Cell Cycle Regulation 9.3

The Normal Cell Cycle Everywhere you see a red dot, there is a check point in the cell cycle. These checkpoints determine whether or not the cell is ready to go on to the next phase of the cell cycle.

The Normal Cell Cycle Special proteins call cyclins bind to an enzyme called Cyclin-dependant kinases to make signal that the cell is clear to pass the checkpoint.

The Normal Cell Cycle If the cell is normal and healthy, the cyclins and Cyclin dependant kinases (CDKs) will bind properly and the cell will continue through the cell cycle. If the cell is not healthy or there is a mistake in the synthesized DNA, the cell will either go back and fix the mistake or it will not continue through the cell cycle.

The Normal Cell Cycle If the cell is not healthy or there is a mistake in the synthesized DNA, the cell will either go back and fix the mistake or it will not continue through the cell cycle.

Cancer Cells Cancer- uncontrolled growth and division of cells. Cancer can develop when the checkpoints in the cell cycle are not properly monitored. If a cyclin or CDK don’t work correctly.

Cancer Cells There are a lot of potential causes for Cancer but they all result from genetic mutations. Things that can cause genetic mutations include Carcinogens Radiation Family history

Cancer Cells Carcinogens- substances or agents known to cause cancer Ex. Tobacco products of any kind (including ecigarettes), asbestos, other specific chemicals

Cancer cells Radiation- an excess of UV ray exposure has been directly linked to the development of skin cancer. Radiation can cause the skin cell DNA to mutate and bond where it shouldn’t bond, causing replication/transcription/translation to not occur properly

Cancer cells Family history- some mutations are often inherited from parents. It takes a lot of mutations in the DNA to result in cancer Mechanisms that both control cell growth AND stop tumor growth must be mutated before cancer can develop DNA is mutated often due to mistakes in replication BUT the cell is very good at correcting its mistakes.

Cell Death Apoptosis- programmed cell death Apoptosis will often be activated in the following types of cells Potential cancer cells Old cells Cells that no longer have a use Ex. In the womb, human fingers and toes are webbed, but due to apoptosis, those skin cells die and are gone before we are born.

Stem cells Stem cells- unspecialized cells that can develop into specialized cells. These cells are not skin cells, kidney cells, heart cells, etc. They are just cells When an egg cell is fertilized by a sperm cell, the formed zygote begins to divide and make stem cells that will eventually become cells to build the body Adults have fewer stem cells than embryos, they have them only to differentiate and replenish certain types of cells.

Key points for 9.3 The cell cycle is a strictly controlled process A lot has to go wrong for Cancer cells to develop Apoptosis is cell death Stem cells are unspecialized cells