What is a karyotype?

A karyotype is defined as a photograph of pairs of homologous chromosomes in a cell. This technique is often used in genetics to examine the number and structure of chromosomes, providing insight into chromosomal abnormalities or genetic disorders. In a karyotype, chromosomes are typically arranged in pairs based on size, shape, and the position of the centromere, allowing for easy comparison and analysis.

Karyotyping is essential in medical diagnostics, as it helps identify conditions such as Down syndrome, which is caused by the presence of an extra chromosome 21. By visualizing the chromosomes, scientists and clinicians can determine whether the typical chromosomal number, which is 46 in humans (23 pairs), is maintained or if there are deviations.

In contrast, the other choices refer to different biological concepts: spindle fibers are involved in chromosome movement during cell division, a haploid cell contains only one set of chromosomes (like gametes), and a diploid organism has two sets of chromosomes, which does not specifically refer to the organization or visualization of chromosomes present in a karyotype. Therefore, identifying a karyotype as a photograph of homologous chromosomes accurately captures its definition and purpose in genetics.