biology - cell division

• Embryonic stem cells

  are the most useful type of stem cell as they are unspecialised
• embryonic stem cells can be isolated and grown into required cell
• Partially specialised are not all completed
• tissue

  aggregation (a collection) of similar cells
• Organs

  collections of tissues performing a physical function
• Organ systems

  organs work together
• The Process by which cells become specialised is called differentiation
• A type of cell that receives and sends messages from the body to the brain and back to the body.

  
• Animal cell

  muscle cell

  contracts and relaxes the fibres slide over each other

  numerous mitochondria

  store glycogen
• Plant cell

  xylem cell

  transports water minerals and ions

  cells are alive at first - lignin builds in cell walls and cells dies forming hollow tubes.

  lignin provides strength

  
• Plant cell

  phloem cell

  transports dissolves foods

  cell walls between cells break down to for sieve plates

  cells are supported by companion cells- which transfer energy for the movement of food

  
• Starch is a store within plants

  
• Order from largest to smallest

  cell nucleus , chromosome and gene