Lost in Translation: The Effects of Mutations

If the genetic code is redundant and multiple codons code for the same amino acid, then a base change might not alter the protein. If the protein remains the same, then the mutation is classified as silent.

If some mutations provide an advantage, such as antibiotic resistance in bacteria or lactose tolerance in humans, then they are beneficial. If mutations can be beneficial, neutral, or harmful, then the statement that they are always harmful is false.

If a mutation changes an amino-acid-specifying codon into UAA, UAG, or UGA, then translation will terminate early. If translation ends too soon, then the resulting truncated protein is the result of a nonsense mutation.

If a mutation occurs in a non-critical area, then function may be preserved. If it occurs in the active site, then function may be lost or changed. However, if the molecule is a protein, then it cannot physically turn into DNA.

If the ribosome reads mRNA in strict triplets and one base is added or removed, then every subsequent triplet is grouped differently. If the groupings change, then every amino acid after the mutation point will likely be incorrect.

If the sixth codon of the beta-globin chain changes from GAG to GTG, then the amino acid Glutamic Acid is replaced by Valine. If this single change causes the protein to clump, then it results in the sickle shape of red blood cells.

If the genotype refers to the DNA sequence and the phenotype refers to the outward trait, then observing changes in the trait allows scientists to measure the physical consequences or effects of the mutation.

If a mutation occurs in a skin cell (somatic), then it stays with that individual. If a mutation occurs in a sperm or egg cell (germ-line), then it can be inherited by the next generation, allowing the trait to spread through the population.

If high-energy radiation or reactive chemicals physically break or alter the chemical structure of DNA, then they are mutagens. While radiation, smoke, and viruses can do this, pure water does not damage DNA structure.

If mutations create new versions of traits (alleles), then some individuals will be better suited to their environment than others. If the environment favors certain traits, then those individuals survive and pass on the mutated genes.

If a mutation increases the activity of an enzyme or allows a receptor to trigger without a signal, then the protein has acquired a new capability. This is logically defined as a gain-of-function.

If a point mutation changes the codon so that it represents a different amino acid (but not a stop codon), then the chemical properties of the protein may change. This specific "mistake" in the amino acid identity is a missense mutation.

If a mutation does not change the protein or occurs in an unused part of the genome, then it has no impact on fitness. If the impact on survival and reproduction is zero, then the effect is classified as neutral.

If a point mutation affects one gene, but a translocation moves an entire segment of a chromosome to a new location, then hundreds of genes may be disrupted or misplaced. If more genes are affected, then the overall impact on the organism is typically much larger.

If the mutation is in the promoter or enhancer rather than the coding sequence, then the "instructions" for the protein are fine, but the "volume knob" for the gene is broken. This is a regulatory mutation.

If the genetic code is degenerate at the third base of many codons, then changing that base often results in the same amino acid. If the amino acid stays the same, then the phenotypic effect of that mutation is minimized.

If a mutation is caused by an outside force rather than an internal replication error, then it is "induced." This includes environmental exposure and deliberate genetic engineering.

If a protein is slightly unstable due to a mutation, then it may work fine at 37°C but unfold at 40°C. If the mutation's impact depends on the environment, then it is a conditional mutation.

If the enzyme building the DNA strand can detect a mismatched base, then it can remove it and try again. If DNA polymerase performs this check, then it significantly reduces the number of permanent mutations.

If every individual in a population started with the exact same DNA, then there would be no variety for evolution to work with. If mutations create new alleles, then they provide the "raw material" that makes all biological diversity possible.