The scientific term for a change in an organism's genetic material is called a mutation. Mutations can occur due to various factors, including errors during DNA replication, exposure to environmental mutagens, or spontaneous changes. These alterations can affect a single nucleotide (point mutations) or larger segments of DNA (deletions, insertions, duplications). Some mutations have no effect, while others can lead to changes in phenotype, contribute to evolution, or cause genetic disorders, making them a critical area of study in genetics and evolution.