TOPIC 1 - REPRODUCTION

• Reproduction- a process by which an organism may produce offspring and perpetuate its species.
• Sexual reproduction- the production of offspring from two parents, one male (father) and one female (mother).
• Sexual Reproduction- The fusion of male and female gametes or sex cells to form a zygote.
• Asexual reproduction- the production of offspring without fertilization; it is also called vegetative propagation.
• Asexual Reproduction- mode of reproduction that does not involve the use of gametes or sex cells.
• Sexual Reproduction

  • involves 2 parents
  • offspring genetic mix of both parents
  • involves specialized sex cells
  • it’s slow
• Asexual Reproduction

  • involves 1 parent
  • offspring genetically identical to parent
  • involves regular body cells
  • it’s quick
• Fertilization - a male reproductive cell and a female reproductive cell combine to form a new cell that can develop into a new organism.
• Internal Fertilization - fertilization that takes place inside the body of the female.
• 3 WAYS BY WHICH OFFSPRING ARE PRODUCED BY INTERNAL FERTILIZATION

  1. Oviparity (egg-laying animals) - fertilized eggs are laid outside, where they receive nourishment from the yolk
  2. Ovoviviparity - fertilized eggs are retained in the female‘s body where they receive nourishment from the yolk. The eggs are laid right before they are hatched
  3. Viviparity - offspring are born directly instead of hatching from the eggs. They receive nutrition from the mother. This can be seen in mammals
• External Fertilization - fertilization that takes place outside the female body. Usually requires a medium such as water, which the sperm can use to swim towards the egg cell.
• Fission/Splitting

  • the body of an organism divides into new bodies
  • duplicates its DNA
  • both new bodies receive a copy of the DNA of the original organism
  • cell division in prokaryotes that forms two genetically identical cells
• Binary Fission - Asexual reproduction in which one cell divides to produce two identical daughter cells.
• Budding

  • small bud grows out of parent cell
  • two different sized cells made (with identical DNA)
  • bud breaks off and grows
  • in yeas and hydra
  • happens in animals without reproductive organs or those with both male and female reproductive organs.
• Hydra - a tiny water animal that usually begins life as a bud that grows on the body of its parent.
• Fragmentation - organisms body is divided into two or more parts, wherein each fragment develops into an organism like its parent.
• Regeneration (Planaria) - repair lost body parts, detached parts of some organisms can grow back.
• Parthenogenesis - females produce eggs that develop without fertilization.
• Sporulation - very rare in animals and are only exhibited in some organism like sponges.