Question

What are the two types of DNA mutations?

Answer 1

Deletions and insertions.

Explanation:

There are actually three, but I'll describe these two because they tend to be more impactful in terms of an effect on the actual genetic sequence.

Deletion: exactly what it sounds like. A nucleotide is essentially just taken out of the DNA sequence. This is pretty impactful because it completely changes the order of the sequence. I can make an analogy to a sentence:
"Hello how are you?"
If I delete the first letter:
"Elloh owa rey ou?"
DNA works in sequences of three nucleotides, which is comparable to the spaces in the sentence. Just deleting one letter completely changed it.

Insertion: Inserting a nucleotide into a sequence. I'll do the sentence thing again:
"Hello how are you?"
If I insert a letter into the sentence but keep the spaces the same:
"Hello who war eyo u?" (I inserted a "w" before the word "how").

Both of these are especially impactful because if the order of a DNA sequence changes, often the stop codon that ends the sequence will not exist anymore, and a new stop codon will emerge earlier in the sequence or much later in the DNA strand.

A third is substitution, where one nucleotide gets replaced by another. Since you can make the same codon with multiple sequences of nucleotides, this often actually has no impact on a DNA sequence, or it only changes one part of it, but doesn't drastically impact the protein that the DNA will make.