Question #1 Controls on cell growth and division turned on and off

Lesson Overview 10.3 Regulating the Cell Cycle

Question #1 Controls on cell growth and division turned on and off 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 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)

Question #2 Cyclins 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 in mitosis when this protein was injected into a nondividing cell, a mitotic spindle formed

Question #3 Internal Regulatory Proteins A group of proteins that respond to events occurring inside a cell 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

Question #4 External Regulatory Proteins A group of proteins that respond to events outside the cell They direct cells to speed up or slow down the cell cycle Growth factors are a group of external regulatory proteins that speed up the cell cycle

Question #5 What are growth factors? A group of external regulatory proteins that stimulate the growth and division of cells They are especially important during embryonic development and wound healing

Question #6 What is apoptosis? A process of programmed cell death Plays a role in development by shaping the structures of 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

Question #7 What is cancer? A disorder in which body cells lose the ability to control cell growth Cancer cells do not respond to the signals that regulate the growth of most cells as a result, the cells divide uncontrollably

Question #8 What is a tumor? A mass of rapidly dividing cells that can damage surrounding tissue

Question #9 Two categories of tumors Benign Noncancerous tumor Does not spread to surrounding healthy tissue or to other parts of the body Malignant Cancerous tumor Invades and destroys surrounding healthy tissue

Question #10 What is the problem with cancer cells? As cancer cells spread (metastasis), they Absorb nutrients needed by other cells Block nerve connections Prevent the organs they invade from functioning properly

Metastasis

Question #11 What causes cancer? 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 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

Question #12 What are treatments for cancer? Some localized tumors can be removed by surgery Many tumors can be treated with targeted radiation (the 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 #13 Characteristics of cancer cells and tumors