How Does the DNA Chromosomes work?

DNA is the genetic material i.e. it contains the instructions to direct all the functions of cells. It performs its role by giving instructions for the synthesis of specifics proteins. Some proteins perform structural roles while the others act as enzymes to control all biochemical reaction of cells. In this way, where a cell does, is actually controlled by its DNA. It other words, DNA makes the characteristic or trait of cell or organism. Let us see how DNA is responsible for this

The traits are made by specific proteins. Specific proteins have specific number and sequence of their amino acids. DNA controls this sequence of amino acids by the sequence of its nucleotides. During protein synthesis, the sequence of DNA nucleotides decides that what will be the sequence of amino acids. For this purpose, the specific sequence of DNA nucleotides is copied in the form of messenger RNA nucleotides. This process is called transcription. The mRNA carries the sequence of its nucleotides to ribosome. The ribosome reads this sequence and joins specific amino acids, according to it, to form protein. This is known as translation.

The part of DNA that contains the instruction for the synthesis of a particular protein in known as a gene. DNA of each chromosome contains thousands of genes. Like chromosomes, genes also occur in pairs, one on each homologous chromosome. The location or positions of genes on chromosomes are known as loci (singular locus).

Each gene determines a particular trait in an organism. Each individual carries at least one pair of genes for each trait. For convenience, pairs of genes are represented by a letter or symbol. Both members of a gene pair may be the same in some individuals and different in others. It means that a gene exists in more than one alternate form.

When chromosomes separate during meiosis, alleles also separate and each gamete gets one of the two alleles. When gametes of both parents unite, the zygote receives one allele from each parent.