cell differentiation and specialisation

• What is differentiation?


  Differentiation is where a cell becomes specialised to do it's job
• Why does differentiation occur in organisms?

  when an animal develops but lots of plants don't.
• what are undifferentiated cells called?

  stem cells
• what are sperm cells specialised cells for?


  reproduction
• A sperm cell is to get the male DNA to the female DNA.It has a long tail to help it swim to the egg. There are lots of mitochondria in the cell that provide energy. It also contains enzymes in it's head to digest through the egg cell membrane.

  
• What are nerve cells specialised for ?


  rapid signalling
• Nerve cells carry electrical signals around the body and are long to cover more distance.They have branched connections at their end to connect to other nerve cells to form a network throughout the body.

  
• what are muscle cells specialised for?


  contraction
• what are root hair cells specialised for?


  absorbing water and minerals
• what are phloem and xylem specialised for?


  transporting substances
• Muscle cells contract quickly, and they are long so they have space to contract. It also contains lots of mitochondria for the energy needed for contraction.

  
• root hair cells are thin, which increases the surface area for absorbing water and minerals.

  
• nerve cells have branched connections called synapses where chemicals can be released into the gap between two neurons to transmit an electrical signal along the next part of the nervous system.
• phloem and xylem contain many tubes that transport substances up and down the plant. They are made from dead cells with thick walls to support them as they transport materials through the plant.
• cells that differentiate in mature animals are mainly used for what?


  repairing and replacing cells such as skin or blood cells
• adult stem cells

  sperm and egg cell creates a zygote and then mitosis happens to create embroys where they can differentiate into any type of cell
• name 2 type of stem cells in animals

  adult stem cells

  embryonic stem cells
• Which two parts of the plant contain meristem tissue?

  tips of shoots and roots
• What do we call the plant tissues that are continually growing and that contain stem cells?

  meristems
• What do we call the plant tissues that are continually growing and that contain stem cells?

  meristems
• what are the parts of the central nervous system (CNS)?

  brain and spinal cord
• whats the role of a receptor

  to detect stimulus
• what's the role of a sensory neurone?

  To transfer a signal from a receptor to the CNS
• What is the role of a motor neurone?

  to transfer a cns to an effector
• stimulus ➔ receptor ➔ sensory neurone ➔ relay neurone ➔ motor neurone ➔ effector ➔ response


  the pathway of a reflex arc
• adult stem cells can differentiate to blood cells
• steps of stem cells in medicine

  1. Extract embryonic stem cells from early embryos.
  2. Grow them in a laboratory.
  3. Stimulate them to differentiate into whichever type of specialised cell that we want.
  4. Give them to the patient to replace their faulty cells.
• 1. The stem cells could be infected with a virus whilst in the laboratory, which could then infect the patient.
  2. As stem cells divide quickly, there is a chance they could divide uncontrollably once they've been transplanted, and then develop into a tumour. 


  risks of using stem cells in medicine
• Give two drawbacks of using embryonic stems cells in stem cell therapy.

  there could be rejections,limited in supply