Cancer - Online Tutor, Practice Problems & Exam Prep

Cancer is characterized by uncontrolled cell division, leading to malignant or benign tumors. Malignant tumors are cancerous, fast-growing, and can metastasize to other organs, causing severe health issues. In contrast, benign tumors are noncancerous, slow-growing, and remain localized. Cell growth is regulated by proto-oncogenes, which promote division, and tumor suppressor genes, which inhibit it. Mutations in these genes can lead to oncogenes, promoting unrestrained cell growth and cancer development. Understanding these concepts is crucial for grasping cancer biology and its implications for health.

Cancer

In this video, we're going to begin our introduction to cancer. Cancer is a disease characterized by uncontrollable cell division which can lead to the development of malignant tumors. A tumor is defined as an overgrowth of cells, or in other words, an abnormal mass of tissue. Tumors can typically cause health complications, and there are two main types of tumors that you should be familiar with. The first main type of tumor are the malignant tumors, which are an overgrowth of cancer cells that migrate or, in other words, metastasize to other organs. Malignant tumors are the most dangerous because they can create a tumor in one area of the body, but then they can migrate or metastasize to a completely different organ within the body and also cause health complications in that other organ. Now, benign tumors are the second type of tumor and these are not cancerous. This is an overgrowth of cells that are not cancer cells, and they do not migrate, so they do not metastasize. Instead, the benign tumors will remain at the same site. Benign tumors can cause health complications but are not nearly as dangerous as the malignant tumors. Notice in our image on the far left, we're showing you malignant tumors, and on the far right, we're showing you benign tumors. The malignant tumors are cancerous, while the benign tumors are noncancerous cells. Malignant tumors, which are cancerous, are non encapsulated, while the benign tumors are encapsulated. The capsule is a structure of tissue that surrounds and encapsulates the cells, essentially containing them in the same area. Malignant tumors tend to be very fast-growing and divide very quickly since they are cancerous cells, whereas benign tumors are more slow-growing. In terms of metastasizing or migrating to other areas of the body, malignant tumors are characterized by migration or metastasis, so they do metastasize. On the other hand, benign tumors do not metastasize, partly because they are encapsulated. This concludes our introduction to cancer and the difference between malignant tumors and benign tumors. In our next lesson video, we'll talk more about cancer by discussing specific genes that control the cell cycle. I'll see you all in that video.

The difference between benign and malignant tumors is:

• A. Malignant tumors do not spread to other sites.
• B. Benign tumors have not lost growth control.
• C. Benign tumors have not spread to other sites.
• D. Malignant tumors have not lost growth or control.

Types of Genes Regulating Cell Growth

In this video, we're going to introduce two types of genes that regulate cell growth. And so, in a healthy and normal cell that is not cancerous and is not part of a tumor, this healthy normal cell is going to have two types of genes that regulate cell growth, and we've got these two labeled down below, number 1 and number 2. And so the first type of gene that's going to regulate cell growth in a healthy normal cell is a proto-oncogene. And so a proto-oncogene is going to be a gene that provides signals that promote appropriate cell division. And so because it's promoting appropriate cell division, a proto-oncogene is pretty much acting like the green light for cell division. And so it's going to allow cell division to proceed.

Now the second type of gene that regulates cell growth is a tumor suppressor gene. And so the tumor suppressor gene, as its name implies, is going to do pretty much the opposite of the proto-oncogene. It's going to provide signals to not promote but inhibit cell division. So it's basically acting like the red light for cell division, to inhibit cell division and to slow it down.

Now, a protein called p53 is an example of a protein that serves as a tumor suppressor gene. And so if we take a look at our image down below over here on the left-hand side, notice we're showing you a proto-oncogene and how it pretty much acts like the cell division gas pedal. It pretty much promotes cell division, so it acts like the green light for cell division to allow cell division to proceed normally and appropriately. And then over here on the right-hand side, notice we're showing you the tumor suppressor gene, which is pretty much acting like the cell division brakes or the brakes to cell division or the red light for cell division that slows down or inhibits cell division.

And so, again, within a healthy and normal cell, there are both proto-oncogenes and tumor suppressor genes that will either promote or inhibit cell division appropriately so that cell division will proceed appropriately. However, although proto-oncogenes and tumor suppressor genes are normal and healthy genes found in normal and healthy cells, they are susceptible to mutations. And mutations in either of these types of genes, in either proto-oncogenes or tumor suppressor genes, can lead to the development of cancer, uncontrollable cell division.

And so all again, although proto-oncogenes are essential, although proto-oncogenes are essential in healthy genes that promote cell division appropriately, again, they are susceptible to mutations that can generate oncogenes, and oncogenes are different from proto-oncogenes. Proto-oncogenes are healthy and normal genes that are needed and required to promote appropriate cell division. However, oncogenes are mutated proto-oncogenes. And so that's exactly how we're defining oncogene down below. They are a mutated gene that is going to promote unrestrained cell growth. Essentially, it's going to promote cancer.

And so this here concludes our introduction to the two types of genes that regulate cell growth, proto-oncogenes and tumor suppressor genes, and how they are normal healthy genes that are required to regulate cell division, and how they are both susceptible to mutations that can lead to the development of cancer. And so this here concludes this video and we'll be able to get some practice applying these concepts as we move forward. So, I'll see you all in our next video.

Which of the following processes do normal proto-oncogenes typically exhibit?

• A. They normally suppress tumor growth.
• B. They enhance tumor growth.
• C. They stimulate normal cell growth and division.
• D. They are underexpressed in cancer cells.

When activated by signals in the cell, Protein X can stop cells from growing and dividing into new cells. What type of gene codes for Protein X?

• A. Oncogene.
• B. Tumor-suppressor gene.
• C. Protein kinase gene.
• D. Protein Vesicle gene.
• E. Proto-oncogene.