Presentation on theme: "Cell Division by Mitosis"— Presentation transcript:
1 Cell Division by Mitosis Cellular ReproductionCell Division by Mitosis
2 Cell Growth all living things start life as a single cell Growth results when your body forms new cells.New cells are formed by cell division
3 Cell Division There are two types of cell division 1. mitosis (division of body cells)2. mieosis (division of sex cells)
4 Mitosis two cells are formed from one cell new cells are similar to old cellthe new cells replace old cellsroot cells, skin cells, muscle cells are examples
5 Mitosis- for many simple organisms (like bacteria and some algae) mitosis = reproduction
6 Mitosis mitosis is NOT a one step process as a cell divides some of the cell parts changeit forms two new cells. The number of cells increases every time cells divide.the number of chromosomes in each cell remains the same
20 Cancer a cell that divides too fast can form a tumor cells divide too fast because of mutations (changes) in the cells DNA - mutations can occur because of1. genetics2. environmental factors- UV radiation from sun- cigarette smoke
22 The Stages of the Cell Cycle 1. Click on picture for cell cycle animation –will go to2. Use alt-tab keys to go between websiteand power point presentation.3. Click on blank space to proceed to next slide.)
23 There are several factors that regulate the cell cycle and assure a cell divides correctly. 1.Before a cell divides, the DNA is checked to make sure it has replicated correctly. (If DNA does not copy itself correctly, a gene mutation occurs.DNA replication animation:click on DNA picture
24 2. Chemical Signals tell a cell when to start and stop dividing. (Target cells animation: click on go sign)
25 Neighboring cells communicate with dividing cells to regulate their growth also. (Normal contact inhibition animation: click on petri dish)
26 Cancer is a disease of the cell cycle Cancer is a disease of the cell cycle. Some of the body’s cells divide uncontrollably and tumors form.Tumors in LiverTumor in Colon
27 DNA mutations disrupt the cell cycle. Mutations may be caused by:1. radiation2. smoking3. Pollutants4. chemicals5. viruses
28 While normal cells will stop dividing if there is a mutation in the DNA, cancer cells will continue to divide with mutation.
29 Due to DNA mutations, cancer cells ignore the chemical signals that start and stop the cell cycle. 2 animations of cancer cells dividing: click on picture
30 Due to DNA mutations, cancer cells cannot communicate with neighboring cells. Cells continue to grow and form tumors.Skin cancer(cancer cells dividing: click on picture.)
31 SUMMARY Normal Cell Division DNA is replicated properly. 2. Chemical signals start and stop the cell cycle.3. Cells communicate with each other so they don’t become overcrowded.Cancer CellsMutations occur in the DNA when it is replicated.2. Chemical signals that start and stop the cell cycle are ignored.3. Cells do not communicate with each other and tumors form.
32 Treating CancersCancer treatments include drugs that can stop cancer cells from dividing.
33 Reflect and Review1. In mitosis, how many cells are formed from each dividing cell?2. What is copied in the nucleus before the cells divide?3. If a cell has 46 chromosomes and divides by mitosis, how many chromosomes will each new cell have?