Final answer:
Human cells contain 46 chromosomes in 23 pairs, half inherited from each parent. These include autosomal chromosomes and one pair of sex chromosomes, which determine the individual's sex. Genes on these chromosomes code for proteins and express traits that form the person's genotype and phenotype.
Step-by-step explanation:
Each human cell typically contains 46 chromosomes, which are arranged in 23 pairs. These pairs are comprised of one set of 23 chromosomes inherited from the mother and an equivalent set from the father. Thus, each parent contributes one chromosome to each of the 23 pairs. In these pairs, one is the sex chromosome pair (XX in females and XY in males), which determines the sex of the individual.
The other 22 pairs are known as autosomal chromosomes that carry the majority of genetic material. Each chromosome contains thousands of genes, sequences of DNA that instruct the cellular creation of proteins. Genes express traits that can be physical, behavioral, or biochemical and are classified as part of the individual's genotype, which becomes evident in the phenotype.
The haploid gametes (sperm and egg cells) contain only one set of 23 chromosomes. During fertilization, they merge to form a diploid cell with 46 chromosomes. Each chromosome in the resulting zygote is part of a homologous pair, where homologous chromosomes are of the same length and have the same loci for genes coding for the same traits but possibly different alleles or variations.