stem cells

Question 1

what is a stem cell?

Answer 1

an undifferentiated cell which can divide to produce more cells of the same type or differentiate to form other cells

Question 2

where are stem cells found in?

Answer 2

-bone marrow
-meristems
-embryos

Question 3

two types of stem cells found in animals

Answer 3

-embryonic
-adult

Question 4

describe how embryonic stem cells are formed?

Answer 4

1. A sperm cell fertilises an egg cell and they form a zygote
2. The cell divides mitosis to form a ball of cells called an embryo
3. The cells in the embryo are known as embryonic stem cells

Question 5

what can adult stem cells differentiate to form?

Answer 5

-cells in the blood (red & white blood cells, platelets)

Question 6

difference between adult and embryonic stem cells

Answer 6

embryonic stem cells can differentiate into any type of cell unlike adult stem cells

Question 7

meristems

Answer 7

plant tissues that is continually growing and contains stem cells

Question 8

where are meristems found?

Answer 8

tips of shoots
tips of roots

Question 9

what are meristems used for?

Answer 9

-produce plant clones quickly and cheaply for research
-grow more plants of rare species to prevent them from going extinct
-used to grow crops of identical plants if they have an ideal characteristic

Question 10

when can stem cells in meristems differentiate?

Answer 10

throughout the plant’s life-anytime

Question 11

what can meristems differentiate into?

Answer 11

any type of plant cell

Question 12

uses of embryonic stem cells

Answer 12

-replace faulty cells
-treat conditions such as paralysis and diabetes as they divide to replicate damaged cells

Question 13

what is paralysis?

Answer 13

when nerve cells are damaged

Question 14

stages of stem cell treatment

Answer 14

1. extract embryonic stem cells from embryos
2. grow them in a laboratory
3. stimulate them to differentiate into whichever specialised cells we want
4. give them to patient to replace faulty cells

Question 15

stages of therapeutic cloning

Answer 15

1. nucleus taken out of human egg cell
2. nucleus from a patient’s cell put into the egg cell
3. egg cell stimulated to divide and develop into an embryo
4. stem cells taken from the embryo after 4-5 days
5. stem cells grow in a container of warm nutrients
6. stem cells treated to develop into required cell types for a patient

Question 16

advantage of therapeutic cloning

Answer 16

the body won’t reject the cells

Question 17

disadvantages of using embryonic cells in stem cell therapy

Answer 17

-risk of rejection
-stem cells in limited supply
-ethical issues as you are destroying a potential human life

Question 18

advantages of adult cells

Answer 18

-won’t cause rejection as taken directly from patient
-taken from patient so not in limited supply

Question 19

disadvantages of adult cells

Answer 19

-have to be extracted from bone marrow which is painful
-can only differentiate into a few types
-could transfer infections

Question 20

risks of stem cells in medicine

Answer 20

-could be infected with a virus in the lab which could infect the patient and make them worse
-chance of dividing uncontrollably and develop into a tumour once transplanted

Question 21

uses of adult cells

Answer 21

differentiate into several cell types to replace dead or damaged tissues

Question 22

what is therapeutic cloning?

Answer 22

a cloning method where an embryo is produced with the same genetic makeup as the patient, stem cell will not be rejected so can be used to treat conditions