What is a karyotype?

• A. A description of genes expressed in a cell
• B. A display of the chromosome pairs of a cell arranged by size and shape.
• C. The sequence of DNA nucleotides
• D. A map of metabolic pathways

Answer: (B)

A karyotype is a visual snapshot of a cell’s chromosomes, showing their number, size, and structure. Cells are prepared so the chromosomes are visible in their condensed form, then arranged in pairs from largest to smallest, matching homologous chromosomes by shape and pattern. This display lets you see if the chromosome count is correct and whether there are structural changes, such as extra or missing chromosomes or rearrangements. It’s not about which genes are active in the cell, nor about the exact DNA sequence or metabolic pathways. A typical human karyotype shows 46 chromosomes in 23 pairs.