Evaluating Advances in Cell Biology: Medicine, Imaging and Forensics

From the lab bench to your life

Everything in this unit (organelles, enzymes, membranes, the four classes of molecules) can sound like it belongs only in a textbook. But each idea has led to technologies that save lives: drugs that block one enzyme in a cancer cell or a virus, scans that follow a single kind of molecule through the body, glowing proteins that let us watch cells at work, and DNA tests that solve crimes.

The curriculum asks you not just to describe these advances but to evaluate them, the way a health-policy researcher, a doctor or a well-informed citizen would.

1. New treatments for cancer

Cancer cells divide out of control because of changes in the proteins that regulate the cell cycle (you met this in SNC2D).

• Targeted therapy. In chronic myeloid leukemia (CML), a chromosome rearrangement creates a fused gene, BCR-ABL, that codes for a kinase enzyme that is always switched on. Kinases transfer a phosphate from ATP to other proteins, and this one keeps sending the "divide" signal. The drug imatinib (approved in 2001) fits into the enzyme's ATP-binding pocket and blocks it. For many patients, a daily pill turned a deadly leukemia into a long-term, manageable condition. It is a direct application of competitive inhibition.
• Immunotherapy (CAR T-cell therapy). A patient's own T cells (immune cells) are collected, genetically modified to carry a receptor that recognizes a protein on the surface of their cancer cells, multiplied and returned to the body. It is used for some leukemias and lymphomas, including in Canada. It can produce lasting remissions where other treatments failed, but it can cause serious side effects and is very expensive, which raises questions about access.

2. HIV

HIV is a virus that infects immune cells. It needs its own enzymes, reverse transcriptase (to copy its RNA into DNA), integrase (to insert that DNA into the host's chromosome) and protease (to cut its proteins into working pieces). Antiretroviral therapy combines drugs that inhibit these enzymes. Since combination therapy began in the mid-1990s, people living with HIV who take treatment can expect to live long, healthy lives. Canadian researcher Mark Wainberg (McGill University) helped discover the antiretroviral drug 3TC (lamivudine).

3. Hepatitis C

Hepatitis C is a virus that damages the liver. Direct-acting antivirals, which block viral enzymes such as its protease and its RNA polymerase, now cure the large majority of patients (well over 90%) in about 8 to 12 weeks of pills. Michael Houghton, a researcher at the University of Alberta, shared the 2020 Nobel Prize in Physiology or Medicine with Harvey Alter and Charles Rice for the discovery of the hepatitis C virus.

4. Radioisotope labelling

A radioactive atom behaves chemically like a normal one, so it can be built into a molecule and followed by its radiation.

• PET scans use fluorodeoxyglucose (FDG), a glucose look-alike carrying radioactive fluorine-18. Very active cells, such as many cancer cells, take up more glucose (through the carrier proteins you studied), so they light up on the scan.
• Radioactive iodine is taken up by the thyroid gland, which uses iodine to make its hormones, so it can be used to image or treat the thyroid.
• Technetium-99m is the isotope used in many diagnostic nuclear-medicine scans of bones, the heart and other organs. Canada has long been one of the world's major producers of medical isotopes: the Chalk River research reactor supplied much of the world's molybdenum-99 (the parent of technetium-99m) until 2018, and today Ontario's nuclear power stations produce isotopes such as cobalt-60 and lutetium-177.
• In research, the pulse-chase experiments from Organelles at Work used radioactive amino acids in the same way.

5. Fluorescence

Green fluorescent protein (GFP) comes from a jellyfish. Scientists can join the GFP gene to the gene for any protein they want to study, so the cell makes that protein with a glowing tag attached. Under a fluorescence microscope, they can then watch where it goes in a living cell. Osamu Shimomura, Martin Chalfie and Roger Tsien shared the 2008 Nobel Prize in Chemistry for discovering and developing GFP. Fluorescent probes are also used to mark specific DNA sequences on chromosomes (FISH, fluorescence in situ hybridization) to diagnose some genetic conditions and cancers.

6. Forensic biology

Every person (except identical twins) has a unique pattern of short repeated DNA sequences. DNA profiling copies these regions from tiny samples (blood, hair roots, saliva) and compares their lengths. The RCMP runs Canada's National DNA Data Bank, which helps link evidence from crime scenes to offenders and has also helped show that some people were wrongly convicted. (You will learn the tools, PCR and gel electrophoresis, in Molecular Genetics.)

How to evaluate an advance

Use the same criteria every time, so your judgment is fair and you can defend it:

1. Evidence: How well does it work, according to clinical trials or peer-reviewed studies?
2. Benefits: to patients, families, society.
3. Risks: side effects, unintended consequences, misuse.
4. Cost and access: Who can get it? Is it covered by provincial health plans? Is it available in remote and Northern communities, or only in large hospitals?
5. Ethical and social issues: consent, privacy (especially for DNA), fairness.
6. Environmental impact, where it applies (for example, radioactive waste from isotope production).

Judging sources (A1.9). Prefer peer-reviewed articles, government health agencies (such as Health Canada or the Public Health Agency of Canada), university and hospital websites, and reputable science journalism. Ask: Who wrote it? When? What evidence does it cite? Is it trying to sell something? Is it balanced?