How can chromosomes mutate

This results in a large number of amino acids being altered, which is called a frameshift mutation. Notice how none of the amino acids in the protein made from the mutated DNA are the same as the original sequence. A third possibility is that the mutated DNA sequence causes the protein production to stop early, so that the protein is shorter than normal.

This is referred to as a nonsense mutation. So, the resulting protein would be shorter than normal and would not function properly. Mutations can be passed down from the mother or father to the developing baby, and these are called inherited mutations.

For example, if your mother had a mutation that caused her to be a lot shorter than average, you could inherit her mutation and be shorter than average yourself. If a person with an inherited mutation has a baby one day, that person would pass the mutation on to the next generation. With the example above, if you gave your son or daughter the short stature mutation your mom gave you, your child could say he is short because of both you and his grandmother your mother.

Other mutations happen after birth, and these are called acquired mutations. Acquired mutations are usually due to something in the environment and their effects are usually only present in the cells that were exposed to that environmental trigger. So, some cells will have the mutation and other cells will have the normal sequence. For example, if you somehow got a mutation in the skin cells on your knee and then scraped your knee and had to make new cells to replace the ones that got hurt, those new cells would contain the mutation.

However, the mutation would not be passed on to your future offspring, if you had a baby later. Sunlight is one thing that can cause mutations. How does sunlight affect our DNA? Sunlight creates structures called thymine dimers , which means that two thymine T bases T on the same DNA strand become connected in an abnormal way, instead of correctly attaching to the complementary base adenine A on the opposite strand.

Thymine dimers create kinks in the DNA shape see Figure 3 [ 2 ]. These kinks make DNA difficult to copy, which can cause a mutation. In order to avoid thymine dimers from developing in our cells, it is very important to use sunscreen to help block ultraviolet A and B UVA and UVB rays. Sunscreen should be reapplied every 2 h or after swimming, sweating, bathing, or using a towel [ 4 ].

Some individuals who have especially sensitive or light skin should consider higher levels of UV protection and are encouraged to consult a doctor called a dermatologist, who is an expert on keeping skin healthy.

X-ray radiation is the kind used in X-rays medical images taken of teeth, bones, and other hard body parts. X-ray radiation has a very high energy level that can create molecules called free radicals. Free radicals are very unstable, and to become more stable, they can steal electrons from DNA, which can lead to mutations [ 5 ].

We can reduce exposure to X-ray radiation by using other forms of medical images when possible and wearing protective equipment to protect the body when x-rays are taken. If you have ever gone to the dentist and had an X-ray of your teeth, you probably remember having a heavy lead apron draped over your body.

The lead apron protects the parts of the body that the dentist is not taking pictures of. Getting X-rays only when necessary is a good practice to prevent any excessive negative effects on your DNA see Table 1 [ 5 ]. This is why X-rays are not taken if a doctor is fairly sure a patient has sprained, not broken, an ankle. How does smoking lead to cancer?

Cigarettes and tobacco products contain chemicals referred to as carcinogens , which are mutagens that are also known to cause cancer. All cancer cells have DNA mutations, and it is the carcinogens that cause the mutations. De novo variants are one explanation for genetic disorders in which an affected child has a variant in every cell in the body, but the parents do not, and there is no family history of the disorder.

Variants acquired during development can lead to a situation called mosaicism, in which a set of cells in the body has a different genetic makeup than others. As cells grow and divide, cells that arise from the cell with the altered gene will have the variant, while other cells will not. When a proportion of somatic cells have a gene variant and others do not, it is called somatic mosaicism.

Depending on the variant and how many cells are affected, somatic mosaicism may or may not cause health problems. When a proportion of egg or sperm cells have a variant and others do not, it is called germline mosaicism. 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. Some studies have also indicated that genes on chromosomes 1 and 2 may play a role in hereditary melanoma.

These mutations are often caused by environmental or lifestyle factors and can also result from mistakes during cell division. This type of mutation is not passed down from parents to children and thus, is not present in every cell in the body.

Alterations in genes, whether they occur in a germline or somatic fashion, change the function of the gene, which may contribute to the development or spread of cancer. Types of mutations There are many classes or types of mutations. Change in a codon that results in the substitution of an amino acid in the protein made by a gene.

Removing DNA that results in a change in the number of DNA bases; deletions can occur in one or more base pairs or may remove an entire gene. Single nucleotide polymorphisms A single nucleotide polymorphism SNP, pronounced snip is one difference in a single base pair, or nucleotide, in a section of DNA.

SNPs result in genetic variation in humans. SNPs can occur with a gene or near a gene, but they are most commonly found in the DNA between genes. SNPs are common and normal variations in the DNA and are responsible for many of the normal differences between people such as eye color, hair color and blood type. On average, SNPs occur once in every nucleotide base pairs, which means that the human genome has roughly 10 million SNPs.

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