Read the passage and answer the questions that follow: Mutations Suppose you pick what you think is a juicy Red Delicious apple to eat. Then you notice that half the apple is yellow. This is an example of a mutation. It is the result of a change in an organism’s DNA. Mutations in nature are random, that is, they are not related to how useful they will be to an organism. Most mutations are neutral or harmless. But some mutations can be helpful to organisms. Still others can be dangerous or even fatal. When a cell divides normally, it makes a perfect copy of its DNA. However,... Show more Read the passage and answer the questions that follow: Mutations Suppose you pick what you think is a juicy Red Delicious apple to eat. Then you notice that half the apple is yellow. This is an example of a mutation. It is the result of a change in an organism’s DNA. Mutations in nature are random, that is, they are not related to how useful they will be to an organism. Most mutations are neutral or harmless. But some mutations can be helpful to organisms. Still others can be dangerous or even fatal. When a cell divides normally, it makes a perfect copy of its DNA. However, sometimes a cell will not copy perfectly. There may be an addition or subtraction of nucleotides. There could also be a substitution of nucleotides. All of these changes result in a mutation. Mutations can be inherited and acquired. There are two ways that a mutation is acquired. A cell’s DNA may make a mistake when copying itself. Most often, cells can repair themselves, but not always. The result is a mutation. Mutations can also happen when an organism is exposed to certain chemicals or to radiation. This can cause the DNA to break down. The addition or subtraction of a nucleotide can cause different proteins to be made. Both can also cause a cell to stop protein production. In either case, the result is usually a harmful mutation. The substitution of one nucleotide for another may not lead to a harmful effect. However, it could alter a protein, so that it cannot function normally. Mutations that are harmful include diseases such as PKU. It is due to a single mutation on chromosome 12 in both parents. If left untreated, it can lead to brain damage and mental retardation. Doctors now regularly test newborns for the mutant gene. Other mutations can be beneficial and help species evolve. An example is the panda’s wrist bone that has evolved into a thumb. This mutation enables pandas to get a better grip on bamboo, which is a major part of their diet. Sickle cell is a mutation that is both harmful and beneficial. People with one sickle cell gene are resistant to malaria, a dangerous disease. But if a person inherits the gene for sickle cell from both parents, the mutation may result in sickle cell anemia, a fatal disease. Show less
Read the passage and answer the questions that follow:
Mutations Suppose you pick what you think is a juicy Red Delicious apple to eat. Then you notice that half the apple is yellow. This is an example of a mutation. It is the result of a change in an organism’s DNA. Mutations in nature are random, that is, they are not related to how useful they will be to an organism. Most mutations are neutral or harmless. But some mutations can be helpful to organisms. Still others can be dangerous or even fatal. When a cell divides normally, it makes a perfect copy of its DNA. However, sometimes a cell will not copy perfectly. There may be an addition or subtraction of nucleotides. There could also be a substitution of nucleotides. All of these changes result in a mutation. Mutations can be inherited and acquired. There are two ways that a mutation is acquired. A cell’s DNA may make a mistake when copying itself. Most often, cells can repair themselves, but not always. The result is a mutation. Mutations can also happen when an organism is exposed to certain chemicals or to radiation. This can cause the DNA to break down. The addition or subtraction of a nucleotide can cause different proteins to be made. Both can also cause a cell to stop protein production. In either case, the result is usually a harmful mutation. The substitution of one nucleotide for another may not lead to a harmful effect. However, it could alter a protein, so that it cannot function normally. Mutations that are harmful include diseases such as PKU. It is due to a single mutation on chromosome 12 in both parents. If left untreated, it can lead to brain damage and mental retardation. Doctors now regularly test newborns for the mutant gene. Other mutations can be beneficial and help species evolve. An example is the panda’s wrist bone that has evolved into a thumb. This mutation enables pandas to get a better grip on bamboo, which is a major part of their diet. Sickle cell is a mutation that is both harmful and beneficial. People with one sickle cell gene are resistant to malaria, a dangerous disease. But if a person inherits the gene for sickle cell from both parents, the mutation may result in sickle cell anemia, a fatal disease.
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