What is the role of chromosomes and genes in the inheritance of traits?

Chromosomes are thread-like structures located inside the nucleus of animal and plant cells. Each chromosome is made of protein and a single molecule of deoxyribonucleic acid (DNA). DNA is the genetic make-up of an organism, it contains the specific instructions to make proteins to carry out cell processes in the body. A gene is a locus of DNA responsible for coding a functional RNA or protein product, and is the molecule of heredity, hence chromosomes comprise of genes. In somatic cells, there are two alleles or variant forms for every gene. In the production of gametes in the parent during the process of reproduction, meiosis takes place and each parent cell divides twice to produce four haploid gametes; each chromosome in the parent cell is replicated and the chromatids separated, one copy of an allele going into each one of the four daughter cells. In sexual reproduction, two gametes, one from each parent cell combines resulting in a fertilized egg cell that gives rise to the offspring. So the offspring cell has one copy of alleles from each parent. As traits are genetically determined characteristics, the offspring inherits traits from both the parents. However, the offspring has some unique traits that are not inherited, owing to independent assortment of chromosomes and crossing over during meiosis.