Biomed II Exam II Lecture 1

Brain cancer is cancer that originates in the cells of the brain. Glial cells, also known as neuroglia, are non-neuronal cells that provide support and protection for neurons in the brain. They play a crucial role in maintaining the structure and function of the nervous system. When these glial cells become cancerous, it results in brain cancer. Therefore, the correct answer is "glial" as it accurately identifies the type of cells affected by brain cancer.

Malignant tumor=cancer

The correct answer is 75. This means that 75% of tumors are caused by environmental factors. This suggests that the majority of tumors are influenced by external factors such as exposure to certain chemicals, pollutants, radiation, or lifestyle choices. It implies that reducing exposure to these environmental factors could potentially lower the risk of developing tumors.

The liver is responsible for removing cells without nuclei and DNA from the body. It performs various functions, including detoxification and filtering of blood. As part of its role in detoxification, the liver eliminates waste products, toxins, and old or damaged cells from the bloodstream. This includes cells without nuclei and DNA, which are likely to be old or damaged. Therefore, the liver is the correct answer for removing such cells from the body.

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Hemocytoblasts are multipotent hematopoietic stem cells, meaning they have the ability to differentiate into multiple types of blood cells. This statement is true because hemocytoblasts are the precursor cells for all blood cells and can give rise to red blood cells, white blood cells, and platelets. They are responsible for the continuous production of new blood cells in the body.

Inherited mutations are less likely the sole cause of cancer. This means that while inherited mutations can increase the risk of developing cancer, they are not the only factor responsible for causing cancer. Other factors such as acquired mutations, environmental factors, and lifestyle choices also play a significant role in the development of cancer. Therefore, it is important to understand that cancer is a complex disease with multiple contributing factors.

The statement is true because p53 is indeed the most frequently mutated gene in human cancer. The p53 gene is responsible for regulating cell division and preventing the formation of tumors. However, when the p53 gene is mutated, it loses its ability to control cell growth and can lead to the development of cancer. Mutations in the p53 gene have been found in a wide range of human cancers, making it the most commonly mutated gene in cancer cases.

EGF (Epidermal Growth Factor) is a signaling molecule that binds to EGFR (Epidermal Growth Factor Receptor). This binding activates EGFR, leading to various cellular responses such as cell growth, proliferation, and differentiation. Therefore, the statement "EGF binds to EGFR" is true.

Cells lining the colon and skin cells replicate a lot because they are constantly being shed and replaced. The cells lining the colon are responsible for absorbing nutrients and water from digested food, and the constant replication ensures that this process can continue efficiently. Similarly, skin cells are constantly being shed and replaced to maintain the integrity and functionality of the skin barrier. On the other hand, muscle cells and neurons have limited ability to replicate, as their primary function is not to undergo rapid replication but rather to perform specialized functions such as contraction or transmission of signals.

Activation of normal p53 leads to cell cycle arrest in G1 and induction of DNA repair by transcriptional up-regulation of GADD45 and CDKN1A (p21). GADD45 is involved in DNA damage repair and is up-regulated by p53 to promote DNA repair. CDKN1A (p21) is a cyclin-dependent kinase inhibitor that inhibits cell cycle progression and is also up-regulated by p53 to induce cell cycle arrest in G1 phase, allowing time for DNA repair to occur.

The correct answer is 85%. This means that 85% of tumors have telomerase. Telomerase is an enzyme that helps maintain the length of telomeres, which are protective caps on the ends of chromosomes. Telomerase is often found to be active in cancer cells, allowing them to divide and replicate indefinitely. This high percentage suggests that telomerase is a common feature in tumor cells, making it a potential target for cancer treatments.

The false statements in the given options are "carcinogens in food causes lung cancer" and "Radon causes colon cancer". While smoking and asbestos are known to be risk factors for lung cancer, and radon is a known cause of lung cancer, there is no evidence to suggest that carcinogens in food cause lung cancer or that radon causes colon cancer.

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Necrosis is a type of cell death that occurs due to injury or disease. During necrosis, the affected cells undergo structural changes, including the fusion of cytoplasmic blobs, which causes them to become larger. Additionally, necrotic cells have dysfunctional organelles, meaning that the organelles are not able to perform their normal functions.

Overstimulation of the ras gene can lead to the development of cancer in various organs, including the breast, ovaries, and stomach. Ras is a proto-oncogene that regulates cell growth and division. When it becomes mutated or overactive, it can promote uncontrolled cell growth and tumor formation. Breast cancer is one of the most common types of cancer in women, while ovarian cancer affects the ovaries, and stomach cancer affects the stomach lining. These cancers can occur when ras signaling pathways are dysregulated, leading to abnormal cell proliferation and tumor growth in these organs.

Large amounts of unrepairable DNA damage can activate p16 and BRCA1/BRCA2. p16 is a tumor suppressor gene that plays a role in cell cycle regulation and prevents the progression of damaged cells into cancerous cells. BRCA1 and BRCA2 are also tumor suppressor genes that are involved in DNA repair. When there is extensive DNA damage that cannot be repaired, these genes are activated to halt cell division and initiate repair mechanisms. Therefore, the correct answer is p16 and BRCA1/BRCA2.