What is the meaning of genetic code?
The genetic code is the set of rules used by living cells to translate information encoded within genetic material (DNA or mRNA sequences) into proteins. The code defines how sequences of nucleotide triplets, called codons, specify which amino acid will be added next during protein synthesis.
The genome of an organism is inscribed in DNA, or in some viruses RNA. The portion of the genome that codes for a protein or an RNA is referred to as a gene. Those genes that code for proteins are composed of tri-nucleotide units called codons, each coding for a single amino acid.
- Acquired (or somatic) mutations occur at some time during a person's life and are present only in certain cells, not in every cell in the body. These changes can be caused by environmental factors such as ultraviolet radiation from the sun, or can occur if an error is made as DNA copies itself during cell division.
- Genetic Code. stored on one of the two strands of a DNA molecules as a linear, non-overlapping sequence of the nitrogenous bases Adenine (A), Guanine (G), Cytosine (C) and Thymine (T).
- The vast majority of living organisms encode their genes in long strands of DNA (deoxyribonucleic acid). DNA consists of a chain made from four types of nucleotide subunits, each composed of: a five-carbon sugar (2'-deoxyribose), a phosphate group, and one of the four bases adenine, cytosine, guanine, and thymine.
Genetic code, the sequence of nucleotides in deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) that determines the amino acid sequence of proteins. Though the linear sequence of nucleotides in DNA contains the information for protein sequences, proteins are not made directly from DNA.
- DNA carries all of the information for your physical characteristics, which are essentially determined by proteins. So, DNA contains the instructions for making a protein. In DNA, each protein is encoded by a gene (a specific sequence of DNA nucleotides that specify how a single protein is to be made).
- Theoretically, the genetic code is universal. This means that the same codon "means" the same amino acid in all organisms. For example, in both humans and bacteria, a codon made of three thymine DNA-letters will code for an amino acid called Phenylalanine. There are about twenty amino acids, and about 64 codons.
- The start codon is the first codon of a messenger RNA (mRNA) transcript translated by a ribosome. The start codon always codes for methionine in eukaryotes and a modified Met (fMet) in prokaryotes. The most common start codon is AUG. The start codon is often preceded by a 5' untranslated region (5' UTR).
Key Features of the Genetic Code
- 61 codons code for 20 amino acids.
- Three codons do not code for any amino acids.
- Each codon codes for only one amino acid, hence, it is unambiguous and specific.
- Some amino acids are coded for by more than one codon, hence the genetic code is degenerate.
- A protein is a chain of amino acids connected together. You can think of this like a beaded necklace. The beads (amino acids) are connected together by a string (bond), which forms a long chain (protein). Therefore, a protein is "intact" or "whole."
- Carbohydrates, proteins, and fats are digested in the intestine, where they are broken down into their basic units: Carbohydrates into sugars. Proteins into amino acids. Fats into fatty acids and glycerol.
- Proteins are made up of smaller building blocks called amino acids, joined together in chains. There are 20 different amino acids. Some proteins are just a few amino acids long, while others are made up of several thousands. These chains of amino acids fold up in complex ways, giving each protein a unique 3D shape.
Updated: 20th September 2018