Essential Molecular Biology and Genetic Engineering Terms
Genomics and Cloning Vectors
Genomic Libraries
A genomic library is a set of clones, each of which contains a fragment of a genome of a given organism.
Cosmids
Cosmids are cloning vectors which have been widely used in the preparation of large-sized genomic DNA libraries, allowing the introduction of DNA inserts up to 45 kb.
Yeast Artificial Chromosomes (YACs)
Yeast Artificial Chromosomes (YACs) are part of cloning vectors that maintain high capacity; in fact, they have the highest capacity (200 kb - 3,000 kb). A YAC is a vector meant to mimic the characteristics of a normal chromosome of a yeast (eukaryote), carrying a centromere and telomere terminals.
Expression Vectors
An expression vector is a bacterial or yeast plasmid used to produce clones of a gene of interest and, in turn, produce the protein for which the insert encodes. For this to be possible, once the insert is "connected" to this vector and introduced into a cell, it is qualified to transfer to successive generations.
Enzymes and Molecular Processes
DNA Polymerase
DNA polymerase is an enzyme that catalyzes the synthesis of DNA from deoxyribonucleotides using a DNA molecule template or mold that is to be replicated.
Klenow DNA Polymerase
Klenow DNA polymerase is a large protein fragment produced by the enzymatic processing of DNA polymerase I from E. coli using the protease subtilisin.
DNA Replication
Replication is the mechanism that allows DNA to double (i.e., synthesize an identical copy).
Transcription Factors
A transcription factor is a protein involved in regulating DNA transcription, but it is not part of the RNA polymerase. Transcription factors may act by recognizing and binding to specific DNA sequences, joining other factors, or by binding directly to RNA polymerase.
Okazaki Fragments
Okazaki fragments are fragments of DNA that are the result of DNA synthesis on the discontinuous strand. These are synthesized in the 5' to 3' direction but discontinuously.
RNA and Protein Synthesis
The 5' Cap
The 5' cap is a modified guanine nucleotide.
RNA Correction and Editing
RNA correction (editing) introduces changes in the proteins encoded by the mRNA (e.g., splicing).
Ribosomes
Ribosomes are supramolecular complexes responsible for synthesizing proteins from the genetic information of DNA that reaches them in the form of transcribed messenger RNA (mRNA).
Ribozymes
Ribozymes have activity based on the transesterification and hydrolysis of the phosphodiester bond.
Selenocysteine
Selenocysteine is present in the mRNA and is encoded by UGA nitrogenous bases.
Mutagenesis and Genetic Engineering
Mutagenesis
In genetics, mutagenesis is the production of mutations on DNA, whether cloned or not.
Mutagens
A mutagen is a physical or chemical agent that alters or changes the genetic information (usually DNA) of an organism and thus increases the frequency of mutations above the natural level.
Transgenic Organisms
A transgenic organism is one that has had its genetic material (genome) altered by artificial introduction through genetic engineering.
Polymerase Chain Reaction (PCR)
The Polymerase Chain Reaction (PCR) is a method for obtaining a large number of copies of a particular DNA fragment, assuming a minimum amount—enough, in theory, from a single copy of the original fragment or mold.
Gene Therapy
Gene therapy consists of inserting genes into the cells or tissues of an individual to treat diseases in general, and hereditary diseases in particular, as well as to perform genetic marking.