3. Why is Cell Division Important?
• billions
Everyday _________________ of red blood cells wear
out and are replaced.
• millions
Everyday _________________ of skin cells wear out and
are replaced.
• Cell division is how single cell organisms reproduce.
4. Why is Cell Division Important?
How do little elephants grow
up to be BIG elephants?
Cell Division
5. Cell Division & the Cell Cycle
Mitosis is a cycle that occurs in most of our cells.
6. Length of a Cycle
• The cell cycle is a series of events that takes place
from one cell division to the next.
• The time it takes to complete a cell cycle is not the
same in all cells.
7. Mitosis & Asexual Reproduction
• Mitosis is the process in which the nucleus divides
to form two new nuclei.
• Mitosis is a form of asexual reproduction.
• Asexual Reproduction
- when a cell doubles its contents and then divides
into two identical cells
- the production of offspring that are genetically
identical
8. Mitosis & Asexual Reproduction
• The process of asexual reproduction begins after a
sperm fertilizes an egg.
12. How can I remember the order?
I Pray More At The Church
13. Interphase
• Most of the life of any eukaryotic cell is spent in a
period of growth and development called
interphase.
• Cells in your body that no longer divide, such as
nerve and muscle cells, are always in interphase.
• An actively dividing cell, such as a skin cell, copies
its hereditary material and prepares for cell division
during interphase.
14. Interphase
• During interphase, each chromosome duplicates.
• When the nucleus is ready to divide, each duplicated
chromosome coils tightly into two thickened, identical
strands called chromatids.
15. Chromosome
• A chromosome is a structure in the nucleus that
contains hereditary material (DNA).
• A chromatid is one-half of a replicated chromosome.
22. Prophase
• The pairs of
chromatids are fully
visible when viewed
under a microscope.
• The nucleolus and the
nuclear membrane
disintegrate.
23. Prophase
• Two small structures
called centrioles move to
opposite ends of the cell.
• Between the centrioles,
spindle fibers begin to
stretch across the cell.
24. Prophase
• Plant cells also form
spindle fibers during
mitosis but do not have
centrioles.
26. Metaphase
• The pairs of chromatids
line up across the
center of the cell.
• The centromere of each
pair usually becomes
attached to two spindle
fibers—one from each
side of the cell.
33. Cytokinesis - division of cytoplasm
• For most cells,
after the nucleus
has divided, the
cytoplasm
separates and two
new cells are
formed.
34. Cytokinesis - division of cytoplasm
• In animal cells, the
cell membrane
pinches in the middle,
like a balloon with a
string tightened
around it, and the
cytoplasm divides.
35. Cytokinesis - division of cytoplasm
• In plant cells, the
appearance of a
cell plate tells you
that the cytoplasm
is being divided.
• Why is this step
different for plant
cells?
36. Cytokinesis - division of cytoplasm
• New cell walls form
along the cell plate,
and new cell
membranes develop
inside the cell walls.
• Now, the period of
growth, or interphase,
begins again.
42. Results of Mitosis
4 important things to remember about Mitosis & Cell Division
1. Mitosis is the division of a nucleus.
2. Mitosis produces 2 new nuclei that are identical to the
original nucleus
• Every cell in your body copies the same hereditary information.
• All of your cells use different parts (genes) of the same
hereditary material to become different types of cells.
3. The original cell no longer exists.
4. Cell division allows growth and replaces worn out or
damaged cells.
43. Other forms of
Asexual Reproduction
• Bacteria cannot reproduce through mitosis because
of what mitosis is. Mitosis is the division of a
nucleus.
• Bacteria do not have a nucleus, so they cannot
undergo mitosis.
• The process they use is called fission.
44. Fission
• Binary fission is the
simplest form of asexual
reproduction.
• Bacteria cells split into
approximately two equal
halves. The process in
bacteria is relatively
rapid.
45. Fission
• The two new organisms
are identical genetically,
except for a random
mutation that may
occasionally occur.
46. Budding
• Hydra, a freshwater
animal, reproduces using
budding. The bud is an
exact copy of the adult
plant.
• Part of the adult buds off,
or breaks off, and a new
organism grows.
