(N/A) The relationship between genes and $DNA$ can be understood through mutations. Deletions or rearrangements in $DNA$ segments lead to loss or gain of gene function.
$1$. Point Mutation: $A$ classic example is the change in a single base pair in the gene for the $\beta$-globin chain,where $Glutamate$ is replaced by $Valine$,resulting in $Sickle$ $Cell$ $Anemia$.
$2$. Frame-shift Mutation: The insertion or deletion of one or two bases changes the reading frame from the point of mutation. For example,consider the sentence: $RAM$ $HAS$ $RED$ $CAP$. If we insert $B$ between $HAS$ and $RED$,it becomes $RAM$ $HAS$ $BRE$ $DCA$ $P$,which changes the entire sequence.
$3$. Insertion/Deletion of three or more bases: If bases are added or deleted in multiples of three,one or more $Amino$ $Acids$ are added or removed,but the reading frame remains unchanged after the site of mutation. This is referred to as frame-shift insertion or deletion mutation.