosperm Reproduction and Biotechnology

• Double fertilization
• One sperm fertilizes the egg
• The other sperm combines with polar nuclei to
  make endosperm.

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Angiosperm Reproduction and Biotechnology

• After fertilization
• Ovule becomes seed
• Ovary becomes fruit
• Endosperm stores nutrients
• Later, the cotyledons store even more food.

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Angiosperm Reproduction and Biotechnology

• Asexual reproduction
• In stable environments
• Stable characteristics
• Can make many copies
• Not frail
• In unstable environments
• No variation, no evolution
• No disbursal of seeds.

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Angiosperm Reproduction and Biotechnology

• Asexual reproduction
• Fragmentation (cuttings)
• Apomixis (making seeds asexually).

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Angiosperm Reproduction and Biotechnology

• Totipotent cells lead to
• Cloning
• Transgenic plants
• Protoplast fusion hybrids.

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Angiosperm Reproduction and Biotechnology

• Uses of biotechnology
• Insect resistance
• Herbicide resistance
• Nutritional improvement.

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Angiosperm Reproduction and Biotechnology

• Possible side effects
• Allergens
• Non-target organisms
• Transgenic escape.