Oncology & Cancer

When does a cancer first arise?

There is no stronger risk factor for cancer than age. At the time of diagnosis, the median age of patients across all cancers is 66. That moment, however, is the culmination of years of clandestine tumor growth, and the answer ...

Oncology & Cancer

Researchers illuminate potential precursors of blood cancers

Utah researchers report significant new insights into the development of blood cancers. In work published today in Blood Cancer Discovery, a journal of the American Association for Cancer Research, scientists describe an ...

Diseases, Conditions, Syndromes

Study suggests S.Africa variant could offer better immunity

A new preliminary study—based on a small sample—has suggested that people previously infected by the COVID-19 variant identified in South Africa may have better immunity against other coronavirus mutations, experts said ...

Oncology & Cancer

Origin of childhood cancer malignant rhabdoid tumour discovered

The first proof of the origin of malignant rhabdoid tumor (MRT), a rare childhood cancer, has been discovered by researchers at the Wellcome Sanger Institute, the Princess Máxima Center for Pediatric Oncology in the Netherlands, ...

Genetics

A genetic patch to prevent hereditary deafness

They can hear well up to about forty years old, but then suddenly deafness strikes people with DFNA9. The cells of the inner ear can no longer reverse the damage caused by a genetic defect in their DNA. Researchers at Radboud ...

Medical research

SARS-CoV-2 mutations in competition

Prior to the emergence of new mutants of the coronavirus, such as the British variant B.1.1.7, the SARS-CoV-2 variant named D614G had already mutated from the original SARS-CoV-2 pathogen that triggered the pandemic. D614G ...

Vaccination

Comparing COVID-19 vaccines: How are they different?

Even if you're still waiting for a vaccine, watching the first people get their COVID-19 vaccinations may have felt like a huge relief. As the weeks pass, countless reports are coming out about the effectiveness of new vaccines ...

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Mutation

In biology, mutations are changes to the nucleotide sequence of the genetic material of an organism. Mutations can be caused by copying errors in the genetic material during cell division, by exposure to ultraviolet or ionizing radiation, chemical mutagens, or viruses, or can be induced by the organism itself, by cellular processes such as hypermutation. In multicellular organisms with dedicated reproductive cells, mutations can be subdivided into germ line mutations, which can be passed on to descendants through the reproductive cells, and somatic mutations, which involve cells outside the dedicated reproductive group and which are not usually transmitted to descendants. If the organism can reproduce asexually through mechanisms such as cuttings or budding the distinction can become blurred. For example, plants can sometimes transmit somatic mutations to their descendants asexually or sexually where flower buds develop in somatically mutated parts of plants. A new mutation that was not inherited from either parent is called a de novo mutation. The source of the mutation is unrelated to the consequence, although the consequences are related to which cells were mutated.

Mutations create variation within the gene pool. Less favorable (or deleterious) mutations can be reduced in frequency in the gene pool by natural selection, while more favorable (beneficial or advantageous) mutations may accumulate and result in adaptive evolutionary changes. For example, a butterfly may produce offspring with new mutations. The majority of these mutations will have no effect; but one might change the color of one of the butterfly's offspring, making it harder (or easier) for predators to see. If this color change is advantageous, the chance of this butterfly surviving and producing its own offspring are a little better, and over time the number of butterflies with this mutation may form a larger percentage of the population.

Neutral mutations are defined as mutations whose effects do not influence the fitness of an individual. These can accumulate over time due to genetic drift. It is believed that the overwhelming majority of mutations have no significant effect on an organism's fitness. Also, DNA repair mechanisms are able to mend most changes before they become permanent mutations, and many organisms have mechanisms for eliminating otherwise permanently mutated somatic cells.

Mutation is generally accepted by the scientific community as the mechanism upon which natural selection acts, providing the advantageous new traits that survive and multiply in offspring or disadvantageous traits that die out with weaker organisms.

This text uses material from Wikipedia, licensed under CC BY-SA