Each and every human cell has a nucleus which is full of information coded in the form of DNA (deoxyribonucleic acid).
This DNA is organized into genes. Every chromosome contains thousands of genes, each with enough information for the production of one protein which can have a small or prominent effect. It may make all the difference between a person having brown or blue eyes, straight or curly hair, etc.
The moment egg is fertilized in the mother’s body, the genes start issuing instructions for the features of a new human being. Every feature that we inherit from our parents is passed on to us through the coding of the genes within the chromosomes.
Below Chromosomes info from Wikipedia (Read More):-
A chromosome is an organized structure of DNA and protein that is found in cells. It is a single piece of coiled DNA containing many genes, regulatory elements and other nucleotide sequences. Chromosomes also contain DNA-bound proteins, which serve to package the DNA and control its functions. The word chromosome comes from the Greek χρῶμα (chroma, color) and σῶμα (soma, body) due to their property of being very strongly stained by particular dyes. Chromosomes vary widely between different organisms. The DNA molecule may be circular or linear, and can be composed of 10,000 to 1,000,000,000[1] nucleotides in a long chain. Typically eukaryotic cells (cells with nuclei) have large linear chromosomes and prokaryotic cells (cells without defined nuclei) have smaller circular chromosomes, although there are many exceptions to this rule. Furthermore, cells may contain more than one type of chromosome; for example, mitochondria in most eukaryotes and chloroplasts in plants have their own small chromosomes.
http://en.wikipedia.org/wiki/Chromosome
