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Although mutations that cause changes in protein sequences can be harmful to an organism, on occasions the effect may be positive in a given environment. In this case, the mutation may enable the mutant organism to withstand particular environmental stresses better than wild-type organisms, or reproduce more quickly.
Random mutations are the ultimate source of genetic variation. Mutations are likely to be rare, and most mutations are neutral or deleterious, but in some instances, the new alleles can be favored by natural selection. Polyploidy is an example of chromosomal mutation. Polyploidy is a condition wherein organisms have three or more sets of ...
Mutations in these cells are the only mutations that can be passed on to offspring, when either a mutated sperm or oocyte come together to form a zygote. [2] After this fertilization event occurs, germ cells divide rapidly to produce all of the cells in the body, causing this mutation to be present in every somatic and germline cell in the ...
The international pictogram for chemicals that are sensitising, mutagenic, carcinogenic or toxic to reproduction. In genetics, a mutagen is a physical or chemical agent that permanently changes genetic material, usually DNA, in an organism and thus increases the frequency of mutations above the natural background level.
These disparities can cause many different phenotypic effects of all intensities, ranging from no observable impact at all to possible inviability. [4] Due to environmental conditions such as climate, diet, oxygen levels, light cycles, and mutagens or chemicals which are strongly related to disease susceptibility, genes expression can vary.
In genetics, the mutation rate is the frequency of new mutations in a single gene, nucleotide sequence, or organism over time. [2] Mutation rates are not constant and are not limited to a single type of mutation; there are many different types of mutations. Mutation rates are given for specific classes of mutations.
As noted above, about 3 or 4 driver mutations and 60 passenger mutations occur in the exome (protein coding region) of a cancer. [17] However, a much larger number of mutations occur in the non-protein-coding regions of DNA. The average number of DNA sequence mutations in the entire genome of a breast cancer tissue sample is about 20,000. [29]
Many of these lesions cause structural damage to the DNA molecule and can alter or eliminate the cell's ability to transcribe the gene that the affected DNA encodes. Other lesions induce potentially harmful mutations in the cell's genome, which affect the survival of its daughter cells after it undergoes mitosis. As a consequence, the DNA ...