1. The Cell Cycle In Your Body Science 9

2. The Cell Cycle In Your Body The cell cycle is responsible for growth and development of all your body’s cells. The cell cycle is responsible for growth and development of all your body’s cells. YOU started out as a single cell but through the process of MITOSIS you became a living system composed of trillions of cells working together. YOU started out as a single cell but through the process of MITOSIS you became a living system composed of trillions of cells working together. Here’s how it works! Here’s how it works!

3. The Cell Cycle In Your Body All of your body cells are specialized (each designed for one particular purpose. All of your body cells are specialized (each designed for one particular purpose. Groups of specialized cells form tissues. Groups of specialized cells form tissues. Groups of specialized tissues form organs. Groups of specialized tissues form organs. Groups of specialized organs form organ systems Groups of specialized organs form organ systems

4. The Cell Cycle In Your Body CELLSformTISSUESformORGANSform ORGAN SYSTEMS formYOU

5. The Cell Cycle In Your Body

6. The cell cycle ensures that the number of chromosomes in the nuclei of your cells will remain constant. The cell cycle ensures that the number of chromosomes in the nuclei of your cells will remain constant. All human beings have the same number of chromosomes in each nucleus of every cell. All human beings have the same number of chromosomes in each nucleus of every cell. How many chromosomes does a human being have? How many chromosomes does a human being have?

7. The Cell Cycle In Your Body Dogs have 78 chromosomes Dogs have 78 chromosomes Tomato plants have 24 chromosomes. Tomato plants have 24 chromosomes. Humans have 46 chromosomes - they are arranged in 23 pairs. Humans have 46 chromosomes - they are arranged in 23 pairs. There are a number of disorders that can affect the number or structure of human chromosomes. There are a number of disorders that can affect the number or structure of human chromosomes.

8. Chromosomal Disorders Patau Syndrome (Trisomy 13)occurs when an extra chromosome develops on the 13th pair. Patau Syndrome (Trisomy 13)occurs when an extra chromosome develops on the 13th pair. Downs Syndrome (Trisomy 21) occurs when an extra chromosome develops on the 21st pair. Downs Syndrome (Trisomy 21) occurs when an extra chromosome develops on the 21st pair.

9. Patau Syndrome Newborns with Patau syndrome share common physical characteristics: Newborns with Patau syndrome share common physical characteristics: Extra fingers or toes (polydactyly) Extra fingers or toes (polydactyly) Deformed feet, known as rocker-bottom feet Deformed feet, known as rocker-bottom feet Neurological problems such as small head (microcephaly), failure of the brain to divide into halves during gestation (holoprosencephaly), severe mental deficiency Neurological problems such as small head (microcephaly), failure of the brain to divide into halves during gestation (holoprosencephaly), severe mental deficiency

10. Patau Syndrome Facial defects such as small eyes (microphthalmia), absent or malformed nose, cleft lip and/or cleft palate Facial defects such as small eyes (microphthalmia), absent or malformed nose, cleft lip and/or cleft palate Heart defects (80% of individuals) Heart defects (80% of individuals) Kidney defects Kidney defects

11. Chormosomal Disorders There are a number of, relatively rare chromosomal disorders that have been identified. There are a number of, relatively rare chromosomal disorders that have been identified. At present there is no cure for any of these since every cell in the body is affected the same way. At present there is no cure for any of these since every cell in the body is affected the same way. There are many websites devoted to support. There are many websites devoted to support.websites

12. Normal Cell Replacement While you grow mitosis and cell division add to the total number of cells in your body. While you grow mitosis and cell division add to the total number of cells in your body. This process continues even after you are fully grown simply because cells do not live forever - they are continually dying. This process continues even after you are fully grown simply because cells do not live forever - they are continually dying.

13. Normal Cell Replacement Some cells have definite life spans programmed into their genetic material. Some cells have definite life spans programmed into their genetic material. These cells die when they receive “instructions” to do so, when they are no longer needed or when they can no longer function properly. These cells die when they receive “instructions” to do so, when they are no longer needed or when they can no longer function properly. Mitosis and cell division are necessary for cells to be replaced after they die. Mitosis and cell division are necessary for cells to be replaced after they die.

14. Normal Cell Replacement Approximately 3 000 000 000 (3 billion) cells die each minute! Approximately 3 000 000 000 (3 billion) cells die each minute! Cells can also die when they do not receive enough food or oxygen or as a result of damage. Cells can also die when they do not receive enough food or oxygen or as a result of damage. Cells must be replaced to maintain a healthy body. Cells must be replaced to maintain a healthy body.

15. Lifespan of Human Body Cells

16. Regeneration Repair of lost body cells, or making of lost body parts is called regeneration. Repair of lost body cells, or making of lost body parts is called regeneration. If you cut your finger or break your leg, cells must be regenerated to repair the cut. If you cut your finger or break your leg, cells must be regenerated to repair the cut. Some animals can regenerate entire limbs. Some animals can regenerate entire limbs. - the northern plateau lizard can regenerate its tail - children under the age of 12 may be able to completely regenerate severed fingertips

17. Aging Research suggests that we age because, as cells die they are either not replaced or are replaced more slowly. Research suggests that we age because, as cells die they are either not replaced or are replaced more slowly. This process results in changes to the structure and function of major body systems This process results in changes to the structure and function of major body systems - skin wrinkles - bones lose density - ability to fight disease weakens

18. Aging Scientists believe that certain changes take place in aging cells that affect their ability to repair themselves. Scientists believe that certain changes take place in aging cells that affect their ability to repair themselves.

19. Cancer What happens if cells begin to divide uncontrollably? What happens if cells begin to divide uncontrollably? The result is called cancer. The result is called cancer.

20. Cancer Cancerous cells interfere with surrounding cells abd disrupt their normal functioning. Cancerous cells interfere with surrounding cells abd disrupt their normal functioning. They continue to divide and pile up on one another. They continue to divide and pile up on one another. Excess cells may produce a tumour or lump that stays constant in one area. Excess cells may produce a tumour or lump that stays constant in one area.

21. Cancer In other cases cancerous cells may move to other areas of the organism and continue to grow and divide uncontrollably. In other cases cancerous cells may move to other areas of the organism and continue to grow and divide uncontrollably. These cells gobble up oxygen and nutrients for themselves, crowding out other cells and robbing them of food These cells gobble up oxygen and nutrients for themselves, crowding out other cells and robbing them of food Exposure to some substances can increase the rate of cancer. Exposure to some substances can increase the rate of cancer.

22. Cancer Some carcogenic substances include… Some carcogenic substances include… Tobacco Tobacco Asbesos Asbesos Certain chemicals Certain chemicals Radioactivity and Ultraviolet Radiation Radioactivity and Ultraviolet Radiation These have all been linked to cancer in humans. These have all been linked to cancer in humans.