Asexual vs Sexual Reproduction

1. Sexual vs. Asexual
Reproduction

2. QUESTION:
How does a parent
organisms produces a
new organisms or
offspring?
PARENTS AND THEIR
OFFSPRINGS

3. REPRODUCTION
Process by which living organisms like humans, plants and
animals form new individual of the same kind.

4. REPRODUCTION
ASEXUAL SEXUAL

5. Sexual Reproduction
A type of reproduction in which the genetic materials from two
different cells combine, producing an offspring
The cells that combine are called sex cells
Female – egg
Male – sperm
Fertilization: an egg cell and a sperm cell join together
A new cell is formed and is called a zygote

6. Advantages: Sexual Reproduction
 Diverse offspring: genetic variation among offspring
Half of the DNA comes from mom
Half of the DNA comes from dad
 Due to genetic variation, individuals within a population
have slight differences
Plants – resist diseases
Traits can develop to resist harsh environments that
allows an organism survive

7. Advantages: Sexual Reproduction
Selective Breeding
Used to develop many types of
plants and animals that have
desirable traits
Agriculture/Farming: better plants,
larger animals
Desirable pets

8. Disadvantages: Sexual Reproduction
Time and Energy
Organisms have to grow and develop until they are old enough
to produce sex cells
Search and find a mate
Searching can expose individuals to predators, diseases, or
harsh environmental conditions
Fertilization cannot take place during pregnancy, which can last
as long as 2 years for some mammals.

9. Examples: Sexual Reproduction

10. Sexual Reproduction in
Plants
(Pistil)
Male Parts
Female Parts
pollen (male) + ovule (female) → single-celled zygote → multi-celled embryo (contained in a seed)
→ new individual

11. Pollen is produced in the
male organs of the
flowers - anthers.
Pollinatio n occurs when
pollen is transferred from
the anthers to the female
organs by wind or by
animals. If the female
stigma is receptive to a
pollen grain, the pollen
produces a pollen tube,
which grows through the
female tissue to the egg,
where fertilization takes
place by the sperm
nucleus.
Sexual Reproduction in
Flowering Plants

12. Pollination
 flowers are designed to lure insects to help with the pollination process
also wind, animals, birds can transport pollen

13. External Fertilization
External fertilization usually requires
a medium such as water, which the
sperms can use to swim towards the
egg cell. External fertilization usually
occur in fish and amphibians.
The females lay the eggs in the
water and the male squirts the
sperm in the same area.

14. Internal Fertilization
 Fertilization occurs within the female.
 Internal fertilization occurs in mammals, insects, birds, reptiles.
Mammals (gorillas, lions, elephants, rats, zebras, and dolphins have live births)
Insects, birds, reptiles lay eggs

15. Sexual Reproduction Summary
Male
Gamete
Female
Gamete
Type of
Union
Result of
Union
Final Result
Plants pollen ovule (egg) pollination single cell
zygote
multi-cell
embryo
(in seed)
Animals sperm egg fertilization single cell
zygote
multi-cell
embryo

16. Asexual Reproduction
One parent: organism produces offspring
without fertilization
Uniform offspring:
Because offspring inherit all of their
DNA from one parent, they are
genetically identical to each other and
to their parent

17. Fission: Asexual Reproduction
 Fission: Cell division in prokaryotes that forms two
genetically identical cells
DNA is copied
The cell begins to grow longer, pulling the two copies
apart
The cell membrane pinches inward in the middle of the
cell
Cell splits to form two new uniform, identical offspring
 Examples: bacteria, Ecoli, pond critters

18. When conditions are good, such as plenty of water,
food, right temperatures, etc., binary fission is a
very effective way of producing many, many
offspring.
For example, the cell of a Paramecium can divide,
grow, and divide again in the space of 8 hours.
Fission: Asexual Reproduction

19. Budding: Asexual Reproduction
 Budding: a new organism grows by mitosis and cell
division on the body of its parent
The bud, or offspring is identical to the parent
The bud, when large enough, can break off of the
parent and live on its own
Offspring may remain attached and form a colony
 Examples: Yeast, Hydra, cactus

20. Regeneration: Asexual Reproduction
 Regeneration: occurs when an offspring grows
from a piece of its parent.
Producing new organisms: Sea Stars
Sea urchins, sea cucumber, sponges, and
planarians
Producing new body parts: Gecko
Newts, tadpoles, crabs, hydra, and zebra fish

21. Parthenogenesis involves the development of an egg that has not
been fertilized into an individual.
Animals like most kinds of wasps, bees, and ants that have no sex
chromosomes reproduce by this process. Some reptiles and fish are
also capable of reproducing in this manner.
Parthenogenesis: Asexual Reproduction

22. SPORE FORMATION
SPORES- single specialized
cells that when released from
PARENT CELLS can
GERMINATE to form new
individuals
Some spores have hard outer
covering and some have flagella
Ex: fungi, algae and protozoans
fern, mosses

23. FRAGMENTATION
Organisms split into
fragments each of which
develop into mature clones
Sometimes they also called
as splitting
Sponges, corals,
echinoderms

24. Vegetative Propagation: Asexual
 Vegetative Propagation: uniform offspring grow
from a part of a parent plant
Parent plants sends out runners
Where the runner touches the ground, roots can
grow
A new plant is produced even if the runner is broken
apart
Each new plant is uniform and identical to the
parent.
Examples: strawberries, potatoes, ivy, crabgrass

25. CUTTINGS
One of the easiest way of
plant propagation
Stem cutting refers to the
process of cutting off a portion
of a plant’s stem, which is
then used to propagate a new
plant. A mature, independent
plant identical to its parent.
cuttings

26. LAYERING
Plant propagations in which a portion
of aerial stem grows root while still
attached to the parent plant and then
detaches as an independent plants
can be accomplished by bending a low
growing, flexible stem to the ground.
Cover part of it with soil, leaving the
remaining 6 to 12 inches above the soil.
Bend the tip into a vertical position and
stake in place

27. GRAFTING
Cutting from some other plant is
attached to the stem of a plant
rooted in the ground. The
tissues of the graft become
integrated with the tissues of
the rooted plant and develop as
a single plant over time.
Joining of the cut stem of two
different plants
Ex: cucumber, watermelon,
eggplant

28. Advantages: Asexual Reproduction
Enables organisms to reproduce
without a mate
No wasted time and energy
Enables some organisms to rapidly
reproduce a large number of uniform
offspring

29. Disadvantages: Asexual Reproduction
 Because their offspring are identical, there is no
genetic variation that can give an organism a
better chance for survival
Example: If a weed killer can kill the parent, it will
also kill the offspring
A whole species can be wiped out from a disease
 Dangerous mutations in DNA – if the parent has
the mutation in their DNA, the offspring will have it
too.

30. Examples: Asexual Reproduction

31. Activity:
Create a creature that reproduces asexually.
Draw the creature
Describe how the creature reproduces asexually
Describe 1 advantage of reproducing this way
Describe 1 disadvantage of reproducing this way
Name your creature