Discovering the Genome
Karyotyping is a visual tool that scientists use to identify and then study chromosomes in a sample of cells. Scientists prepare the cells during cell division when chromosomal strands have coiled together. The normal human karyotype consists of 46 chromosomes (23 pairs).
The pairs of chromosomes are called “ homologous” chromosomes. One chromosome comes from your mother and one from your father. They carry similar but not identical information.
Sometimes things go wrong during cell division and replication. When part of a chromosome is transferred to a non-homologous chromosome, it is called a “ translocation .” If no genetic material is gained or lost in the cell, a person will be unaffected, typically. This is called a “balanced translocation.” An “unbalanced translocation,” which can lead to genetic disorders, occurs when a chromosome with extra or missing genetic material is inherited from a parent with a balanced translocation.
Credit: National Cancer Institute [public domain] via Wikimedia Commons