Gene therapy

Question 1

Gene therapy

Answer 1

Transfer of a therapeutic or working copy of a gene from a healthy person into specific cells of an individual in order to repair a faulty gene, only one gene needs to be changed

Question 2

Gene therapy uses and targets

Answer 2

Uses stem cells, Targets somatic cells (body cells, aren’t passed on), Easier to use gene therapy to treat diseases caused by single gene defect (point mutations)

Question 3

Cell replacement therapy

Answer 3

Cell replacement therapy involves the transfer of cells from the healthy person with the relevant function to the patient

Question 4

Cell replacement therapy uses

Answer 4

Uses stem cells- undifferentiated cells that are capable of repeated mitotic divisions and can differentiate into specialised cells, Any disorder involving loss of or injury to normal cells could possibly have these cells replaced by the use of cell replacement therapy

Question 5

Vectors in gene/cell therapy

Answer 5

Introduces DNA to a host (body) cell, Viruses are favoured by plasmids can also be used, Introduced in vivo or in vitro

Question 6

In vivo

Answer 6

Into the person

Question 7

In vitro

Answer 7

In cells in a lab

Question 8

Gene therapy in vitro

Answer 8

Cells are removed from the patient who requires gene therapy (so cells aren’t later rejected through cell-mediated immunity), Gene from a healthy donor is removed using restriction enzymes, Same restriction enzymes are used to cut the DNA of a vectors DNA (virus), Gene of interest is combined with the vectors DNA through ligation using DNA ligase, Altered virus is mixed with the patients cells in the lab, Virus infects the patients cells with the gene of interest, Patient cells become genetically altered and are injected back into the patient (where they came from), Genetically altered cells produce the desired protein

Question 9

Gene therapy in vivo

Answer 9

Gene from a healthy donor is removed using restriction enzymes, Same restriction enzyme is used to cut the DNA of the vector (virus), Gene of interest is combined with the vectors DNA through ligation using DNA ligase, Altered virus is injected into the patient, Virus infects the patients cells with the gene of interest genetically altering them, Genetically altered cells produce the desired protein

Question 10

Cystic fibrosis and gene therapy

Answer 10

Gene therapy can be used to transplant the CFTR gene so that the patients lung cells produce the CTFR protein

Question 11

Huntington’s disease

Answer 11

Caused by a faulty gene on chromosome 4, Causes a range of problems in affected individuals but the brain is most affected

Question 12

What must viral vectors do (4)

Answer 12

Target the right cells, Integrate the gene into the host cell DNA, Activate the gene, Avoid harmful side-effects

Question 13

Disadvantages of viral vectors (3)

Answer 13

Can only carry a limited amount of genetic material, Can cause illness in patient, Can be destroyed by the immune system

Question 14

Plasmid vectors

Answer 14

Can transfer larger amounts of DNA, Less efficient at getting DNA into cells, Sometimes wrap in a cell membrane (liposomes) to make it easier to enter a cell

Question 15

Parkinson’s and Alzheimer’s

Answer 15

Neurodegenerative disorders where cell replacement therapy can be used, Dying neurons can be replaced with healthy neurons derived from stem cells

Question 16

Tissue engineering

Answer 16

Uses stem cells, Uses a scaffold on which stem cells are induced to grow on, to produce a three dimensional tissue, Cell-covered scaffold is implanted into the patient at the site where new tissue is needed, Used so far for tissues including bone, skin, cartilage and adipose tissue

Question 17

Cell replacement therapy and gene therapy working together

Answer 17

Stem cells would be taken from the patient, Mutant gene is replaced by normal gene using gene therapy (in vitro), Cells undergo mitosis, Cells are transferred back into the patient with working copy of the gene