Question

How many amino acids are coded by a structural gene of 900 nucleotides?

Answer 1

The basic construction block of nucleic acids is a nucleotide.Polymers that are made of long nucleotide chains are RNA and DNA.A nucleotide consists of either ribose in RNA or deoxyribose in DNA, a sugar molecule bound to a phosphate group and a nitrogen-containing base.

Complete answer:
The nucleotides are made up of three subunit molecules: a nucleobase, a five-carbon sugar (ribose or deoxyribose) and a group of phosphates consisting of one or three phosphates. Guanine, adenine, cytosine and thymine are the four nucleobases in DNA; in RNA, uracil is used in place of thymine.

At a basic, cellular level, nucleotides also play a central role in metabolism.They provide chemical energy in the cell in the form of nucleoside triphosphates, adenosine triphosphate (ATP), guanosine triphosphate (GTP), cytidine triphosphate (CTP) and uridine triphosphate (UTP), for the many cellular functions that require energy, including the synthesis of amino acids, proteins and cell membranes, the movement of cells and pieces of cells (both internally and intracellularly), and for the cellular functions that require energy.

A codon is a DNA or RNA trinucleotide sequence that corresponds to a particular amino acid. The genetic code describes the relationship between a gene's sequence of DNA bases (A, C, G, and T) and the corresponding sequence of proteins it encodes. The cell reads the sequence of the gene inside groups of three bases.

For each particular amino acid, a codon codes and is constituted by a triplet of nucleotides, i.e. three nucleotides. Therefore we can assume that for one amino acid, three nucleotides can code.

Therefore for 900 nucleotides, we would make:
900 nucleotides/3 nucleotides per amino acids
which equals 300 amino acids.

Note: DNA and RNA molecules are written in the language of four nucleotides; 20 amino acids are also used in the language of proteins. Codons provide the key that enables the conversion of these two languages into one another. Each codon corresponds to a single amino acid (or stop signal), and the full set of codons is called the genetic code. The genetic code comprises 64 possible permutations, or variants, of the three-letter nucleotide sequence that can be made from the four nucleotides.