Transcript Asexual reproduction

Asexual reproduction
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How do cells make new cells
What happens when you cut a worm in half?
Why do you think you can grow new skin
over a cut on your hand but you can’t grow
new fingers?
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What is reproduction?
Reproduction is the process by which
organisms produce more of their own kind.
 Think about it – Without reproduction, all
life on earth would no longer exist.
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The cell cycle in your body
 Cells don’t live forever, they eventually die.
 Some cells life spans:
Brain cells: 30 – 50 years
Red blood cells: 120 days
Stomach lining cells: 2 days
Skin cells: 20 days
 You need mitosis and cell division to replace these
cells.
 In your body about 3 billion cells die every minutes.
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 Skin and bones can be healed because
they undergo mitosis and can replace
injured cells.
 Research says that we age because as
some cells die, they are not replaced or
they are replaced more slowly , it is not
known for sure.
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Cancer
 Cancer occurs when cells begin to divide
uncontrollably.
 Cancerous cells interfere with surrounding
cells and disrupt their normal functioning.
 Tumors/lumps are formed from the cells
that pile up on each other.
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 When you cut yourself, cells in that area
over time multiply, fix the cut, and then
slow their growth. Cancer stems from
mutated cells who do not stop growing.
 Cancerous cells start with a mutation in
the cell's DNA. Mutations in a cells DNA
can be caused by either genetic
inheritance or the environment (ie.
smoking, sunlight exposure, radiation, etc)
(http://nanopedia.case.edu)
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 Once the mutation occurs, the cell begins
to multiply at an increased rate, passing its
mutated DNA on to further generations.
They continue to grow and lead to an
unwanted, benign cluster.
 Cancer becomes malignant and fatal once
its growth becomes intrusive on nearby
tissues and organs.
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What is Asexual Reproduction?
 Only one parent is involved.
 Offspring are genetically identical to their
parents.
 All cells that come from a single cell are
genetically identical to it and to each other;
they are all clones.
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Types of Asexual Reproduction
1. Mitosis - is the exact
duplication of the
nucleus of a cell so as
to form two identical
nuclei during cell
division.
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Types of Asexual Reproduction
2.
Binary Fission - occurs
in one-celled organisms
such as the ameba and
paramecium. The nucleus
divides by mitosis and the
cytoplasm divides,
forming 2 new daughter
cells of equal size.
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Types of Asexual Reproduction
3. Budding - Occurs in Hydra and yeast. The division of
cytoplasm is unequal so one of the daughter cells is
larger than the other. The daughter cells can separate
or remain attached. A copy of the nucleus is made,
then a tiny bud begins to form on the cell wall. This
bud, containing the new nucleus continues to grow and
eventually breaks away.
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Types of Asexual Reproduction
4. Sporulation - occurs in
molds, mosses, etc
 Spores are produced in
large numbers by mitosis.
 Spores are surrounded by a
tough coat to help them
survive harsh environmental
conditions. When mature, and
the sporangium explode, and
the spores can now float on air
currents and begin the whole
process over again.
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Types of Asexual Reproduction
5.Regeneration Refers to the
replacement or
regrowth of lost
or damaged
body parts
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Types of Asexual Reproduction
6. Fragmentation – a small piece or
fragment, breaks away from the main
mass and grows into a new individual.
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Types of Asexual Reproduction
7.Vegetative Propagation
Occurs only in plants.
Meristemic cells (non
specialized cells) help
new plants to develop
from the roots, stems, or
leaves of the parent plant.
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Types of Asexual Reproduction
Runners- Runners are
 Grafting- horticultural
specialized stems called stolons.
These stems grow horizontally
outward and downward from
plants and produce baby plants at
their tips. . (ex. strawberries)
techniques used to join
parts from two or more
plants so that they appear
to grow as a single plant.
(For instance, a Macintosh seed will grow
into an apple tree, but not into a Macintosh
apple tree, which can only be achieved
through grafting.)
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Tissue Culture
Asexual reproduction– Brain Pop
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