A chemical called dioxin is produced as a by-product of some chemical manufacturing processes. This substance was present in Agent Orange, a defoliant sprayed on vegetation during the Vietnam War. There has been a continuing controversy over its effects on soldiers exposed to it during the war. Animal tests have suggested that dioxin can be lethal and can cause birth defects, cancer, organ damage, and immune system suppression. But its effects on humans are unclear, and even animal tests are inconclusive. Researchers have discovered that dioxin enters a cell and binds to a protein that in turn attaches to the cell’s DNA. How might this mechanism help explain the variety of dioxin’s effects? How might you determine whether a particular individual became ill as a result of exposure to dioxin?
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- Why are proteins so absolutely necessary for all cells? a. They are like the workers of cells b. They store genetic information c. They store water d. They are used for inheritancearrow_forwardCancer can arise spontaneously, but it can also be induced as a result of environmental factors such as sun exposure, infections, and tobacco smoking. If you were asked to help allocate resources to cancer research, what emphasis would you place on research to find cancer cures, compared to that placed on education about cancer prevention?arrow_forwardCancer is a disease that happens when a cell accumulates mutations in cell cycle control genes and begins to divide in an out-of-control way. The immune system has ways to recognize cancer cells as abnormal and destroy them. When a person first begins to develop cancer, the immune system is very good at killing the cancer cells. However, as a cancer progresses, more and more of the cancer cells resist the attacks of the immune system. How would an evolutionary biologist EXPLAIN WHY the cancer is more resistant to the immune system over time? a. There was variation in the resistance of the cancer cells to the immune system, and the most resistant cancer cells made the most daughter cells. b. The cancer cells needed to resist the attacks of the immune system in order to survive, so the cancer became more resistant over time. c. At first, most cancer cells were susceptible to immune system attack, but as the cancer progresses, more cells are resistant. d. The attacks of…arrow_forward
- Stem Cell ResearchThe inner cell mass in a blastocyst is pluripotent. Pluripotency means that each one of the cells is capable of differentiating into any type of cell in the human body.These pluripotent cells can be used to create any cells, tissues, or organs in the body. They can replace organs without the patients having to worry about organ rejection or taking immune-suppressing medication for the rest of their lives in order to reduce the chance of organ rejection. The pluripotent cells can also be used to help those with diabetes, spinal cord injury, multiple sclerosis, or cancer, among many of diseases. There are several different sources of pluripotent cells. The best and most reliable source is the stem cells from an embryo. There are other types of stem cells such as induced pluripotent cells and embryonic stem cells created through various processes. In Canada, unused embryos from an in vitro fertilization procedure may be donated for stem cell research. However, the gamete…arrow_forwardNew treatments for several conditions are being developed using stem cells in medical waste, such as biopsy material, teeth, menstrual blood, umbilical cords, and fatty tissue removed in liposuction. For example, fat samples from injured horses are used to grow stem cells to treat tendon injuries. Explain how the two defining characteristics of stem cells enable them to be used to replace damaged or diseased tissue, so that the new tissue functions as opposed to forming a scar.arrow_forwardWhich of the following best describes a gene that codes for a tumor-suppressor protein? a. One that helps to prevent progression through the cell cycle. b. One that helps prevent apoptosis. c. One that codes for a DNA repair enzyme. d. One that supports part of a growth factor signaling pathway.arrow_forward
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- Muscle cells differ from nerve cells mainly because they(A) express different genes.(B) contain different genes.(C) use different genetic codes.(D) have unique ribosomes.arrow_forwardOne important biological effect of a large dose of ionizing radiation is to halt cell division. How does this occur?arrow_forwardReports in the media about stem cells usually state that they “turn into any kind of cell in the body.” Explain why this statement is only partially correct, including a description of how a stem cell maintains the population of stem cells.arrow_forward
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