differentiation and specialized cells

• Specialized cells


  Different types of cells that make up complex organisms like animals and plants
• Examples of specialized cells in animals

  • Sperm cells
  • Muscle cells
  • Nerve cells
• Examples of specialized cells in plants

  • Root hair cells
  • Phloem cells
  • Xylem cells
• Sperm cell


  • Has half the genetic material of a normal adult cell
  • Has a flagellum to swim
  • Is streamlined to swim
  • Has many mitochondria for energy
  • Has digestive enzymes to break into egg
• Specialized cells


  Have a specific role, shape, structure, and organelle composition to fulfill that role
• Differentiation


  The process by which cells become specialized
• Differentiation


  1. Single zygote cell divides

  2. Cells remain identical at first

  3. Cells then undergo changes to become specialized
• Stem cells


  Cells that can repeatedly divide by mitosis and differentiate into different specialized cell types
• Which specialised cell is adapted for transmitting messages from one part of the body to another?

  Nerve cells 
• How are sperm cells specialised

  Its role is to deliver genetic material to an egg cell to fertilise it

  It has half as much genetic material as a normal cell, so that the sperm and egg together will have the normal amount

  It has lots of mitochondria to provide the energy for movement

  It has a flagellum to allow it to swim to reach the egg

  It is streamlined to make swimming easier

  It has digestive enzymes in its head to break through the wall of the egg
• Which cells are adapted to their roles by having a large surface area?

  Red blood cells

  Root hair cells
• Heart muscle tissue has to be able to beat continually without stopping. What adaptation would you expect heart cells to have?

  A lot of mitochondria
• In animals, almost all cells differentiate at an early stage and then lose this ability
• Most specialised cells can make more of the same cell by undergoing mitosis
• Other specialised cells like red blood cells (which lose their nucleus) cannot divide and are replaced by adult stem cells.
• In mature animals, cell division mostly only happens to repair or replace damaged cells.
• In plants, growth occurs by a special process called cell elongation.
• Cell Elongation


  Plant cells can grow longer in a specific direction by absorbing water into their vacuoles and this is controlled by substances called auxins.
• How does cancer occur?

  Cancer occurs as a result of mutations in cells that lead to uncontrolled cell division. The group of cells that results from this uncontrolled division is called a tumour.
• The tumours that result from cancer are either malignant or benign.
• Malignant tumours


  
  

  • Malignant tumours can invade neighbouring tissues and spread throughout the body in the blood, creating more secondary tumours.
• Benign tumours


  • Benign tumours stay in a specific part of the body, often within a membrane.