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• Reproduction


  The process by which an organism produces offspring of the same kind
• Types of Reproduction


  • Asexual
  • Sexual
• Asexual Reproduction


  • One parent
  • No reproductive organs
  • No genetic variation
  • Mitosis and Cytokinesis
  • Offspring are identical to parent
• Sexual Reproduction


  • Two parents
  • Sex cells
  • Meiosis
  • Genetic variation
  • Survival of species
• Asexual reproduction is the primary form of reproduction for single-celled organisms (e.g. bacteria)
• Many plants and fungi reproduce asexually as well
• Some animals reproduce asexually as well (e.g. sponges, hydras)
• Advantages of Asexual Reproduction

  • Fast
  • Easy
• Disadvantages of Asexual Reproduction

  • Same DNA (genetically identical to parent), therefore no variation
• Types of Asexual Reproduction

  • Budding
  • Binary Fission
  • Regeneration
• Budding


  Process by which a new-duplicate plant or animal begins to form at the side of the parent and enlarges until an individual is created (separates)

  
• Binary Fission


  Becoming two by division of the complete organism. A type of cell division where DNA replicates, cell grows and splits, resulting in 2 identical cells
• Regeneration (Fragmentation)


  The ability to restore lost or damaged tissues, organs or limbs. A common feature in invertebrates like worms, starfish and some reptiles
• Cutting


  A form of asexual reproduction in plants where a small part of the parent plant (with buds) is cut and buried in soil to grow into a new plant

  
• Layering


  A form of asexual reproduction in plants where a branch is pulled towards the ground, part is covered with soil, and roots develop from the buried part
• Sexual Reproduction


  Requires the involvement of a male and a female parent. The offspring share similarities with parents but have a unique genetic makeup
• Advantages of Sexual Reproduction

  • Plants don't have to move
  • Mixes DNA
• Disadvantages of Sexual Reproduction (for plants)

  • Need external source for pollination to take place (wind, water, bee, bat, butterfly etc.)
• Depending on the species, plants can reproduce both sexually and asexually
• Sepals and Petals


  Often brightly colored, sterile leaf-like structures that protect other flower parts and attract pollinators
• Stamens


  Male reproductive flower structure that produces pollen (male gamete)
• Carpel (Pistil)


  Female reproductive flower structure that produces ovules (female gamete)
• Sexual Reproduction in Plants

  Pollen (male) + Ovule (female) → Single-celled zygote → Multi-celled embryo (contained in a seed) → New individual
• Pollination Vectors


  • Wind
  • Water
  • Flies
  • Moths
  • Bees
  • Butterflies
  • Beetles
  • Birds
  • Bats
• Steps for Pollination


  1. Pollen transferred from filament to stigma

  2. Pollen descends style & reaches ovule

  3. Pollen & ovule unite to produce a seed
• Hermaphrodites


  Organisms with both ovaries and testes in the same individual, common in slow or sessile organisms like worms, hydras, snails
• Gametogenesis


  The process of producing gametes (sperm and eggs)
• Spermatogenesis


  The process of producing sperm cells in males
• Oogenesis


  The process of producing egg cells in females
• Differences between Sperm and Egg

  • Sperm are small, many, mobile, complex shaped

  Eggs are larger, few, non-mobile, round, may have yolk
• Fertilization


  The process where a sperm and egg cell of the same species combine
• Types of Fertilization in Animals

  • External fertilization
  • Internal fertilization
• Fertilization must take place in a moist environment
• Fertilization Process


  Sperm swim to egg

  Sperm releases enzymes to make hole in egg

  Sperm injects nucleus into egg

  Fertilization membrane forms around egg

  Joining of sperm nucleus and egg nucleus to form diploid zygote
• External Fertilization


  Female releases eggs in water, male releases sperm in water
• Internal Fertilization


  Safer, occurs in terrestrial animals and some aquatic, requires moist female reproductive tract, fewer eggs needed, specialized organs
• Parthenogenesis


  Egg develops without sperm, occurs in some insects like unfertilized eggs of queen bees
• Stages of Embryonic Development

  • Cleavage
  • Blastula
  • Gastrulation
  • Differentiation

  
• Cleavage


  Mitotic cell divisions resulting in a solid ball of smaller cells, no growth in cell size
• Blastula


  Ball of cells with a fluid-filled cavity (blastocoel) in the center