Properties of dna
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This document discusses the physical and chemical properties of DNA. Physically, DNA absorbs UV light strongest at 260nm, which can be measured with a spectrophotometer using the Beer-Lambert law. Chemically, DNA can be denatured by heat, acids, and alkalis causing the strands to separate, and renatured when conditions are reversed. It is also susceptible to attack by nucleophiles like hydrazine and alkylating agents which can modify the nitrogen bases.
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DNA Denaturation and Renaturation, Cot curves
The document discusses DNA denaturation and renaturation, including:
- Denaturation involves unwinding the DNA double helix into single strands through heating or chemical treatment, disrupting hydrogen bonds between base pairs. This increases UV absorption.
- Renaturation is the spontaneous rewinding of single strands back into the original double helix structure when denaturing conditions are removed, through base pairing of complementary strands.
- C0t curves plot the fraction of single strands renatured versus the product of DNA concentration and time, and can indicate the complexity and size of the original DNA sample based on renaturation rates. More complex DNA with more dissimilar sequences takes longer to renature
Denaturation and renaturation of dna
DNA is a double-helix molecule that carries genetic instructions. It is composed of two strands of polynucleotides made up of nucleotides, each containing a nitrogenous base, sugar, and phosphate. The strands are stabilized by hydrogen bonds between complementary bases and base-stacking interactions. DNA can be denatured into single strands by elevated temperature, extreme pH, low salt concentrations, or chemicals that disrupt hydrogen bonding between strands. Denaturation temperature depends on factors like base composition and length. Renaturation occurs when double-stranded DNA is cooled under conditions that allow the strands to re-form hydrogen bonds and complementary base pairing.
DNA footprinting
DNA footprinting is a technique used to identify protein binding regions on DNA. It involves treating DNA with nucleases like DNase I, which will degrade the DNA except for regions bound by proteins. These protected regions, called footprints, can identify transcription factor binding sites that regulate gene expression. The technique was originally developed in 1978 to study the binding specificity of the lac repressor protein, and it provides information on DNA-protein interactions and transcriptional regulation.
Homologous recombination
1. The document discusses models of homologous recombination including the Holliday model and the double-strand break repair model. It describes the key steps and proteins involved in each model.
2. Recombination involves the breakage and rejoining of DNA. In eukaryotes, the MRN/X complex processes DNA breaks. The Rad51 and Rad54 proteins then facilitate strand invasion and D-loop formation during homologous pairing.
3. Homologous recombination proteins from bacteria and eukaryotes catalyze different steps of the process. In E. coli, RecBCD introduces breaks and generates single strands for RecA to perform strand exchange, while RuvAB and Ruv
Dna binding proteins
The document discusses DNA binding proteins. It describes how DNA is wrapped around histone proteins to form nucleosomes, which resemble "beads on a string". There are five main types of histone proteins - H1, H2A, H2B, H3, and H4. Histone proteins can be modified through processes like acetylation and methylation, which affect gene expression. Other non-histone proteins use motifs like zinc fingers and helix-turn-helix to bind DNA in a sequence-specific manner and regulate transcription.
MODELS OF REPLICATION
The document discusses three models of DNA replication:
1) Asymmetric replication - the leading and lagging strands are replicated differently due to the 5' to 3' directionality of DNA polymerase. The leading strand replicates continuously while the lagging strand replicates discontinuously in short Okazaki fragments.
2) D-loop model - replication in mitochondria where one strand is displaced to form a D-loop and replicates first before the other strand.
3) Rolling circle model - used by plasmids and viruses where one strand is nicked and displaced to be used as a template, forming multiple copies linked together in a concatemer.
A, b, and z forms of dna
There are three main forms of DNA structure: A-DNA, B-DNA, and Z-DNA. B-DNA is the most common form found under physiological conditions, having a right-handed double helix with 10.5 base pairs per turn. A-DNA forms under dehydrating conditions and has a wider helix with 11 base pairs per turn. Z-DNA is a left-handed helix that forms with alternating purine-pyrimidine sequences, containing 12 base pairs per turn in a narrow, zig-zag structure. While B-DNA is most prevalent, the structure can vary depending on sequence and environmental conditions.
Cot curve
Cot value and Cot Curve analysis is a technique for measuring DNA complexity based on renaturation kinetics. DNA is denatured and allowed to reanneal, with larger DNA taking longer. Cot value accounts for DNA concentration, time, and buffer effects, representing repetitive sequences - lower Cot means more repeats. Examples show bacteria have nearly all single-copy DNA, while mouse has varying proportions of single-copy, middle repetitive, and highly repetitive sequences. Cot curve analysis provides information on genome size, complexity, and proportions of sequence types.
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DNA Denaturation and Renaturation, Cot curves
The document discusses DNA denaturation and renaturation, including:
- Denaturation involves unwinding the DNA double helix into single strands through heating or chemical treatment, disrupting hydrogen bonds between base pairs. This increases UV absorption.
- Renaturation is the spontaneous rewinding of single strands back into the original double helix structure when denaturing conditions are removed, through base pairing of complementary strands.
- C0t curves plot the fraction of single strands renatured versus the product of DNA concentration and time, and can indicate the complexity and size of the original DNA sample based on renaturation rates. More complex DNA with more dissimilar sequences takes longer to renature
Denaturation and renaturation of dna
DNA is a double-helix molecule that carries genetic instructions. It is composed of two strands of polynucleotides made up of nucleotides, each containing a nitrogenous base, sugar, and phosphate. The strands are stabilized by hydrogen bonds between complementary bases and base-stacking interactions. DNA can be denatured into single strands by elevated temperature, extreme pH, low salt concentrations, or chemicals that disrupt hydrogen bonding between strands. Denaturation temperature depends on factors like base composition and length. Renaturation occurs when double-stranded DNA is cooled under conditions that allow the strands to re-form hydrogen bonds and complementary base pairing.
DNA footprinting
DNA footprinting is a technique used to identify protein binding regions on DNA. It involves treating DNA with nucleases like DNase I, which will degrade the DNA except for regions bound by proteins. These protected regions, called footprints, can identify transcription factor binding sites that regulate gene expression. The technique was originally developed in 1978 to study the binding specificity of the lac repressor protein, and it provides information on DNA-protein interactions and transcriptional regulation.
Homologous recombination
1. The document discusses models of homologous recombination including the Holliday model and the double-strand break repair model. It describes the key steps and proteins involved in each model.
2. Recombination involves the breakage and rejoining of DNA. In eukaryotes, the MRN/X complex processes DNA breaks. The Rad51 and Rad54 proteins then facilitate strand invasion and D-loop formation during homologous pairing.
3. Homologous recombination proteins from bacteria and eukaryotes catalyze different steps of the process. In E. coli, RecBCD introduces breaks and generates single strands for RecA to perform strand exchange, while RuvAB and Ruv
Dna binding proteins
The document discusses DNA binding proteins. It describes how DNA is wrapped around histone proteins to form nucleosomes, which resemble "beads on a string". There are five main types of histone proteins - H1, H2A, H2B, H3, and H4. Histone proteins can be modified through processes like acetylation and methylation, which affect gene expression. Other non-histone proteins use motifs like zinc fingers and helix-turn-helix to bind DNA in a sequence-specific manner and regulate transcription.
MODELS OF REPLICATION
The document discusses three models of DNA replication:
1) Asymmetric replication - the leading and lagging strands are replicated differently due to the 5' to 3' directionality of DNA polymerase. The leading strand replicates continuously while the lagging strand replicates discontinuously in short Okazaki fragments.
2) D-loop model - replication in mitochondria where one strand is displaced to form a D-loop and replicates first before the other strand.
3) Rolling circle model - used by plasmids and viruses where one strand is nicked and displaced to be used as a template, forming multiple copies linked together in a concatemer.
A, b, and z forms of dna
There are three main forms of DNA structure: A-DNA, B-DNA, and Z-DNA. B-DNA is the most common form found under physiological conditions, having a right-handed double helix with 10.5 base pairs per turn. A-DNA forms under dehydrating conditions and has a wider helix with 11 base pairs per turn. Z-DNA is a left-handed helix that forms with alternating purine-pyrimidine sequences, containing 12 base pairs per turn in a narrow, zig-zag structure. While B-DNA is most prevalent, the structure can vary depending on sequence and environmental conditions.
Cot curve
Cot value and Cot Curve analysis is a technique for measuring DNA complexity based on renaturation kinetics. DNA is denatured and allowed to reanneal, with larger DNA taking longer. Cot value accounts for DNA concentration, time, and buffer effects, representing repetitive sequences - lower Cot means more repeats. Examples show bacteria have nearly all single-copy DNA, while mouse has varying proportions of single-copy, middle repetitive, and highly repetitive sequences. Cot curve analysis provides information on genome size, complexity, and proportions of sequence types.
C value
The document discusses the C-value paradox, which is the lack of relationship between genome size and organism complexity. It provides data on the wide range of genome sizes across different taxonomic groups. Introns and exons are described, with exons comprising the coding sequences and introns being removed from transcripts by splicing. Alternative splicing can generate multiple protein isoforms from a single gene. Repeated sequences, including satellites, minisatellites, microsatellites, transposons, SINEs and LINEs comprise a large portion of eukaryotic genomes.
Site specific recombination
This document discusses site-specific recombination, including the structures and mechanisms involved. It describes two classes of recombinases - tyrosine recombinases and serine recombinases. Tyrosine recombinases involve cleavage of DNA through formation of a protein-DNA bond using a tyrosine residue. Serine recombinases utilize a phosphoserine bond between DNA and a conserved serine residue. The document provides examples of applications for site-specific recombination such as tracking cell lineage, altering gene expression, and targeted gene knockout.
Protein dna interactions
Protein-DNA interactions can be either specific or non-specific. Specific interactions involve transcription factors that regulate gene expression by binding to DNA motifs through domains like helix-loop-helix, leucine zipper, or zinc finger motifs. Non-specific interactions involve histones that help structure DNA into nucleosomes within chromatin and can be chemically modified through methylation, demethylation, acetylation, and phosphorylation.
Restriction enzymes
Restriction enzymes are molecular scissors found in bacteria that cut DNA molecules at specific recognition sequences. They serve as a defensive mechanism for bacteria against bacteriophages by cleaving the phage DNA. There are over 3000 known restriction enzymes that are classified into four main types based on their composition, cofactors, and cutting mechanisms. Restriction enzymes are important tools in biotechnology for manipulating DNA sequences through cutting DNA fragments with specific sticky or blunt ends, which can then be recombined through techniques like cloning.
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Mitochondrial DNA
It is the DNA located in the mitochondria.Mitochondrial DNA (mtDNA or mDNA) is the DNA located in the mitochondria.
They are double stranded circular DNA molecule.
It is only 16 kb in length – contains 16,600 bp.
It is haploid in nature.
It codes for 37 genes.
13 genes provide instructions for making enzymes involved in oxidative phosphorylation.
It is a process that uses oxygen and simple sugars to create ATP, the cells main energy source.
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SOS repair
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Site specific recombination
This document discusses site-specific recombination, including the structures and mechanisms involved. It describes two classes of recombinases - tyrosine recombinases and serine recombinases. Tyrosine recombinases involve cleavage of DNA through formation of a protein-DNA bond using a tyrosine residue. Serine recombinases utilize a phosphoserine bond between DNA and a conserved serine residue. The document provides examples of applications for site-specific recombination such as tracking cell lineage, altering gene expression, and targeted gene knockout.
Protein dna interactions
Protein-DNA interactions can be either specific or non-specific. Specific interactions involve transcription factors that regulate gene expression by binding to DNA motifs through domains like helix-loop-helix, leucine zipper, or zinc finger motifs. Non-specific interactions involve histones that help structure DNA into nucleosomes within chromatin and can be chemically modified through methylation, demethylation, acetylation, and phosphorylation.
Restriction enzymes
Restriction enzymes are molecular scissors found in bacteria that cut DNA molecules at specific recognition sequences. They serve as a defensive mechanism for bacteria against bacteriophages by cleaving the phage DNA. There are over 3000 known restriction enzymes that are classified into four main types based on their composition, cofactors, and cutting mechanisms. Restriction enzymes are important tools in biotechnology for manipulating DNA sequences through cutting DNA fragments with specific sticky or blunt ends, which can then be recombined through techniques like cloning.
Maxam–Gilbert sequencing
This document discusses DNA sequencing methods. It describes the Maxam-Gilbert sequencing method developed in 1976-1977 which uses chemical modification and cleavage of DNA at specific bases, followed by electrophoresis to separate fragments by size. It also mentions the popular Sanger sequencing method. The procedure for Maxam-Gilbert sequencing involves labeling DNA, cleaving it with chemicals, running the fragments on a gel, and analyzing the results to deduce the DNA sequence. Advantages include no premature termination and ability to sequence stretches not possible with enzymatic methods, while disadvantages include use of radioactivity and toxic chemicals.
Mitochondrial DNA
It is the DNA located in the mitochondria.Mitochondrial DNA (mtDNA or mDNA) is the DNA located in the mitochondria.
They are double stranded circular DNA molecule.
It is only 16 kb in length – contains 16,600 bp.
It is haploid in nature.
It codes for 37 genes.
13 genes provide instructions for making enzymes involved in oxidative phosphorylation.
It is a process that uses oxygen and simple sugars to create ATP, the cells main energy source.
cDNA Library
This is a brief overview of the process of making a complementary DNA (cDNA) library from mRNA (messenger RNA).
Fidelity of DNA replication
DNA replication involves the synthesis of new DNA strands through a semi-conservative process whereby each new molecule contains one old strand and one new strand synthesized using the old strand as a template. Key enzymes involved include helicase, which unwinds the DNA double helix, primase, which initiates DNA synthesis, and DNA polymerase, which catalyzes phosphodiester bond formation to elongate the new strands. Fidelity is maintained through proofreading mechanisms that remove incorrectly incorporated nucleotides and DNA repair pathways that correct errors made during replication.
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Electrophoretic mobility shift assay
This is technique used widely for protein separation from a mixture and is very easy and less costly method. Slides cover all essential points about EMSA and it is quite interesting to know that how it detect and separate different proteins and their mobility shift assay.
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DNA repair mechanisms in prokaryotes involve direct repair, excision repair, and mismatch repair. Direct repair converts damaged nucleotides directly back to their original structure using enzymes like photolyase. Excision repair removes damaged sections of DNA through base excision repair which removes single damaged bases using glycosylases and AP endonucleases, or nucleotide excision repair which removes short oligonucleotides. Mismatch repair recognizes and fixes errors made during DNA replication by distinguishing the parental DNA strands and excising the newly synthesized strand containing mistakes.
Regulation of lac operon positive nd negative
The document summarizes the regulation of the lac operon in E. coli. It describes how the lac operon can be regulated both positively and negatively in response to the presence of lactose or glucose. In negative regulation, the lac repressor binds to the operator site in the absence of lactose, preventing transcription. In the presence of lactose, it binds to allolactose and dissociates from DNA, allowing transcription. Positive regulation involves cAMP and the catabolite activator protein activating transcription in the absence of glucose.
Abzymes
Abzymes, also known as catalytic antibodies, are monoclonal antibodies that exhibit enzymatic activity. They are able to bind to transition states of enzyme-catalyzed reactions with high specificity and affinity, stabilizing the transition state and increasing reaction rates. Abzymes can be artificially produced by immunizing animals with transition state analogs of reactions. They have potential applications in drug development, cancer treatment, and developing therapies for viral infections like HIV. Researchers have engineered an abzyme that can degrade an essential region of the HIV envelope protein, rendering the virus unable to infect cells.
Sos repair mechanism
SOS repair
a system that repairs severely damaged bases in DNA by base excision and replacement, even if there is no template to guide base selection. This process is a last resort for repair and is often the cause of mutations.
Translation in prokaryotes
This document summarizes the process of translation in prokaryotes. It begins with an introduction to translation occurring in the cytoplasm where ribosomes synthesize proteins using messenger RNA (mRNA). The three main stages of translation are then described in detail: initiation, elongation, and termination. Initiation involves assembly of the ribosome and initiation factors on the mRNA start codon. Elongation is the process of adding amino acids to the growing polypeptide chain through binding of transfer RNA (tRNA) and the actions of elongation factors. Termination occurs when a stop codon is reached and release factors trigger hydrolysis and release of the completed protein. Key components of translation like ribosomes, mRNA, tRNA, and their functions are
Rolling circle mechanism ppt
Rolling circle replication is a process that can rapidly synthesize multiple copies of circular DNA or RNA molecules. It involves the unidirectional replication of circular nucleic acids. The process begins with an initiator protein nicking one strand of the circular DNA. DNA polymerase then uses the 3' end of the nicked strand to initiate replication, displacing the 5' end. Replication continues around the circle to produce a long concatemer of copies. The concatemer is then cleaved and ligated to form multiple double-stranded circular DNA molecules. Rolling circle replication is used by some viruses and plasmids to replicate their genomes and can be harnessed for applications like signal amplification in biosensing.
post translational modifications of protein
Post-translational modifications (PTMs) are chemical modifications of proteins that occur after translation. PTMs play a key role in regulating protein function by modifying activity, localization, and interactions. The main types of PTMs discussed are phosphorylation, glycosylation, ubiquitination, S-nitrosylation, methylation, N-acetylation, lipidation, and proteolysis. These modifications are identified through techniques like mass spectrometry, HPLC, radioactive labeling, and gel electrophoresis. PTMs are important for processes like cell signaling, growth, and apoptosis.
Translation in Prokaryotes
Translation in prokaryotes involves three main stages - initiation, elongation, and termination. During initiation, the small ribosomal subunit binds to an mRNA with help from initiation factors and forms the initiation complex. In elongation, tRNAs bring amino acids to the ribosome according to mRNA codons and peptide bonds are formed. Termination occurs when a stop codon signals for the release of the complete polypeptide from the ribosome. The process requires several RNA and protein molecules working together, including ribosomes, tRNAs, and various factors, to translate the genetic message into a polypeptide product.
Polyacrylamide gel electrophoresis
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widely used and has very much importance.
COMPLETE PROCEDURE & USES are described in the slide.
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DNA = Deoxyribonucleic acid (DNA) is a molecule that encodes the genetic instructions used in the development and functioning of all known living organisms
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FORMS OF DNA
The document discusses different forms of DNA structure that can be adopted based on environmental conditions. The main forms discussed are B-DNA, A-DNA, Z-DNA, C-DNA, D-DNA and E-DNA. B-DNA is the most common form, having a right-handed double helix structure with 10 base pairs per turn. A-DNA and Z-DNA are also double helical but have different structural characteristics than B-DNA such as base pair spacing and groove size. The various forms arise in response to changes in humidity, ionic conditions and DNA sequence composition.
Prokaryotic DNA replication
DNA replication in prokaryotes begins with the unwinding of DNA at the origin of replication by enzymes like DnaA and DnaB helicase. This produces two replication forks that move in opposite directions. The leading strand is replicated continuously while the lagging strand is replicated discontinuously in short segments called Okazaki fragments. DNA polymerase III is the main enzyme that synthesizes new DNA. Replication terminates at the terminus region when the DnaB helicase is stopped by protein Tus bound to Ter sequences.
DNA Replication
DNA replication is the process by which a cell makes an identical copy of its DNA before cell division. It involves unwinding the DNA double helix at an origin of replication and using each strand as a template to synthesize new partner strands. RNA primers are used to initiate DNA synthesis, which occurs semi-conservatively and bidirectionally from the replication fork to produce two identical copies of the original DNA molecule.
DNA structure, Functions and properties
This document discusses the structure, properties, and functions of DNA. It describes DNA as a polymer composed of deoxyribonucleotides that carries the genetic information found in chromosomes, mitochondria, and chloroplasts. The basic structure of DNA involves two anti-parallel strands coiled around each other to form the familiar double helix structure, held together by hydrogen bonds between complementary nucleotide base pairs and base stacking interactions. DNA exists in various structural forms and undergoes compaction in the cell, ultimately forming chromatin through association with histone proteins. The primary function of DNA is to serve as the template for its own replication and transcription into RNA to direct protein synthesis.
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The document summarizes a study on dye sensitized solar cells that use 2-naphthaldehyde dye as the sensitizer. Key points:
1) ZnO nanostructured electrodes were prepared using a hydrothermal method and used as the photoanode. 2-naphthaldehyde dye was synthesized and characterized. Dye sensitized solar cells were assembled using the dye and iodide/triiodide electrolyte solution.
2) The efficiency of cells using the synthesized 2-naphthaldehyde dye and its polymer derivative were tested and compared to using 2-naphthol as the starting material. The polymer dye showed the highest efficiency of 0.266%.
3) Characterization of
Solvents and solvent effect in UV - Vis Spectroscopy, By Dr. Umesh Kumar sh...
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This document discusses solvent effects on UV-visible spectroscopy. It begins by explaining that UV spectra are usually measured in dilute solutions using solvents that are transparent in the wavelength range and do not interact strongly with the solute. Common solvents mentioned are ethanol, hexane, and water. The document then discusses various solvent effects including bathochromic shifts, hypsochromic shifts, hyperchromic shifts, and hypochromic shifts. It provides examples of how solvents can alter absorption wavelengths and intensities. The document concludes by mentioning several reference texts on this topic.Research Paper Presentation by Ariful Islam
The document summarizes a research presentation on the synthesis and characterization of new zinc, copper, and nickel complexes based on an imine ligand containing a 2-aminothiophenol moiety. Specifically, it describes the synthesis of a tridentate Schiff base ligand and its dimeric complexes with zinc, copper, and nickel ions. It then discusses the various techniques used to characterize the ligand and complexes, including IR spectroscopy, UV-Vis spectroscopy, NMR spectroscopy, conductivity measurements, computational modeling, and X-ray crystallography. The key findings are that the complexes were stable in solid and solution states, with the ligand acting as a tridentate chelating agent, and DFT calculations provided insights into their frontier
A Chiroptical Photoswitchable DNA Complex
The interesting structural, electronic, and optical properties
of DNA provide fascinating opportunities for developing nanoscale smart
materials by integrating DNA with opto-electronic components. In this
article we demonstrate the electrostatic binding of an amine-terminated
dithienylethene (DET) molecular switch to double-stranded synthetic
polynucleotides. The DET switch can undergo photochemical ring-closure
and opening reactions. Circular dichroism (CD) and UVvis spectroscopy
show that both the open, 1o, and the closed, 1c, forms of the switch bind
to DNA. Upon addition of DNA to a solution of 1o or 1c, the UVvis
spectrum displays a hypochromic effect, indicative of an interaction between the switch and the DNA. The chirality of the DNA
double-helix is transmitted to the switching unit which displays a well-defined CD signal upon supramolecular complexation to the
DNA. Additionally, the CD signal of the DNA attenuates, demonstrating that both components of the complex mutually influence
each other's structure; the DNA induces chirality in the switch, and the switch modifies the structure of the DNA. Modulation of the
chiroptical properties of the complex is achieved by photochemically switching the DET between its ring open and closed isomers.
A pH dependence study of the binding shows that when the pH is increased the switches lose their binding ability, indicating that
electrostatic interactions between protonated amines and the negatively charged phosphate backbone are the dominant driving
force for binding to the DNA. A comparison of poly(deoxyguanylic-deoxycytidylic) acid [poly(dGdC)2] polynucleotides with
poly(deoxyadenylic-deoxythymidylic) acid [poly(dAdT)2] shows distinct differences in the CD spectra of the complexes. Original Source: http://pubs.acs.org/doi/abs/10.1021/jp205893y
Denaturation of DNA
DNA is a double-helix molecule that carries genetic instructions. It is composed of two strands of polynucleotides made up of nucleotides, each containing a nitrogenous base, sugar, and phosphate. The strands are stabilized by hydrogen bonds between complementary bases and base-stacking interactions. DNA can be denatured into single strands by elevated temperature, extreme pH, low salt concentrations, or chemicals that disrupt hydrogen bonding between strands. Denaturation temperature depends on factors like base composition and length. Renaturation occurs when double-stranded DNA is cooled under conditions that allow the strands to re-form hydrogen bonds and complementary base pairing.
DNA denaturation.pdf
DNA denaturation is the separation of the DNA double strands into two separate single strands, which is as a result of several factors such as temperature, pH, e.t.c.
ppt.ppt
This chapter discusses carbon-carbon bond formation through reactions between nucleophilic carbon intermediates and electrophilic carbons. It focuses on the alkylation of enolates, enamines, and imine anions generated from ketones, aldehydes, esters, amides, and nitriles. Key topics include the factors that determine the stability and reactivity of various carbon nucleophiles, such as substituents and reaction conditions. Solvent effects and the regioselectivity, stereoselectivity, and site selectivity of alkylation reactions are also examined. Specific examples illustrate principles such as kinetic vs. thermodynamic control and the use of chiral auxiliaries to achieve enantioselectivity.
Fac/Mer Isomerism in Fe(II) Complexes
The document summarizes an experiment investigating fac/mer isomerism in a low spin iron(II) complex. A complex was synthesized from iron(II) tetrafluoroborate, benzylamine, and 2-pyridinecarboxaldehyde, yielding 79.7% product. NMR showed a high ratio of facial to meridional isomers. UV-vis spectroscopy determined molar extinction coefficients of 6081.9 and 4518.4 L/mol-cm at 516.5 and 561.3 nm, respectively.
synthesis and characterization of hydrazone ligand and their metal complexes
This slide mainly contain the synthesis, characterization of a few hydrazine based heterocyclic ligand such as hydralazone and phenyl hydralazone and also their metal complexes. so in this work, my aim is to synthesise the ligands; 2-thiophenecarboxylaldehydehydralazone and 2,3-butanedionephenylhydrazone. also to characterized the synthesised hydrazones by different physiochemical techniques.
INDO US poster
Generation of white light from lanthanide-doped nanoparticles is demonstrated through down conversion. Core-shell nanoparticles doped with Tm3+, Tb3+, and Eu3+ lanthanide ions in specific orders and amounts are prepared. The inert shells protect the lanthanide ions from surface quenching. Upon excitation at 280 nm, a continuous white light emission spectrum is observed from the nanoparticles due to energy transfer between the lanthanide ions. Characterization with FTIR, NMR and fluorescence spectroscopy confirm the successful synthesis of oleic acid stabilized lanthanide-doped core-shell LaVO4 nanoparticles that generate white light through down conversion.
Cot curve and tm
This document discusses the absorption of UV light by nucleic acids and the denaturation and renaturation of DNA molecules. Some key points:
1. Nucleic acids absorb UV light due to their conjugated double bonds and ring structures, with absorption maximum at 260nm. More ordered structures absorb less light.
2. DNA denaturation involves separating the two strands by disrupting hydrogen bonds, usually through increased temperature. This is measured by increased UV absorption.
3. The melting temperature (Tm) is when half the DNA molecules are denatured. Molecules with more GC pairs have a higher Tm.
4. Denatured DNA can renature by re-
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Properties of dna
- 2. Physical properties Ultraviolet absorption Denaturation Renaturation Chemical properties Nucleophiles Hydrazine Hydozlyamine
- 3. Alkylating agents Nitrous acid Bifunctional alkylating agents Electophiles
- 4. DNA absorbs uv in range of (240nm-280nm). MAX absorption at 260nm. This absorption is monitored by spectrophotometer Calculations are done by using BEER LAMBERT LAW A=ECl
- 5. E FOR DNA IS 6600L/MOL cm. Absorbance(A)=1 at 260nm is equivalent to 50ug/ml DNA. A260/A280 is a measure of DNA purity. Single stranded DNA has absorbance 40% more then double stranded. Absorbance at 260nm free bases 1.60 units single strand 1.37 units double strand 1.00 units
- 8. When two strands of the DNA separate as single strands. Effect of various factors on DNA TEMPERATURE ACIDS ALKALI
- 10. TM linear relationship between Base stacking energy G+C CONTENT Temp. at which 50% of the DNA melts Melting temperature(Tm) TEMPERATURE Increase in temp. disrupts H-bond & shell of hydration.
- 11. ACIDS PH<2 ionizes the bases of two strands Thus disrupts H bonding & base stacking. Phosphodiester bond & glycosidic bond are susceptible to lowPh. ALKALI Above ph 12 base tend to change polarity Disrupts H bonding
- 13. Renaturation Denatured DNA may reform when Hbond forms btw complementary base pairs. Slow cooling or addition of ions may lead to renaturation. The rate limiting step in this reaction is collision of complementary DNA molecules. Once the nucleation has initiated, rest double helix coils very fastly.
- 14. NUCLEOPHILE Electron rich reagent that can attack on +ve ly charged carbon next to nitrogen in nitrogen bases.
- 15. H2N-NH2 It is widely used to modify DNA.
- 16. Stronnucleophile and powerfull mutagen. It can disrupt h bonding physically by formation of hydroxlamino group thus prevent A-T & C-G pairing.
- 17. Seek an unbranched electron pair. Good site for e attack are ring nitrogen and oxygen on nitrogen bases. ALKYLATING AGENTS Ethylmethylsulphonate Ethylnitrosourea N –methyl-N’-nitro-N-nitosoguanidino
- 18. Depending upon site of alkylation they may alter keto enol equillibrium. Bulky alkyl adduct on the base will affect H bonding. Bifunctional alkylating agents Have two reactive group Nitogen and sulphur mustard gas They form intra or inter crosslinking btw two strands of DNA
- 19. HNO2 REACTS WITH AMINO GROUP OF C,G OR A in an oxidative deamination rx The deamination leads to carbonyl group cytosine uracil Reverse h bond polarity adenine hypoxa nthine Reverse H bond polarity guanine xanthine No mismatch pairing
- 20. Richard r sinden Voet and voet Cell and molecular biology genarld karp
Editor's Notes
- ing