10.3 regulating the cell cycle - enfield high...
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Lesson OverviewLesson Overview Regulating the Cell CycleRegulating the Cell Cycle
Lesson OverviewLesson Overview10.3 Regulating 10.3 Regulating 10.3 Regulating 10.3 Regulating
the Cell Cyclethe Cell Cycle
Lesson OverviewLesson Overview Regulating the Cell CycleRegulating the Cell Cycle
When cells are grown in the laboratory, most cells will divide until they come into contact with each other – once they do, they usually stop dividing and growing
Question #1Controls on cell growth and division turned on and off
If cells are scraped away, the remaining cells begin dividing again until they once again make contact with other cells
Similar with injury (closes breaks in the skin and bone)
Lesson OverviewLesson Overview Regulating the Cell CycleRegulating the Cell Cycle
Cyclins are proteins that regulate the timing of the cell cycle in eukaryotic cells
In the 1980s, biologists discovered a protein in cells that were
Question #2Cyclins
In the 1980s, biologists discovered a protein in cells that were in mitosis – when this protein was injected into a nondividing cell, a mitotic spindle formed
Lesson OverviewLesson Overview Regulating the Cell CycleRegulating the Cell Cycle
A group of proteins that respond to events occurring inside a cell
They allow the cell cycle to proceed only when certain events
Question #3Internal Regulatory Proteins
They allow the cell cycle to proceed only when certain events have occurred in the cell itself
Some internal regulatory proteins make sure a cell does not enter mitosis until its chromosomes have replicated
Another internal regulatory protein prevents a cell from entering anaphase until the spindle fibers have attached to the chromosomes
Lesson OverviewLesson Overview Regulating the Cell CycleRegulating the Cell Cycle
A group of proteins that respond to events outside the cell
They direct cells to speed up or slow down the cell cycle
Question #4External Regulatory Proteins
Growth factors are a group of external regulatory proteins that speed up the cell cycle
Lesson OverviewLesson Overview Regulating the Cell CycleRegulating the Cell Cycle
A group of external regulatory proteins that stimulate the growth and division of cells
They are especially important during embryonic development
Question #5What are growth factors?
They are especially important during embryonic development and wound healing
Lesson OverviewLesson Overview Regulating the Cell CycleRegulating the Cell Cycle
A process of programmed cell death
Plays a role in development by shaping the structures of tissues and organs in plants and animals
Question #6What is apoptosis?
tissues and organs in plants and animals
Once apoptosis is triggered, a cell undergoes a series of controlled steps leading to its self-destruction
First, the cell and its chromatin shrink and parts of the cell’s membrane break off
Neighboring cells then quickly clean up the cell’s remains
Lesson OverviewLesson Overview Regulating the Cell CycleRegulating the Cell Cycle
A disorder in which body cells lose the ability to control cell growth
Cancer cells do not respond to the signals that regulate the
Question #7What is cancer?
Cancer cells do not respond to the signals that regulate the growth of most cells – as a result, the cells divide uncontrollably
Lesson OverviewLesson Overview Regulating the Cell CycleRegulating the Cell Cycle
A mass of rapidly dividing cells that can damage surrounding tissue
Question #8What is a tumor?
Lesson OverviewLesson Overview Regulating the Cell CycleRegulating the Cell Cycle
Benign
� Noncancerous tumor
� Does not spread to surrounding healthy tissue or to other parts of the body
Question #9Two categories of tumors
parts of the body
Malignant
� Cancerous tumor
� Invades and destroys surrounding healthy tissue
Lesson OverviewLesson Overview Regulating the Cell CycleRegulating the Cell Cycle
As cancer cells spread (metastasis), they…
� Absorb nutrients needed by other cells
� Block nerve connections
� Prevent the organs they invade from functioning properly
Question #10What is the problem with cancer cells?
� Prevent the organs they invade from functioning properly
Lesson OverviewLesson Overview Regulating the Cell CycleRegulating the Cell Cycle
Metastasis
Lesson OverviewLesson Overview Regulating the Cell CycleRegulating the Cell Cycle
Defects in genes that regulate cell growth and division� Sources of gene defects include smoking or chewing tobacco,
radiation exposure, other defective genes, and even viral infections
Question #11What causes cancer?
Some cancer cells will no longer respond to external regulators, while others fail to produce the internal regulators that ensure orderly growth
Many cancer cells have a defect in a gene called p53, which normally halts the cell cycle until all chromosomes have been properly replicated
� This causes the cell to lose the information needed to respond to
growth signals
Lesson OverviewLesson Overview Regulating the Cell CycleRegulating the Cell Cycle
Some localized tumors can be removed by surgery
Many tumors can be treated with targeted radiation (the radiation damages the DNA of cancer cells)
Question #12What are treatments for cancer?
radiation damages the DNA of cancer cells)
Chemotherapy, the use of compounds that kill or slow the growth of rapidly dividing cells, can also be used to treat cancer
The problem with most treatments for cancer is that normal cells can be damaged and/or killed in the process
Lesson OverviewLesson Overview Regulating the Cell CycleRegulating the Cell Cycle
Question #13Characteristics of cancer cells and tumors
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