The Treatment Mechanism:
The Cloning Process:
Step 1: A nucleus is removed from one of the patient's body cells (such as a skin cell).
Step 2: A donor unfertilised egg cell has its nucleus removed and discarded. This creates an enucleated egg (an egg cell that specifically does not contain its own genetic material).
Step 3: The patient's nucleus is inserted into the enucleated egg cell.
Step 4: An electric shock is applied to the egg to stimulate it to divide.
Step 5: The cell divides by mitosis to form an embryo.
Step 6: After 4–5 days, embryonic stem cells are harvested from the embryo (which destroys the embryo in the process).
Step 7: These cells are cultured and triggered to differentiate into the specialised cells needed by the patient.
Students often write that stem cells 'turn into' or 'heal' the damaged area. You must use the specific scientific term 'differentiate' and state that they 'replace' damaged or faulty cells.
When explaining why therapeutic cloning prevents rejection, you must explicitly state that the cells have the 'same genes' or 'same DNA' as the patient.
For AQA diabetes treatments, always refer to the specific cells formed as 'insulin-producing cells' (the mark scheme prefers this over the more advanced term 'beta cells').
In a 4-6 mark question describing therapeutic cloning, examiners award specific marks for mentioning the use of an 'electric shock' to stimulate the cell to divide by 'mitosis'.
Stem cell
An undifferentiated cell of an organism which is capable of giving rise to many more cells of the same type, and from which specialised cells can arise.
Differentiation
The process by which an unspecialised cell changes to become specialised for a specific function or job.
Embryonic stem cells
Stem cells derived from an early embryo that have the potential to differentiate into almost any type of human cell.
Paralysis
The loss of the ability to move (and sometimes feel) in part or most of the body, typically resulting from injury to the nerves or spinal cord.
Insulin-producing pancreatic cells
Specialised cells in the pancreas that secrete the hormone insulin to regulate blood glucose levels.
Nerve cells
Specialised cells (neurones) that carry electrical impulses around the body, communicating between the brain, spinal cord, and muscles.
Therapeutic cloning
A medical process where an embryo is produced with the same genes as the patient to provide a source of stem cells that will not be rejected.
Immune rejection
The process where a patient's immune system attacks and destroys transplanted cells or organs that it identifies as foreign.
Immunosuppressant drugs
Medication used to prevent the immune system from attacking a transplant, which has the side effect of weakening overall immunity.
Enucleated egg
An egg cell that has had its nucleus removed.
Mitosis
A type of cell division that results in two genetically identical daughter cells, used for growth and repair.
Put your knowledge into practice — try past paper questions for Biology
Stem cell
An undifferentiated cell of an organism which is capable of giving rise to many more cells of the same type, and from which specialised cells can arise.
Differentiation
The process by which an unspecialised cell changes to become specialised for a specific function or job.
Embryonic stem cells
Stem cells derived from an early embryo that have the potential to differentiate into almost any type of human cell.
Paralysis
The loss of the ability to move (and sometimes feel) in part or most of the body, typically resulting from injury to the nerves or spinal cord.
Insulin-producing pancreatic cells
Specialised cells in the pancreas that secrete the hormone insulin to regulate blood glucose levels.
Nerve cells
Specialised cells (neurones) that carry electrical impulses around the body, communicating between the brain, spinal cord, and muscles.
Therapeutic cloning
A medical process where an embryo is produced with the same genes as the patient to provide a source of stem cells that will not be rejected.
Immune rejection
The process where a patient's immune system attacks and destroys transplanted cells or organs that it identifies as foreign.
Immunosuppressant drugs
Medication used to prevent the immune system from attacking a transplant, which has the side effect of weakening overall immunity.
Enucleated egg
An egg cell that has had its nucleus removed.
Mitosis
A type of cell division that results in two genetically identical daughter cells, used for growth and repair.