Gene Expression- Stem Cells

Question 1

Where do all specialised cell types originate from?

Answer 1

Stem cells

Question 2

What are stem cells?

Answer 2

Unspecialised cells that can develop into other types of cell

Question 3

What do stem cells divide to do?

Answer 3

To become new cells which then become specialised

Question 4

Where are stem cells found?

Answer 4

In the embryo and in some adult tissues

Question 5

What are totipotent cells?

Answer 5

Stem cells that can mature into any type of body cell in an organism

Question 6

When are totipotent cells present in mammals?

Answer 6

Only in the first few cell divisions of an embryo

Question 7

What do embryonic stem cells become after the first few cell divisions?

Answer 7

Pluripotent

Question 8

What are pluripotent cells?

Answer 8

Can still specialise into any cells in the body but have lost the ability to become the cells that make up the placenta

Question 9

What are the two types of stem cells present in adult mammals?

Answer 9

Multipotent and unipotent

Question 10

What are multipotent cells?

Answer 10

Able to differentiate into different types of cell

Question 11

What are unipotent cells?

Answer 11

Can only differentiate into one type of cell

Question 12

Why do stem cells become specialised?

Answer 12

They all contain the same genes but during development, not all of them are transcribed and translated

Question 13

What happens to genes under the right conditions?

Answer 13

Some genes are expressed and others are switched off

Question 14

What happens to mRNA?

Answer 14

It is only transcribed from specific genes and the mRNA from these genes is then translated into proteins, and these proteins modify the cell by determining the cell structure and controlling cell processes

Question 15

Why does a cell stay specialised?

Answer 15

Changes produced by proteins are difficult to reverse

Question 16

What are cardiomyocytes?

Answer 16

Heart muscle cells that make up a lot of tissues in our hearts

Question 17

What do some scientists now think about cardiomyocytes?

Answer 17

Old or damaged cardiomyocytes can be replaced by new cardiomyocytes derived from a small supply of unipotent stem cells in the heart

Question 18

Do stem cell therapies currently exist?

Answer 18

Yes for some diseases affecting the blood and immune system

Question 19

What does bone marrow contain?

Answer 19

Stem cells that can become specialised to form any type of blood cell

Question 20

How can bone marrow transplants be used?

Answer 20

To replace the faulty bone marrow in patients that produce abnormal blood cells- stem cells in transplanted bone marrow divide and specialise to produce healthy blood cells

Question 21

How have stem cell therapies been successfully used?

Answer 21

To treat leukaemia and lymphoma as well as genetic disorders such as sickle-cell anaemia and severe combined immunodeficiency

Question 22

How could stem cell therapies treat spinal cord injuries?

Answer 22

Stem cells could be used to replace damaged nerve tissue

Question 23

How could stem cell therapies treat heart disease and damage caused by heart attacks?

Answer 23

Stem cells could be used to replace damaged heart tissue

Question 24

How could stem cell therapies treat bladder conditions?

Answer 24

Stem cells could be used to grow whole bladders which are then implanted in patients to replace diseased ones

Question 25

How could stem cell therapies treat respiratory diseases?

Answer 25

Donated windpipes can be stripped down to their simple collagen structure and then covered with tissue generated by stem cells and this can then be transplanted into patients

Question 26

How could stem cell therapies treat organ transplants?

Answer 26

Organs could be grown from stem cells to provide new organs for people on donor waiting lists

Question 27

What are 2 benefits of using stem cells in medicine?

Answer 27

• Could save many lives as stem cells could be used to grow organs for those people awaiting transplants
• Could improve quality of life for many people

Question 28

What are the 3 main potential sources of human stem cells?

Answer 28

Adult stem cells, embryonic stem cells and induced pluripotent stem cells (iPS cells)

Question 29

Where are adult stem cells obtained from?

Answer 29

Body tissues of an adult

Question 30

When can adult stem cells be obtained?

Answer 30

In a relatively simple operation with very little risk involved but with quite a lot of discomfort

Question 31

How are adult stem cells not as flexible as embryonic stem cells?

Answer 31

They can only specialise into a limited range of cells, not all body cell types

Question 32

Where are embryonic stem cells obtained from?

Answer 32

Embryos at an early stage of development

Question 33

Where are embryos created?

Answer 33

In a laboratory using in vitro fertilisation

Question 34

What happens once the embryos are approximately 4 to 5 days old?

Answer 34

Stem cells are removed from them and the rest of the embryo is destroyed

Question 35

What are embryonic stem cells?

Answer 35

Pluripotent because they can divide an unlimited number of times and develop into all types of body cells

Question 36

What are iPS cells?

Answer 36

Created by scientists in a lab- involves ‘reprogramming’ specialised adult body cells so that they become pluripotent

Question 37

Why are iPS cells made?

Answer 37

To express a series of transcription factors that are normally associated with pluripotent stem cells

Question 38

What is one of the ways these transcription factors can be introduced to adult stem cells?

Answer 38

By infecting them with a specially-modified virus that has the genes coding for the transcription factors within its DNA

Question 39

What are the ethical issues surrounding embryonic stem cell use?

Answer 39

• Involves destroying an embryo that could potentially become a fetus if placed in a womb
• That embryo has a right to life
• Scientists should only use adult stem cells because their production doesn’t create destruction