6.5 Stem Cells

Question 1

Differentiation

Answer 1

Process of a cell becoming specialised

Question 2

Stem cells

Answer 2

Undifferentiated cells that have the potential to differentiate into many cell types

Question 3

Why does the activity of stem cells need to be controlled?

Answer 3

Division not fast enough - tissues not efficiently replaced, causing ageing
Uncontrolled division - cause masses, such as cancer

Question 4

Potency

Answer 4

Ability of stem cell to differentiate into any type of cell

Question 5

Types of stem cells

Answer 5

Totipotent
Pluripotent
Multipotent

Question 6

Totipotent

Answer 6

Can differentiate into any type of cell

Zygotes are Totipotent cells - form a whole organism and tissues such as a amnion and umbilicus

Question 7

Pluripotent

Answer 7

Can form all tissue types but not whole organisms

Present in early embryos

Question 8

Multi potent

Answer 8

Can only form a range of cells within a certain type of tissue
Haematopoetic stem cells in bone marrow are multi potent - form many types of blood cell

Question 9

Why do RBCs have a short lifespan?

Answer 9

Lack of nucleus and organelles

Question 10

How long do RBCs live for?

Answer 10

120 days

Question 11

How long do neutrophils live for?

Answer 11

6 hours

Question 12

Sources of adult stem cells

Answer 12

Embryonic stem cells

Tissue (adult stem cells)

Question 13

Embryonic stem cells

Answer 13

Present at very early stage of embryo development
Totipotent
After 7 days, blastocyst is formed and the cells become pluripotent, stay this way until birth

Question 14

Tissue stem cells

Answer 14

Present throughout life from birth
Found in specific areas such as bone marrow
Can also be harvested from umbilical cords of new born babies

Question 15

Advantages of using umbilical cord stem cells

Answer 15

Plentiful supply
Invasive surgery is not required
Can be stored

Question 16

Sources of plant stem cells

Answer 16

Meristematic tissue
Growing regions of plants - root shoots and tips
Found between xylem and phloem, vascular cambium
Pluripotent nature of stem cells continue throughout life of plant

Question 17

Possible treatments using stem cells

Answer 17

Heart disease - replace damaged heart tissue
Type 1 diabetes
Parkinson’s disease
Alzheimer’s disease
Macular degeneration - can cause blindness
Birth defects
Spinal injuries

Question 18

Existing use of stem cells

Answer 18

Treating burns - stem cells grown on biodegradable meshes can produce new skin for burn patients
Drug trials - test on stem cells before animals and humans
Developmental biology

Question 19

Ethics of using embryonic stem cells

Answer 19

Destruction of embryos after extracting stem cells
Some people regard that as murder
Who owns the genetic material being used for research?
Religious objections