ASEXUAL REPRODUCTION

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ASEXUAL REPRODUCTION

• The formation of a new individual that is
  genetically identical to its parent
  reproduction involving ONE parent

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How do they do it? Let me count the ways

• From the simple to the more complex, all kingdoms
  of organisms have some species that can reproduce
  asexually
• Bacteria binary fission
• Protists binary fission
• Fungi fragmentation, budding, sporulation
• Animals regeneration, budding
• Plants cloning, sporulation, runners, layering,
  grafting

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Binary Fission

• process used by bacteria and protists in which
  the single chromosome duplicates and the cell
  divides itself into to equal or near equal parts
• the new smaller cells are referred to as
  daughter cells
• Image taken from http//biodidac.bio.uottawa.ca/t
  humbnails/filedet.htm?File_nameOLIH023PFile_type
  GIF

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Fragmentation

• the kingdom Fungi consists of moulds, yeasts and
  mushrooms
• all fungi are composed of many tiny filaments
  called hyphae
• in fragmentation, a small piece breaks away from
  the main mass of hyphae and grows into a new
  individual
• Images taken from http//www.world-of-fungi.org/M
  ostly_Mycology/Richard_Clarke/fungiphoto/hyphae.jp
  g and http//lamington.nrsm.uq.edu.au/images/fungi
  /fungi070.JPG

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Sporulation

• Sporulation is the process in which a mould
  reproduces asexually to form a spore
• A spore is the reproductive cell produced by a
  mould during mitotic division
• Spores are coated with a tough protective
  membrane that allow them to exist for weeks (even
  years) under harsh environmental conditions such
  as drought, temperature extremes and high
  radiation
• For the spore to become active and develop into a
  new organism, it requires a moist environment
  with plenty of food available
• Images taken from http//www.alliedlead.com/funga
  l-microbial-information.htm

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Budding

• In this type of asexual reproduction, a new
  organism is formed from a protrusion (bud) from
  another organism
• this type of reproduction is common in yeasts and
  in some simple animals (i.e. hydra)
• Images taken from http//www.microscope-microscop
  e.org/gallery/Mark-Simmons/pages/hydra2.htm and
  http//www.acad.carleton.edu/curricular/BIOL/facul
  ty/szweifel/

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Regeneration

• Not a true form of asexual reproduction, just the
  repairing of injured cells or the replacement of
  lost body parts
• Very common amongst invertebrates
• Each piece of the organism can reform an entire
  organism
• Images taken from http//www.vsf.cape.com/jdale/
  science/regeneration.htm and http//www.rzuser.uni
  -heidelberg.de/bu6/Introduction03.html

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Asexual Reproduction in Plants

• Unlike most animals, plants grow continuously
  throughout their lives
• Why? Their root tips contain unspecialized
  cells, called meristematic cells, that undergo
  repeated mitotic division
• At a certain point in their development, these
  cells will specialize and form specific plant
  tissues and they no longer undergo division. If
  they are damaged or destroyed, new meristematic
  cells are activated and repairs are made
• Image taken from http//virtual.yosemite.cc.ca.us
  /randerson/Lynn's20Bioslides/43.jpg

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Cuttings

• The simplest way of propagating plants is to use
  a cutting
• When taking a cutting, a length of parent stem
  is used to establish offspring that are
  gentically identical to the parent plant
• This process is also called cloning
• Image taken from http//www.hydroempire.com/store
  /hydroponic-cloning.php

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Runners

• Runners are special stems sent out by plants
  which can form new roots and therefore a new
  plant
• By placing the leafy offshoot in contact with
  soil, it will begin to form a new root base
• When the new roots are firmly established, the
  runner can be detached from the original plant
• Layering is the process in which a portion of the
  stem of the parent plant is buried in soil.
  Roots will eventually grow from this buried stem
  and the exposed tip will grow into a new shoot
  (new plant)
• Images taken from http//biodidac.bio.uottawa.ca/
  thumbnails/filedet.htm?File_nameRosa003bFile_typ
  egif and http//www.botgard.ucla.edu/html/botanyt
  extbooks/generalbotany/typesofshoots/stolon/b0072t
  x.html

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Grafting

• In grafting, stems from plants with desirable
  qualities are attached (grafted) to the rooted
  stocks of other similar plants
• The advantages of grafting plants is that you can
  combine characteristics that do not naturally
  occur in a single plant (i.e. flavourful fruit
  and disease resistant plant roots)
• This technique is commonly used with apples,
  grapes and roses
• Images taken from http//www.tiscali.co.uk/refere
  nce/encyclopaedia/hutchinson/images/c01139.jpg
  and http//www.cocoatree.org/assets/images/picture
  s/grafting.jpg