Cell Differentiation and Cell Growth Regulators Chapter 10
Cell Differentiation and Cell Growth Regulators
Chapter 10
Why did we use Onion Root Tip Cells?
Why did we use Onion Root Tip Cells?
Roots grow deep into the dirt and some surface cells are“scratched” away
So… Root Tip Cells must divide rapidly = MITOSIS!
Why do cells divide?
Cell division allows organisms to grow and reproduce.
Also, cells cannot function effectively if they are too large. Compare the surface area to volume ratio.
Why do cells divide?
Cell Differentiation
Cell differentiation: when cells take on specific structures and functions Different organisms may have different
types of cells (e.g. bacterium) There may be many different types of
cells in the SAME organism (e.g. human)
Examples of Slow Dividing Cells Neurons (top)
Conduct impulses throughout our body so that we can move, think, feel, etc
Some NEVER divide
Muscle cells (bottom) Used for movement Works like a spring
Examples of Fast Dividing Cells
Cheek cells (top) Divide approximately
every three days because food scrapes off surface layers
Intestinal cells (bottom) Divides quickly because
food and bile scrape off surface layers
Frequently have cilia (hair-like projections) to help “move” food down the digestive tract
How is cell growth regulated? Proteins called cyclins control parts of the
cell cycle.
Internal regulators are cyclins that control events INSIDE the cell. For example, some cyclins pause mitosis until
chromosomes are copied. Once this occurs, then it resumes mitosis.
External regulators are cyclins that control events OUTSIDE of the cell. For example, cells grow until they reach other
cells (e.g. healing a wound). Some cyclins tell the cells to stop dividing so that it won’t interfere with other tissues.
What is cancer?
Cancer is uncontrolled cell division.
Since cancerous cells belong to the organism itself, the organism’s body has difficulty detecting and fighting the cancerous cells. Glycoproteins on cell
membrane are “self markers”
What is cancer?
Cancerous cells tend to form a clump called a tumor, but sometimes in later stages of cancer, the cancerous cells metastasize. Metastasize means that
they move to other parts of the body. For example, a cancerous lung cell might migrate to the brain and spread the cancer.
Causes
Inherited Genetic Mutation Carcinogens (e.g. certain
chemicals in cigarettes) Overexposure to
radiation (e.g. sunlight) Diet / Exercise Other
Treatments
Surgery
Radiation
Chemotherapy
Magnets???
Alternative Options