Dolphins produce a variety of vocalizations, usually in the form of clicks and whistles. Dolphins are sometimes hunted in places like Japan, in an activity known as dolphin drive hunting. Besides drive hunting, they also face threats from bycatch, habitat loss, and marine pollution.
The DNA sequence of a gene can be altered in a number of ways. Gene mutations have varying effects on health, depending on where they occur and whether they alter the function of essential proteins. The types of mutations include:his type of mutation is a change in one DNA base pair that results in the substitution of one amino acid for another in the protein made by a gene.
As previously mentioned, DNA in any cell can be altered by way of a number of factors, including environmental influences, certain chemicals, spontaneous mutations, and errors that occur during the process of replication. Each of these mechanisms is discussed in greater detail in the following sections.igure Detail. As mentioned, sickle-cell anemia is the result of a change in a single nucleotide, and it represents just one class of mutations called point mutations. Changes in the DNA sequence can also occur at the level of the chromosome, in which large segments of chromosomes are altered.