21. F - Cells tend to stop dividing when they come into contact with other cells.
32. F - Cell division slows down when the healing process nears completion.
43. F – Proteins called cyclins regulate the timing of the cell cycle in eukaryotic cells.
54. T – If chromosomes have not attached to spindle fibers during metaphase, an internal regulatory proteins will prevent the cell from entering anaphase
65. F – Growth factors are external regulatory proteins that speed up the cell cycle
76. T – Once apoptosis is triggered, a cell proceeds to self-destruct.
87.Cyclins – Tell a cell when to begin steps of cell cycle (growth, copy DNA, mitosis, cytokinesis)Internal regulatory proteins – stop a cell from going to next phase if internal events have not occurred (ex: can’t go to mitosis until chromosomes are replicated)External regulatory proteins – speed up cell cycle (ex: for embryonic growth or wound healing) or slow down cell growth (ex: so one body tissue’s growth doesn’t disrupt another’s)
98. Cancer is a disorder in which some of the body’s own cells lose the ability to control growth
109. Tumors may be malignant or benign. Malignant – cancerous, invade and destroy healthy tissuesBenign – noncancerous, doesn’t spread
1110. Rapidly dividing cancer cells take nutrients away from healthy tissues. This leads to disruption of the proper functioning of body organs that causes illness and may lead to death
1211. Defects in genes that regulate cell growth and division causes cancer
1312.Radiation disrupts the cancer cycle by interfering with the copying of DNA.Chemotherapy kills cancer cells (targets rapidly dividing cells)
1413. Cancer cells do not respond to signals that regulate cell GROWTH Cancer cells form a mass of cells called a TUMORCancer cells may break loose and SPREAD throughout the bodyCancer cells form tumors in other tissues by METASTASIS
1514.The chemicals stop cell division in both cancer cells and healthy cells, such as ones that produce hair. With no new cells being added to the hair shafts, they break and fall out.