Final answer:
Chromosomes are structures within the nucleus containing DNA, which is responsible for hereditary traits like eye and hair color. Each chromosome consists of genes that control these traits through variations called alleles. Humans have approximately 22,000 genes distributed across 46 chromosomes.
Step-by-step explanation:
The subject of this question is a chromosome, which is a twisted and coiled strand of DNA located within the nucleus that carries codes for reproductive traits such as eye and hair color. Chromosomes are made up of deoxyribonucleic acid (DNA), which is a double helix-shaped molecule consisting of nucleotide base pairs. Each chromosome houses sequences of DNA that are organized into genes, responsible for controlling or partially controlling various visible traits. These traits are determined by different alleles, which are specific versions of a gene.
During cell division, chromatin, which is DNA wrapped around proteins called histones, condenses into chromosomes. This ensures the safe transport of DNA to daughter cells. Humans have around 22,000 genes located on 46 chromosomes in almost every cell. The unique sequence of nucleotides within these genes encodes the genetic instructions essential for building and maintaining the body.