on 01-Mar-2018 (Thu)

In mathematics, a Borel set is any set in a topological space that can be formed from open sets (or, equivalently, from closed sets) through the operations of countable union, countable intersection, and relative complement.

The Borel algebra on X is the smallest σ-algebra containing all open sets

Borel sets are important in measure theory, since any measure defined on the open sets of a space, or on the closed sets of a space, must also be defined on all Borel sets of that space.

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Atrocity propaganda is the spreading information about the crimes committed by an enemy, especially deliberate fabrications or exaggerations.

William Shakespeare ( / ˈ ʃ eɪ k s p ɪər / ; 26 April 1564 (baptised) – 23 April 1616)^[a] was an English poet, playwright and actor, widely regarded as the greatest writer in the English language and the world's pre-eminent dramatist.

The Hundred Years' War was a series of conflicts waged from 1337 to 1453 by the House of Plantagenet, rulers of the Kingdom of England, against the House of Valois, rulers of the Kingdom of France, over the succession to the French throne.

A lingua franca ( / ˌ l ɪ ŋ ɡ w ə ˈ f r æ ŋ k ə / ; lit.  Frankish tongue ),^[1] also known as a bridge language, common language, trade language or vehicular language, is a language or dialect systematically used to make communication possible between people who do not share a native language or dialect, particularly when it is a third language that is distinct from both native languages.^[2]

The Weimar Republic (German: Weimarer Republik [ˈvaɪmaʁɐ ʁepuˈbliːk] ( [imagelink] listen ) ) is an unofficial, historical designation for the German state as it existed between 1919 and 1933.

Enlightened absolutism refers to the conduct and policies of European absolute monarchs during the 18th and 19th centuries who were influenced by the ideas of the Enlightenment.

The Weimar Republic (German: Weimarer Republik [ˈvaɪmaʁɐ ʁepuˈbliːk] ( [imagelink] listen ) ) is an unofficial, historical designation for the German state as it existed between 1919 and 1933.

The rulers commonly known as the "Five Good Emperors" were Nerva, Trajan, Hadrian, Antoninus Pius and Marcus Aurelius.^[4] The term was coined based on what the political philosopher Niccolò Machiavelli said in 1503:

The Roman Kingdom, or regal period, was the period of the ancient Roman civilization characterized by a monarchical form of government of the city of Rome and its territories.

The Roman Republic (Latin: Res publica Romana ; Classical Latin: [ˈreːs ˈpuːb.lɪ.ka roːˈmaː.na] ) was the era of ancient Roman civilization beginning with the overthrow of the Roman Kingdom, traditionally dated to 509 BC, and ending in 27 BC with the establishment of the Roman Empire.

Octavian's power was then unassailable and in 27 BC the Roman Senate formally granted him overarching power and the new title Augustus, effectively marking the end of the Roman Republic.

• The nitrogenous bases of nucleotides include two types of purines and three types of pyrimidines. • A nucleotide consists of a nitrogenous base, a ribose or deoxyribose sugar, and one or more phosphate groups. • DNA contains adenine, guanine, cytosine, and thymine deoxyribonucleotides, whereas RNA contains adenine, guanine, cytosine, and uracil ribonucleotides.

The most common purines are adenine (A) and guanine (G), and the major pyrimidines are cytosine (C), uracil (U), and thymine (T). The purines form bonds to a five-carbon sugar (a pentose) via their N9 atoms, whereas pyrimidines do so through their N1 atoms (Table 3-1). In ribonucleotides, the pentose is ribose, while in deoxyribonucleotides (or just deoxynucleotides), the sugar is 2ⴕ-deoxyribose (i.e., the carbon at position 2¿ lacks a hydroxyl group)

A nucleoside consists only of a base and a pentose.

In a ribonucleotide or a deoxyribonucleotide, one or more phosphate groups are bonded to atom C3¿ or atom C5¿ of the pentose to form a 3¿-nucleotide or a 5¿-nucleotide, respectively (Fig. 3-1). When the phosphate group is absent, the compound is known as a nucleoside. A 5¿-nucleotide can therefore be called a nucleoside-5¿-phosphate. Nucleotides most commonly

contain one to three phosphate groups at the C5¿ position and are called nu- cleoside monophosphates, diphosphates, and triphosphates.

Perhaps the best known nucleotide is adenosine triphosphate (ATP), a nucleotide containing adenine, ribose, and a triphosphate group. ATP is often mistakenly referred to as an energy-storage molecule, but it is more accurately termed an energy carrier or energy transfer agent.

Identify the purines and pyrimidines commonly found in nucleic acids. • Practice drawing the structures of adenine, adenosine, and adenylate. • Describe the chemical differences between a ribonucleoside triphosphate and a deoxyribonucleoside monophosphate

starch synthesis in plants proceeds by repeated additions of glu- cose units donated by ADP–glucose

The phosphates of these polynucleotides are acidic, so at physiological pH, nucleic acids are polyanions. The linkage between individual nucleotides is known as a phos- phodiester bond, so named because the phosphate is esterified to two ribose units.

The terminal residue whose C5¿ is not linked to another nucleotide is called the 5¿ end, and the terminal residue whose C3¿ is not linked to another nucleotide is called the 3¿ end. By convention, the sequence of nucleotide residues in a nucleic acid is written, left to right, from the 5¿ end to the 3¿ end.

Although there appear to be no rules governing the nucleotide composition of typical RNA molecules, DNA has equal numbers of adenine and thymine residues (A ⫽ T) and equal numbers of guanine and cytosine residues (G ⫽ C). These relation- ships, known as Chargaff’s rules, were discovered in the late 1940s by Erwin Chargaff, who devised the first reliable quantitative methods for the composi- tional analysis of DNA.

Watson and Crick’s accomplishment, which is ranked as one of science’s major intellectual achievements, was based in part on two pieces of evidence in addition to Chargaff’s rules: the correct tautomeric forms of the bases and indications that DNA is a helical molecule. The purine and pyrimidine bases of nucleic acids can assume different tautomeric forms (tautomers are easily converted isomers that differ only in hydrogen positions; Fig. 3-4). X-Ray, nuclear magnetic resonance (NMR), and spectroscopic investigations have firmly established that the nucleic acid bases are overwhelmingly in the keto tautomeric forms

Many bacteria are able to resist infection by bacteriophages (viruses that are specific for bacteria) by virtue of a restriction–modification system. The bac- terium modifies certain nucleotides in specific sequences of its own DNA by adding a methyl (¬CH 3 ) group in a reaction catalyzed by a modification methylase. A restriction endonuclease, which recognizes the same nucleotide sequence as does the methylase, cleaves any DNA that has not been modified on at least one of its two strands. (An endonuclease cleaves a nucleic acid within the polynucleotide strand; an exonuclease cleaves a nucleic acid by re- moving one of its terminal residues.) This system destroys foreign (phage) DNA containing a recognition site that has not been modified by methyla- tion. The host DNA is always at least half methylated, because although the daughter strand is not methylated until shortly after it is synthesized, the parental strand to which it is paired is already modified (and thus protects both strands of the DNA from cleavage by the restriction enzyme).

Negatively charged molecules such as DNA migrate through the gel matrix toward the anode in response to an applied electric field. Because smaller molecules move faster, the molecules in each lane are separated according to size. Following electrophoresis, the separated molecules may be visualized by staining or fluorescence

Until recent years, the most widely used technique for sequencing DNA was the chain-terminator method, which was devised by Frederick Sanger. The first step in this procedure is to obtain single polynucleotide strands. Complementary DNA strands can be separated by heating, which breaks the hydrogen bonds between bases. Next, polynucleotide fragments that terminate at positions corresponding to each of the four nucleotides are generated. Finally, the fragments are separated and detected.

The chain-terminator method (also called the dideoxy method) uses an E. coli enzyme to make complementary copies of the single-stranded DNA being sequenced. The en- zyme is a fragment of DNA polymerase I, one of the enzymes that partic- ipates in replication of bacterial DNA (Section 25-2A). Using the single DNA strand as a template, DNA polymerase I assembles the four deoxynu- cleoside triphosphates (dNTPs), dATP, dCTP, dGTP, and dTTP, into a com- plementary polynucleotide chain that it elongates in the 5¿S3¿ direction (Fig. 3-18). DNA polymerase I can sequentially add deoxynucleotides only to the 3¿ end of a polynucleotide. Hence, replication is initiated in the presence of a short polynucleotide (a primer) that is complementary to the 3¿ end of the template DNA and thus becomes the 5¿ end of the new strand. The primer base-pairs with the template strand, and nucleotides are sequentially added to the 3¿ end of the primer. If the DNA being sequenced is a restriction frag- ment, as it usually is, it begins and ends with a restriction site.

In the chain-terminator technique (Fig. 3-19), the DNA to be sequenced is incubated with DNA poly- merase I, a suitable primer, and the four dNTP substrates (reactants in enzy- matic reactions) for the polymerization reaction. The key component of the reaction mixture is a small amount of a 2ⴕ,3ⴕ-dideoxynucleoside triphos- phate (ddNTP), which lacks the 3¿-OH group of deoxynucleotides.When the dideoxy analog is incorporated into the growing polynucleotide in place of the corresponding normal nucleotide, chain growth is terminated because addition of the next nucleotide re- quires a free 3¿-OH.

By using only a small amount of the ddNTP, a series of truncated chains is generated, each of which ends with the dideoxy analog at one of the positions occupied by the corresponding base. Each ddNTP bears a different fluorescent “tag” so that the products of the polymerase reaction can be readily detected. Gel electrophoresis separates the newly synthesized DNA segments, which differ in size by one nucleotide. Thus, the sequence of the replicated strand can be di- rectly read from the gel. Note that the sequence obtained by the chain-termi- nator method is complementary to the DNA strand being sequenced

In pyrosequencing, molecules of the template DNA are immobilized on the surfaces of microscopic plastic beads that are deposited in small wells in a fiber-optic slide with one bead per well. A primer and DNA polymerase are added, and then a dNTP substrate is introduced. If DNA polymerase adds that nucleotide to the new DNA strand, pyrophosphate is released and trig- gers a chemical reaction involving the firefly enzyme luciferase, which gener- ates a flash of light. Solutions of each of the four dNTPs are successively washed across the immobilized DNA template, and a detector records whether light is produced in the presence of a particular dNTP. In this way, the se- quence of nucleotides complementary to the template strand can be deduced, and no electrophoretic separation is needed.

In metagenomic sequencing, the DNA sequences of multiple organisms are analyzed as a single data set. This approach is used to characterize com- plex microbial communities, such as those in marine environments, where in- dividual species—including many not yet identified—cannot be cultured and sequenced one by one. Metagenomic sequence data reveal the overall gene number and an estimate of the collective metabolic capabilities of the com- munity. Over 3 million genes have been identified in a metagenomic analysis of the microorganisms that inhabit the human gut, representing some 1000 bacterial species. While most humans share a common core set of about 60 gut microorganisms, significant differences appear to correlate with metabolic variables such as body mass.

Rather, it appears that vertebrate proteins them- selves are more complex than those of invertebrates; that is, vertebrate proteins tend to have more domains (modules) than invertebrate proteins, and these modules are more often selectively expressed through alternative gene splic- ing (a phenomenon in which a given gene transcript can be processed in multiple ways so as to yield different proteins when translated; Section 26-3B). In fact, most vertebrate genes encode several different although similar proteins.

Phylogenetic relationships can be revealed by comparing the sequences of similar genes in different organisms. The number of nucleotide differences be- tween the corresponding genes in two species roughly indicates the degree to which the species have diverged through evolution. The regrouping of prokary- otes into archaea and bacteria (Section 1-2C) according to rRNA sequences present in all organisms illustrates the impact of sequence analysis.

Recombinant DNA technology, also called molecular cloning or genetic engineering, makes it possible to isolate, amplify, and mod- ify specific DNA sequences.

Ligase Joins Two DNA Segments. A DNA segment to be cloned is often obtained through the action of restriction endonucleases. Most restriction en- zymes cleave DNA to yield sticky ends (Section 3-4A). Therefore, as Janet Mertz and Ron Davis first demonstrated in 1972, a restriction fragment can be inserted into a cut made in a cloning vector by the same restriction enzyme (Fig. 3-24). The complementary ends of the two DNAs form base pairs (an- neal) and the sugar–phosphate backbones are covalently ligated, or spliced together, through the action of an enzyme named DNA ligase. (A ligase pro- duced by a bacteriophage can also join blunt-ended restriction fragments.) A great advantage of using a restriction enzyme to construct a recombinant DNA molecule is that the DNA insert can later be precisely excised from the cloned vector by cleaving it with the same restriction enzyme.

It is essential to select only those host organisms that have been transformed and that contain a properly constructed vector. In the case of plasmid transfor- mation, selection can be accomplished through the use of antibiotics and/or chromogenic (color-producing) substances. For example, the lacZ gene in the pUC18 plasmid (see Fig. 3-22) encodes the enzyme ␤-galactosidase, which cleaves the colorless compound X-gal to a blue product:

Cells of E. coli that have been transformed by an unmodified pUC18 plasmid form blue colonies. However, if the plasmid contains a foreign DNA insert in its polylinker region, the colonies are colorless because the insert interrupts the protein-coding sequence of the lacZ gene and no functional ␤-galactosidase is produced. Bacteria that have failed to take up any plasmid are also colorless due to the absence of ␤-galactosidase, but these cells can be excluded by adding the antibiotic ampicillin to the growth medium (the plasmid includes the gene amp R , which confers ampicillin resistance). Thus, successfully transformed cells

The cloned set of all DNA fragments from a particular organism is known as its genomic library. Genomic libraries are generated by a procedure known as shotgun cloning. The chromosomal DNA of the organism is isolated, cleaved to frag- ments of cloneable size, and inserted into a cloning vector. The DNA is usu- ally fragmented by partial rather than exhaustive restriction digestion so that the genomic library contains intact representatives of all the organism’s genes, including those that contain restriction sites. DNA in solution can also be me- chanically fragmented (sheared) by rapid stirring.

A different type of DNA library contains only the expressed sequences from a particular cell type. Such a cDNA library is constructed by isolating all the cell’s mRNAs and then copying them to DNA using a specialized type of DNA polymerase known as reverse transcriptase because it synthesizes DNA using RNA templates (Box 25-2). The complementary DNA (cDNA) molecules are then inserted into cloning vectors to form a cDNA library. A cDNA library can also be used to construct a DNA microarray (DNA chip), in which each different cDNA is immobilized at a specific position on a slide. A DNA chip can be used for detecting the presence of mRNA in a biological sample (the mRNA, if pres- ent, will bind to its complementary cDNA

Colonies are transferred from a “master” culture plate by replica plating. Clones containing the DNA of interest are identified by the ability to bind a specific probe.

In PCR, a DNA sample is separated into single strands and incubated with DNA polymerase, dNTPs, and two oligonucleotide primers whose sequences flank the DNA segment of interest. The primers direct the DNA polymerase to synthesize com- plementary strands of the target DNA (Fig. 3-27). Multiple cycles of this process, each doubling the amount of the target DNA, geometrically amplify the DNA starting from as little as a single gene copy. In each cycle, the two strands of the duplex DNA are separated by heating, then the reaction mixture is cooled to allow the primers to anneal to their complementary segments on the DNA. Next, the DNA polymerase directs the synthesis of the complementary strands. The use of a heat-stable DNA polymerase, such as Taq polymerase isolated from Thermus aquaticus, a bacterium that thrives at 75°C, eliminates the need to add fresh enzyme after each round of heating (heat inactivates most en- zymes). Hence, in the presence of sufficient quantities of primers and dNTPs, PCR is carried out simply by cyclically varying the temperature.

Bacteria can produce eukaryotic proteins only if the recombinant DNA that carries the protein-coding sequence also includes bacterial transcriptional and translational control sequences. Synthesis of eukaryotic proteins in bacte- ria also presents other problems. For example, many eukaryotic genes are large and contain stretches of nucleotides (introns) that are transcribed and excised before translation (Section 26-3A); bacteria lack the machinery to excise the introns. In addition, many eukaryotic proteins are posttranslationally modi- fied by the addition of carbohydrates or by other reactions. These problems can be overcome by using expression vectors that propagate in eukaryotic hosts, such as yeast or cultured insect or animal cells.

process of evolution and allows predictions about the structural and functional roles of particular amino acids in a protein to be rigorously tested in the laboratory

An open source package is usually distributed as a compressed archive containing all source code and header files plus build scripts and documentation. A dev package , sometimes referred to as a -devel package by Linux package managers, is usually dis- tributed as an archive containing a lib plus its associated header files

This device driver understands the device controller and provides the rest of the operating system with a uniform interface to the device