Cancer and the Cell Cycle

Controls on Cell Division How do cells know when to divide? How do cells know when to divide? How do cells regulate the cell cycle? How do cells regulate the cell cycle?

Proteins Regulate!!! The cell cycle is regulated by proteins both inside and outside the cell. The cell cycle is regulated by proteins both inside and outside the cell.

Regulation The controls on cell growth and division can be turned on and off. The controls on cell growth and division can be turned on and off. –Broken bone - cells are stimulated to divide rapidly to heal. –The rate of cell division slows as the healing process nears completion. Cells respond to cells in close proximity.

When cells are grown in a laboratory, which of the following is a factor that can stop normal cells from dividing? A) contact with other cells B) growth factors C) a cut in the skin D) injection of cyclin

Cyclins Cyclins are a family of proteins that regulate the timing of the cell cycle in eukaryotic cells. Cyclins are a family of proteins that regulate the timing of the cell cycle in eukaryotic cells.

Regulatory Proteins Internal regulators are proteins that respond to events inside a cell. Internal regulators are proteins that respond to events inside a cell. They allow the cell cycle to proceed only once certain processes have happened inside the cell. They allow the cell cycle to proceed only once certain processes have happened inside the cell.

Regulatory Proteins External regulators are proteins that respond to events outside the cell. External regulators are proteins that respond to events outside the cell. They direct cells to speed up or slow down the cell cycle. They direct cells to speed up or slow down the cell cycle.

External Regulators Growth factors are external regulators that stimulate the growth and division of cells. Growth factors are external regulators that stimulate the growth and division of cells. They are important during embryonic development and wound healing. They are important during embryonic development and wound healing.

Which of the following are external regulators of the cell cycle? a.cyclins b.growth factors c.mitotic spindles d.cancer cells

Cyclins are a family of closely related proteins that a.regulate the cell cycle. b.produce p53. c.cause cancer. d.work to heal wounds.

How do cancer cells differ from other cells? Cancer cells do not respond to the signals that regulate the growth of most cells. Cancer cells do not respond to the signals that regulate the growth of most cells. As a result, the cells divide uncontrollably. As a result, the cells divide uncontrollably.

Cancer Cancer is a disorder in which body cells lose the ability to control growth. Cancer is a disorder in which body cells lose the ability to control growth. Cancer cells divide uncontrollably to form a mass of cells called a tumor. Cancer cells divide uncontrollably to form a mass of cells called a tumor.

Tumors A benign tumor is noncancerous. A benign tumor is noncancerous. It does not spread to the cells around it. It does not spread to the cells around it.

Tumors A malignant tumor is cancerous. A malignant tumor is cancerous. It invades and destroys healthy tissue around it. It invades and destroys healthy tissue around it.

Metastasis It can spread to other parts of the body It can spread to other parts of the body –This spreading is call metastasis.

Why are cancer cells a problem? Cancer cells absorb nutrients needed by other cells Cancer cells absorb nutrients needed by other cells They block nerve connections They block nerve connections They prevent organs from functioning properly. They prevent organs from functioning properly.

Cells grown in a petri dish tend to divide until they form a thin layer covering the bottom of the dish. If cells are removed from the middle of the dish, the cells bordering the open space will begin dividing until they have filled the empty space. What does this experiment show? A) Cell division is a completely random process B) Once cells divide, they can never divide again. C) The controls on cell growth and division can be turned on and off. D) There is only a limited amount of DNA available to a given group of cells.

What Causes Cancer? Cancers are caused by defects in genes that regulate cell growth and division. Cancers are caused by defects in genes that regulate cell growth and division. –The control over the cell cycle has broken down.

What Causes Cancer? There are several sources that cause this defect. There are several sources that cause this defect. –Smoking or chewing tobacco –Radiation exposure –Defective genes –Viral infection

Gene p53 This gene is responsible for halting the cell cycle until all chromosomes have been properly replicated. This gene is responsible for halting the cell cycle until all chromosomes have been properly replicated.

p53 A large number of cancer cells have a defective p53 gene. A large number of cancer cells have a defective p53 gene. –When this gene is damaged, it causes the cells to lose the information needed to respond to signals that normally control their growth.

Treatments for Cancer Some localized tumors can be removed by surgery. Some localized tumors can be removed by surgery. Many tumors can be treated with targeted radiation. Many tumors can be treated with targeted radiation. Chemotherapy is the use of compounds that kill or slow the growth of cancer cells. Chemotherapy is the use of compounds that kill or slow the growth of cancer cells.

Cancer is a disorder in which some cells have lost the ability to control their A) size. B) spindle fibers. C) growth rate. D) surface area.

A cell with a defective p53 gene is likely to A) stop responding to growth regulators. B) stop dividing to produce daughter cells. C) generate hormones that combat tumors. D) produce cells without a defective p53 gene.

Cell Differentiation During the development of an organism, cells differentiate into many types of cells. During the development of an organism, cells differentiate into many types of cells.

Differentiation in Mammals Cell differentiation in mammals is controlled by a number of interacting factors in the embryo. Cell differentiation in mammals is controlled by a number of interacting factors in the embryo.

Differentiation Adult cells generally reach a point at which their differentiation is complete and they can no longer become other types of cells. Adult cells generally reach a point at which their differentiation is complete and they can no longer become other types of cells.

Stem Cells Stem cells are the unspecialized cells from which differentiated cells develop. Stem cells are the unspecialized cells from which differentiated cells develop.

Stem cells are cells that: a.) are specialized and therefore cannot become any type of cell. b.) are unspecialized and therefore can become any type of cell. c.) are only found in plants. d.) are differentiated into set categories.

Totipotent Cells Totipotent cells are stems cells that are able to become any tissue in the body. (These cells can construct a complete, viable organism) Totipotent cells are stems cells that are able to become any tissue in the body. (These cells can construct a complete, viable organism)

Human Development After about four days of development a human embryo develops into a blastocyst. After about four days of development a human embryo develops into a blastocyst.

Blastocyst A blastocyst is a hollow ball of cells with a cluster of cells inside known as the inner cell mass.

Pluripotent The cells of the inner cell mass are said to be pluripotent. The cells of the inner cell mass are said to be pluripotent.

Pluripotent Cells Pluripotent stem cells are capable of developing into nearly all of the body’s cell types. Pluripotent stem cells are capable of developing into nearly all of the body’s cell types. ( By themselves, however, these cells cannot construct a complete, viable organism) ( By themselves, however, these cells cannot construct a complete, viable organism)

Totipotent cells: a.) can only become certain types of cells b.) are stronger than multipotent cells c.) are capable of becoming many but not all types of cells. d.) can become any tissue in the body.

Stem Cells There are two types of stem cells. There are two types of stem cells. – Embryonic stem cells – Adult stem cells

Embryonic Stem Cells Embryonic stem cells are found in the inner cell mass of the early embryo. Embryonic stem cells are found in the inner cell mass of the early embryo.

Embryonic Stem Cells Embryonic stem cells are pluripotent. Embryonic stem cells are pluripotent.

Embryonic Stem Cells Researchers have grown stem cells isolated from human embryos in culture. Researchers have grown stem cells isolated from human embryos in culture.

Their experiments confirmed that embryonic stem cells have the capacity to produce most cell types in the human body. Their experiments confirmed that embryonic stem cells have the capacity to produce most cell types in the human body.

Embryonic stem cells: a.) come from the inner cell mass of an early embryo b.) are extracted from adult bone marrow c.) can become any tissue in the body d.) are multipotent

Adult Stem Cells Adult organisms contain some types of stem cells. Adult organisms contain some types of stem cells.

Adult Stem Cells Adult stem cells are multipotent. Adult stem cells are multipotent. – They can produce many types of differentiated cells.

Adult Stem Cells Adult stem cells of a particular tissue produce only the types of cells that are unique to that tissue. Adult stem cells of a particular tissue produce only the types of cells that are unique to that tissue.

The Promise of Stem Cell Research Stem cells offer the potential benefit of using undifferentiated cells to repair or replace badly damaged cells or tissue. Stem cells offer the potential benefit of using undifferentiated cells to repair or replace badly damaged cells or tissue.

Benefits of Stem Cell Research Stem cell research may lead to new ways to repair the cellular damage that results from heart attack, stroke, and spinal cord injuries. Stem cell research may lead to new ways to repair the cellular damage that results from heart attack, stroke, and spinal cord injuries.

Why are stem cells important? a.They have specialized DNA. b.They are incapable of becoming cancer cells c.They have the potential to undergo cell division. d.They have the potential to develop into other cell types.

Which of the following is a possible future benefit of stem cell research? A) developing a vaccine for cancer B) reversing damage from a heart attack C) generating embryos from nonliving tissue D) increasing a person’s intelligence quotient