Transcript Asexual Reproduction - South Buffalo Charter School

Methods of
Asexual Reproduction
This is what it would look like if humans reproduced
by fragmentation!
bud
Budding
• A new organism grows
on another one and then
separates from the
parent organism only
when it is mature.
• Examples of organisms
that reproduce by budding
include: yeasts, sponges
and hydra
bud
bud
Binary Fission
• Division into two parts
(daughter cells) which
each daughter cell has
the potential to grow to
the size of the original
cell (parent cell)
• An example of an
organism that reproduces
by binary fission is a
paramecium.
Daughter cells
Regeneration
• When an animal that is
capable of regeneration loses
a body part, it can grow a
replacement part.
• If the lost body part
contains enough genetic
information from the parent,
it can regenerate into an
entirely new organism.
• Echinoderms and the hydra
in molds are examples of
organisms that reproduce by
regeneration.
Fragmentation
• A new organism grows
from a fragment of the
parent.
• Each fragment develops
into a mature, fully grown
individual.
• Examples of organisms
that reproduce by
fragmentation include:
molds and planaria.
Vegetative Reproduction
• New individuals are
formed without the
production of seeds or
spores
• May produce bulbs,
tubers or rhizomes
(runners)
• Examples of organisms
that reproduce by
vegetative reproduction
include: tulips, dahlia,
strawberries
rhizome
bulb
Vegetative Propagation
• The production of a new
plant from a portion of
another plant, such as a
stem or branch.
• Examples of organisms
that reproduce by
vegetative propagation
include: spider plants,
potatoes, aloe and various
other plants.
cutting
New spider
plant
Spores
• In some organisms,
meiosis leads to the
formation of haploid
spores rather than
gametes. These spores
grow into multicellular
individuals without
being fertilized.
• Examples of organisms
that reproduce by forming
spores include:
mushrooms, molds and
ferns
spores
Asexual Reproduction
Method
Asexual
Number Genetics
of
Parents
1 parent
•
•
Pros
Identical • No mate
100% of • Identical
genes
to parent
come
from 1
parent
Cons
• Mutations
are
definite
• No variety
Sexual Reproduction
Sexual Reproduction
• Two parents
• Genetically speaking, the
offspring get info from both
parents:
½ from mother (egg)
½ from father (sperm)
There are 46 chromosomes in human cells,
so 23 from mom + 23 from dad = 46 total
Sexual Reproduction
• Requires sex cells (gametes)
– Male sex cell (gamete) – sperm
– Female sex cell (gamete) – egg
• Fertilization is the process in which sperm and
egg unite
– Chromosomes double
Ex) 2 + 2 = 4
Cell division by mitosis
Step 3
Chromosomes line up along the
middle of the
cell and each centromere attaches
to a
spindle fiber.
Step 4
• Mitosis is cell division
of body cells
• Mitosis produces exact
copies of the parent cell
• The new daughter cells
have the diploid
number of
chromosomes
Meiosis
• Cell division that
results in the formation
of gametes (sex cells)
– Sperm and egg
– Cells are haploid
• Cells are NOT identical
– Each cell contains half
the number of
chromosomes but not
necessarily the same
chromosomes as the
others
How many chromosomes?
• Humans have 23 pairs of
chromosomes like these
• The diploid number of
chromosomes is
23x2 = 46
• Sex cells (gametes) have 23
single chromosomes - the
haploid (half) number
So……what’s the point?
• An egg cell is haploid
• A sperm cell is haploid
• When they join at fertilization the resulting
cell is diploid
• This makes a full set of instructions to make
a new organism!
Mitosis vs Meiosis