What is a karyotype?

What is a karyotype?

• A. The number and visual appearance of the chromosomes in a cell.
• B. The sequence of nucleotides in a gene.
• C. The full set of proteins expressed in a cell.
• D. The order of genes along a chromosome.

Answer: (A)

A karyotype refers to the number and visual appearance of the chromosomes in a cell. It is created by preparing cells in metaphase, staining them, and arranging the chromosomes in pairs by size and banding pattern so you can see their number and structure. This helps detect abnormalities such as extra or missing chromosomes or structural rearrangements, like translocations or deletions. For example, a karyotype can reveal trisomy 21, which is associated with Down syndrome. This concept is different from the nucleotide sequence of a gene (that’s the genetic code itself), the full set of proteins a cell expresses (the proteome), or the order of genes along a chromosome (a gene map). Those describe DNA sequence, expressed proteins, or gene organization, respectively, rather than the visible chromosomal complement.

A karyotype refers to the number and visual appearance of the chromosomes in a cell. It is created by preparing cells in metaphase, staining them, and arranging the chromosomes in pairs by size and banding pattern so you can see their number and structure. This helps detect abnormalities such as extra or missing chromosomes or structural rearrangements, like translocations or deletions. For example, a karyotype can reveal trisomy 21, which is associated with Down syndrome.

This concept is different from the nucleotide sequence of a gene (that’s the genetic code itself), the full set of proteins a cell expresses (the proteome), or the order of genes along a chromosome (a gene map). Those describe DNA sequence, expressed proteins, or gene organization, respectively, rather than the visible chromosomal complement.