Stem Cells

Question 1

What is cell differentiation?

Answer 1

The process where cells develop special structures needed to carry out their specific role

Question 2

Why is cell differentiation important?

Answer 2

Multi-cellular organisms require specialised cells to carry out specific functions

Question 3

What are stem cells?

Answer 3

Undifferentiated cells that can mature into any type of cell, all specialised cells originally came from stem cells, stem cells divide to become new cells which then become specialised

Question 4

What is self renewal?

Answer 4

The ability to go through numerous cycles of cell division while maintaining the undifferentiated state

Question 5

Where are embryonic stem cells found?

Answer 5

Early stages of development, very flexible

Question 6

Where are adult tissue stem cells found?

Answer 6

Found in fetus-adult, specific to particular tissue/organ, allow self regeneration only

Question 7

What are totipotent stem cells?

Answer 7

Can produce all cell types (embryo and placenta) only present during the first few cell divisions

Question 8

What are pluripotent stem cells?

Answer 8

Can become body cells found in an embryo but not the placenta (can divide in unlimited numbers so used in medicine)

Question 9

What are multipotent stem cells?

Answer 9

Found in adults, give rise to several different types of specialised cells, but are restricted to a certain organ or tissue types e.g. blood cells

Question 10

What are unipotent stem cells?

Answer 10

Found in adults, can only make one type of cell e.g. epidermal skin cells

Question 11

What is meant by totipotent?

Answer 11

Total potential, have the ability to develop into any cell found in the human body and during its development, useful during embryo development, as we start of as a single cell, but are eventually a collection of millions of different cell types

Question 12

What are embryonic stem cells?

Answer 12

For the first few weeks, the developing embryo contains unspecialised cells, we call these embryonic stem cells, embryonic stem cells are important because they can differentiate into any type of cell

Question 13

In terms of DNA and genes, what makes a cell become specialised/what makes a liver cell different from a skin cell?

Answer 13

Specialised cells all contain the same genetic information but different genes are expressed therefore only some DNA is translated into proteins

Question 14

Do all cells in the body make all of the products they are genetically capable? Explain your answer

Answer 14

No, waste of resources/energetically unfavourable

Question 15

How is gene expression controlled?

Answer 15

Some genes are permanently expressed, some genes are never expressed, some switch on and off

Question 16

What happens as a result of some genes switching on and off?

Answer 16

Differentiated cells produce different proteins as a result

Question 17

What happens when the gene is expressed?

Answer 17

mRNA transcribed and translated into proteins, proteins modify the cell, cell becomes specialised for a particular function

Question 18

What happens if the gene is switched off?

Answer 18

mRNA not transcribed, protein not produced

Question 19

What are cardiomyocytes?

Answer 19

Heart muscle cells, originally thought they were unable to divide to replicate themselves in mature mammals, now thought that we have unipotent stem cells in the heart that can replace the old/damaged cardiomyocytes

Question 20

When does a heart attack occur?

Answer 20

When the coronary arteries are blocked, with no blood flow, the cells die, causing cardiac tissue to die, once these tissues are lost, they cannot be replaced thus permanent damage, current research has shown that it may be possible to repair damages cardiac tissue with stem cells, human embryonic stem cells can differentiate into cardiomyocytes under appropriate conditions

Question 21

How is a heart attach treated with stem cells?

Answer 21

Stem cells filtered from bone marrow removed from a patients hip, the cells are injected into the heart’s damaged area, the cells embed themselves and produce proteins that signal the growth of new blood vessels and heart muscle

Question 22

How are human embryonic stem cells used?

Answer 22

Cells taken from the early stages of an embryo, grown in vitro, induced to develop into tissues, used to treat burns and Parkinson’s disease

Question 23

What is Parkinson’s disease?

Answer 23

Degenerative neurological disorder that affects the body’s motor system, caused by a lack of dopamine made by brain cells, 10 million sufferers

Question 24

What are iPS cells?

Answer 24

Induced pluripotent stem cells that are produced from unipotent cells

Question 25

How are iPS cells created?

Answer 25

Genetically altered so that they have the characteristics of embryonic stem cells (pluripotent), this is done by inducing genes and transcriptional factors to be expressed (switches on ‘off’ genes)

Question 26

What does the production of iPS cells show us about adult stem cells?

Answer 26

Since the gene can be ‘switched on’ it shows that adult stem cells retain the genetic info that was present in the embryonic stage

Question 27

What is an interesting feature of iPS cells?

Answer 27

Similar to embryonic stem cells, capable of self-renewal, have the potential to divide indefinitely

Question 28

How could iPS cells be useful?

Answer 28

Replace embryonic stem cells in research and treatments, removes ethical implications

Question 29

Do plants have stem cells? Explain your answer

Answer 29

Mature plants have many totipotent cells, this allows them to form clones from a single cell

Question 30

What are the arguments for stem cells uses?

Answer 30

Huge potential to cure debilitating disease, wrong to allow suffering when it can be relieved, embryos created for other purposes (IVF), embryos less than 14 days not recognisably human so do not command same respect, no risk of research including fetuses due to current legislation, adult stem cells not as suitable as embryonic

Question 31

What are the arguments against stem cells uses?

Answer 31

It is wrong to use potential humans as a means to an end, embryos are human and deserve respect, slippery slope to use of fetuses, could lead to research and development of human cloning, undermines respect for life, should focus on developing adult stem cells