Transcript Asexual Reproduction

Asexual and Sexual Reproduction
Objective: Students will explain
asexual (binary fission, budding,
vegetative, mitosis) and sexual
reproduction (angiosperms, mammals)
Asexual Reproduction
Process by which a single parent
reproduces by itself without the joining
of gametes (reproductive cells)
Sexual Reproduction
Process by which male and female
gametes unite to produce the first cell
of a new organism
Asexual Reproduction
• Does not involve
meiosis or the joining
of haploid gametes
• Cells are diploid (2N)
• Produces offspring
that are genetically
identical to the
parent
Examples:
– Spore Formation
– Binary Fission
– Vegetative
Reproduction
– Regeneration
– Budding
– Mitosis
Spore Formation
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Spores - (“mummified” bacterium) – dormant non-reproductive body
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Protective coating encase key parts of the bacterium
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Spores formed by certain bacteria in response to harsh
environmental conditions
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Spore able to survive for weeks
(even years) through drought,
heat, even radiation
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When conditions become more
favorable, bacterium “comes to life”
(transforming from a spore back to a cell)
•
Also produced by certain fungi,
algae, and non-flowering plants.
Binary Fission
(p. 475)
• One cell splits into
two cells
• Offspring are
genetically identical
to parent
• Occurs in
Prokaryotes
(organisms w/out a
nucleus) i.e. Bacteria
Vegetative Reproduction
• Also called vegetative
propagation
• Process by which new plant
"individuals" arise or are
obtained without production
of seeds or spores (without
sexual reproduction)
• produce new plants from
existing vegetative
structures by cutting from
stems, leaves, roots, parts
of leaves and thick canes
Budding
Budding Yeast
• Formation of a new
organism by the protrusion
of part of another organism.
• Very common in plants and
fungi (vegetative
Reproduction), but may be
found in animal organisms,
as well.
• Shortly, the new organism
will break away from parent
and live independently
• New organism is genetically
identical to the primary one
(a clone)
A new hydra budding
from an existing hydra
Regeneration
Planaria
• Form of tissue
repair and/or healing
• Ability to regrow lost limbs,
severed nerve connections,
damaged tissues and organs
• Example of plant
regeneration - when grass is
cut, the blade regrows
Starfish
Mitosis
Mitosis produces two cells with the same
number of chromosomes as the parent cell.
Mitosis of a diploid cell (2n) produces two
diploid daughter cells.
Sexual Reproduction
• Process by which male and female
gametes unite to produce the first cell
of a new organism
• Involves the joining of haploid gametes
that have been produced by meiosis
• Offspring are not genetically identical
to either parent
Sexual Reproduction
In Mammals
• Reproduce by internal
fertilization (male
deposits sperm inside
the reproductive tract
of the female – where
fertilization occurs)
• Meiosis used to
produce the gametes:
sperm and egg
In Angiosperms
(Flowering Plants)
• Meiosis used to
produce the spores -which in time will
produce the gametes
(pollen -male; egg female)
• Reproduce by crosspollination (transfer of
pollen to female
reproductive structure)
Angiosperms
(CH 24-1, pp. 612-621)
• Flowering plant that produces seeds within
an ovary that develops into a fruit; therefore,
the seeds are covered
• Most abundant plant on Earth
• Terrestrial and lack locomotion
– Poses a problem
– Gametes are delicate single cells. For two plants
to cross-pollinate, there must be a mechanism
for the two gametes to reach each other safely
Reproductive Parts
of a Flower
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The flower is the reproductive organs of angiosperms
Stamen - male organ that produces pollen (consists of the anther &
filament)
Carpel (also called pistil) – female organ that produces egg
Other parts of the flower
– Sepal – green (resemble leaves) protect the flower while it’s developing
– Petal – often brightly colored – attract pollinators (i.e. insects) to flower
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Most angiosperm flowers contain both the stamen and pistil
Active Art
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webcode cbp-7241
(click the link to go to activity)
Answer the questions.
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What is the function of flowers?
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An angiosperm is a plant that produces seeds that are enclosed in a _______________.
The male structure of a flower is known as the _______________.
The female structure of a flower is known as the _______________ .
List the structures that make up the stamen.
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List the structures that make up the carpel.
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Describe the function of petals on a flower.
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Where does meiosis take place?
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Where does pollination take place?
Life Cycle of an Angiosperm