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Cassette Mutagenesis
Cassette mutagenesis is a type of site-directed mutagenesis that uses a short, double-stranded oligonucleotide sequence (gene cassette) to replace a fragment of target DNA. It uses complementary restriction enzyme digest ends on the target DNA and gene cassette to achieve specificity. It is different from methods that use single oligonucleotide in that a single gene cassette can contain multiple mutations. Unlike many site directed mutagenesis methods, cassette mutagenesis also does not involve primer extension by DNA polymerase. Mechanism First, restriction enzymes are used to cleave near the target sequence on DNA contained in a suitable vector. This step removes the target sequence and everything between the restriction sites. Then, the synthetic double stranded DNA containing the desired mutation and ends that are complementary to the restriction digest ends are ligated in place of the sequence removed. Finally, the resultant construct is sequenced to check that the targe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amino Acid
Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha amino acids appear in the genetic code. Amino acids can be classified according to the locations of the core structural functional groups, as Alpha and beta carbon, alpha- , beta- , gamma- or delta- amino acids; other categories relate to Chemical polarity, polarity, ionization, and side chain group type (aliphatic, Open-chain compound, acyclic, aromatic, containing hydroxyl or sulfur, etc.). In the form of proteins, amino acid ''residues'' form the second-largest component ( water being the largest) of human muscles and other tissues. Beyond their role as residues in proteins, amino acids participate in a number of processes such as neurotransmitter transport and biosynthesis. It is thought that they played a key role in enabling li ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Molecular Genetics
Molecular genetics is a sub-field of biology that addresses how differences in the structures or expression of DNA molecules manifests as variation among organisms. Molecular genetics often applies an "investigative approach" to determine the structure and/or function of genes in an organism's genome using genetic screens. The field of study is based on the merging of several sub-fields in biology: classical Mendelian inheritance, cellular biology, molecular biology, biochemistry, and biotechnology. Researchers search for mutations in a gene or induce mutations in a gene to link a gene sequence to a specific phenotype. Molecular genetics is a powerful methodology for linking mutations to genetic conditions that may aid the search for treatments/cures for various genetics diseases. History For molecular genetics to develop as a discipline, several scientific discoveries were necessary. The discovery of DNA as a means to transfer the genetic code of life from one c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genetics Techniques
Genetics is the study of genes, genetic variation, and heredity in organisms.Hartl D, Jones E (2005) It is an important branch in biology because heredity is vital to organisms' evolution. Gregor Mendel, a Moravian Augustinian friar working in the 19th century in Brno, was the first to study genetics scientifically. Mendel studied "trait inheritance", patterns in the way traits are handed down from parents to offspring over time. He observed that organisms (pea plants) inherit traits by way of discrete "units of inheritance". This term, still used today, is a somewhat ambiguous definition of what is referred to as a gene. Trait inheritance and molecular inheritance mechanisms of genes are still primary principles of genetics in the 21st century, but modern genetics has expanded to study the function and behavior of genes. Gene structure and function, variation, and distribution are studied within the context of the cell, the organism (e.g. dominance), and within the contex ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plasmid
A plasmid is a small, extrachromosomal DNA molecule within a cell that is physically separated from chromosomal DNA and can replicate independently. They are most commonly found as small circular, double-stranded DNA molecules in bacteria; however, plasmids are sometimes present in archaea and eukaryotic organisms. In nature, plasmids often carry genes that benefit the survival of the organism and confer selective advantage such as antibiotic resistance. While chromosomes are large and contain all the essential genetic information for living under normal conditions, plasmids are usually very small and contain only additional genes that may be useful in certain situations or conditions. Artificial plasmids are widely used as vectors in molecular cloning, serving to drive the replication of recombinant DNA sequences within host organisms. In the laboratory, plasmids may be introduced into a cell via transformation. Synthetic plasmids are available for procurement over the in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Expression Cloning
Expression cloning is a technique in DNA cloning that uses expression vectors to generate a library of clones, with each clone expressing one protein. This ''expression library'' is then screened for the property of interest and clones of interest are recovered for further analysis. An example would be using an expression library to isolate genes that could confer antibiotic resistance. Expression vectors Expression vectors are a specialized type of cloning vector in which the transcriptional and translational signals needed for the regulation of the gene of interest are included in the cloning vector. The transcriptional and translational signals may be synthetically created to make the expression of the gene of interest easier to regulate. Purpose Usually the ultimate aim of expression cloning is to produce large quantities of specific proteins. To this end, a bacterial expression clone may include a ribosome binding site ( Shine-Dalgarno sequence) to enhance translation o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mutagenesis (molecular Biology Technique)
In molecular biology, mutagenesis is an important laboratory technique whereby DNA mutations are deliberately engineered to produce libraries of mutant genes, proteins, strains of bacteria, or other genetically modified organisms. The various constituents of a gene, as well as its regulatory elements and its gene products, may be mutated so that the functioning of a genetic locus, process, or product can be examined in detail. The mutation may produce mutant proteins with interesting properties or enhanced or novel functions that may be of commercial use. Mutant strains may also be produced that have practical application or allow the molecular basis of a particular cell function to be investigated. Many methods of mutagenesis exist today. Initially, the kind of mutations artificially induced in the laboratory were entirely random using mechanisms such as UV irradiation. Random mutagenesis cannot target specific regions or sequences of the genome; however, with the development o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
M13 Bacteriophage
M13 is one of the Ff phages (fd and f1 are others), a member of the family filamentous bacteriophage ( inovirus). Ff phages are composed of circular single-stranded DNA ( ssDNA), which in the case of the m13 phage is 6407 nucleotides long and is encapsulated in approximately 2700 copies of the major coat protein p8, and capped with about 5 copies each of four different minor coat proteins (p3 and p6 at one end and p7 and p9 at the other end). The minor coat protein p3 attaches to the receptor at the tip of the F pilus of the host ''Escherichia coli''. The life cycle is relatively short, with the early phage progeny exiting the cell ten minutes after infection. Ff phages are chronic phage, releasing their progeny without killing the host cells. The infection causes turbid plaques in ''E. coli'' lawns, of intermediate opacity in comparison to regular lysis plaques. However, a decrease in the rate of cell growth is seen in the infected cells. M13 plasmids are used for many recombi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gene
In biology, the word gene (from , ; "... Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a basic unit of heredity and the molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protein-coding genes and noncoding genes. During gene expression, the DNA is first copied into RNA. The RNA can be directly functional or be the intermediate template for a protein that performs a function. The transmission of genes to an organism's offspring is the basis of the inheritance of phenotypic traits. These genes make up different DNA sequences called genotypes. Genotypes along with environmental and developmental factors determine what the phenotypes will be. Most biological traits are under the influence of polygenes (many different genes) as well as g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Regulatory Sequence
A regulatory sequence is a segment of a nucleic acid molecule which is capable of increasing or decreasing the expression of specific genes within an organism. Regulation of gene expression is an essential feature of all living organisms and viruses. Description In DNA, regulation of gene expression normally happens at the level of RNA biosynthesis ( transcription). It is accomplished through the sequence-specific binding of proteins (transcription factors) that activate or inhibit transcription. Transcription factors may act as activators, repressors, or both. Repressors often act by preventing RNA polymerase from forming a productive complex with the transcriptional initiation region ( promoter), while activators facilitate formation of a productive complex. Furthermore, DNA motifs have been shown to be predictive of epigenomic modifications, suggesting that transcription factors play a role in regulating the epigenome. In RNA, regulation may occur at the level of prote ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Codon
The genetic code is the set of rules used by living cells to translate information encoded within genetic material ( DNA or RNA sequences of nucleotide triplets, or codons) into proteins. Translation is accomplished by the ribosome, which links proteinogenic amino acids in an order specified by messenger RNA (mRNA), using transfer RNA (tRNA) molecules to carry amino acids and to read the mRNA three nucleotides at a time. The genetic code is highly similar among all organisms and can be expressed in a simple table with 64 entries. The codons specify which amino acid will be added next during protein biosynthesis. With some exceptions, a three-nucleotide codon in a nucleic acid sequence specifies a single amino acid. The vast majority of genes are encoded with a single scheme (see the RNA codon table). That scheme is often referred to as the canonical or standard genetic code, or simply ''the'' genetic code, though variant codes (such as in mitochondria) exist. History Ef ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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