Question

$6$p $23$ in chromosome nomenclature indicates band number.

• A. $6$ in short arm of chromosome $23$
• B. $3$ in region $2$ of short arm of chromosome $6$
• C. $3$ in region $2$ of long arm of chromosome $6$
• D. $6$ in long arm of chromosome $23$

Answer 1

The correct option is A $6$ in short arm of chromosome $23$

The combination of numbers and letters provide a gene's “address” on a chromosome. This address is made up of several parts:

-The chromosome on which the gene can be found. The first number or letter used to describe a gene's location represents the chromosome. Chromosomes 1 through 22 (the autosomes) are designated by their chromosome number. The sex chromosomes are designated by X or Y.

-The arm of the chromosome. Each chromosome is divided into two sections (arms) based on the location of a narrowing (constriction) called the centromere. By convention, the shorter arm is called p, and the longer arm is called q. The chromosome arm is the second part of the gene's address. For example, 5q is the long arm of chromosome 5, and Xp is the short arm of the X chromosome.

-The position of the gene on the p or q arm. The position of a gene is based on a distinctive pattern of light and dark bands that appear when the chromosome is stained in a certain way. The position is usually designated by two digits (representing a region and a band), which are sometimes followed by a decimal point and one or more additional digits (representing sub-bands within a light or dark area). The number indicating the gene position increases with distance from the centromere.

So, the correct option is 'A'