Are changes to the order of nucleotides in a segment of dna that codes for a protein.
proto-oncogenes
tumor suppressor genes
gene mutations
negative regulators

Gene mutations

Explanation:

Gene mutations are changes that happen within the structure of DNA, the hereditary material of life. Gene mutations occur by changes in the order of nucleotides in a DNA segment that encodes a protein.

Gene mutations are punctual and may originate through the addition, substitution or loss of nitrogenous bases in a portion of the DNA molecule, which causes a change in protein coding. A classic example of gene mutation is that which occurs in sickle cell anemia, where the deformation of the sickle-shaped red blood cell comes from the exchange of the glutamic amino acid by the hemoglobin-forming valine, which causes a clustering of this protein. In addition to altering the morphology of red blood cells, once the red blood cells are grouped, they block blood vessels, reducing tissue oxygenation and, consequently, causing the death of the individual.

the answer would be 2, if crossing over doesn’t occur 2 out of 4 of the daughter cells will have that allele.

hope this : )