Mutations must occur in what type of cells

Mutations in these parts of the genome can substantially change the way the organism is built. Many organisms have powerful control genes that determine how the body is laid out. For example, Hox genes are found in many animals including flies and humans and designate where the head goes and which regions of the body grow appendages. So evolving a major change in basic body layout may not be so unlikely; it may simply require a change in a Hox gene and the favor of natural selection.

Weird Fact: Mutations to control genes can transform one body part into another. Scientists have studied flies carrying Hox mutations that sprout legs on their foreheads instead of antennae! The causes of mutations. A case study of the effects of mutation: Sickle cell anemia.

Transversion substitution refers to a purine being replaced by a pyrimidine, or vice versa; for example, cytosine, a pyrimidine, is replaced by adenine, a purine. Mutations can also be the result of the addition of a base, known as an insertion, or the removal of a base, also known as deletion.

Sometimes a piece of DNA from one chromosome may get moved to another chromosome or to another region of the same chromosome; this is also known as translocation. Mutations in repair genes have been known to cause cancer. Many mutated repair genes have been implicated in certain forms of pancreatic cancer, colon cancer, and colorectal cancer. Mutations can affect either somatic cells or germ cells.

If many mutations accumulate in a somatic cell, they may lead to problems such as the uncontrolled cell division observed in cancer. If a mutation takes place in germ cells, the mutation will be passed on to the next generation, as in the case of hemophilia and xeroderma pigmentosa. DNA polymerase can make mistakes while adding nucleotides. Most mistakes are corrected, but if they are not, they may result in a mutation defined as a permanent change in the DNA sequence.

Mutations can be of many types, such as substitution , deletion , insertion , and translocation. Mutations in repair genes may lead to serious consequences such as cancer. Mutations can be induced or may occur spontaneously. Answer the question s below to see how well you understand the topics covered in the previous section.

This short quiz does not count toward your grade in the class, and you can retake it an unlimited number of times. Use this quiz to check your understanding and decide whether to 1 study the previous section further or 2 move on to the next section. Skip to main content. As all the cells divide during growth and development, cells that arise from the cell with the altered gene will have the mutation, while other cells will not. Depending on the mutation and how many cells are affected, mosaicism may or may not cause health problems.

Most disease-causing gene mutations are uncommon in the general population. However, other genetic changes occur more frequently. Genetic alterations that occur in more than 1 percent of the population are called polymorphisms.

In this situation, an unaffected parent can pass a genetic condition to their child. Most variants do not lead to development of disease, and those that do are uncommon in the general population.

Some variants occur often enough in the population to be considered common genetic variation. Several such variants are responsible for differences between people such as eye color, hair color, and blood type. Other chapters in Help Me Understand Genetics. Genetics Home Reference has merged with MedlinePlus. Learn more. The information on this site should not be used as a substitute for professional medical care or advice.

Contact a health care provider if you have questions about your health. What is a gene variant and how do variants occur?