Stem Cells

Question 1

What are stem cells?

Answer 1

Undifferentiated cells formed from mitosis or meiosis

Question 2

What happens if stem cells do not divide enough or divide too much?

Answer 2

Not enough - Tissues not efficiently replaced so aging

Too much - Forms tumors that lead to cancer

Question 3

What is potency?

Answer 3

Stem cell’s ability to differentiate into different cell types

Question 4

What is meant by totipotent? (2)

Answer 4

• Can differentiate into any type of cell

- e.g. Fertilised egg can eventually create a whole organism

Question 5

What is meant by pluripotent? (2)

Answer 5

• Can differentiate into all tissue types but not whole organisms
• Present in early embryos

Question 6

What is meant by multipotent? (2)

Answer 6

• Can only form a range of cells within a certain type of tissue
• e.g. hematopoietic stem cells in bone marrow.

Question 7

Where are all blood cells derived from?

Answer 7

Bone marrow

Question 8

Why do cells differentiate?

Answer 8

To take on different roles in tissues and organs

Question 9

Why do erythrocytes and neutrophils need to be replaced constantly?

Answer 9

• Erythrocytes last 120 days

- Neutrophils live 6 hours

Question 10

Features of embryonic stem cells? (3)

Answer 10

• Found at very early stage of embryo
• Totipotent
• After 7 days, the cells are now pluripotent

Question 11

Features of tissue (adult) stem cells? (4)

Answer 11

• Present from birth until end of life
• Found in bone marrow
• Multipotent
• Can be taken from umbilical cord - plentiful supply and can be stored for later use

Question 12

Features of plant stem cells? (2)

Answer 12

• Found in meristem tissue (between phloem and xylem vessel called the vascular cambium)
• Pluripotent

Question 13

What are the potential uses for stem cells? (7)

Answer 13

• Heart disease
• Type 1 diabetes
• Parkinson’s disease
• Alzheimer’s disease
• Macular degeneration
• Birth defects
• Spinal injuries

Question 14

What are stem cells currently used for? (3)

Answer 14

• Treatment of burns (producing new skin)
• Drug trials (Can test on cultures of cells)
• Developmental biology (study)

Question 15

What are the ethical issues for stem cells? (7)

Answer 15

• Legal to create embryos for stem cells
• Destroys the embryo
• Religious objections
• Moral objections (think life begins at embryo and so it’s murder)
• Lack of consensus as to when the embryo has rights
• Lack of consensus as to who owns the genetic material that is being used for research
• Plant cells don’t have the same ethical issues