3-5: Biotechnology

Question 1

Recombinant DNA can be used for medical treatment. One example is treatment of patients with chemo-resistant leukemia. The patient’s __-cells can be reprogrammed to attack __-cells. (4 steps)

Answer 1

T-cells; B-cells.

1. Remove most of the viral genome and replace it with a specially designed DNA construct that encodes a new protein that recognizes B-cells.
2. Infect T-cells with the virus so they will express the new protein, a cell-surface receptor that recognizes B-cells.
3. Transgenic T-cells are reprogrammed to attack and kill B-cells, killing the cancerous cells.
4. Some of the transgenic T-cells survive and reproduce. These newly reproduced T-cells can identify and attack new cancerous B-cells.

Question 2

Transgenic cells can be used to treat cancer. The transgenic cells are given new capabilities to ______ and ______ cancer cells. For a long-lasting “cure”, the transgenic cells must _________________ and _________.

Answer 2

recognize; attack

survive in the patient; proliferate

Question 3

Response to transgenic-cell treatment is rapid and sustained. Upon infusion of transgenic T-cells, the patient experiences _______ _______ ______________ within the first month. If treatment is successful, patient shows no evidence of cancer for up to three years.

Answer 3

tumor lysis syndrome: chills, nausea, fever - signs showing that the treatment is working.

Question 4

Limitations and risks of treatment (4)

Answer 4

1. Cost: $20,000 per patient. T-cells must be synthesized specific to individual patient.
2. Immune suppression: transgenic T-cells attack healthy B-cells.
3. Tumor Lysis Syndrome - debris from dying tumor cells can damage kidneys and other organs.
4. Cytokine storm: patient’s physiological response to the T-cell “attack” can be dangerous.

Question 5

Hurdles to overcome in using transgenic cells (recombinant DNA) for medical treatment:

1. How can you reprogram immune cells to attack each other?
2. How can you insert new genes into a patient’s T-cells?
3. Will those cells persist as a long-term “cure”?

Answer 5

1. Design and insert new gene into the cells. This new gene can code for new cells that can attack immune cells.
2. Use vectors as transport modules.
3. Yes, evidence is strong from research so far.

Question 6

An example of a vector is _________ ____. (3)

Answer 6

modified HIV.

1. Vectors can be used to transfer genetic material into “target” cells.
2. Normal HIV targets T-cells and inserts viral genome into the cell’s genome.
3. Modified HIV inserted specifically engineered recombinant transgenes instead of viral genome.

Question 7

Modified HIV treatment requires recombinant transgenes to be expressed in ______. The protein that recognizes the __-cells is a chimeric protein that’s encoded by fragments of several different genes (3).

Answer 7

T-cells.
B-cells.
1. VH fragment of DNA encodes the portion of the chimeric protein that recognizes B-cells; it is found on the extracellular surface of the transgenic T-cells.
2. Human CD&a Hinge and TM encodes the transmembrane domain of the chimeric protein.
3. 4-1BB encodes the intracellular domain of the chimeric protein, which activates T-cells that have “found” B-cells, causing them to kill B-cells.