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12: Modern Applications of Microbial Genetics - Biology

12: Modern Applications of Microbial Genetics - Biology


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12: Modern Applications of Microbial Genetics

Chapter 8: Modern Applications of Microbial Genetics

Figure 8.1 A thermal cycler (left) is used during a polymerase chain reaction (PCR). PCR amplifies the number of copies of DNA and can assist in diagnosis of infections caused by microbes that are difficult to culture, such as Chlamydia trachomatis (right). C. trachomatis causes chlamydia, the most common sexually transmitted disease in the United States, and trachoma, the world’s leading cause of preventable blindness. (credit right: modification of work by Centers for Disease Control and Prevention)
Chapter Outline

BIOLOGY 206 OpenStax Microbiology Test Bank- Chapter 12&colon Modern Applications of Microbial Genetics

BIOLOGY 206 OpenStax Microbiology Test Bank- Chapter 12&colon Modern Applications of Microbial GeneticsBIOLOGY 206 OpenStax Microbiology Test Bank- Chapter 12&colon Modern Applications of Microbial GeneticsBIOLOGY 206 OpenStax Microbiology Test Bank- Chapter 12&colon Modern Applications of Microbial GeneticsBIOLOGY 206 OpenStax Microbiology Test Bank- Chapter 12&colon Modern Applications of Microbial GeneticsBIOLOGY 206 OpenStax Microbiology Test Bank- Chapter 12&colon Modern Applications of Microbial GeneticsBIOLOGY 206 OpenStax Microbiology Test Bank- Chapter 12&colon Modern Applications of Microbial GeneticsBIOLOGY 206 OpenStax Microbiology Test Bank- Chapter 12&colon Modern Applications of Microbial GeneticsBIOLOGY 206 OpenStax Microbiology Test Bank- Chapter 12&colon Modern Applications of Microbial GeneticsBIOLOGY 206 OpenStax Microbiology Test Bank- Chapter 12&colon Modern Applications of Microbial GeneticsBIOLOGY 206 OpenStax Microbiology Test Bank- Chapter 12&colon Modern Applications of Microbial GeneticsBIOLOGY 206 OpenStax Microbiology Test Bank- Chapter 12&colon Modern Applications of Microbial GeneticsBIOLOGY 206 OpenStax Microbiology Test Bank- Chapter 12&colon Modern Applications of Microbial GeneticsBIOLOGY 206 OpenStax Microbiology Test Bank- Chapter 12&colon Modern Applications of Microbial GeneticsBIOLOGY 206 OpenStax Microbiology Test Bank- Chapter 12&colon Modern Applications of Microbial GeneticsBIOLOGY 206 OpenStax Microbiology Test Bank- Chapter 12&colon Modern Applications of Microbial GeneticsBIOLOGY 206 OpenStax Microbiology Test Bank- Chapter 12&colon Modern Applications of Microbial GeneticsBIOLOGY 206 OpenStax Microbiology Test Bank- Chapter 12&colon Modern Applications of Microbial GeneticsBIOLOGY 206 OpenStax Microbiology Test Bank- Chapter 12&colon Modern Applications of Microbial GeneticsBIOLOGY 206 OpenStax Microbiology Test Bank- Chapter 12&colon Modern Applications of Microbial GeneticsBIOLOGY 206 OpenStax Microbiology Test Bank- Chapter 12&colon Modern Applications of Microbial GeneticsBIOLOGY 206 OpenStax Microbiology Test Bank- Chapter 12&colon Modern Applications of Microbial Genetics


12: Modern Applications of Microbial Genetics - Biology

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BIOLOGY 206 OpenStax Microbiology Test Bank- Chapter 12&colon Modern Applications of Microbial Genetics&solBIOLOGY 206 OpenStax Microbiology Test Bank- Chapter 12&colon Modern Applications of Microbial Genetics

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BIOLOGY 206 OpenStax Microbiology Test Bank- Chapter 12&colon Modern Applications of Microbial Genetics&solBIOLOGY 206 OpenStax Microbiology Test Bank- Chapter 12&colon Modern Applications of Microbial Genetics

BIOLOGY 206 OpenStax Microbiology Test Bank- Chapter 12&colon Modern Applications of Microbial GeneticsBIOLOGY 206 OpenStax Microbiology Test Bank- Chapter 12&colon Modern Applications of Microbial GeneticsBIOLOGY 206 OpenStax Microbiology Test Bank- Chapter 12&colon Modern Applications of Microbial GeneticsBIOLOGY 206 OpenStax Microbiology Test Bank- Chapter 12&colon Modern Applications of Microbial GeneticsBIOLOGY 206 OpenStax Microbiology Test Bank- Chapter 12&colon Modern Applications of Microbial GeneticsBIOLOGY 20&period&period&period

  • Bundle
  • Exam (elaborations)
  • &bull 17 pages &bull
  • by QUIZDASH &bull
  • uploaded 06-06-2021

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BIOLOGY 206 OpenStax Microbiology Test Bank- Chapter 12&colon Modern Applications of Microbial GeneticsBIOLOGY 206 OpenStax Microbiology Test Bank- Chapter 12&colon Modern Applications of Microbial GeneticsBIOLOGY 206 OpenStax Microbiology Test Bank- Chapter 12&colon Modern Applications of Microbial GeneticsBIOLOGY 206 OpenStax Microbiology Test Bank- Chapter 12&colon Modern Applications of Microbial GeneticsBIOLOGY 206 OpenStax Microbiology Test Bank- Chapter 12&colon Modern Applications of Microbial GeneticsBIOLOGY 20&period&period&period


Modern Microbial Genetics , Second Edition

The text is divided into three sections: DNA Metabolism, Genetic Response, and Genetic Exchange. The first addresses how DNA replicates, repairs itself, and recombines, as well as how it may be manipulated. The second section is devoted to how microorganisms interact with their environment, including chapters on sporulation and stress shock, and the final section contains the latest information on classic exchange mechanisms such as transformation and conjugation.

  • Gene Expression and Its Regulation
  • Single-Stranded DNA Phages
  • Genetic Tools for Dissecting Motility and Development of Myxococcus xanthus
  • Molecular Mechanism of Quorum Sensing
  • Transduction in Gram-Negative Bacteria
  • Genetic Approaches in Bacteria with No Natural Genetic Systems

The editors also cultivate an attention to global regulatory systems throughout the book, elucidating how certain genes and operons in bacteria, defined as regulons, network and cooperate to suit the needs of the bacterial cell. With clear appreciation for the impact of molecular genomics, this completely revised and updated edition proves that Modern Microbial Genetics remains the benchmark text in its field.


Practice of Toxicologic Pathology

Abstract

Numerous genetic, microbial, environmental, and experimental factors work together to influence development of the lesions studied by the toxicologic pathologist. The pathologist needs to understand how factors associated with the laboratory animal, the animal care and use program, the research facility environment, and the study conditions contribute to study findings so that the results of toxicity experiments can be properly evaluated. The changes that are occurring in laboratory animal care and use practices are driven in part by recent advances in animal welfare concerns. Future standards for animal care and use will likely differ from those employed today. As advances are made, greater emphasis will be placed on understanding the mechanistic underpinnings of the interplay between host susceptibility factors, toxicant exposure, and environment.


Microbial genetics

Microbial genetics is a branch of genetics concerned with the transmission of hereditary characters in microorganisms . Within the usual definition, microorganisms include prokaryotes like bacteria , unicellular or mycelial eukaryotes e.g., yeasts and other fungi , and viruses , notably bacterial viruses (bacteriophages). Microbial genetics has played a unique role in developing the fields of molecular and cell biology and also has found applications in medicine, agriculture, and the food and pharmaceutical industries.

Because of their relative simplicity, microbes are ideally suited for combined biochemical and genetic studies, and have been successful in providing information on the genetic code and the regulation of gene activity. The operon model formulated by French biologists Fran ç ois Jacob (1920 – ) and Jacques Monod (1910 – 1976) in 1961, is one well known example. Based on studies on the induction of enzymes of lactose catabolism in the bacterium Escherichia coli, the operon has provided the groundwork for studies on gene expression and regulation, even up to the present day. The many applications of microbial genetics in medicine and the pharmaceutical industry emerge from the fact that microbes are both the causes of disease and the producers of antibiotics . Genetic studies have been used to understand variation in pathogenic microbes and also to increase the yield of antibiotics from other microbes.

Hereditary processes in microorganisms are analogous to those in multicellular organisms. In both prokaryotic and eukaryotic microbes, the genetic material is DNA the only known exceptions to this rule are the RNA viruses. Mutations , heritable changes in the DNA, occur spontaneously and the rate of mutation can be increased by mutagenic agents. In practice, the susceptibility of bacteria to mutagenic agents has been used to identify potentially hazardous chemicals in the environment. For example, the Ames test was developed to evaluate the mutagenicity of a chemical in the following way. Plates containing a medium lacking in, for example, the nutrient histidine are inolculated with a histidine requiring strain of the bacterium Salmonella typhimurium. Thus, only cells that revert back to the wild type can grow on the medium. If plates are exposed to a mutagenic agent, the increase in the number of mutants compared with unexposed plates can be observed and a large number of revertants would indicate a strong mutagenic agent. For such studies, microorganisms offer the advantage that they have short mean generation times, are easily cultured in a small space under controlled conditions and have a relatively uncomplicated structure.

Microorganisms, and particularly bacteria, were generally ignored by the early geneticists because of their small in size and apparent lack of easily identifiable variable traits. Therefore, a method of identifying variation and mutation in microbes was fundamental for progress in microbial genetics. As many of the mutations manifest themselves as metabolic abnormalities, methods were developed by which microbial mutants could be detected by selecting or testing for altered phenotypes. Positive selection is defined as the detection of mutant cells and the rejection of unmutated cells. An example of this is the selection of penicillin resistant mutants, achieved by growing organisms in media containing penicillin such that only resistant colonies grow. In contrast, negative selection detects cells that cannot perform a certain function and is used to select mutants that require one or more extra growth factors. Replica plating is used for negative selection and involves two identical prints of colony distributions being made on plates with and without the required nutrients. Those microbes that do not grow on the plate lacking the nutrient can then be selected from the identical plate, which does contain the nutrient.

The first attempts to use microbes for genetic studies were made in the USA shortly before World War II, when George W. Beadle (1903 – 1989) and Edward L. Tatum (1909 – 1975) employed the fungus, Neurospora, to investigate the genetics of tryptophan metabolism and nicotinic acid synthesis. This work led to the development of the "one gene one enzyme" hypothesis. Work with bacterial genetics, however, was not really begun until the late 1940s. For a long time, bacteria were thought to lack sexual reproduction, which was believed to be necessary for mixing genes from different individual organisms — a process fundamental for useful genetic studies. However, in 1947, Joshua Lederberg (1925 – ) working with Edward Tatum demonstrated the exchange of genetic factors in the bacterium, Escherichia coli. This process of DNA transfer was termed conjugation and requires cell-to-cell contact between two bacteria. It is controlled by genes carried by plasmids , such as the fertility (F) factor, and typically involves the transfer of the plasmid from donor torecipient cell. Other genetic elements, however, including the donor cell chromosome, can sometimes also be mobilized and transferred. Transfer to the host chromosome is rarely complete, but can be used to map the order of genes on a bacterial genome.

Other means by which foreign genes can enter a bacterial cell include transformation , transfection, and transduction . Of the three processes, transformation is probably the most significant. Evidence of transformation in bacteria was first obtained by the British scientist, Fred Griffith (1881 – 1941) in the late 1920s working with Streptococcus pneumoniae and the process was later explained in the 1930s by Oswald Avery (1877 – 1955) and his associates at the Rockefeller Institute in New York. It was discovered that certain bacteria exhibit competence, a state in which cells are able to take up free DNA released by other bacteria. This is the process known as transformation, however, relatively few microorganisms can be naturally transformed. Certain laboratory procedures were later developed that make it possible to introduce DNA into bacteria, for example electroporation, which modifies the bacterial membrane by treatment with an electric field to facilitate DNA uptake. The latter two processes, transfection and transduction, involve the participation of viruses for nucleic acid transfer. Transfection occurs when bacteria are transformed with DNA extracted from a bacterial virus rather than from another bacterium. Transduction involves the transfer of host genes from one bacterium to another by means of viruses. In generalized transduction, defective virus particles randomly incorporate fragments of the cell DNA virtually any gene of the donor can be transferred, although the efficiency is low. In specialized transduction, the DNA of a temperate virus excises incorrectly and brings adjacent host genes along with it. Only genes close to the integration point of the virus are transduced, and the efficiency may be high.

After the discovery of DNA transfer in bacteria, bacteria became objects of great interest to geneticists because their rate of reproduction and mutation is higher than in larger organisms i.e., a mutation occurs in a gene about one time in 10,000,000 gene duplications, and one bacterium may produce 10,000,000,000 offspring in 48 hours. Conjugation, transformation, and transduction have been important methods for mapping the genes on the chromosomes of bacteria. These techniques, coupled with restriction enzyme analysis, cloning DNA sequencing, have allowed for the detailed studies of the bacterial chromosome. Although there are few rules governing gene location, the genes encoding enzymes for many biochemical pathways are often found tightly linked in operons in prokaryotes. Large scale sequencing projects revealed the complete DNA sequence of the genomes of several prokaryotes, even before eukaryotic genomes were considered.

See also Bacterial growth and division Bacteriophage and bacteriophage typing Cell cycle (eukaryotic), genetic regulation of Cell cycle (prokaryotic), genetic regulation of Fungal genetics Mutations and mutagenesis Viral genetics Viral vectors in gene therapy


Recombinant DNA Technology and Pharmaceutical Production

Genetic engineering has provided a way to create new pharmaceutical products called recombinant DNA pharmaceuticals. Such products include antibiotic drugs, vaccines, and hormones used to treat various diseases. Table 1 lists examples of recombinant DNA products and their uses.

Table 1. Some Genetically Engineered Pharmaceutical Products and Applications
Recombinant DNA Product Application
Atrial natriuretic peptide Treatment of heart disease (e.g., congestive heart failure), kidney disease, high blood pressure
DNase Treatment of viscous lung secretions in cystic fibrosis
Erythropoietin Treatment of severe anemia with kidney damage
Factor VIII Treatment of hemophilia
Hepatitis B vaccine Prevention of hepatitis B infection
Human growth hormone Treatment of growth hormone deficiency, Turner’s syndrome, burns
Human insulin Treatment of diabetes
Interferons Treatment of multiple sclerosis, various cancers (e.g., melanoma), viral infections (e.g., Hepatitis B and C)
Tetracenomycins Used as antibiotics
Tissue plasminogen activator Treatment of pulmonary embolism in ischemic stroke, myocardial infarction

For example, the naturally occurring antibiotic synthesis pathways of various Streptomyces spp., long known for their antibiotic production capabilities, can be modified to improve yields or to create new antibiotics through the introduction of genes encoding additional enzymes. More than 200 new antibiotics have been generated through the targeted inactivation of genes and the novel combination of antibiotic synthesis genes in antibiotic-producing Streptomyces hosts. [3]

Genetic engineering is also used to manufacture subunit vaccines, which are safer than other vaccines because they contain only a single antigenic molecule and lack any part of the genome of the pathogen (see Vaccines). For example, a vaccine for hepatitis B is created by inserting a gene encoding a hepatitis B surface protein into a yeast the yeast then produces this protein, which the human immune system recognizes as an antigen. The hepatitis B antigen is purified from yeast cultures and administered to patients as a vaccine. Even though the vaccine does not contain the hepatitis B virus, the presence of the antigenic protein stimulates the immune system to produce antibodies that will protect the patient against the virus in the event of exposure. [4] [5]

Genetic engineering has also been important in the production of other therapeutic proteins, such as insulin, interferons, and human growth hormone, to treat a variety of human medical conditions. For example, at one time, it was possible to treat diabetes only by giving patients pig insulin, which caused allergic reactions due to small differences between the proteins expressed in human and pig insulin. However, since 1978, recombinant DNA technology has been used to produce large-scale quantities of human insulin using E. coli in a relatively inexpensive process that yields a more consistently effective pharmaceutical product. Scientists have also genetically engineered E. coli capable of producing human growth hormone (HGH), which is used to treat growth disorders in children and certain other disorders in adults. The HGH gene was cloned from a cDNA library and inserted into E. coli cells by cloning it into a bacterial vector. Eventually, genetic engineering will be used to produce DNA vaccines and various gene therapies, as well as customized medicines for fighting cancer and other diseases.

Think about It

  • What bacterium has been genetically engineered to produce human insulin for the treatment of diabetes?
  • Explain how microorganisms can be engineered to produce vaccines.

Definition of genetics:

“The branch of the science deals with the study of the heredity and variation in genes and genotype is called genetics. “

“The study of structure and function of DNA, genes, chromosomes and related alterations are called genetics.”

The term “Genetics” was coined by William Bateson is 1905.

The term “genetics” was derived from the Greek word “genetikos” and “genesis”. Genetikos: generative and genesis: origin.

Several applications of genetics are given below,


Highlights

Microbial consortia exhibit advantages over monocultures, including division of labor, spatial organization, and robustness to perturbations.

Synthetic biology tools are used to construct and control consortia by manipulating communication networks, regulating gene expression via exogenous inputs, and engineering syntrophic interactions.

Synthetic biology approaches to control the behaviors of individual species within a consortium include population control, distribution of tasks, and spatial organization.

Constructing microbial consortia is enhanced by computational models, which can predict preferred metabolic cross-feeding networks and infer population dynamics over time.

Microbial biotechnology benefits from consortia due to the unique catalytic activities of each member, their ability to use complex substrates, compartmentalization of pathways, and distribution of molecular burden.

Microbial consortia have been used in biotechnology processes, including fermentation, waste treatment, and agriculture, for millennia. Today, synthetic biologists are increasingly engineering microbial consortia for diverse applications, including the bioproduction of medicines, biofuels, and biomaterials from inexpensive carbon sources. An improved understanding of natural microbial ecosystems, and the development of new tools to construct synthetic consortia and program their behaviors, will vastly expand the functions that can be performed by communities of interacting microorganisms. Here, we review recent advancements in synthetic biology tools and approaches to engineer synthetic microbial consortia, discuss ongoing and emerging efforts to apply consortia for various biotechnological applications, and suggest future applications.


Watch the video: Neal Barnard, MD - Interview - Your Body In Balance: The New Science Of Food, Hormones, And Health (June 2022).


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