Changes to short stretches of nucleotides are called gene-level mutations, because these mutations affect the specific genes that provide instructions for various functional molecules, including ...

How could a "bad" gene-- the mutation that causes the sometimes lethal sickle cell disease -- also be beneficial? On the other hand, if it didn't provide some survival advantage, why had the ...

In other words, mutations occur randomly with respect to whether their effects are useful. Thus, beneficial DNA changes do not happen more often simply because an organism could benefit from them.

While most known types of DNA damage are fixed by our cells' in-house DNA repair mechanisms, some forms of DNA damage evade repair and can persist for many years, new research shows. This means that ...