TOPIC 7: MODERN GENETICS

Question 1

What type of cell are adult stem cells

Answer 1

1. Multipotent

Question 2

List some problems regarding adult stem cells

Answer 2

1. Rejection by the immune system
2. Difficult to grow and prepare for the transfer
3. The white blood cells in bone marrow transplants may damage the recipient

Question 3

How are IPS cells formed

Answer 3

1. Take fribroblasts from skin sample and add genes
2. These genes create patient-specific IPS cells
3. These are then repaired and differentiated to other cells

Question 4

What are some ethical issues with IPS cells

Answer 4

1. The genes used can promote cancer development

2. The cells can sometimes be rejected by a body

Question 5

Explain the advantages of using stem cells from the patient instead of using stem
cells from a donor.

Answer 5

1. No risk of rejection

2. less risk of infectiom

Question 6

Suggest why it may be better to produce differentiated cells from iPS cells
than from pluripotent stem cells

Answer 6

1. No embryo is used so is more ethical

2. Limited supply of embryos

Question 7

(i) Explain what is meant by the term pluripotent stem cell.

Answer 7

1. Undifferentiated cell

2. Gives rise to most specialised cells

Question 8

(b) State three potential sources of human stem cells.

Answer 8

1. Umbilical cord
2. Bone marrow
3. skin cells

Question 9

Explain what is meant by the term totipotent stem cell

Answer 9

1. Give rise to any cell types

2. They are undifferentiated cells

Question 10

(i) Describe how small samples of DNA can be amplified.

Answer 10

1. PCR
2. Polymerase enzyme added with primers and nucleotides
3. 90-98 degrees to seperate DNA strands
4. 50-65 degrees to get primers to bind to DNA strand
5. 70-75 degrees for DNA polymerase to catalyse the reactions between nucleotides
6. Cycle must be repeated several times to make several copies of DNA

Question 11

) Name one technique that could be used to analyse the amplified DNA
samples

Answer 11

Gel electrophoresis

Question 12

Explain the meaning of the term Human Genome

Answer 12

All of the DNA of the human species including chromosomal and mitochondrial DNA

Question 13

Suggest how these DNA profiles obtained from PCR were compared.

Answer 13

1. Gel electrophoresis
2. Restriction enzymes are added to the DNA Sample to seperate it into fragments and fluorescent tags are applied
3. DNA fragments loaded onto wells on agarose gell
4. A current is applied
5. The negatively charged DNA move towards the positive electrode and are seperated into bands

Question 14

How do you produce recombinant DNA

Answer 14

1. Isolate the gene
2. Insert gene into a vector (plasmids)
   plasmid is cut with the same endonucleuse enzyme that was used to isolate the genes this leaves complementary sticky ends the gene and the open plasmid are mixed and the bases complementary pair
3. To get the recombinant DNA into cell we use a virus

Question 15

Name three different methods of isolating the gene for recombinant DNA production

Answer 15

1. Use a restriction endonuclease which cuts out a section of the DNA
2. Reverse transcriptase can be used to work out the DNA from MrNa sequence
3. Sequence can be worked out from anino acid

Question 16

Name three different ways youc an get recombinant DNA into the cell

Answer 16

1. Gene gun
2. Microinjection
3. DNA enclosed in liposome