Transcript Asexual and Sexual Reproduction & Animal Development

Asexual and Sexual
Reproduction
I can identify the difference
between sexual and asexual
reproduction.
QW#6 What is the difference
between sexual and asexual
reproduction?
State Standards
• 6th Grade Life Science 4
 Recognize that an individual organism does not live forever; therefore
reproduction is necessary for the continuation of every species and traits are
passed onto the next generation through reproduction
• 6th Grade Life Science 5
 Describe that in asexual reproduction all of the inherited traits come from one
single parent
• 6th Grade Life Science 6

Describe that in sexual reproduction an egg and sperm unite and some traits come from each parent, so the
offspring is never identical to either of its parents
• 8th Grade Life Science 1

Describe that asexual reproduction limits the spread of detrimental characteristics through a species and
allows for genetic continuity
Reproduction
• There are about 1.5
million different types
of living species
known
 Some reproduce
sexually, asexually, or
both
Purpose of Reproduction
• To make sure a species can continue.
 Definition: Reproduction is the process by
which an organism produces others of its
same kind.
Asexual Reproduction
• Asexual reproduction= is a process that
involves only one parent and produces
offspring that are identical to the parent
• Advantage- asexual reproduction limits the
spread of detrimental characteristics
• Disadvantage- is asexual reproduction the
organism can not adapt to change in the
environment
1st Type of Asexual
Reproduction
• Budding is another form of asexual
reproduction where a growth of a
copy of the adult buds from the
adult itself until the bud breaks off
and becomes its own organism
 This happens in yeast
 Very Common in Plants
Budding Example
• Fungi are eukaryotic organisms.
 They are also saprophytic (this means they
get their food from dead organic matter)
 Fungi can be multicellular or unicellular (yeast)
 Some are parasitic (ringworm, athlete’s foot)
Budding Example
• Yeast
 Yeast are unicellular fungi that reproduce by
budding
• Budding occurs rapidly under ideal conditions
(mixed with sugar and water in warm temps)
2nd Type of Asexual
Reproduction
• Fission (Binary) is another form used by some
•
single-celled organisms such as bacteria or
amoeba
Becoming two by division of the complete
organism.
 The organism divides by mitosis to make a
new cell
Protists
• Protists are single-celled
eukaryotic organisms
 Protozoans are named b/c
they are “animal-like” and
actually resemble
eukaryotes in the way they
work than prokaryotes like
bacteria
• Ex: Paramecium can
reproduce asexually by
fission or sexually by
conjugation
3rd Type of Asexual
Reproduction
• Regeneration
• The ability to restore
•
lost or damaged
tissues, organs or
limbs.
It is a common feature
in invertebrates, like
worms and starfish.
Sexual Reproduction
• Asexual Reproduction – genetic material of one individual
•
is passed onto the next
Sexual Reproduction – genetic material of two individuals
are combined
 In sexual reproduction an egg and sperm unite and
some traits come from each parent, so the offspring is
never identical to either of its parents produced in
meiosis
 Combining two individual’s genes creates variability in the
population (an advantage in a changing environment)
Sexual Reproduction
• When a zygote is formed, it divides by mitosis creating 2,
•
•
•
4, and 8 celled stages and then forms a mass of cells
called a morula
Further mitosis creates a hollow ball of cells called a
blastula (~1,000 cells)
Subsequent divisions create tissue layers in the gastrula
Gestation (the period of time it takes for an embryo to
grow and change into an individual) can take no more
than 3 weeks for a chicken but up to 2 years for an
elephant
 Humans ~ 9 months
Sexual Reproduction
• Look at prepared slides of
the following stages of
starfish development:
 Egg
 2-cell stage
 4-cell stage
 8-cell stage
 Morula
 Blastula
 Gastrula