molecular biology


  • [43] 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.

  • 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, assuming that no
    post-transcriptional regulation occurs and that the levels of mRNA reflect proportional levels of the corresponding protein being produced.

  • During 1962–1964, through the use of conditional lethal mutants of a bacterial virus,[22] fundamental advances were made in our understanding of the functions and interactions
    of the proteins employed in the machinery of DNA replication, DNA repair, DNA recombination, and in the assembly of molecular structures.

  • [2][9] Molecular biology also plays a critical role in the understanding of structures, functions, and internal controls within individual cells, all of which can be used
    to efficiently target new drugs, diagnose disease, and better understand cell physiology.

  • [35] The PCR technique can be used to introduce restriction enzyme sites to ends of DNA molecules, or to mutate particular bases of DNA, the latter is a method referred to
    as site-directed mutagenesis.

  • [4] Molecular biology is not simply the study of biological molecules and their interactions; rather, it is also a collection of techniques developed since the field’s genesis
    which have enabled scientists to learn about molecular processes.

  • The basic principle is that DNA fragments can be separated by applying an electric current across the gel – because the DNA backbone contains negatively charged phosphate
    groups, the DNA will migrate through the agarose gel towards the positive end of the current.

  • Since multiple arrays can be made with exactly the same position of fragments, they are particularly useful for comparing the gene expression of two different tissues, such
    as a healthy and cancerous tissue.

  • [29] Techniques of molecular biology For more extensive list on protein methods, see protein methods.

  • Analogous methods to western blotting can be used to directly stain specific proteins in live cells or tissue sections.

  • [6] PCR is a reaction which amplifies small quantities of DNA, and it is used in many applications across scientific disciplines.

  • 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.

  • 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.

  • 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.

  • [46] Western blots can be used to determine the size of isolated proteins, as well as to quantify their expression.

  • [17] Another notable contributor to the DNA model was Phoebus Levene, who proposed the “polynucleotide model” of DNA in 1919 as a result of his biochemical experiments on

  • Griffith advanced another theory, stating that gene transfer occurring in member of same generation is known as horizontal gene transfer (HGT).

  • Introducing DNA into eukaryotic cells, such as animal cells, by physical or chemical means is called transfection.

  • 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.

  • PCR can also be used to determine whether a particular DNA fragment is found in a cDNA library.

  • Molecular cloning[edit] Main article: Molecular cloning Transduction image Molecular cloning is used to isolate and then transfer a DNA sequence of interest into a plasmid

  • In this experiment, as in most molecular biology techniques, a control must be used to ensure successful experimentation.

  • [38] Proteins can also be separated on the basis of size 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.

  • [23] Molecular biologists today have access to increasingly affordable sequencing data at increasingly higher depths, facilitating the development of novel genetic manipulation
    methods in new non-model organisms.

  • The membrane is then exposed to a labeled DNA probe that has a complement base sequence to the sequence on the DNA of interest.

  • The plasmid vector usually has at least 3 distinctive features: an origin of replication, a multiple cloning site (MCS), and a selective marker (usually antibiotic resistance).

  • Molecular genetics, the study of gene structure and function, has been among the most prominent sub-fields of molecular biology since the early 2000s.

  • 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.

  • Likewise, CRISPR-Cas9 gene editing experiments can now be conceived and implemented by individuals for under $10,000 in novel organisms, which will drive the development of
    industrial and medical applications [25] Relationship to other biological sciences The following list describes a viewpoint on the interdisciplinary relationships between molecular biology and other related fields.

  • Transduction is a process in which the bacterial DNA carry the fragment of bacteriophages and pass it on the next generation.

  • A variation of this technique allows the gene expression of an organism at a particular stage in development to be qualified (expression profiling).

  • PCR has many applications, including the study of gene expression, the detection of pathogenic microorganisms, the detection of genetic mutations, and the introduction of
    mutations to DNA.

  • It is one of the most basic tools for determining at what time, and under what conditions, certain genes are expressed in living tissues.

  • Likewise, synthetic molecular biologists will drive the industrial production of small and macro molecules through the introduction of exogenous metabolic pathways in various
    prokaryotic and eukaryotic cell lines.

  • 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.

  • [32][33] DNA coding for a protein of interest is now inside a cell, and the protein can now be expressed.

  • Watson and Crick described the structure of DNA and conjectured about the implications of this unique structure for possible mechanisms of DNA replication.

  • [40] The concentration of protein in the Bradford assay can then be measured using a visible light spectrophotometer, and therefore does not require extensive equipment.

  • Genetics attempts to predict how mutations, individual genes and genetic interactions can affect the expression of a phenotype[28] While researchers practice techniques specific
    to molecular biology, it is common to combine these with methods from genetics and biochemistry.

  • Antibodies that specifically bind to the protein of interest can then be visualized by a variety of techniques, including colored products, chemiluminescence, or autoradiography.

  • This research then lead to finding DNA material in other microorganisms, plants and animals.

  • The Bradford Assay[edit] Main article: The Bradford Assay The Bradford Assay is a molecular biology technique which enables the fast, accurate quantitation of protein molecules
    utilizing the unique properties of a dye called Coomassie Brilliant Blue G-250.

  • [41] Proteins in the assay bind Coomassie blue in about 2 minutes, and the protein-dye complex is stable for about an hour, although it’s recommended that absorbance readings
    are taken within 5 to 20 minutes of reaction initiation.

  • Arrays can also be made with molecules other than DNA.

  • In brief, PCR allows a specific DNA sequence to be copied or modified in predetermined ways.

  • The reaction is extremely powerful and under perfect conditions could amplify one DNA molecule to become 1.07 billion molecules in less than two hours.

  • [4] Molecular biology was first described as an approach focused on the underpinnings of biological phenomena – uncovering the structures of biological molecules as well as
    their interactions, and how these interactions explain observations of classical biology.

  • This is also a type of horizontal gene transfer.

  • [29] Northern blotting[edit] Main article: Northern blot Northern blot diagram The northern blot is used to study the presence of specific RNA molecules as relative comparison
    among a set of different samples of RNA.

  • The field of genetics arose as an attempt to understand the molecular mechanisms of genetic inheritance and the structure of a gene.


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