3.8.2 - Stem cells

Question 1

What is a stem cell?

Answer 1

Undifferentiated cell that continually divides

Question 2

What is a totipotent stem cell?

Answer 2

Embryonic stem cells that can differentiate into ANY type of cell

Question 3

What is a pluripotent stem cell?

Answer 3

• Embryonic stem cell

- Can specialise into ANY type of body cell EXCEPT placental cells

Question 4

What is a multipotent stem cell?

Answer 4

• Adult stem cell

- Can differentiate into a limited number of cell types

Question 5

What is a unipotent stem cell?

Answer 5

• Adult stem cell
• Can differentiate into ONE type of cell
  e. g. cardiomyocytes - heart muscle cells

Question 6

How can stem cells be used in medical treatment?

Answer 6

• used to generate tissues or organs to replace cells damaged by illness or injury

Question 7

Sources of stem cells for medical treatment

Answer 7

• Adult somatic cells (usually from patient or sibling)
  e. g. multipotent stem cells from bone marrow
• Embryonic pluripotent stem cells using IVF
• Induced pluripotent stem cells iPS Cells

Question 8

How are IPS cells made?

Answer 8

1. Reprogramming specialised adult body cells so that they become pluripotent - injected with a genetically modified virus
2. Adult cells are made to express transcription factors
3. Transcription factors cause adult body cells to express genes that are associated with pluripotency

Question 9

Evaluating the use of stem cells in treating human disorders

Answer 9

Advantages

• used to grow organs, replace eye tissue
• bone marrow stem cells to treat leukaemia

Disadvantages

• obtaining embryonic SC involves destruction of embryo
• obtaining adult SC causes discomfort
• adult SC can’t develop into all types of cell
• SC can divide uncontrollably and create tumours