细胞功能测定

Mitochondrial genome integrity is an important issue in somatic mitochondrial genetics. Development of quantitative methods is indispensable to somatic mitochondrial genetics as quantitative studies are required to characterize heteroplasmy and mutation processes, ...

The ability to measure molar concentrations of deoxyribonucleoside 5′-triphosphates (dNTPs) within the mitochondrial matrix is important for several reasons. First, the spontaneous mutation rate for the mitochondrial genome is much higher than that for the nuclear genome, and dN ...

This exercise provides an introduction to the important techniques of microscale DNA isolation and analysis. Techniques such as these are central to modern molecular biology and provide an interesting contrast to the more traditional large-scale biochemical methodologies. The ...

This experiment introduces colony hybridization, a technique central to genetic engineering technology. Why this technique is so important can be seen by considering the following problem. A scientific group wishes to clone in bacteria a particular human chromosomal gene. There wou ...

The generation of recombinant clones usually involves joining together covalently (also called ligating) two or more restriction fragments. This can be done with the enzyme DNA ligase. There are two major sources of the enzyme: Escherichia, coli DNA ligase, which requires Mg2+ and NAD+ as cofa ...

Extraction of DNA or RNA fragments from agarose or acrylamide gels is an important tool in genetic engineering. A mixture of fragments can be separated by electrophoresis, and a particular fragment eluted and used for subsequent analysis or cloning.

The first preliminary characterization of any newly isolated DNA fragment usually involves restriction site mapping. For this, a family of bacterial enzymes called restriction endonucleases, or restriction enzymes, are utilized. These enzymes recognize specific sequences ...

It is no exaggeration to say that genetic engineering has been made possible by the discovery and isolation of enzymes that recognize specific nucleotide sequences in DNA and can cleave the DNA at a precise point within the sequence. These enzymes are known as Type II restriction endonucleases, a ...

A mutagen is any treatment or chemical substance that can induce heritable changes in genetic material and thereby increase mutation rates. For many decades scientists have been making use of such mutagens with aims as diverse as, on the one hand, increasing yields in strains used for commercial ...

A major limitation to the results that could be achieved using traditional methods in the study of microbial genetics has been the barriers to fusion that exist both between isolates belonging to different species, and also often between different isolates of the same species. Thus a scientif ...

The ability of microorganisms to adapt their enzyme complement in response to varying growth conditions has been established since the early years of this century. The experiments reported here use the unicellular green alga, Chlorella fusca, in a study of the induction of the enzyme isocit ...

Bacteria can vary their enzymic composition markedly when grown in different conditions. In particular, specific enzymes required to utilize a given carbon or nitrogen source are usually only present when they are essential for growth. Such enzymes are known as inducible. In contrast, so ...

This experiment introduces the student to two commonly used immunoelectrophoretic techniques; rocket immunoelectrophoresis, also known as electroimmunoassay, and 2-D immunoelectrophoresis.

Antibodies are globulin proteins produced by vertebrates in response to specific antigenic (immunogenic) challenge, and are a major feature of vertebrate immune defense against microbial disease. Antigens (immunogens) are substances capable of eliciting such responses bec ...

Plasmids first hit the scientific headlines when it was discovered that they are the means by which bacteria are able to transfer properties, such as resistance to an antibiotic, from one cell to another. It is now known that plasmids are circular, double-stranded molecules of non-chromosomal D ...

In 1950, Edman published a chemical method for the stepwise removal of amino acids from the N-terminus of a peptide (1). This series of reactions has come to be known as the Edman degradation, and although modifications of this technique have been introduced from time to time, the Edman degradation met ...

For many years Sephadex gel filtration of proteins has been a valuable tool for separating proteins on the basis of size difference. Sephadex is a bead-formed gel prepared by crosslinking dextran, and is available in a variety of G-types that differ in their degree of crosslinking (1). Depending on t ...

Protein blotting simply involves transferring separated protein bands from an acrylamide gel onto a more stable and immobilizing medium, such as nitrocellulose paper. Once transferred to the immobilizing medium, a variety of analytical procedures may be carried out on the proteins t ...

Isoelectric focusing (IEF) is an electrophoretic method for the separation of proteins, according to their isoelectric points (pI), in a stabilized pH gradient. The method involves casting a layer of polyacrylamide gel containing a mixture of carrier ampholytes (low-molecular-we ...

Polyacrylamide gel electrophoresis (PAGE) is a quick and sensitive method for analyzing the composition of mixtures of proteins. Since the early 1970s, this method has become a routine and frequently used analytical procedure in all protein chemistry laboratories, and as such, biology ...