Download NOTES: 10.3 - 10.4 - Control of the Cell Cycle / Cancer

NOTES: 10.3-10.4 - Regulating the Cell Cycle / Cell Differentiation
Key Concepts:
● How is the cell cycle regulated?
● How are cancer cells different from other cells?
● What causes cancer?
The Cell Cycle – review of the basics:
● Genetic information is in the form of DNA
● Cell cycle = process of cell division
 The cell grows;
 DNA is copied;
 The contents of the nucleus are divided;
An Interesting Fact About Cell Division
 Cytoplasm is divided;
 Two new cells exactly like the original cell!
● Not all cells move through the
-Ex: most
cells &
cells do not divide at all once they have developed
-Ex: skin cells and cells lining our intestines complete the cell cycle every
-Ex: frog embryo cells take
!
CONTROLS ON CELL DIVISION
● Controls can be observed in a lab
-Cells in a petri dish containing nutrient broth (food) will grow and divide forming a thin layer.
-When the cells come into contact with each other, they
.
-If cells from the center are removed, growth and division will continue until cells are in
once again
Cell Cycle Regulators
● Several scientists discovered that cells in mitosis contained a
● If this protein was injected into a non-dividing cell, the mitotic spindle would
-scientists called this protein
-Scientists have since discovered a family of closely related proteins (cyclins) & dozens
of other proteins that help
.
Regulatory Proteins:
● The cell cycle is controlled by regulatory proteins, both inside & outside of the cell
Regulatory Proteins: INTERNAL
● Respond to events
● Allow the cell cycle to proceed only when certain events have occurred in the cell itself
● Example: some regulatory proteins make sure a cell
until its chromosomes
have been replicated
● Example: a regulatory protein prevents a cell from entering anaphase until the spindle fibers have attached to all
chromosomes.
Regulatory Proteins: EXTERNAL
● Respond to events occurring
● GROWTH FACTORS:
-important during
&
● Other external regulators cause cells to
their cell cycles…this
& keeps body tissues from disrupting one another.
Recent studies suggest…
● The portion of interphase just before DNA replication is a key control period in the cell cycle;
● There are several proteins identified as controlling the cell cycle…
● RECALL: Proteins are coded for by DNA! So…
● A mistake (
) in the DNA (
) that codes for one or more of these
control factors/enzymes could lead to a
.
Uncontrolled Cell Growth
● What can happen if the cell cycle is not regulated so carefully?
-
!
● Cancer cells do not respond to
that regulate the growth of most cells.
● The result? They form masses of cells called
that can damage the surrounding tissues
-Benign vs. malignant
● Cancer cells can also break off and spread throughout the body (
Recent Research
● Many cancer cells have a defect in a gene called p53
)
can spread through lymph nodes
-The protein made from this segment of DNA normally
until all
chromosomes have been replicated properly (without mutations)
-If it isn’t working, damaged DNA can replicate
-The cell may have lost the information it needs to respond to growth control signals
● Cancer is a disease of the
Cancer is the 2nd leading cause of death in the U.S.
● It can affect any tissue, but the most commonly affected are:




What causes the loss of growth control?



Cancer Prevention:
● There is a clear link between healthy lifestyle and reducing the incidence of cancer;
● Diet low in
and high in
●
and
●
;
●
(fruits, vegetables, & grains);
(A, C, E, & calcium);
;
●
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Treatments
●
●
(for benign tumors)
●
10.4: Cell Differentiation
Key Concepts:
● How do cells become specialized for different functions?
● What are stem cells?
● What are some possible benefits & issues associated with stem cell research?
Cell Differentiation:
● the process by which cells become
● we all started as an individual
;

 adult organism
● cell differentiation is controlled by a number of interacting factors in an embryo…many of which we still don’t
completely understand!
STEM CELLS:
● how do so many specialized, differentiated cell types develop from just a single cell?
● such a cell is said to be TOTIPOTENT
● TOTIPOTENT = able to
● PLURIPOTENT = able to
● STEM CELLS = the
from which differentiated cells develop
● TYPES of stem cells:
● EMBRYONIC: pluripotent cells
…mouse embryonic stem cells have been
triggered to differentiate into: nerve cells, muscle cells, & even sperm & egg cells!
● ADULT: groups of cells that differentiate to
cells in the adult body; more
limited than embryonic stem cells
● Example: adult stem cells in the bone marrow can develop into several types of
● Example: adult stem cells in the brain can produce
● BENEFITS of Stem Cell Research:
● stem cells offer excellent prospects to
that is the cause of many human life-
threatening conditions:
● Example:
● Example: strokes & spinal cord injuries
& cause paralysis
● ETHICAL ISSUES:
● adult stem cells can be harvested from willing adult donors
● embryonic stem cells are harvested from
many ethical discussions involving issues of life and death…
● in the future, technology may help to reduce these ethical concerns (i.e.
to behave like an embryonic stem cell)
…this has led to