reproduction

• Sexual reproduction


  Process of creating new individual using two parent organisms
• Asexual reproduction


  Process of creating new individual using one parent organism
• Offspring


  New organism that results from reproduction
• Gamete


  Sex cell (in males: sperm; in females: eggs)
• Fertilization


  The joining of gametes to form a new organism
• Zygote


  Cell formed during the fusion of two gametes
• Binary fission


  Single parent cell doubles its DNA, then divides into two cells
• Budding


  Small growth on surface of parent breaks off, resulting in the formation of two individuals
• Fragmentation


  Organisms break into two or more fragments that develop into a new individual
• Parthenogenesis


  An embryo develops from an unfertilized cell
• Types of asexual reproduction


  • Binary fission
  • Budding
  • Fragmentation
  • Parthenogenesis
• Sexual reproduction is not necessarily "better" than asexual reproduction, or vice versa
• Budding and fragmentation are not the same thing
• Some organisms are able to do both sexual and asexual reproduction
• In a hermaphroditic situation, two gametes are involved, so it is considered sexual reproduction
• Parthenogenesis


  Asexual reproduction in which an unfertilized egg develops into a new individual
• Organisms that exhibit parthenogenesis

  • Some invertebrates
  • Some fish
  • Some amphibians
  • Some reptiles
• Parthenogenesis in cold-blooded organisms


  May be related to them being cold-blooded
• Parthenogenesis triggered by sperm


  1. Sperm cells penetrate the egg

  2. Sperm later degenerates

  3. Only maternal chromosomes remain
• In parthenogenesis triggered by sperm, the sperm makes no genetic contribution</b>
• Budding


  A form of asexual reproduction in yeast cells
• Cell division

  1. Single cell divides to make two cells

  2. Two cells divide to make four cells

  3. And so on
• Yeast


  A unicellular fungus, an example result of budding
• Bacteria


  Belong to the Kingdom Monera
• Both asexual and sexual reproduction require DNA
• Viruses are not considered living because they require a host to replicate
• Beluga whales reproduce sexually
• Fragmentation reproduction (e.g. in starfish) results in clones with the same DNA as the original
• Propagating a plant cutting is an example of clonal reproduction with the same DNA as the parent plant
• sporulation- the spore formation as in fern plants and mushrooms
• budding - yeast cells produce buds that grow into new organisms, e.g. hydra
• fragmentation - some animals can break off part of their body which grows into a whole new animal, e.g. planaria
• asexual reproduction produces offspring genetically identical to parents
• sexual reproduction involves fusion of gametes from two different individuals
• asexual reproduction involves only one parent
• fertilisation occurs when sperm cell unites with egg cell
• meiosis reduces chromosome number by half so that there are haploid gametes
• in sexual reproduction, genetic variation occurs due to recombination of genes during crossing over