Biology Chapter 2
- Created by: elliebaxter
- Created on: 04-01-17 19:17
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- Biology Chapter 2 - Part 1
- Cell division, growth and differentiation
- Mitosis
- Parent cell makes exact copies of 23 pairs of chromosomes to make 46 pairs. Cell then splits into two exact daughter cells
- Meiosis (only gametes)
- Starts with mitosis and then daughter cells split again to make 4 cells with only 23 chromosomes
- In early development of animal and plant embryos, the cells are unspecialised (stem cells)
- Some differentiated cells cannot divide so become adult stem cells such as those found in bone marrow
- Mitosis
- Stem Cells
- Found in adult bone marrow and human embryo
- An embryo is formed when an egg and sperm cell fuse to form a zygote and this divides many times to make a ball of cells (embryotic stem cells)
- Stem cells can be made to differentiate into needed cells, could treat paralysis, called therapeutic cloning
- Found in adult bone marrow and human embryo
- Cell growth and cancer
- Healthy cell has cell cycle but mutations make it divide uncontrolably
- A mass of abnormally growing cells is a tumour
- Benign = does not invade other tissues
- Malignant = spread (metastase) to healthy tissues
- Some malignant cells enter the bloodstream to form secondary tmours
- A mass of abnormally growing cells is a tumour
- Causes of cancer
- Carcinogens = chemicals such as tobacco smoke and asbestos
- Ionising radiation = UV light and X-rays
- Healthy cell has cell cycle but mutations make it divide uncontrolably
- Cell division, growth and differentiation
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