Transcript Cell Division! - Cipriano`s Science Spot

Reproduction
How organisms produce offspring
There are two kinds of
Reproduction
1. Asexual reproduction
2. Sexual reproduction
Asexual reproduction
• The organism makes two or more offspring which
are exact genetic copies of itself.
• There are several methods of asexual
reproduction:
http://www.brainpop.com/science/cell
ularlifeandgenetics/asexualreproducti
on/
1.Budding
2. Cuttings
3. Runners
Strawberries
4. Cell Division
Bacteria
All living things come from other cells.
To form a new cell, one cell must
enlarge and divide into two
new cells.
This results in growth of
The organism or replacement
Of new tissue. MITOSIS
How do organisms grow
bigger?
Cell Division!
This regular sequence of growth and cell
division is called the Cell Cycle.
The 3 stages of the cell cycle are:
1. Interphase
2. Mitosis
3. Cytokinesis
Interphase
1. Chromosomes are copied. This is called DNA
replication. Each daughter cell must have a
complete set of DNA to survive.
2. Chromosomes appear as threadlike coils (chromatin)
at the start,but each chromosome and its copy
(sister chromosome) change to sister chromatids
Mitosis
During mitosis, one complete copy of the
DNA is distributed into each of the two
daughter cells.
There are 4 phases in mitosis
Prophase
•Mitosis begins
•Centrioles (or poles) appear
and begin to move to opposite
ends of the cell
•Spindle fibers form between
the poles
•The nuclear membrane breaks
down
Metaphase
•The chromosomes line up across the
center of the cell (meet in the middle)
• the chromatids (or pairs of
chromosomes) attach to the spindle fibers
at the centromeres
Anaphase
• Chromatids separate and begin to
move to opposite ends of the cell
•The cell stretches out
•Look for the “A”
Telophase
•Two new nuclei form
•Chromosomes appear as chromatin
(threads rather than rods)
•Mitosis ends
Cytokinesis
•Cell membrane moves inward to create two
daughter cells –each with its own nucleus
with identical chromosomes.
Remember this for mitosis:
Individuals
(interphase)
Please
(prophase)
Make
(metaphase)
All
(anaphase)
The
(telophase)
Cells
(cytokinesis)
Make your own “Mnemonic”
I
P
M
A
T
C
Animal Cells –
•During cytokinesis, the cell membrane
squeezes together around the middle of
the cell.
•The cytoplasm pinches into two cells.
•Each get about half of the organelles.
Plant Cells –
•The rigid cell wall cannot
squeeze together.
•Instead, a cell plate forms
across the middle of the
cell and then a new cell
wall forms
Mitosis Review
Used in all forms of
asexual reproduction
One division of a celltwo identical diploid
cell (2N)
The number and types
of chromosomes are
the same in daughter
and parent cell
Large organisms use
mitosis for growth and
healing.
Simple organisms use
it to reproduce
Biology is the only science in
which multiplication means the
same
thing as division
- Unknown
To Review
http://www.nclark.net/MitosisRap.mp3
http://www.nclark.net/itsmitosistime.ppt
Meiosis is the type of cell
division by which gametes
(eggs and sperm) are
produced.
Makes gametes used in
sexual reproduction.
•Meiosis involves a reduction in the
amount of genetic material.
•The final cells have half the number of
chromosomes.
•When sperm and egg combine during
fertilization all required genetic
information is in the fertilized egg.
•Interphase
Before
meiosis
begins,
genetic
material is
duplicated.
•First division of meiosis
•Prophase 1: Duplicated chromatin condenses. Each
chromosome consists of two, closely associated sister
chromatids.
•Metaphase 1: Chromosomes align at the equatorial
plate. “meet in the middle”
•Anaphase 1: Pairs separate
with sister chromatids
remaining together.
•Telophase 1: Two daughter
cells are formed with each
daughter containing only one
chromosome of the pair.
•Second division of meiosis: Gamete
formation
•Prophase 2: DNA does not replicate.
•Metaphase 2: Chromosomes align at the
equatorial plate.
•Anaphase 2:
Centromeres divide and
sister chromatids
migrate separately to
each pole.
•Telophase 2: Cell
division is complete.
Four haploid daughter
cells are obtained
Haploid means
that each cell
has half the
number of
chromosomes.
Meiosis I ---
Meiosis II ---
Meiotic Cell Division Reviewed
-makes gametes used in sexual
reproduction.
1. gametes (sperm and egg cells) formed
during meiotic cell division have only ½ of
the organism’s genetic information
(23 chromosomes each)
When sperm and
egg combine
during
fertilization
all required
genetic
information is in
the fertilized
http://www.brainpop.com/science/cellularlifean
dgenetics/genetics/
Comparing Mitosis and Meiosis
http://www.pbs.org/wgbh/nova/baby/divide.html#
Comparison
Mitosis
(somatic/body)
Meiosis
(gamete/sex cell)
Number of cell divisions
One
Two
Exchange of genetic
material between
chromosomes
No
Yes
Number functioning cells
produced from original
Two
Four sperm (male)
One Egg (female)
Genetic makeup of
functioning cells produced
Same as original
Variable-gametes
produced from two
parents
Functioning of cells
produced in multicellular
organisms
Growth or
replacement of
body cells
Combine to form the
zygote for
reproduction
Asexual Reproduction
Review
http://www.brainpop.com/s
cience/cellularlifeandgeneti
cs/cloning/
Cloning:
a.The same result as ASEXUAL
reproduction.
b. Cut a piece of stem from a plant
and it grows roots and develops a
new plant.
**this could be a clone of the plant
Plant cloning
c. Recently cloning animals that
normally reproduce sexually
has been done. “Dolly The Sheep”.
http://www.brainpop.co
m/science/diversityoflife
/dollythesheep/
What is it?
A human ear!!
The mouse lacks an immune system so the ear grows!
Regeneration: asexual reproduction
Sexual Reproduction Review:
• Used to form sperm or an egg (gametes)
• Will result in genetically different
offspring.
• From two parent cells.
Compare Mitosis and Meiosis