Molecular biology is the study of biology at a molecular level. Foundations of modern biology There are five unifying principles In Chemistry, a molecule is defined as a sufficiently stable electrically neutral group of at least two Atoms in a definite arrangement held together by The field overlaps with other areas of biology and chemistry, particularly genetics and biochemistry. Foundations of modern biology There are five unifying principles Chemistry (from Egyptian kēme (chem meaning "earth") is the Science concerned with the composition structure and properties Genetics (from Ancient Greek grc-Latn genetikos, “genitive” and that from grc-Latn genesis, “origin” a discipline of Biology, is Biochemistry is the study of the chemical processes in living Organisms It deals with the Structure and function of cellular components such as Molecular biology chiefly concerns itself with understanding the interactions between the various systems of a cell, including the interactions between DNA, RNA and protein biosynthesis and learning how these interactions are regulated. Deoxyribonucleic acid ( DNA) is a Nucleic acid that contains the genetic instructions used in the development and functioning of all known Ribonucleic acid ( RNA) is a Nucleic acid that consists of a long chain of Nucleotide units Protein biosynthesis (synthesis is the process in which cells build Proteins The term is sometimes used to refer only to protein translation but more
". Nature is a prominent Scientific journal, first published on 4 November 1869 William Thomas Astbury FRS (Bill Astbury 25 February, 1898 &mdash 4 June, 1961) was an English Physicist and . . not so much a technique as an approach, an approach from the viewpoint of the so-called basic sciences with the leading idea of searching below the large-scale manifestations of classical biology for the corresponding molecular plan. It is concerned particularly with the forms of biological molecules and . . . . . is predominantly three-dimensional and structural - which does not mean, however, that it is merely a refinement of morphology - it must at the same time inquire into genesis and function. " 
Researchers in molecular biology use specific techniques native to molecular biology (see Techniques section later in article), but increasingly combine these with techniques and ideas from genetics and biochemistry. Genetics (from Ancient Greek grc-Latn genetikos, “genitive” and that from grc-Latn genesis, “origin” a discipline of Biology, is Biochemistry is the study of the chemical processes in living Organisms It deals with the Structure and function of cellular components such as There is not a defined line between these disciplines. The following figure is a schematic that depicts one possible view of the relationship between the fields:
Much of the work in molecular biology is quantitative, and recently much work has been done at the interface of molecular biology and computer science in bioinformatics and computational biology. Bioinformatics is the application of information technology to the field of molecular biology Computational biology is an interdisciplinary field that applies the techniques of Computer science, Applied mathematics, and Statistics to address problems As of the early 2000s, the study of gene structure and function, molecular genetics, has been amongst the most prominent sub-field of molecular biology. Molecular genetics is the field of Biology which studies the structure and function of Genes at a molecular level
Increasingly many other fields of biology focus on molecules, either directly studying their interactions in their own right such as in cell biology and developmental biology, or indirectly, where the techniques of molecular biology are used to infer historical attributes of populations or species, as in fields in evolutionary biology such as population genetics and phylogenetics. See also List of basic cell biology topics. Cell biology (also called cellular biology or formerly cytology, from the Developmental Biology is the official journal of the Society for Developmental Biology. In Biology a population is the collection of inter-breeding organisms of a particular Species; in Sociology In Biology, a species is one of the basic units of Biological classification and a Taxonomic rank. eVolution is the third Album by eLDee, it was due to be released in 2008 Population genetics is the study of the Allele frequency distribution and change under the influence of the four evolutionary forces Natural selection, Genetic There is also a long tradition of studying biomolecules "from the ground up" in biophysics. A biomolecule is any organic Molecule that is produced by living Organisms including large Polymeric molecules such as Proteins Biophysics (also biological physics) is an Interdisciplinary Science that employs and develops theories and methods of the Physical sciences for
Since the late 1950s and early 1960s, molecular biologists have learned to characterize, isolate, and manipulate the molecular components of cells and organisms. These components include DNA, the repository of genetic information; RNA, a close relative of DNA whose functions range from serving as a temporary working copy of DNA to actual structural and enzymatic functions as well as a functional and structural part of the translational apparatus; and proteins, the major structural and enzymatic type of molecule in cells. Deoxyribonucleic acid ( DNA) is a Nucleic acid that contains the genetic instructions used in the development and functioning of all known Ribonucleic acid ( RNA) is a Nucleic acid that consists of a long chain of Nucleotide units Proteins are large Organic compounds made of Amino acids arranged in a linear chain and joined together by Peptide bonds between the Carboxyl In Chemistry, a molecule is defined as a sufficiently stable electrically neutral group of at least two Atoms in a definite arrangement held together by The cell is the structural and functional unit of all known living Organisms It is the smallest unit of an organism that is classified as living and is often called
One of the most basic techniques of molecular biology to study protein function is 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 In this technique, DNA coding for a protein of interest is cloned (using PCR and/or restriction enzymes) into a plasmid (known as an expression vector). Molecular cloning refers to the procedure of isolating a defined DNA sequence and obtaining multiple copies of it In vivo. A restriction enzyme (or restriction Endonuclease) is an Enzyme that cuts double-stranded DNA at specific recognition Nucleotide A plasmid is an extra-chromosomal DNA molecule separate from the chromosomal DNA which is capable of replicating independently of the chromosomal DNA An expression vector, otherwise known as an expression construct, is generally a Plasmid that is used to introduce and express a specific Gene into a target This plasmid may have special promoter elements to drive production of the protein of interest, and may also have antibiotic resistance markers to help follow the plasmid. In Biology, a promoter is a region of DNA that facilitates the transcription of a particular Gene. Antibiotic resistance is the ability of a Microorganism to withstand the effects of Antibiotics. A selectable marker is a Gene introduced into a cell, especially a Bacterium or to cells in culture, that confers a trait suitable for Artificial
This plasmid can be inserted into either bacterial or animal cells. Introducing DNA into bacterial cells can be done by transformation (via uptake of naked DNA), conjugation (via cell-cell contact) or by transduction (via viral vector). In Molecular biology, transformation is the genetic alteration of a cell resulting from the uptake genomic incorporation and expression of foreign Bacterial conjugation is the transfer of genetic material between bacteria through direct cell-to-cell contact Transduction is the process by which DNA is transferred from one Bacterium to another by a Virus. Introducing DNA into eukaryotic cells, such as animal cells, by physical or chemical means is called transfection. Animals Plants fungi, and Protists are eukaryotes (juːˈkærɪɒt or -oʊt Organisms whose cells are organized into complex Transfection is the process of introducing nucleic acids into cells by non-viral methods. Several different transfection techniques are available, such as calcium phosphate transfection,electroporation, microinjection and liposome transfection. Electroporation, or electropermeabilization, is a significant increase in the Electrical conductivity and permeability of the cell plasma membrane caused New gene transfer methodsMicroinjection genes by injection A procedure that is now almost routine with animal cells and in medicine has so far proved very difficult with plant cells the direct Lipofection (or Liposome Transfection) is a technique used to inject genetic material into a cell by means of liposomes which are vesicles that can easily merge with DNA can also be introduced into eukaryotic cells using viruses or bacteria as carriers, the latter is sometimes called bactofection and in particular uses Agrobacterium tumefaciens. Agrobacterium tumefaciens is the causal agent of Crown Gall disease (the formation of Tumours in over 140 species of Dicot. The plasmid may be integrated into the genome, resulting in a stable transfection, or may remain independent of the genome, called transient transfection.
In either case, DNA coding for a protein of interest is now inside a cell, and the protein can now be expressed. A variety of systems, such as inducible promoters and specific cell-signaling factors, are available to help express the protein of interest at high levels. Large quantities of a protein can then be extracted from the bacterial or eukaryotic cell. The protein can be tested for enzymatic activity under a variety of situations, the protein may be crystallized so its tertiary structure can be studied, or, in the pharmaceutical industry, the activity of new drugs against the protein can be studied. In Biochemistry and Chemistry, the tertiary structure of a Protein or any other Macromolecule is its three-dimensional structure as defined
The polymerase chain reaction is an extremely versatile technique for copying DNA. In brief, PCR allows a single DNA sequence to be copied (millions of times), or altered in predetermined ways. For example, PCR can be used to introduce restriction enzyme sites, or to mutate (change) particular bases of DNA, the latter is a method referred to as "Quick change". PCR can also be used to determine whether a particular DNA fragment is found in a cDNA library. In Genetics, complementary DNA ( cDNA) is DNA synthesized from a mature MRNA template in a reaction catalyzed by the enzyme Reverse In Molecular biology, a library is a collection of molecules in a stable form that represents some aspect of an organism PCR has many variations, like reverse transcription PCR (RT-PCR) for amplification of RNA, and, more recently, real-time PCR (QPCR) which allow for quantitative measurement of DNA or RNA molecules. In Molecular biology, reverse transcription polymerase chain reaction (RT-PCR is a Laboratory technique for amplifying a defined piece of a Ribonucleic In Molecular biology, real-time polymerase chain reaction, also called quantitative real time polymerase chain reaction (qPCR or kinetic polymerase chain reaction
Gel electrophoresis is one of the principal tools of molecular biology. The basic principle is that DNA, RNA, and proteins can all be separated by means of an electric field. In agarose gel electrophoresis, DNA and RNA can be separated on the basis of size by running the DNA through an agarose gel. Agarose Gel electrophoresis is a method used in Biochemistry and Molecular biology to separate DNA, or RNA molecules by size Proteins can be separated on the basis of size by using an SDS-PAGE gel, or on the basis of size and their electric charge by using what is known as a 2D gel electrophoresis. SDS-PAGE, Sodium dodecyl sulfate Polyacrylamide gel Electrophoresis, is a technique widely used in Biochemistry, forensics Electric charge is a fundamental conserved property of some Subatomic particles which determines their Electromagnetic interaction. Two-dimensional gel electrophoresis, abbreviated as 2-DE or 2-D electrophoresis, is a form of Gel electrophoresis commonly used to analyze proteins
Named after its inventor, biologist Edwin Southern, the Southern blot is a method for probing for the presence of a specific DNA sequence within a DNA sample. A Southern blot is a method routinely used in Molecular biology to check for the presence of a DNA sequence in a DNA sample Professor Sir Edwin Mellor Southern, FRS (born 1938) is a 2005 Lasker Award -winning molecular biologist His award is for the invention A Southern blot is a method routinely used in Molecular biology to check for the presence of a DNA sequence in a DNA sample DNA samples before or after restriction enzyme digestion are separated by gel electrophoresis and then transferred to a membrane by blotting via capillary action. A restriction enzyme (or restriction Endonuclease) is an Enzyme that cuts double-stranded DNA at specific recognition Nucleotide Capillary action, capillarity, capillary motion, or wicking is the ability of a substance to draw another substance into it The membrane is then exposed to a labeled DNA probe that has a complement base sequence to the sequence on the DNA of interest. Most original protocols used radioactive labels, however non-radioactive alternatives are now available. Southern blotting is less commonly used in laboratory science due to the capacity of other techniques, such as PCR, to detect specific DNA sequences from DNA samples. These blots are still used for some applications, however, such as measuring transgene copy number in transgenic mice, or in the engineering of gene knockout embryonic stem cell lines. A transgene is a Gene or genetic material that has been transferred by any of a number of Genetic engineering techniques from one organism to another This article is about organisms which have been genetically modified A gene knockout is a genetic technique in which an organism is engineered to carry genes that have been made inoperative (have been "knocked out" of the organism A stem cell line is a family of constantly-dividing cells the product of a single parent group of Stem cells.
The northern blot is used to study the expression patterns a specific type of RNA molecule as relative comparison among of a set of different samples of RNA. The northern blot is a technique used in Molecular biology research to study Gene expression. The northern blot is a technique used in Molecular biology research to study Gene expression. It is essentially a combination of denaturing RNA gel electrophoresis, and a blot. A denaturing gel is a type of Electrophoresis in which the native structure of Macromolecules that are run within the gel is not maintained In Molecular biology and Genetics, a blot is a method of transferring Proteins DNA or RNA, onto a carrier (for example a Nitrocellulose In this process RNA is separated based on size and is then transferred to a membrane that is then probed with a labeled complement of a sequence of interest. In Molecular biology, complementarity is a property of double-stranded Nucleic acids such as DNA and RNA as well as DNARNA duplexes The results may be visualized through a variety of ways depending on the label used; however, most result in the revelation of bands representing the sizes of the RNA detected in sample. The intensity of these bands is related to the amount of the target RNA in the samples analyzed. The procedure is commonly used to study when and how much gene expression is occurring by measuring how much of that RNA is present in different samples. It is one of the most basic tools for determining at what time, and under what conditions, certain genes are expressed in living tissues.
Antibodies to most proteins can be created by injecting small amounts of the protein into an animal such as a mouse, rabbit, sheep, or donkey (polyclonal antibodies)or produced in cell culture (monoclonal antibodies). The western blot (alternatively immunoblot) is an Analytical technique used to detect specific Proteins in a given sample of tissue homogenate or Antibodies (also known as immunoglobulins, abbreviated Ig) are Gamma globulin Proteins that are found in Blood or other Bodily Proteins are large Organic compounds made of Amino acids arranged in a linear chain and joined together by Peptide bonds between the Carboxyl Polyclonal antibodies (or antisera are antibodies that are derived from different B cell lines Monoclonal antibodies ( mAb or moAb) are monospecific antibodies that are identical because they are produced by one type of immune cell These antibodies can be used for a variety of analytical and preparative techniques.
In western blotting, proteins are first separated by size, in a thin gel sandwiched between two glass plates in a technique known as SDS-PAGE (sodium dodecyl sulfate polyacrylamide gel electrophoresis). The western blot (alternatively immunoblot) is an Analytical technique used to detect specific Proteins in a given sample of tissue homogenate or SDS-PAGE, Sodium dodecyl sulfate Polyacrylamide gel Electrophoresis, is a technique widely used in Biochemistry, forensics Sodium lauryl sulfate ( SLS) or sodium dodecyl sulfate ( SDS or NaDS ( C 12 H 25 S[[oxygen O]]4 The proteins in the gel are then transferred to a PVDF, nitrocellulose, nylon or other support membrane. This membrane can then be probed with solutions of antibodies. Antibodies that specifically bind to the protein of interest can then be visualized by a variety of techniques, including colored products, chemiluminescence, or autoradiography. Chemiluminescence (sometimes " chemoluminescence " is the emission of Light ( Luminescence) with limited emission of heat as the result of a chemical An autoradiograph is an image on an X-ray film or nuclear emulsion produced by the pattern of decay emissions (e Often, the antibodies are labeled with an enzymes. When a chemiluminescent substrate is exposed to the enzyme it allows detection. Chemiluminescence (sometimes " chemoluminescence " is the emission of Light ( Luminescence) with limited emission of heat as the result of a chemical Enzymes are Biomolecules that catalyze ( ie increase the rates of Chemical reactions Almost all enzymes are Proteins Using western blotting techniques allows not only detection but also quantitative analysis.
Analogous methods to western blotting can be used to directly stain specific proteins in live cells or tissue sections. The cell is the structural and functional unit of all known living Organisms It is the smallest unit of an organism that is classified as living and is often called Tissue is a cellular organizational level intermediate between cells and a complete organism However, these immunostaining methods, such as FISH, are used more often in cell biology research. Immunostaining is a general term in Biochemistry that applies to any use of an Antibody -based method to detect a specific Protein in a sample FISH ( Fluorescent In situ hybridization) is a cytogenetic technique that can be used to detect and localize the presence or absence See also List of basic cell biology topics. Cell biology (also called cellular biology or formerly cytology, from the
The terms "western" and "northern" are molecular biology jokes that play on the term southern blot. The first blots were with DNA, and since they were done by Ed Southern, they came to be known as Southerns. Patricia Thomas, inventor of the RNA blot, which became known as a "northern", actually didn't use the term. . To carry the joke further, one can find reference in the literature to "southwesterns" (Protein-DNA interactions) and "farwesterns" (Protein-Protein interactions). PubMed is a free search engine for accessing the MEDLINE database of citations and abstracts of biomedical research articles
A DNA array is a collection of spots attached to a solid support such as a microscope slide where each spot contains one or more single-stranded DNA oligonucleotide fragment. For terminology see glossary below A DNA microarray is a High-throughput technology used in Molecular biology and in Deoxyribonucleic acid ( DNA) is a Nucleic acid that contains the genetic instructions used in the development and functioning of all known A microscope slide was originally a 'slider' made of ivory or bone containing specimens held between disks of transparent mica An oligonucleotide (or oligo) is a short segment of RNA or DNA, typically with twenty or fewer bases. Arrays make it possible to put down a large quantity of very small (100 micrometre diameter) spots on a single slide. Each spot has a DNA fragment molecule that is complementary to a single DNA sequence (similar to Southern blotting). A variation of this technique allows the gene expression of an organism at a particular stage in development to be qualified (expression profiling). Gene expression is the process by which inheritable information from a Gene, such as the DNA sequence, is made into a functional Gene product, such In this technique the RNA in a tissue is isolated and converted to labeled cDNA. In Genetics, complementary DNA ( cDNA) is DNA synthesized from a mature MRNA template in a reaction catalyzed by the enzyme Reverse This cDNA is then hybridized to the fragments on the array and visualization of the hybridization can be done. Since multiple arrays can be made with the exact same position of fragments they are particularly useful for comparing the gene expression of two different tissues, such as a healthy and cancerous tissue. Also, one can measure what genes are expressed and how that expression changes with time or with other factors. For instance, the common baker's yeast, Saccharomyces cerevisiae, contains about 7000 genes; with a microarray, one can measure qualitatively how each gene is expressed, and how that expression changes, for example, with a change in temperature. Yeasts are a growth form of eukaryotic Microorganisms classified in the kingdom Fungi, with about 1500 Species currently described Saccharomyces cerevisiae is a Species of Budding Yeast. It is perhaps the most useful Yeast owing to its use since ancient times There are many different ways to fabricate microarrays; the most common are silicon chips, microscope slides with spots of ~ 100 micrometre diameter, custom arrays, and arrays with larger spots on porous membranes (macroarrays). There can be anywhere from 100 spots to more than 10,000 on a given array.
Arrays can also be made with molecules other than DNA. For example, an antibody array can be used to determine what proteins or bacteria are present in a blood sample. Antibodies (also known as immunoglobulins, abbreviated Ig) are Gamma globulin Proteins that are found in Blood or other Bodily Proteins are large Organic compounds made of Amino acids arranged in a linear chain and joined together by Peptide bonds between the Carboxyl The Bacteria ( singular: bacterium) are a large group of unicellular Microorganisms Typically a few Micrometres in length bacteria have
Allele specific oligonucleotide (ASO) is a technique that allows detection of single base mutations without the need for PCR or gel electrophoresis. An Allele Specific Oligonucleotide (or ASO) is a short piece of synthetic DNA complementary to the sequence of a variable target DNA Short (20-25 nucleotides in length), labeled probes are exposed to the non-fragmented target DNA. Hybridization occurs with high specificity due to the short length of the probes and even a single base change will hinder hybridization. The target DNA is then washed and the labeled probes that didn't hybridize are removed. The target DNA is then analyzed for the presence of the probe via radioactivity or fluorescence. In this experiment, as in most molecular biology techniques, a control must be used to ensure successful experimentation.
As new procedures and technology become available, the older technology is rapidly abandoned. A good example is methods for determining the size of DNA molecules. Prior to gel electrophoresis (agarose or polyacrylamide) DNA was sized with rate sedimentation in sucrose gradients, a slow and labor intensive technology requiring expensive instrumentation; prior to sucrose gradients, viscometry was used. Agarose Gel electrophoresis is a method used in Biochemistry and Molecular biology to separate DNA, or RNA molecules by size SDS-PAGE, Sodium dodecyl sulfate Polyacrylamide gel Electrophoresis, is a technique widely used in Biochemistry, forensics Sedimentation describes the motion of Molecules in Solutions or particles in suspensions in response to an external force such as gravity Sucrose gradient centrifugation is a type of Centrifugation often used to purify enveloped Viruses (with densities 1 The basis for determination of Molecular weight according to the Staudinger method (since replaced by the more general Mark -Houwink equation is the fact that
Aside from their historical interest, it is worth knowing about older technology as it may be useful to solve a particular problem.
Molecular biology was established in the 1930s, the term was first coined by Warren Weaver in 1938 however. The history of molecular biology begins in the 1930s with the convergence of various previously distinct biological disciplines Biochemistry, Genetics, Microbiology Warren Weaver (b July 17 1894 in Reedsburg Wisconsin d November 24 1978 in New Milford Connecticut) was an American Warren was director of Natural Sciences for the Rockefeller Foundation at the time and believed that biology was about to undergo a period of significant change given recent advances in fields such as X-ray crystallography. The Rockefeller Foundation (RF is a prominent Philanthropic organization and Private foundation based at 420 Fifth Avenue New York City. X-ray crystallography is a method of determining the arrangement of Atoms within a Crystal, in which a beam of X-rays strikes a crystal and scatters He therefore channeled significant amounts of (Rockefeller Institute) money into biological fields.