Asexual vs. Sexual
Reproduction
Part 1of 3
UNIT QUESTION:
What new information has modern
day biology been able to uncover
about planarian stem cells and
regeneration and what do these
findings tell us about the human
capacity for regeneration?
Superhero Science - Limb Regeneration
(2:18)
Objective
 To
compare methods of sexual
and asexual reproduction
Reading - Two Methods of Reproduction
Asexual Reproduction
vs. Sexual Reproduction
• Asexual Reproduction
– involves only 1 parent
– offspring genetically
identical to parent
– involves regular body
cells
– its quick
• Sexual Reproduction
– involves 2 parents
– offspring genetic mix
of both parents
– involves specialized
sex cells
– its slow
Asexual Reproduction
• Binary fission
– happens in bacteria, amoeba, some algae
– one parent cell splits into 2 identical daughter
cells
• Budding
– happens in yeast, hydra, corals
– parent produces a bud
– bud gets detached and develops into offspring
which is identical to parent
Types of Asexual
Reproduction


Binary
Fission




1. Organism divides in half
2. 2 identical daughter cells
produced
3. Daughter cells are half
the parent’s size
4. Daughter cells grow, then
divide too
5. In bacteria (amoeba,
paramecium)
Binary Fission - Asexual Reproduction
Rod-Shaped Bacterium,
hemorrhagic E. coli
Bacteria reproducing video (45 sec)
2 daughter cells are identical to parent
Types of Asexual
Reproduction

Budding




1. Small bud grows out of
parent cell
2. Two different sized cells
made (with identical DNA)
3. Bud breaks off and
grows
4. In yeast and hydra
Budding - Asexual Reproduction
A hydra is a multi-cellular freshwater animal.
Yeast is a single-celled fungi.
There are over 1500 known
species of fungi but that might
only be 1 % of all fungal species.
Yeast and Hydra - Budding video (2:47)
Budding in a Hydra (1:27)
Types of Asexual
Reproduction

Regeneration


(Fragmentation)


1. Repair/ grow lost body parts
2. Left over cells divide to make
more cells
3. Lobsters, starfish, lizards,
planarian
Fragmentation (Regeneration)
Sea Star RegenerationBucket of Stars (2:07)
Sea Star Regeneration (1:07)
Planarian video (7:17)
Sea-urchin
Sand dollar
Parthenogenesis
Parthenogenesis is a form of asexual reproduction where growth and
development of embryos occur without fertilization.
In plants, parthenogenesis means development of an embryo from an unfertilized
egg cell.
The word parthenogenesis comes from the Greek παρθένος, parthenos, meaning
"virgin", and γένεσις, genesis, meaning "birth".
The term is sometimes used inaccurately to describe reproduction modes in
hermaphroditic species that can reproduce by themselves because they contain
reproductive organs of both sexes in a single individual's body.
Parthenogenesis occurs naturally in many plants, some invertebrate animal species
(including nematodes, water fleas, some scorpions, aphids, some bees, some
Phasmida, and parasitic wasps) and a few vertebrates (such as some
fish,amphibians, reptiles,and very rarely birds). This type of reproduction has been
induced artificially in a few species including fish and amphibians.
Parthenogenesis
The three Whiptail Lizards on view in the Hall of Reptiles and Amphibians all play a
part in one of the greatest mysteries of nature. The New Mexico Whiptail, pictured
here, is an all-female species.
When the New Mexico Whiptail, as well as several other all-female species of whiptail
lizard, does reproduce, and all of its offspring are female. Moreover, it reproduces by
parthenogenesis -- its eggs require no fertilization, and its offspring are exact and
complete genetic duplicates of the mother.
Scientists understand only partially how this reproductive mode developed, and it
raises many questions. One of the most intriguing is how this cloning affects the
lizard's ability to adapt to environmental changes. Since there is no genetic variation
except that which occurs through mutation, the New Mexico Whiptail cannot evolve as
other species do.
The New Mexico Whiptail Lizard also offers an extraordinary opportunity to learn more
about the role of sperm in fertilization, as well as about cloning.
Asexual Reproduction contd.
• Spore Formation
– happens in fungi, green algae, molds and
non- flowering plants (e.g. ferns)
– spores are produced and each spore
develops into offspring which are identical to
parent
• Vegetative Reproduction
– does not involve seeds
– some offspring can grow from cuttings (e.g.
coleus), runners (e.g. strawberries), tubers
(e.g. potatoes) or bulbs (e.g. tulips)… which
are part of the parent plant
Fungi
Spore Formation
Fern
Fungi (3:03)
Mold and How it
Affects Your Body
(2:09)
Bread mold (:25)
Fern reproduction (1:30 )
Sugarcane Vegetative
Reproduction
(:30)
Vegetative
Reproduction
What are Root
Flower Bulbs?
(2:40)
Can Grass
Grow From
Clippings?
(1:01)
Potato Sequence (:24)
How to Grow
Avocado Plants (2:38)
Asexual Ant - Females Only!
• Mycocepurus_smithii (1:30)
Asexual Reproduction Review

Asexual
Reproduction





1. One parent
2. No sex cells
3. Offspring produced by
cell division
4. Offspring identical to
parent (same DNA)
5. Several types in plants
and animals