Mitosis II BIO 105 Cr.4
UW - L
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This 0 page Class Notes was uploaded by MaKena Betler on Thursday November 5, 2015. The Class Notes belongs to BIO 105 Cr.4 at University of Wisconsin - La Crosse taught by a professor in Fall 2015. Since its upload, it has received 24 views. For similar materials see General Biology in Biology at University of Wisconsin - La Crosse.
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Date Created: 11/05/15
Lecture 24 Mitosis II 0 Regulation of the cell cycle and cancer 0 Cell cycle checkpoints are proliferative controls G1 checkpoint Signaled to enter the center by external mitogens No DNA damage is identi ed Suf cient resources and space 02 checkpoint DNA is completely replicated No DNA damage is identi ed Metaphase checkpoint Chromosomes are all attached to the mitotic spindle 0 Cells will only arrest here when things have gone horribly wrong 0 Oncogenes cancer causing genes Protooncogenes promote the cell cycle in carious ways accelerator Tumor suppressor genes inhibit the cell cycle in various ways brakes Both normally regulated in coordination with organism s growth plan If either mutates may lose control and become oncogene Tumor suppressors block progression Lossof function mutations in both copies of a tumor suppressor Progression past the checkpoint can t be stopped Protooncogenes trigger progression Gainof function mutations in any copy of a protooncogene turning it into an oncogene 39Accelerate through the checkpoint regardless of any signals Apoptosis o quotprogrammed cell deathquot 0 Signal protein p53tumor suppressor protein Stops cycle at G1 when DNA damaged Initiates DNA attempt at repair 0 If successful cycle continues to mitosis o If not apoptosis is initiated 0 Appears to be absent in many cancerous cells 0 Cancer is essentially a failure of cell division control unrestrained uncontrolled cellular growth 0 One origin of cancermutations in DNA repair mechanisms Every person has these cell cycle protooncogenes but not every person has cancer Why might this be 0 Protooncogenes have to become mutant in order for cancer to occur 0 The protooncogenes are called oncogenes when mutant 0 What does it mean to be predisposed to cancer Predisposition to cancer means that you inherit one copy of a cell gene 0 Why has cancer been so tough to eradicate Cancer is a disease of our own cells and genes that have been altered in some way Because these cells look and behave like our cells there is no plethora of foreign antigens for our immune system to recognize Drugs that kill tumor cells also kill our normal cells There are hundreds of different cancers 0 The nature of how cancerous cells evade the checkpoints with genetic changes tends to further accelerate acquisition of more genetic changes Once a cell has escaped proliferative control they will accumulate more mutations they breeze through checkpoints Either becomes nonfunctional or an aggressive malignant cancer In a perverse way cancer is an evolutionary process where cancer cells compete with all the other noncancerous cells for survival
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