Transcript Control of the Cell Cycle

10.3 and 10.4 Notes
Control of the Cell Cycle
• The cell cycle is controlled by proteins called
cyclins and enzymes that bind to those proteins
• Regulation can be internal or external depending
on whether the signal to divide comes from
inside or outside the cell
Apoptosis
• A process of programmed cell death
• Occurs naturally during development or
can be a result of diseases such as
Parkinson’s or AIDS
Cancer
• When the segment of DNA (gene) that codes for
the regulatory proteins is damaged the cell may
divide uncontrollably
• Cancer is a growth (tumor) resulting from
uncontrolled cell division
Cancer
• Scientists have identified p53 as a tumor
suppressing gene that controls cell
division
• Cells with damaged p53 genes do not
respond to signals to divide normally.
Cancer
• Tumors can be benign or malignant
depending on whether they affect healthy
cells
• Malignant tumors affect surrounding
healthy tissue by depriving them of
nutrients or blocking nerve connections
• Sometimes cancer can travel to other
parts of the body, this is called metastisis
Cancer Causes and Prevention
• Can be caused by genetic or
environmental factors (ex: cancer runs in
families, smoking, pollution, UV rays)
• Healthy choices about diet, exercise and
tobacco use can help prevent cancer
Screening for Cancer
• Doctors can use imaging techniques such
as radiology to search for cancer
• Biopsies involve taking a sample of cells
or tissues to examine
Do You See the Gorilla?
80% of radiologists did not!
Cancer Treatments
• Surgery if tumor is contained
• Radiation targets cells that divide rapidly
• Chemotherapy consists of chemical
compounds that target dividing cells and
can therefore interfere with normal division
in healthy cells
• Fluorescence
microscopy allows
scientists to label
parts of the cell and
view the phases of
the cell cycle in
more detail
http://images.wellcome.ac.uk/indexplus/obf_images/3e/cf/
46fa21b8a66206e8763cf29f58d4.jpg
Check For Understanding…
1. The type of protein which controls the cell
cycle is
a. tubulin
b. keratin
c. cyclin
d. collagen
2. Which of the following best describes
apoptosis?
a.
b.
c.
d.
programmed cell death
cancer cells migrate to other parts of the body
cells divide repeatedly
taking a sample of cells
3. Which disease is a result of uncontrolled
cell division?
a. diabetes
b. flu
c. cystic fibrosis
d. cancer
4. Which of the following is most likely to
result from a malignant tumor?
a. cancer migrates to a different part of
the body
b. rapidly dividing cells are destroyed
c. it remains isolated and usually
harmless
d. genetic mutations
5. Which of the following is NOT a potential
cause for cancer?
a. genetics
b. tobacco
c. lots of fruits and vegetables
d. UV radiation
Cell Differentiation
• Each of us starts life as a single cell
• All multicellular organisms pass through
the stage called an embryo
• Cells become specialized for perform
different functions through the process of
differentiation
• Scientists can map the fate of every single
cell division in some organisms ( C.
elegans)
Stem Cells
• Remember that every
living thing starts out as a
single cell. That cell is
said to be totipotent
because it can become
any type of cell.
• Cells that are pluripotent
can develop into most,
but not all, cells in the
body.
• Stem cells are
undifferentiated cells
from which specific
cell types develop.
There are two types
of stem cells
– Embryonic stem cells
which are pluripotent
and can become
most cell types
• Adult stem cells which are found throughout the body
after development and are multipotent because they can
develop into several different types of cells
Stem Cell Research
• Benefits: stem cells offer the benefit of
using undifferentiated cells to replace or
repair those damaged by heart attack,
stroke or spinal cord injury
• Ethics: most ethical questions come from
obtaining embryonic stem cells because
harvesting the cells causes destruction of
the embryo
– The funding of stem cell research has
become an important political issue
– It is controversial because the arguments for
and against involve ethical issues of life and
death
Technological Solutions
• There has been research suggesting it's
possible to extract a small number of stem
cells from an embryo without damaging it
• It may also be possible to switch “on" and
reprogram adult stem cells so they can
differentiate into a greater variety of cells
Check For Understanding…
1. Cells becoming specialized to perform
different functions is known as
a. metastasis
b. differentiation
c. apoptosis
d. chemotherapy
2. Cells that can become any type of cell
are known as
a.
b.
c.
d.
totipotent
pluripotent
multipotent
adult stem cells
3. Embryonic cells that can become most,
but not all, cell types are called
a.
b.
c.
d.
totipotent
pluripotent
multipotent
adult stem cells
4. Adult stem cells can become several
different types of cells. They are known as
a.
b.
c.
d.
totipotent
pluripotent
multipotent
adult stem cells
5. Which of the following is NOT a benefit of
stem cell research?
a. treating stroke victims
b. treating heart attack victims
c. treating cancer
d. treating spinal cord injuries