Genetics is the science of heredity and variation in living organisms. Knowledge that desired characteristics were inherited has been implicitly used since prehistoric times for improving crop plants and animals through selective breeding. However, the modern science of genetics, which seeks to understand the mechanisms of inheritance, only began with the work of Gregor Mendel in the mid-1800s.
The genetic information of cellular organisms is contained within the chemical structure of DNA (deoxyribonucleic acid) molecules. Individually inherited traits, corresponding to regions in the DNA sequence, are called genes. Genes encode the information necessary for synthesizing proteins-- complex molecules generally responsible for enzymatic reactions, synthesis, communication and structure within a cell. DNA sequence is transcribed into an intermediate RNA (ribonucleic acid) molecule, "messenger RNA", and ribosomes translate this sequence to form a chain of amino acids, thereby creating a protein molecule. It is through their proteins that most genes have a biological effect.
A variety of techniques exist for manipulating DNA in the laboratory. Restriction enzymes are a commonly used enzyme that cuts DNA at specific sequences, producing predictable fragments of DNA. The use of ligation enzymes allows these fragments to be stitched back together, and by ligating fragments of DNA together from different sources, researchers can recombinant DNA. Often associated with genetically modified organisms, recombinant DNA is commonly used in the context of plasmids -- short circular DNA fragments with a few genes on them. By inserting plasmids into bacteria and growing those bacteria on plates of agar (to isolate clones of bacteria cells), researchers can clonally amplify the inserted fragment of DNA. read more.....
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