Transcript 2 Issues of Mitosis

Issues of Mitosis
“The Life and Times of the
Cell”
Summary of Mitosis
Prophase:
Replicated chromatin condense into chromatid pair
Centrioles move to opposite poles
Nuclear envelope disappears
Spindle fibers start to form
Metaphase
Chromatid pairs line up at the equator
Anaphase
Chromatid pairs split
Chromosomes are pulled to opposite poles by the spindle fibers
Telophase
Chromosomes de-condense into chromatin
Nuclear envelope reappears
Cytoplasm is divided into 2 cells
Cytokenesis
One more Phase – GAP 0 (G0)
Some cells do not
replicate their centrioles
during Prophase.
They lose their ability to
divide
They enter the Gap 0
stage
Neurons of the Spinal
cord / Brain cells
Mitosis in Plant vs. Animal Cells
The Rivalry Continues
Plants have no
centrioles but still
form spindle
fibers
Plant cells divide
from the inside
out
Cell Plate
“Messy
Metaphase”
Importance of Mitosis
Method of reproduction for
all single celled
organisms
Allows us to regenerate
cells (tissue) repair cuts,
bone breaks, etc
Growth – one cell to trillions
How Long does the Cell Cycle
Last?
Pick up a textbook and turn to page 249.
Read the section titled “Life Spans of
Cells” and answer the 4 questions that
follow.
Meiosis
Special cell division
that produces Haploid
sex cells
Consists of one
replication and two
cell divisions
Sexual vs. Asexual
Asexual Reproduction
Reproduction that doesn't
involve sex cells
Produces ‘clones’ of
previous cells
Ex: 1. Binary Fission
2. Fragmentation
3. Budding
Sexual Reproduction
Reproduction involving
sex cells
Produces genetically
different offspring
Sperm + egg = Zygote
(n) + (n) = (2n)
Cancer
A disease of uncontrolled cell division
Starts with a single cell that loses its control
mechanisms due to a genetic mutation (mistakes in
DNA replication)
Can be caused naturally or by carcinogens (i.e.:
tobacco smoke, chemicals, etc.)
That cell starts dividing without limit, possibly killing
the host (without treatment)
Cancer Treatment
Three basic treatments:
– Surgery to remove cancer
– Radiation to kill affected cells
– New drugs are becoming available (Chemotherapy)
It is hard to remove cancer (tumors often lack clear boundaries)
– Some tumors are very small and are found throughout the body (advanced
stages)
Radiation and chemotherapy are aimed at killing cancer cells
– The body then has to replace those dead cells which requires a lot of energy
– Therefore treatment must be balanced with overall patient health
Unfortunately due to natural selection cancer that seems to have
disappeared can come back in the future in a form that is resistant to
the radiation / chemotherapy
Using multiple drugs can decrease the risk of relapse
– Multiple drugs decrease the probability of cells acquiring immunity
Types of Cancer
Lung Cancer
Breast Cancer
Brain Cancer
Skin Cancer
Ovarian Cancer
Uterine Cancer
Cervical Cancer
Testicular Cancer
Kidney Cancer
Prostate Cancer
Leukemia
Eye Cancer
Lymphatic Cancer
Mouth Cancer
Colon Cancer
Pancreatic Cancer
Bone Cancer
Penile Cancer
The cure is out there !