Transcript Sexual Reproduction

Sexual
Reproduction
Advantages and Disadvantages
Sexual Reproduction
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This is the process through which two
parents cells join to produce offspring.
The sex cells have half the number of
chromosomes of a normal cell.
For instance, a cat cell has 32
chromosomes……
sex cells would have 16 chromosomes
(mother) and 16 chromosomes (father)
Meiosis
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Meiosis is the process that ensures
that a cell produced by sexual
reproduction has the correct number
of chromosomes.
Unlike mitosis, meiosis involves two
series of division.
Meiosis
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At the end of meiosis, one cell has
produced four cells that each have half
the number of chromosomes as the
original cell.
Because the original cell in meiosis has
different homologous chromosomes,
each of the 4 daughter cells will have
one or the other of each homologous
chromosome. This gives variation to
each daughter cell.
Meiosis
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In the male, the four cells that are
produced are sperm cells.
In the female, the four cells that are
produced are egg cells.
Advantage
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Advantage: the offspring are not
genetically identical to either parent.
Two partners can produce offsprings
with different DNA combinations.
This provides the variation needed to
help organisms survive in nature.
Disadvantage
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Two partners are needed
Asexual and Sexual
Reproduction
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Some organisms can reproduce by both asexual and
sexual reproduction depending on the environment.
If conditions are harsh and large numbers of offspring
are needed, asexual reproduction will be the way to
reproduction for this type of organism.
However, if environmental conditions are changing,
variations in the hereditary information are
needed…..sexual reproduction provides more of a benefit
for that particular species.
Reproduction in Plants
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Almost half of all plants reproduce sexually
to make seeds.
Pollen in plants contains the sperm cells and
must be carried to the female part of a
flower in order to find the egg cell.
The sperm joins with the egg cell and grows
into a seed which can become a new plant.
Asexual Reproduction in
Plants
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They produce branches or buds that spread
out around the parent plant and can grow
into complete new plants.
Blackberry bushes reproduce by allowing
their branches to grow roots wherever the
stems touches the ground. They also
reproduce sexually by making seeds.