A gene is the basic physical and functional unit of heredity.
Gene are sequences of DNA nucleotides which code for the building of a polypeptide chain at the ribosome which will be folded into a protein inside the rough ER. Proteins are long chains of amino acids (polypeptide chains) that are folded into specific 3-D shapes and have certain functions within the body. Genes can code for proteins involved in producing different traits. Genes are arranged, one after another, on chromosomes, which are found in the cell nucleus and sometimes the mitochondria. Genes determine a persons traits. But did you know that only about 1 percent of DNA is made up of protein-coding genes. So what is the other 99% of DNA used for? The other 99% is called noncoding DNA or "junk DNA". Noncoding DNA does not provide instructions for making proteins. However, it is becoming clear that at least some of this "junk DNA" is essential to the function of cells, particularly the control of gene activity. For example, noncoding DNA contains sequences that act as regulatory elements, determining when and where genes are turned on and off. Noncoding DNA also has many other functions. Most genes are the same in all people, but a small number of genes (less than 1 percent of the total) are slightly different between people. Alleles are forms of the same gene that a slightly different versions. These small differences contribute to each person’s unique physical features. |
|