Reproduction Part 1
Asexual vs. Sexual Reproduction
Objectives
• Compare and contrast sexual reproduction
vs. asexual reproduction
• Understand and explain the 5 types of
asexual reproduction
Asexual vs. Sexual Reproduction
• What are the main differences between
sexual and asexual reproduction?
• List any advantages and disadvantages of
each.
Types of Asexual Reproduction
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1. Binary Fission
2. Budding
3. Regeneration
4. Sporulation (Spore Formation)
5. Vegetative Propagation
Binary Fission
• Binary Fission:
• Occurs in single celled organisms such as
bacteria, protists (amoeba, euglena, etc.),
algae.
• The cell increases in size until it divides
into two new cells
• No parent is left.
Binary Fission
Budding
• Budding:
• Occurs in single celled and some simple
multicellular organisms such as yeast,
hydra, and sponges.
• A small bud or outgrowth forms on the
organism
• The organism divides into two unequal
parts – the bud is smaller than the parent
organism it sprouted from.
• Budding in single celled
yeast.
• Budding in hydra
Regeneration
• Regeneration:
• Occurs in simple multicellular organisms
(hydra, starfish, sponges, earthworms)
• If cut into pieces, pieces will grow into new
organisms.
• Simpler organisms (sponges, cnidarians,
echinoderms) are rich in embryonic stem
cells which can differentiate to regenerate
tissue.
• More complex organisms such as humans
lack these stem cells as adults and cannot
regenerate.
An entire starfish can regenerate
from a lost limb (ray)!!!
Sporulation: Spore formation
• Occurs in fungus, algae and mold
• Process in which any cell of an organism
produces one or more reproductive cells inside
its cell walls
• Tiny spores form inside the parent cell and are
released
• Spores are released and carried to a favorable
environment (by swimming, wind, etc.) where
they can grow into an adult organism.
Spore formation in mold
Vegetative Reproduction
• Vegetative Reproduction:
• Some plants can grow from roots, stems,
and leaves.
• Bulbs and tubers are underground stem
structures that can grow to form new
plants.
• Examples include tulips, potatoes,
strawberries, irises.
Vegetative Reproduction
• Tubers: Enlarged
portion of an
underground stem
that contains stored
nutrients (starch).
• Potatoes can be cut
into pieces with
each piece having
an “eye” which can
grow into a new
potato plant.
Vegetative Reproduction
• Bulbs: Short
underground stems
surrounded by thick
fleshy leaves that
contain stored food.
• As the plant grows
small new bulbs
sprout from the old
one.
• Each bulb can grow
into a new plant
• Ex. Onions, tulips,
garlic.
Vegetative Reproduction
• Runner (stolon):
Stem that grows
sideways along the
surface of the
ground.
• Runners have buds
that can grow into
new plants when
they contact soil.
• Ex. Strawberry
plants, silverweed.
Vegetative Reproduction
• Rhizome: Stem that
grows sideways
underground.
• Rhizomes are thick
and fleshy and contain
stored food.
• Enlarged portions
called nodes grow into
buds which can form
new plants.
• Ex. Irises, ginger.
Methods of Artificial Vegetative
Reproduction
• Cutting: Any vegetative part of a plant (stem,
leaf, root) that is used to make a new plant.
• Layering: Stem is bent over so part of it is
covered with soil. When covered part roots, new
plant may be cut from parent plant.
• Grafting: Stem or bud is removed from one
plant and permanently joined to the stem of
another closely related plant. Many fruits and
roses are propagated using grafting.
Grafting consists of two parts, the
stock and the scion
SCION
STOCK
Begonia plants growing from
cuttings
Grafting in cactus plants