3.8.2.1 - STEM CELLS

Question 1

MDS are a group of malignant cancers. in MDS, the bone marrow does not produce healthy blood cells.

haematopoietic stem cell transplantation (HSCT) is one treatment for MDS. in HSCT, the patient receives stem cells from the bone marrow of a person who does not have MDS. before the treatment starts, the patient’s faulty bone marrow is destroyed.

for some patients, HSCT is an effective treatment for MDS. explain how (3)

Answer 1

1. only produce normal/healthy red blood cells
2. no MDS/faulty/cancerous blood cells
3. stem cells divide/replicate

Question 2

MDS are a group of malignant cancers. in MDS, the bone marrow does not produce healthy blood cells.

haematopoietic stem cell transplantation (HSCT) is one treatment for MDS. in HSCT, the patient receives stem cells from the bone marrow of a person who does not have MDS. before the treatment starts, the patient’s faulty bone marrow is destroyed.

MDS can develop from epigenetic changes to tumour suppressor genes. in some patients, the drug AZA has reduced the effects of MDS. AZA is an inhibitor of DNA methyltransferases. these enzymes add methyl groups to cytosine bases.

suggest and explain how AZA can reduce the effects of MDS in some patients (3)

Answer 2

1. AZA reduces methylation of DNA
2. tumour suppressor gene is expressed/transcribed
3. so prevents uncontrollable cell division

Question 3

sickle cell disease (SCD) is a group of inherited disorders. people with SCD have sickle-shaped red blood cells. a single base substitution mutation can cause one type of SCD. this mutation causes a change in the structure of the beta polypeptide chains in haemoglobin.

haematopoietic stem cell transplantation (HSCT) is a long-term treatment for SCD. in HSCT, the patient received stem cells from the bone marrow of a person who does not have SCD. the donor is often the patient’s brother or sister. before treatment starts, the patient’s faulty bone marrow cells have to be destroyed.

use this information to explain how HSCT is an effective long-term treatment for SCD (3)

Answer 3

1. produce healthy red blood cells/haemoglobin
2. no sickle cells produced
3. stem cells continuously divide

Question 4

scientists have investigated the use of different types of stem cell to treat damage to the heart after a myocardial infarction, a number of different cell types in the heart die. his includes cardiomyocytes which are heart muscle cells.

embryonic pluripotent stem cells (ESCs) can divide and differentiate into a wide range of different cell typed.

using the information given, suggest one reason why ESCs might be suitable to treat damage to the heart (1)

Answer 4

ESCs can replace any type of (heart) cell

Question 5

scientists have investigated the use of different types of stem cell to treat damage to the heart after a myocardial infarction, a number of different cell types in the heart die. his includes cardiomyocytes which are heart muscle cells.

embryonic pluripotent stem cells (ESCs) can divide and differentiate into a wide range of different cell types.

ESCs have not yet been used to treat people who have had a myocardial infarction. this is because of concern that the use of ESCs might lead to more harm to the person. one way that ESCs might lead to more harm is by differentiating into the wrong types of cells.

suggest one other way that putting ESCs into a person’s heart might lead to more harm to the person (2)

Answer 5

1. might divide out of control
2. leading to tumour/cancer

Question 6

suggest how the growth of new blood vessels into damaged heart tissues could increase the rate of repair of tissues (3)

Answer 6

1. greater blood supply
2. bringing more oxygen for respiration
3. bringing more amino acids for protein synthesis
4. for cell division/mitosis