Even in the most stable conditions cells undergo mutations. So in humans(an example) with millions of cells, mutations must be a common affair. But how is that we are still basically the same throughout the life, and no random mutations cause sudden disorders in us. Even if mutations are rare, they cannot be nil and how are they controlled.
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2$\begingroup$ A rule of thumb is one mutation per cell division. Most cellular organisms have various error proof and repair mechanisms, to reduce the number of mutations. When these accumulate, they do cause sudden disruptions, such as cancer. $\endgroup$– Roger V.Commented Jun 26, 2021 at 6:27
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3$\begingroup$ I think you haven't researched on the topic. Try googling "Mutation Repair" or "DNA Repair". You'll find various articles related to the same. $\endgroup$– biologist_JaishreeCommented Jun 26, 2021 at 7:00
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There are many reasons why humans rarely experience the deleterious effects of mutations. Many mutations arise from errors in normal biological processes such as DNA replication or recombination. DNA repair mechanisms and apoptosis (programmed cell death) are some ways of 'dealing with' mutated or damaged DNA. Another reason that we rarely see deleterious effects of mutations is because of the way amino acids are encoded.
There are approx. 20 amino acids encoded by the genome, yet each amino acid can be encoded by approx. 4 different codons. For example threonine is encoded by ACU, ACC, ACA, ACG. This means a point mutation is unlikely to make any difference to the final protein product as there is a high chance that the mutation will still code for the same amino acid. This is what is called a silent mutation, and there are other types mutations that do not have deleterious effects.
https://www.nature.com/scitable/topicpage/genetic-mutation-441/
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2$\begingroup$ There are no amino acids in the genome — it is DNA. $\endgroup$– DavidCommented Jun 27, 2021 at 18:49
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1$\begingroup$ Sorry about that, clearly what I mean is there are 20 amino acids encoded by the genome. I will edit that. $\endgroup$ Commented Jun 28, 2021 at 10:13