Asexual vs. Sexual Reproduction Part 1of 3
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 reproductionReading - 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
2 daughter cells are identical to parent
Bacteria reproducing video (45 sec)
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
Yeast and Hydra - Budding video (2:47)Budding in a Hydra (1:27)
Yeast is a single-celled fungi. There are over 1500 known species of fungi but that might only be 1 % of all fungal species.
A hydra is a multi-cellular freshwater animal.
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)
Planarian video (7:17)
Sea Star Regeneration- Bucket of Stars (2:07)
Sea Star Regeneration (1:07)
Sea-urchin Sand dollar
ParthenogenesisParthenogenesis 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
Spore FormationFungi
Fern
Fern reproduction (1:30 )
Fungi (3:03)
Mold and How it Affects Your Body (2:09)
Bread mold (:25)
Vegetative Reproduction
Sugarcane - Vegetative Reproduction (:30)
Potato Sequence (:24)
How to Grow Avocado Plants (2:38)
What are Root Flower Bulbs? (2:40)
Can Grass Grow From Clippings? (1:01)
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