STEM CELLS

Question 1

What are totipotent cells

Answer 1

Totipotent cells are able to mature into any type of body cell

Question 2

what are multipotent cells

Answer 2

Able to differentiate into a few different types of cell

eg both RBC and WBC can be formed from multipotent stem cells found in bone marrow

Question 3

what are unipotent cells

Answer 3

these can only differentiate into one type of cell

eg there is a type of unipotent stem cell which can only divide to produce epidermal skin cells

Question 4

how did specialised cells originate

Answer 4

from stem cells

Question 5

where are totipotent stem cells found

Answer 5

only found in mammals in the first few cell divisions of an embryo

Question 6

what stage do stem cells develop into after they have been totipotent

Answer 6

they then become pluripotent

Question 7

what is a pluripotent cell

Answer 7

they are still able to specialise into any type of body cell but loose the ability to become the cells that make up the placenta

Question 8

why do stem cells become specialised

Answer 8

they become specialised as different genes are expressed

During their development they only transcribe and translate part of their DNA

Question 9

what are cardiomyocytes

Answer 9

heart muscle cells that make up a lot of the tissue in our hearts

Question 10

can cardiomyocytes be replaced and if so with what

Answer 10

yes

with unipotent stem cells in the heart

Question 11

give an example of stem cell therapy

Answer 11

Bone marrow stem contains stem cells that can become specialised to form any type of blood cell
Bone marrow transplants can used to replace the faulty bone marrow in patients that produce abnormal blood cells
Stem cells in the transported bone marrow divide and specialise to produce healthy blood cells

Question 12

how could stem cells be used to treat spinal cord injuries

Answer 12

stem cells could be used to replace damaged nerve tissue

Question 13

how could stem cells be used to treat heart disease

Answer 13

stem cells could be used to replace damaged heart tissue

Question 14

how could stem cells be used to treat bladder conditions

Answer 14

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

Question 15

how could stem cells be used to treat respiratory diseases

Answer 15

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

Question 16

how could stem cells be used to treat organ transplants

Answer 16

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

Question 17

what are the 3 sources of stem cells

Answer 17

Adult stem cells
Embryonic stem cells
iPS cells (induced pluripotent stem cells)

Question 18

Advantages and disadvantages of adult stem cells

Answer 18

Easily obtained from body tissues of an adult
Eg found in bone marrow
Obtained via a simple operation
Little risk but lots of discomfort
Arent as flexible as embryonic stem cells
Can only specialise into a limited range of cells (as multipotent)

Question 19

Advantages and disadvantages of embryonic stem cells

Answer 19

Obtained from embryos at early stage of development
Embryos are created in lab using vitro fertilisation (IVF)- egg cells are fertilised outside the womb
When embryo 4-5 days old stem cells are removed and then rest of embryo is destroyed
Can divide an unlimited number of times
Can develop into all types of body cells (as pluripotent)

Question 20

How do iPS stem cells get created/ work

Answer 20

Created in the lab by reprogramming specialised adult body cells so they become pluripotent
Adult cells are made to express a series of transcription factors that are associate with pluripotent cells
Then adult stem cells express these pluripotent genes
Can be as flexible as the embryonic stem cell
iPS cells can be used in medicine

Question 21

what is the ethical issue surrounding embryonic stem cells

Answer 21

-destruction of the embryo after stem cells have been obtained