Final answer:
Mutations can cause both devastating and beneficial effects, such as causing diseases like muscular dystrophy or providing disease resistance. Mutations arise from internal processes and external factors like cigarette smoke and can alter chromosome length.
Step-by-step explanation:
Effects of Mutations
It is true that mutations can have devastating effects such as causing diseases like muscular dystrophy and epilepsy, which can lead to developmental delays, structural abnormalities, or other varied effects. Beneficial mutations can also occur, for example, those providing resistance to certain diseases, which demonstrate that mutations are not always harmful. Exposure to mutagens like cigarette smoke can induce mutations leading to cancer due to the damage they cause to DNA. Mutations are not always caused by external factors; they can also arise spontaneously during processes like DNA replication. Additionally, some mutations can indeed alter the length of chromosomes through insertions or deletions.
Duchenne muscular dystrophy (DMD) is a well-known condition that results in the gradual loss of muscle function due to a mutation in a gene located on the X chromosome. Other disorders such as Tay-Sachs disease and thalassemia arise from genetic mutations that affect crucial physiological processes, leading to significant health impairments.
Huntington's disease illustrates how dominant lethal alleles can remain in the population, since this condition often manifests after the affected individuals have had children. Such pernicious effects underscore the complexity and potentially severe impact of mutations on human health.