stem cells

Question 1

stem cells

Answer 1

unspecialised cells that can develop into other types of cell

Question 2

stem cells in embryo

Answer 2

become all specialised cells needed to form a fetus

Question 3

stem cells in adult tissue

Answer 3

become specialised cells that need to be replaced

Question 4

totipotent stem cells

Answer 4

can specialise into any type of body cell

only present in first few divisions of embryo

Question 5

pluripotent stem cells

Answer 5

can specialise into any type of body cell

lost ability to become cells that make up the placenta

Question 6

multipotent stem cells

Answer 6

specialise into a few different types of cell

e.g. red and white BC cn be formed from multipotent stem cells found in bone marrow

Question 7

unipotent stem cells

Answer 7

specialise into only one type of cell

e.g. unipotent stem cell that can only divide to produce epidermal skin cells (outer layer of skin)

Question 8

how do stem cells become specialised

Answer 8

contain all same genes but during development not all are transcribed and translated (expressed)
proteins modify the cell - determine cell structure and control cell processes
once specialised stays specialised

Question 9

cardiomyocytes

Answer 9

heart muscle cells
made from unipotent cells
(researchers unsure of how fast being made)

Question 10

stem cell therapy

Answer 10

diseases affecting blood and immune system
bone marrow transplants replace faulty bone marrow which produces abnormal blood cells
used to treat leukemia

Question 11

other diseases stem cells could treat (research)

Answer 11

1. spinal chord injuries - replace damaged nerve tisue
2. heart disease and damage caused by heart attacks - replace heart tissue
3. bladder conditions - could grow whole bladders which are implanted
4. respiratory diseases - donated windpipes can be covered with tissue generated by stem cells and transplanted
5. organ transplants - grow organs for people on donor waiting list

Question 12

benefits of stem cells in medicine

Answer 12

could save many lives

could improve quality of life for many people

Question 13

source of stem cells (adult stem cells)

Answer 13

obtained from body tissue of an adult
simple operation little risk but discomfort
aren’t as flexible as embryonic - specialise into limited range of cells (multipotent)

Question 14

source of stem cells (embryonic)

Answer 14

obtained from embryo at early stage of development
created in lab using IVF - egg cells fertilised by sperm outside womb
4-5 days old stem cells removed and rest of embryo destroyed
can divide unlimited number of times and into all types of body cells (pluripotent)

Question 15

source of stem cells (induced pluripotent)

Answer 15

created in lab
involves reprogramming specialised adult body cells so become pluripotent
made to express transcription factors which cause them to express genes associated with pluripotency
e.g. infect with specially modified virus (inserts transcriptional factor into DNA)
could be made from patients own cells - body wont reject
more research needed

Question 16

ethical issues

Answer 16

1. embryos - could become fetus if placed in womb - moment of fetilisation = right to life
2. fewer objections to stem cells obtained from egg cells that havent been fertilised but artificially activated
3. IPS potential to be as flexible as embryonic and adult stem cells - arent same ethical issues