Welcome to the show everybody! I'm Lottie, here with Mr H. And Mr H, I was reading this cell biology paper last night, and it described cell division as a highly regulated orchestra. But then, when it came to cancer, it said the orchestra essentially loses its conductor and just starts playing at maximum volume, completely out of control. That is a remarkably dramatic way to put it, Lottie, but scientifically speaking, it is not far off. We are looking at AQA specification point 4.2.2.6 today, which is Cancer. At its core, a tumour is simply a mass of cells formed by uncontrolled cell growth and division. The normal regulatory mechanisms--what you might call the "off" switch--have completely failed. Right, so the cell just keeps dividing, copy-pasting itself over and over. And that forms this physical lump, the tumour. But they aren't all the same, right? My aunt had a benign growth removed, and her doctor told her not to panic because it wasn't actually cancer. And her doctor was entirely correct. This is the first major distinction the examiner will test you on: benign versus malignant. A benign tumour is a growth of abnormal cells, but--and this is your key exam phrase--it is contained within one area, usually within a membrane. So "contained within a membrane" is the phrase to lock in. It means they're basically trapped in a little cellular sleeping bag. They can't wander off and invade neighboring tissues. Precisely. They do not invade other parts of the body. Now, contrast that with a malignant tumour. This is what we officially classify as cancer. Malignant cells are not politely staying put. They invade neighbouring tissues and, crucially, they find their way into the bloodstream. And once they're in the blood, that's like getting onto the highway. They can travel absolutely anywhere in the body. Exactly. They circulate in the blood system and hook onto other organs, where they begin dividing again to form secondary tumours. The scientific term for this process of spreading is metastasis. You must know that word. M-E-T-A-S-T-A-S-I-S. Metastasis. Metastasis. That's a massive term. So, if a student just writes "the cancer spreads to other parts," will they get the mark? Here is the Mr. H Mark Scheme Warning. Writing "the cancer spreads" is a one-way ticket to zero marks. You must state that cells break off, travel in the bloodstream, and form secondary tumours. The examiner wants the mechanism, Lottie, not a vague summary. Right, mechanism is key. Got it. So, let's talk about how this cellular lawlessness actually starts. We hear a lot about risk factors. What actually triggers that "off" switch to break? Well, we categorize these into lifestyle factors and genetic factors. Let's start with lifestyle, because the exam board loves a direct link. Take smoking, for instance. It is a massive risk factor, specifically linked to lung, mouth, bowel, and stomach cancers. The chemical carcinogens in the smoke directly damage the DNA. DNA damage, right. And then there's obesity, which I think surprises some people. It's not just about heart health; it's linked to bowel, liver, and kidney cancers. Indeed. And we must also include ultraviolet light--UV radiation--from overexposure to the sun or tanning beds. That directly damages skin cells, leading to skin cancer. Finally, biological agents like viral infections. For example, infection with the Human Papillomavirus, or HPV, is heavily linked to the development of cervical cancer. Wow, so a virus can actually hijack the cell's machinery and trigger cancer. That's terrifying. But what about people who don't smoke, eat incredibly healthily, stay out of the sun, and still get cancer? That is where genetics enter the equation. You can inherit a predisposition to certain cancers. A classic example is the mutated BRCA genes. If you inherit a faulty version of the BRCA1 or BRCA2 gene, your risk of developing breast and ovarian cancer increases quite dramatically. So it's a double whammy--some risks are written into our code before we're even born, and others are influenced by how we live. Exactly. But remember, having a genetic risk factor doesn't mean you are guaranteed to get the disease. It simply means your baseline risk is higher. Now, Lottie, let's test you. If a student writes in their exam that "smoking makes cancer," what will I do? Oh, you'll probably have a fit. We don't say "makes" or "causes" with absolute certainty. We have to say it "increases the risk of" because it's a correlation, not a guaranteed 1:1 outcome. Spot on. "Increases the risk." Keep your language scientific. And please, don't write that a malignant tumour is "bad" or "evil." It is invasive and capable of metastasis. Use the vocabulary of a scientist, not a medieval poet. No medieval poetry in Biology Paper 1. Noted. It's fascinating how a microscopic error in a single cell's instruction manual can completely change the course of an organism's life. It really makes you appreciate how hard our bodies work to keep things running smoothly most of the time. It is a finely balanced system, Lottie. And next time, we are leaving the human body behind to look at how plants organize their own systems. We'll be diving into 4.2.3 Plant Tissues, Organs and Systems. I will prepare myself to talk to the green things. See you next time, Mr. H!
Audio Coursesby Jellypod