8.4 Stem Cells

Question 1

What are stem cells?

Answer 1

Cells that are not yet specialised to do any particular function.

Question 2

What is a zygote?

Answer 2

A type of cell that all human life starts from, which goes through mitosis to increase in number.

Question 3

Name the 3 embryo layers:

Answer 3

• Ectoderm
• Mesoderm (middle layer)
• Endoderm (inner layer)

Question 4

What does the ectoderm (outer layer) of an embryo form?

Answer 4

Forms the exoskeleton.

Eg. Brain and spinal cord

Question 5

What does the mesoderm (middle layer) of an embryo develop into? Give an example:

Answer 5

Develops into organs.

Eg. Kidney

Question 6

Name the 2 types of stem cells:

Answer 6

• Embryonic

- Adult

Question 7

What does the term potency refer to?

Answer 7

The number of types of cells a stem cell can become (differentiate in).

Question 8

What is a blastocyst?

Answer 8

When an embryo becomes a hollow ball, which starts to specialise (differentiate) as it develops layers.

Question 9

What does the ectoderm (inner layer) of an embryo form? Give an example:

Answer 9

Forms the lining of organs.

Eg. Lungs

Question 10

Name the 4 types of stem cell potency:

Answer 10

• Totipotent
• Pluripotent
• Multipotent
• Unipotent

Question 11

What does it mean if a stem cell is totipotent?

Answer 11

When a stem cell can become any cell type or even another embryo.

Question 12

What does it mean if a stem cell is pluripotent?

Answer 12

When a stem cell can become any of the 3 germ cell layers.

Question 13

What does it mean if a stem cell is multipotent? Give an example:

Answer 13

It can become multiple types but limited.

Eg. Certain stem cells in bone marrow can become any blood type.

Question 14

What does it mean if a stem cell is unipotent?

Answer 14

Can only turn into one type of cell but can replicate repeatedly.

Question 15

What are embryonic stem cells?

Answer 15

Cells from zygote to blastocyst stage, which can replicate indefinitely and become many different types of cell.

Question 16

What are adult stem cells?

Answer 16

Cells that are present in small numbers in some adult tissues, which can only become certain types of cells and cannot replicate indefinitely,

Question 17

What is the function of adult stem cells?

Answer 17

To repair and regenerate damaged and aged tissue.

Question 18

How are stem cells possibly going to be used by scientists in the future?

Answer 18

A great deal of research is underway to utilize stem cells to treat individuals with conditions such as Parkinson’s disease and type 1 diabetes.

Question 19

What are the advantages of embryonic stem cells?

Answer 19

• Unlimited supply
• Cell division can occur indefinitely
• Can grow into large quantities
• Can become any cell type

Question 20

What are the advantages of adult stem cells?

Answer 20

Already programed to be a particular cell type and so can be used for specific conditions

Question 21

What are the advantages of induced pluripotent stem cells?

Answer 21

• Use normal adult cells

- No immune system rejections as cells come from the original patient

Question 22

Name 3 disadvantages of embryonic stem cells:

Answer 22

• Can’t grow cells of every possible tissue type yet
• Ethical objections
• Potential for uncontrolled cell growth

Question 23

Name 3 disadvantages of adult stem cells:

Answer 23

• Limit on cell types which they can differentiate into
• Smaller number of cells
• Potential for uncontrolled growth

Question 24

Name 3 disadvantages of induced pluripotent stem cells:

Answer 24

• Technology not yet fully developed
• Maybe limited in differentiation type
• Potential for uncontrolled growth