4.1.2.3 Stem Cells

Question 1

Stem cell:

Answer 1

An undifferentiated/unspecialised cell which an self-renew to produce more cells of the same type or specialise to carry out a specific function

Question 2

Unspecialised cells:

Answer 2

• They can become any type ofcell
• stem cells

Question 3

Specialised cells:

Answer 3

• These cells are fixed
• They can onlydivide to make its own type of cell

Question 4

When do plant stem cells differentiate?

Answer 4

Many plant cells retain the ability to differentiate throughout their lives

Question 5

Where are plant stem cells found?

Answer 5

• Plants have layers of unspecialised stem cells in the roots and shoots
  
  • The layers are called the meristem

Question 6

What can the meristem tissue in plant cells differentiate into?

Answer 6

Meristem tissue in plants can differentiate into any type of plant cell, throughout the life of the plant

Question 7

Why are plant stem cells useful

Answer 7

• Stem cells from meristems in plants can be used to produce clones of plants quickly and economically
  
  • Rare species can be cloned to protect them from extinction
  • Crop plants with special features such as disease resistance can be cloned to produce large numbers of identical plants for farmers so more crops can survive
  • Large numbers of plants can be produced for self-economic benefit
• Research?
• Food?

Question 8

What are all the types of human stem cells?

Answer 8

• Embryonic stem cells
• Umbilical stem cells
• Adult stem cells
• Therapeutic stem cells (therapeutic cloning)

Question 9

Where are embryonic stem cells found?

Answer 9

Developing cells of an embryo (3-5 days old)

Question 10

What can embryonic stem cell differentiate into?

Answer 10

Any type of cell

Question 11

What are the positives of embryonic stem cells?

Answer 11

• Can differentiate into any type of cell
• [Uses ‘wasted’ embryos from IVF]
• All types of tissues can be grown
• Replace cells that have been damaged or destroyed e.g. paralysis

Question 12

What re the negatives of embryonic stem cells?

Answer 12

• Ethical issues - destroying the embryo and therefore a chance of life
• Need to take immunosuppressant drugs
• Technology is still developing
• Expensive

Question 13

Where are umbilical stem cells found?

Answer 13

In the umbilical cord after the birth of a child

Question 14

What can umbilical stem cells differentiate into?

Answer 14

Blood cells - often used to treat blood disorder in the child later in life

Question 15

What are some positives of umbilical stem cells?

Answer 15

• Many stem cells available in one umbilical cord
• No embryos involved
• Success at treating blood disorders
• Stored for later use
• No rejection
• No ethical issues

Question 16

What are some negatives of umbilical stem cells?

Answer 16

• Only treats blood diseases
• Requires saving the umbilical cord – expensive!
• Mothers consent needed
• Needs to be frozen – expensive and can only help that particular child

Question 17

Where are adult stem cells found?

Answer 17

• Brain
• Eyes
• Blood
• Heart
• Liver
• Bone marrow
• Skin
• Muscle

Question 18

What can adult stem cells differentiate into?

Answer 18

Only types of cells from the tissue they were found in

Question 19

What are the positives of adult stem cells?

Answer 19

• Own cells used so no rejection – no immunosuppressant drugs needed
• No embryos involved
• Adults can give their own consent
• Treatment of serious diseases e.g. cancer

Question 20

What are the negatives of adult stem cells?

Answer 20

• Only found in certain locations
• Can only differentiate into cells from the tissue they were found in
• Painful to extract

Question 21

What are positives of therapeutic stem cells?

Answer 21

• People argue that they are purposely made so and weren’t made to become life so no ethical issues about destroying a chance of life
• Can differentiate into any type of cell
• No need for immunosuppressant drugs as an embryo is produced with the same genes as the patient so are easier to use for medical treatment

Question 22

What are negatives of therapeutic stem cells?

Answer 22

• Ethical issues – using and destroying embryos (life)
• [less ethical issues if made for purpose and isn’t an actual embryonic cell which had the possibility of becoming life?]
• Egg cell possibly need to be donated – lack of donors?
• Technology is still developing
• Expensive

Question 23

What can stem cells be used to treat in medicine?

Answer 23

• Treat diabetes
• Treat paralysis

Question 24

Why is therapeutic cloning less ethically wrong than destroying embryonic stem cells?

Answer 24

Because your artificially making stem cells, which would never had the chance to become life, to be destroyed rather destroying an actual embryonic cell which had the chance of becoming an individual

Question 25

What has led to the development of stem cell technology?

Answer 25

• For an organism to grow, cells must divide by mitosis providing two new identical cells
• If cells are isolated at any early stage of growth before they have become too specialised, they can retain their ability to turn Ito a range of different types of cells
• This phenomenon has led to the development of stem cell technology
• This is a new branch of medicine that allows doctors to repair damaged organs by growing new tissues from stem cells