10.3 regulating the cell cycle - enfield high...

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


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)


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


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


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


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


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


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


A mass of rapidly dividing cells that can damage surrounding tissue

Question #8What is a tumor?


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


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


Metastasis


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


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


Question #13Characteristics of cancer cells and tumors

10.3 regulating the cell cycle - enfield high...

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