stem cells and differentiation
- Created by: aryan26
- Created on: 09-04-19 10:57
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- stem cells and differentiation
- stem cells are unspecialised cells- they can develop into any type of cell
- stem cells differentiate into specialised cells
- in animals stem cells are used to replace damaged cells
- in plants stem cells are needed to make new shoots and roots as they are always growing
- they can divide to produce more undifferentiated stem cells
- stem cells differentiate into specialised cells
- cells in the bone marrow differentiate into blood cells- erythrocytes (red) neutrophils (white)
- in plants stem cells are found in the meristems
- in the root, stem cells of the vascular cambium divide and differentiate to become xylem vessels and phloem sieve tubes
- in plants stem cells are found in the meristems
- specialised animal cells
- neutrophils- white blood cell that defends against disease
- flexible shape allows them to engulf particles
- many lysosomes in the cytoplasm to break down engulfed particles
- erythrocytes- red blood cells that carry oxygen in the blood
- biconcave disc shape gives a large SA for gas exchange
- have no nucleus so there's the maximum room for haemoglobin
- epithelial cells- cover surfaces of organs
- joined by interlinking membranes and a membrane at their base
- ciliated epithelia in the airways- have cilia to move particles away
- squamous epithelia are very thin to allow efficient gas exchange
- sperm cells- male sex cells
- have flagellum so they can swim to the egg
- lots of mitochondria to provide energy to swim
- acrosome contains digestive enzymes so they can penetrate the surface of the egg
- neutrophils- white blood cell that defends against disease
- specialised plant cells
- palisade mesophyll cells- carry out photosynthesis
- contain many chloroplasts to absorb a lot of sunlight
- walls are thin so carbon dioxide can easily diffuse into the cell
- root hair cells- absorb water and mineral ions from the soil
- large SA to absorb the maximum amount
- thin permeable cell wall
- extra mitochondria to provide energy for active transport
- guard cells- found in pairs with a gap between them to form a stoma
- stoma are tiny pores in the surface for gas exchange
- in the light, guard cells take up water and become tugid
- thin outer walls and thin inner walls makes them bend outwards opening the stomata- allows gas exchange
- palisade mesophyll cells- carry out photosynthesis
- stem cells are unspecialised cells- they can develop into any type of cell
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