explain why calix's cells having more dna than a normal cat meant point mutation was not the cause.

Calix’s cells having more DNA than a normal cat means that the change in his genome is large‑scale , so it cannot be explained by a tiny base‑level change like a point mutation.

Point mutation vs extra DNA

• A point mutation is a change in just one nucleotide (or a very small number of nucleotides) in the DNA sequence.

• Even if a base is substituted, inserted, or deleted, the total amount of DNA in the cell barely changes at all; you are altering the sequence , not adding whole chunks of DNA.

So, if point mutation were the cause of Calix’s condition, his cells would have essentially the same amount of DNA as a normal cat, just with a few letters changed.

What “more DNA” really implies

• When a lab finds that Calix’s cells have more DNA than a normal cat, that points to something like:
  • extra whole chromosomes (aneuploidy, such as XXY), or
  • duplications of big chromosome segments, or
  • a failure to split DNA properly during cell division (nondisjunction).

• These are chromosomal or large‑scale genome changes, which physically increase how much DNA is present, not just how it is spelled.

Because of this, the observation “Calix’s cells have more DNA than a normal cat” rules out a simple point mutation and instead supports a chromosomal‑level event (for male calicos, typically an XXY karyotype from nondisjunction) as the underlying cause.

TL;DR: A point mutation only changes a few DNA letters and does not meaningfully increase DNA quantity, but Calix’s cells clearly had extra DNA, which means a larger chromosomal change— not a point mutation—must be responsible.

Information gathered from public forums or data available on the internet and portrayed here.