DNA replication is the process where a cell makes an identical copy of its DNA before cell division. It is semiconservative, with each parental DNA strand serving as a template for a new daughter strand. Key events include unwinding of the DNA double helix by helicase, addition of nucleotides to the new strands by DNA polymerase, and joining of Okazaki fragments by DNA ligase. Replication occurs bidirectionally from an origin of replication and requires enzymes such as DNA polymerase, helicase, primase, ligase and topoisomerases. Errors can occur but are corrected by proofreading to maintain high-fidelity copying of the genome.
Replication (prokaryotes and eukaryotes) FN 312.pptsultanasadia912
The traditional monoclonal antibody (mAb) production process usually starts with generation of mAb-producing cells (i.e. hybridomas) by fusing myeloma cells with desired antibody-producing splenocytes (e.g. B cells). These B cells are typically sourced from animals, usually mice. After cell fusion, large numbers of clones are screened and selected on the basis of antigen specificity and immunoglobulin class. Once candidate hybridoma cell lines are identified, each "hit" is confirmed, validated, and characterized using a variety of downstream functional assays. Upon completion, the clones are scaled up where additional downstream bioprocesses occur.
The document discusses DNA replication. It describes early experiments that showed DNA carries genetic information, such as the Avery-MacLeod-McCarty experiment. It also describes Chargaff's rules about DNA base composition and the Watson and Crick model of the DNA double helix structure. The process of DNA replication is then explained, including semi-conservative replication, the role of enzymes like DNA polymerase and helicase, and leading and lagging strand synthesis.
1. DNA replication is the process by which a cell makes an identical copy of its DNA before cell division. This ensures that each daughter cell has the full set of genetic instructions.
2. The DNA double helix unwinds and each strand acts as a template for new strand synthesis. RNA primers are added and DNA polymerase builds the new strands in the 5' to 3' direction.
3. The leading strand is synthesized continuously but the lagging strand is synthesized in fragments called Okazaki fragments that are later joined by DNA ligase. This semi-conservative mode of replication results in two identical DNA molecules after replication.
1) James Watson and Francis Crick discovered the double helix structure of DNA in 1953, which showed that DNA is the genetic material that directs the inheritance of traits.
2) Experiments in the 1940s-1950s provided evidence that DNA, not protein, was the genetic material: Avery, McCarty, and MacLeod showed DNA was the transforming principle in bacteria; Hershey and Chase showed that DNA, not protein, enters the host cell during bacterial virus infection.
3) Watson and Crick developed the double helix model of DNA structure in 1953 based on evidence such as Chargaff's rules of base pairing and X-ray crystallography images from Franklin - their model explained
1) DNA was identified as the genetic material through experiments in the 1940s-1950s studying bacteria, viruses, and their ability to transform cells.
2) Watson and Crick developed the double helix model of DNA structure in 1953 based on evidence including X-ray crystallography images that showed DNA had a regular helical structure.
3) DNA replication is semi-conservative and involves unwinding the DNA double helix, synthesizing new strands based on base-pairing rules, and producing two identical copies of the original DNA molecule before cell division.
DNA replication is semiconservative and involves unwinding of the DNA double helix by helicase, stabilization by SSB proteins, and use of RNA primers by primase. DNA polymerase extends the primers using free 3'OH groups and dNTPs. Replication is continuous on the leading strand but discontinuous on the lagging strand, producing Okazaki fragments. RNA primers are replaced by DNA and gaps sealed by ligase. DNA sequencing uses dideoxynucleotides and DNA polymerase to differentially terminate DNA strand extension, producing fragments of different lengths that can be resolved by gel electrophoresis to determine the DNA sequence.
The document discusses several key aspects of DNA structure and replication:
1. The Hershey-Chase experiment provided definitive evidence that DNA, not protein, carries the genetic material of organisms. They found that labeled viral DNA entered infected bacteria cells, while labeled viral proteins did not.
2. Rosalind Franklin's X-ray crystallography of DNA provided data that helped Watson and Crick discover the double helix structure of DNA. DNA is made of nucleotides with a phosphate group, sugar, and nitrogenous base.
3. DNA replication is semi-conservative and relies on complementary base pairing between DNA strands. It involves enzymes that unwind, separate, and replicate both DNA strands.
The document discusses the central dogma of molecular biology, which states that DNA is transcribed into RNA and then translated into protein. It describes the process of DNA replication, including initiation, elongation, and termination. DNA replication is semiconservative and bidirectional, with the leading strand synthesized continuously and the lagging strand synthesized discontinuously in fragments. The mechanisms of DNA replication are largely similar between prokaryotes and eukaryotes.
Replication (prokaryotes and eukaryotes) FN 312.pptsultanasadia912
The traditional monoclonal antibody (mAb) production process usually starts with generation of mAb-producing cells (i.e. hybridomas) by fusing myeloma cells with desired antibody-producing splenocytes (e.g. B cells). These B cells are typically sourced from animals, usually mice. After cell fusion, large numbers of clones are screened and selected on the basis of antigen specificity and immunoglobulin class. Once candidate hybridoma cell lines are identified, each "hit" is confirmed, validated, and characterized using a variety of downstream functional assays. Upon completion, the clones are scaled up where additional downstream bioprocesses occur.
The document discusses DNA replication. It describes early experiments that showed DNA carries genetic information, such as the Avery-MacLeod-McCarty experiment. It also describes Chargaff's rules about DNA base composition and the Watson and Crick model of the DNA double helix structure. The process of DNA replication is then explained, including semi-conservative replication, the role of enzymes like DNA polymerase and helicase, and leading and lagging strand synthesis.
1. DNA replication is the process by which a cell makes an identical copy of its DNA before cell division. This ensures that each daughter cell has the full set of genetic instructions.
2. The DNA double helix unwinds and each strand acts as a template for new strand synthesis. RNA primers are added and DNA polymerase builds the new strands in the 5' to 3' direction.
3. The leading strand is synthesized continuously but the lagging strand is synthesized in fragments called Okazaki fragments that are later joined by DNA ligase. This semi-conservative mode of replication results in two identical DNA molecules after replication.
1) James Watson and Francis Crick discovered the double helix structure of DNA in 1953, which showed that DNA is the genetic material that directs the inheritance of traits.
2) Experiments in the 1940s-1950s provided evidence that DNA, not protein, was the genetic material: Avery, McCarty, and MacLeod showed DNA was the transforming principle in bacteria; Hershey and Chase showed that DNA, not protein, enters the host cell during bacterial virus infection.
3) Watson and Crick developed the double helix model of DNA structure in 1953 based on evidence such as Chargaff's rules of base pairing and X-ray crystallography images from Franklin - their model explained
1) DNA was identified as the genetic material through experiments in the 1940s-1950s studying bacteria, viruses, and their ability to transform cells.
2) Watson and Crick developed the double helix model of DNA structure in 1953 based on evidence including X-ray crystallography images that showed DNA had a regular helical structure.
3) DNA replication is semi-conservative and involves unwinding the DNA double helix, synthesizing new strands based on base-pairing rules, and producing two identical copies of the original DNA molecule before cell division.
DNA replication is semiconservative and involves unwinding of the DNA double helix by helicase, stabilization by SSB proteins, and use of RNA primers by primase. DNA polymerase extends the primers using free 3'OH groups and dNTPs. Replication is continuous on the leading strand but discontinuous on the lagging strand, producing Okazaki fragments. RNA primers are replaced by DNA and gaps sealed by ligase. DNA sequencing uses dideoxynucleotides and DNA polymerase to differentially terminate DNA strand extension, producing fragments of different lengths that can be resolved by gel electrophoresis to determine the DNA sequence.
The document discusses several key aspects of DNA structure and replication:
1. The Hershey-Chase experiment provided definitive evidence that DNA, not protein, carries the genetic material of organisms. They found that labeled viral DNA entered infected bacteria cells, while labeled viral proteins did not.
2. Rosalind Franklin's X-ray crystallography of DNA provided data that helped Watson and Crick discover the double helix structure of DNA. DNA is made of nucleotides with a phosphate group, sugar, and nitrogenous base.
3. DNA replication is semi-conservative and relies on complementary base pairing between DNA strands. It involves enzymes that unwind, separate, and replicate both DNA strands.
The document discusses the central dogma of molecular biology, which states that DNA is transcribed into RNA and then translated into protein. It describes the process of DNA replication, including initiation, elongation, and termination. DNA replication is semiconservative and bidirectional, with the leading strand synthesized continuously and the lagging strand synthesized discontinuously in fragments. The mechanisms of DNA replication are largely similar between prokaryotes and eukaryotes.
The document discusses the structure and replication of DNA. It explains that DNA has a double helix structure that allows it to efficiently store and replicate genetic information. DNA replication is carried out by a complex system of enzymes and involves unwinding the DNA double helix, synthesizing new strands to complement the existing strands, and joining fragments on the lagging strand. While most of the DNA codes for proteins, some regions have important regulatory functions or code for other molecules like tRNAs.
Dna replication and importance of its inhibition pdfssuserf4e856
A research topic submitted by some students of the first year in Al-Azhar Pharmacy in Assiut in 2020 in the subject of cell biology under the supervision of Dr. Omar Mohafez holds a PhD in biochemistry and is a professor at the same college.
DNA sequencing involves determining the order of nucleotides (adenine, guanine, cytosine, thymine) in a DNA molecule. There are three main methods: 1) Maxam-Gilbert chemical degradation, 2) Sanger dideoxynucleotide chain termination, and 3) direct sequencing using PCR. Gene synthesis chemically builds DNA base-by-base without a template, and has applications in forensics, agriculture, and solving crimes.
1) DNA replication is a semiconservative process where the parental DNA strands separate and each acts as a template for new complementary strands to be synthesized in the 5' to 3' direction by DNA polymerase.
2) On the leading strand, DNA synthesis is continuous while on the lagging strand it is discontinuous resulting in short Okazaki fragments that are later joined by DNA ligase.
3) DNA and RNA primers, DNA helicase, single-stranded DNA binding proteins, DNA polymerase, and DNA ligase all play important roles in facilitating the replication process.
This document discusses DNA replication in prokaryotes and eukaryotes. It provides an overview of the key steps and enzymes involved in DNA replication for both prokaryotes and eukaryotes. For prokaryotes, it describes initiation at the origin of replication involving DNA A protein, elongation by DNA polymerase III, and termination when replication forks meet. For eukaryotes, it outlines initiation involving pre-replication complexes, elongation involving leading and lagging strand synthesis, and the various enzymes involved such as DNA polymerases and helicases.
DNA replicates in a semi-conservative manner, as proven by Meselson and Stahl's experiment in 1958. Replication begins with initiation, where helicase unwinds the DNA double helix and primase lays down RNA primers. During elongation, DNA polymerase adds nucleotides to the 3' end of the primers on the leading and lagging strands. Okazaki fragments are formed and ligated on the lagging strand. Replication terminates when DNA polymerase reaches the telomeres at the end of the DNA strands.
DNA replication is the process by which DNA copies itself for cell division. It involves unwinding the DNA double helix and using each strand as a template to synthesize two new strands of DNA. This process is semi-conservative, meaning each new DNA molecule contains one original and one newly synthesized strand. DNA replication is catalyzed by enzymes and ensures the genetic information is accurately copied and passed on to daughter cells.
This document provides an overview of genome organization and DNA structure. It discusses the nucleic acids RNA and DNA, including their composition of nucleotides with nitrogenous bases and pentose sugars. The document describes the Watson-Crick model of DNA structure as a double helix with antiparallel strands held together by complementary base pairing of A-T and G-C. It also mentions other DNA conformations like B, Z, A, and triple-stranded DNA. The objectives are to define nucleic acids, describe DNA structure and conformations, and explain DNA modifications and their effects in cells.
The document provides an overview of DNA replication through several key experiments and findings:
1. The Meselson-Stahl experiment in 1958 supported the semiconservative model of DNA replication proposed by Watson and Crick. They found that E. coli DNA replicated semiconservatively after growing bacteria in media containing different nitrogen isotopes.
2. DNA replication requires unwinding of the DNA double helix by helicase, stabilization by SSB proteins, and relaxation of supercoiling by topoisomerase.
3. RNA primers are added by primase and extended by DNA polymerase, which can only extend from a 3' OH group. Replication is continuous on the leading strand but discontinuous via Ok
B.tech biotechnology ii elements of biotechnology unit 2 structure of dnaRai University
James Watson and Francis Crick discovered the double helical structure of DNA in 1953. DNA is made up of nucleotides containing a nitrogenous base (adenine, guanine, cytosine, or thymine), a pentose sugar, and a phosphate group. Adenine pairs with thymine through two hydrogen bonds, and guanine pairs with cytosine through three hydrogen bonds. DNA stores genetic information, takes the double helix form, and can undergo structural variations like hairpin loops or cruciform structures. DNA has characteristic absorption, density, denaturation, and hybridization properties that provide information about its structure and sequence.
1. Nucleic acids are polymers of nucleotides that store genetic information. There are two types: DNA and RNA. (1 sentence)
2. DNA is found in the nucleus and contains the genes, while RNA is involved in protein synthesis and can be found in various cellular locations. The structures of DNA and RNA are similar but DNA contains thymine while RNA contains uracil. (1 sentence)
3. DNA replicates semi-conservatively to produce two identical DNA molecules during cell division. RNA is synthesized from a DNA template in a process called transcription. There are three main types of RNA: mRNA, tRNA, and rRNA, which have different roles in protein synthesis. (1 sentence)
The genetic material of any organisms is the substance that stores information about structure, function and
Development of various characteristics of a living
organisms.
1. The document discusses microbial genetics and the flow of genetic information. It defines key terms like genetics, genes, genome, genotype, and phenotype.
2. It describes the structure of DNA and how it carries genetic information as a double-stranded molecule made up of nucleotides. DNA replication is semi-conservative and involves unwinding the strands, creating an RNA primer, and synthesizing new strands in the 5' to 3' direction.
3. The process of transcription is described, where RNA polymerase reads the genetic code from DNA and synthesizes mRNA, which is then translated to produce proteins. Both prokaryotes and eukaryotes undergo transcription but differ in initiation, processing, and coupling with
The document discusses DNA structure and replication. It begins by summarizing Griffith's experiments which showed genetic material can be transferred between bacteria. Next, it describes the discovery of DNA's double helix structure by Watson and Crick in 1953, including its key features like base pairing and antiparallel strands. The document then reviews three proposed models of DNA replication before summarizing Meselson and Stahl's experiment which supported the semiconservative model where each new DNA molecule contains one original and one new strand. Finally, it provides an overview of the molecular mechanism of DNA replication from the origin of replication to DNA polymerase adding nucleotides.
DNA is the genetic material that is made up of nucleotides containing deoxyribose sugar, phosphate groups, and nitrogenous bases. DNA exists in the form of a double helix with the two strands held together by hydrogen bonds between complementary nucleotide base pairs. The structure of DNA was discovered by Watson and Crick in 1953 based on experimental evidence from Chargaff, Franklin, and others. DNA replication is semi-conservative and involves unwinding of the DNA double helix, synthesis of new strands, and ligation to form two identical DNA molecules. DNA carries genetic information that is expressed through transcription of DNA into RNA and translation of RNA into proteins.
DNA replication is the process where new DNA molecules are produced that have the same base sequence as the original DNA molecule. It occurs in three stages - initiation, elongation, and termination. Initiation occurs at the origin of replication where enzymes help unwind and separate the DNA strands. Elongation involves DNA polymerase adding new nucleotides in the 5' to 3' direction based on complementarity. Termination occurs at specific termination sites where the replication forks meet. DNA replication is semi-conservative, producing two DNA molecules each with one original and one new strand.
The document provides an overview of DNA structure and function, including:
- DNA is a double-helix structure with bases pairing between strands.
- DNA replication is semiconservative and involves unwinding of the strands followed by synthesis of new strands using the old strands as templates.
- Gene expression involves two main steps - transcription of DNA to mRNA in the nucleus, and translation of mRNA to proteins in the cytoplasm using transfer RNA and ribosomes.
- Gene expression is regulated at multiple levels including chromatin structure, transcription factors, RNA processing, and mRNA translation controls.
The nucleotide structure ,consists of
the nitrogenous base ,attached to the 1’ carbon of deoxyribose
,
the phosphate group attached to the 5’ carbon of deoxyribose
,
a free hydroxyl group (-OH) ,at the 3’ carbon of deoxyribose,1. DNA HELICASES,
to separate the strand,
2. GYRASE (Topoisomerases),
unwind the supercoil,
3. Single strand binding protein (SSBP)
, activity of helicase,
keep two strand separate,
protect DNA from nuclease degradation,
release after replication,
1. DNA replication in prokaryotes involves unwinding of the DNA double helix by helicase, synthesis of an RNA primer by primase, and addition of nucleotides to the 3' ends of primers by DNA polymerase.
2. Replication occurs bidirectionally from an origin of replication, with continuous synthesis on the leading strand and discontinuous synthesis in fragments on the lagging strand.
3. In eukaryotes, DNA replication initiates at multiple origins of replication along each chromosome and involves additional mechanisms to address challenges like chromosome length and nucleosome assembly.
The document discusses the structure and replication of DNA. It explains that DNA has a double helix structure that allows it to efficiently store and replicate genetic information. DNA replication is carried out by a complex system of enzymes and involves unwinding the DNA double helix, synthesizing new strands to complement the existing strands, and joining fragments on the lagging strand. While most of the DNA codes for proteins, some regions have important regulatory functions or code for other molecules like tRNAs.
Dna replication and importance of its inhibition pdfssuserf4e856
A research topic submitted by some students of the first year in Al-Azhar Pharmacy in Assiut in 2020 in the subject of cell biology under the supervision of Dr. Omar Mohafez holds a PhD in biochemistry and is a professor at the same college.
DNA sequencing involves determining the order of nucleotides (adenine, guanine, cytosine, thymine) in a DNA molecule. There are three main methods: 1) Maxam-Gilbert chemical degradation, 2) Sanger dideoxynucleotide chain termination, and 3) direct sequencing using PCR. Gene synthesis chemically builds DNA base-by-base without a template, and has applications in forensics, agriculture, and solving crimes.
1) DNA replication is a semiconservative process where the parental DNA strands separate and each acts as a template for new complementary strands to be synthesized in the 5' to 3' direction by DNA polymerase.
2) On the leading strand, DNA synthesis is continuous while on the lagging strand it is discontinuous resulting in short Okazaki fragments that are later joined by DNA ligase.
3) DNA and RNA primers, DNA helicase, single-stranded DNA binding proteins, DNA polymerase, and DNA ligase all play important roles in facilitating the replication process.
This document discusses DNA replication in prokaryotes and eukaryotes. It provides an overview of the key steps and enzymes involved in DNA replication for both prokaryotes and eukaryotes. For prokaryotes, it describes initiation at the origin of replication involving DNA A protein, elongation by DNA polymerase III, and termination when replication forks meet. For eukaryotes, it outlines initiation involving pre-replication complexes, elongation involving leading and lagging strand synthesis, and the various enzymes involved such as DNA polymerases and helicases.
DNA replicates in a semi-conservative manner, as proven by Meselson and Stahl's experiment in 1958. Replication begins with initiation, where helicase unwinds the DNA double helix and primase lays down RNA primers. During elongation, DNA polymerase adds nucleotides to the 3' end of the primers on the leading and lagging strands. Okazaki fragments are formed and ligated on the lagging strand. Replication terminates when DNA polymerase reaches the telomeres at the end of the DNA strands.
DNA replication is the process by which DNA copies itself for cell division. It involves unwinding the DNA double helix and using each strand as a template to synthesize two new strands of DNA. This process is semi-conservative, meaning each new DNA molecule contains one original and one newly synthesized strand. DNA replication is catalyzed by enzymes and ensures the genetic information is accurately copied and passed on to daughter cells.
This document provides an overview of genome organization and DNA structure. It discusses the nucleic acids RNA and DNA, including their composition of nucleotides with nitrogenous bases and pentose sugars. The document describes the Watson-Crick model of DNA structure as a double helix with antiparallel strands held together by complementary base pairing of A-T and G-C. It also mentions other DNA conformations like B, Z, A, and triple-stranded DNA. The objectives are to define nucleic acids, describe DNA structure and conformations, and explain DNA modifications and their effects in cells.
The document provides an overview of DNA replication through several key experiments and findings:
1. The Meselson-Stahl experiment in 1958 supported the semiconservative model of DNA replication proposed by Watson and Crick. They found that E. coli DNA replicated semiconservatively after growing bacteria in media containing different nitrogen isotopes.
2. DNA replication requires unwinding of the DNA double helix by helicase, stabilization by SSB proteins, and relaxation of supercoiling by topoisomerase.
3. RNA primers are added by primase and extended by DNA polymerase, which can only extend from a 3' OH group. Replication is continuous on the leading strand but discontinuous via Ok
B.tech biotechnology ii elements of biotechnology unit 2 structure of dnaRai University
James Watson and Francis Crick discovered the double helical structure of DNA in 1953. DNA is made up of nucleotides containing a nitrogenous base (adenine, guanine, cytosine, or thymine), a pentose sugar, and a phosphate group. Adenine pairs with thymine through two hydrogen bonds, and guanine pairs with cytosine through three hydrogen bonds. DNA stores genetic information, takes the double helix form, and can undergo structural variations like hairpin loops or cruciform structures. DNA has characteristic absorption, density, denaturation, and hybridization properties that provide information about its structure and sequence.
1. Nucleic acids are polymers of nucleotides that store genetic information. There are two types: DNA and RNA. (1 sentence)
2. DNA is found in the nucleus and contains the genes, while RNA is involved in protein synthesis and can be found in various cellular locations. The structures of DNA and RNA are similar but DNA contains thymine while RNA contains uracil. (1 sentence)
3. DNA replicates semi-conservatively to produce two identical DNA molecules during cell division. RNA is synthesized from a DNA template in a process called transcription. There are three main types of RNA: mRNA, tRNA, and rRNA, which have different roles in protein synthesis. (1 sentence)
The genetic material of any organisms is the substance that stores information about structure, function and
Development of various characteristics of a living
organisms.
1. The document discusses microbial genetics and the flow of genetic information. It defines key terms like genetics, genes, genome, genotype, and phenotype.
2. It describes the structure of DNA and how it carries genetic information as a double-stranded molecule made up of nucleotides. DNA replication is semi-conservative and involves unwinding the strands, creating an RNA primer, and synthesizing new strands in the 5' to 3' direction.
3. The process of transcription is described, where RNA polymerase reads the genetic code from DNA and synthesizes mRNA, which is then translated to produce proteins. Both prokaryotes and eukaryotes undergo transcription but differ in initiation, processing, and coupling with
The document discusses DNA structure and replication. It begins by summarizing Griffith's experiments which showed genetic material can be transferred between bacteria. Next, it describes the discovery of DNA's double helix structure by Watson and Crick in 1953, including its key features like base pairing and antiparallel strands. The document then reviews three proposed models of DNA replication before summarizing Meselson and Stahl's experiment which supported the semiconservative model where each new DNA molecule contains one original and one new strand. Finally, it provides an overview of the molecular mechanism of DNA replication from the origin of replication to DNA polymerase adding nucleotides.
DNA is the genetic material that is made up of nucleotides containing deoxyribose sugar, phosphate groups, and nitrogenous bases. DNA exists in the form of a double helix with the two strands held together by hydrogen bonds between complementary nucleotide base pairs. The structure of DNA was discovered by Watson and Crick in 1953 based on experimental evidence from Chargaff, Franklin, and others. DNA replication is semi-conservative and involves unwinding of the DNA double helix, synthesis of new strands, and ligation to form two identical DNA molecules. DNA carries genetic information that is expressed through transcription of DNA into RNA and translation of RNA into proteins.
DNA replication is the process where new DNA molecules are produced that have the same base sequence as the original DNA molecule. It occurs in three stages - initiation, elongation, and termination. Initiation occurs at the origin of replication where enzymes help unwind and separate the DNA strands. Elongation involves DNA polymerase adding new nucleotides in the 5' to 3' direction based on complementarity. Termination occurs at specific termination sites where the replication forks meet. DNA replication is semi-conservative, producing two DNA molecules each with one original and one new strand.
The document provides an overview of DNA structure and function, including:
- DNA is a double-helix structure with bases pairing between strands.
- DNA replication is semiconservative and involves unwinding of the strands followed by synthesis of new strands using the old strands as templates.
- Gene expression involves two main steps - transcription of DNA to mRNA in the nucleus, and translation of mRNA to proteins in the cytoplasm using transfer RNA and ribosomes.
- Gene expression is regulated at multiple levels including chromatin structure, transcription factors, RNA processing, and mRNA translation controls.
The nucleotide structure ,consists of
the nitrogenous base ,attached to the 1’ carbon of deoxyribose
,
the phosphate group attached to the 5’ carbon of deoxyribose
,
a free hydroxyl group (-OH) ,at the 3’ carbon of deoxyribose,1. DNA HELICASES,
to separate the strand,
2. GYRASE (Topoisomerases),
unwind the supercoil,
3. Single strand binding protein (SSBP)
, activity of helicase,
keep two strand separate,
protect DNA from nuclease degradation,
release after replication,
1. DNA replication in prokaryotes involves unwinding of the DNA double helix by helicase, synthesis of an RNA primer by primase, and addition of nucleotides to the 3' ends of primers by DNA polymerase.
2. Replication occurs bidirectionally from an origin of replication, with continuous synthesis on the leading strand and discontinuous synthesis in fragments on the lagging strand.
3. In eukaryotes, DNA replication initiates at multiple origins of replication along each chromosome and involves additional mechanisms to address challenges like chromosome length and nucleosome assembly.
The binding of cosmological structures by massless topological defectsSérgio Sacani
Assuming spherical symmetry and weak field, it is shown that if one solves the Poisson equation or the Einstein field
equations sourced by a topological defect, i.e. a singularity of a very specific form, the result is a localized gravitational
field capable of driving flat rotation (i.e. Keplerian circular orbits at a constant speed for all radii) of test masses on a thin
spherical shell without any underlying mass. Moreover, a large-scale structure which exploits this solution by assembling
concentrically a number of such topological defects can establish a flat stellar or galactic rotation curve, and can also deflect
light in the same manner as an equipotential (isothermal) sphere. Thus, the need for dark matter or modified gravity theory is
mitigated, at least in part.
BREEDING METHODS FOR DISEASE RESISTANCE.pptxRASHMI M G
Plant breeding for disease resistance is a strategy to reduce crop losses caused by disease. Plants have an innate immune system that allows them to recognize pathogens and provide resistance. However, breeding for long-lasting resistance often involves combining multiple resistance genes
Or: Beyond linear.
Abstract: Equivariant neural networks are neural networks that incorporate symmetries. The nonlinear activation functions in these networks result in interesting nonlinear equivariant maps between simple representations, and motivate the key player of this talk: piecewise linear representation theory.
Disclaimer: No one is perfect, so please mind that there might be mistakes and typos.
dtubbenhauer@gmail.com
Corrected slides: dtubbenhauer.com/talks.html
Nucleophilic Addition of carbonyl compounds.pptxSSR02
Nucleophilic addition is the most important reaction of carbonyls. Not just aldehydes and ketones, but also carboxylic acid derivatives in general.
Carbonyls undergo addition reactions with a large range of nucleophiles.
Comparing the relative basicity of the nucleophile and the product is extremely helpful in determining how reversible the addition reaction is. Reactions with Grignards and hydrides are irreversible. Reactions with weak bases like halides and carboxylates generally don’t happen.
Electronic effects (inductive effects, electron donation) have a large impact on reactivity.
Large groups adjacent to the carbonyl will slow the rate of reaction.
Neutral nucleophiles can also add to carbonyls, although their additions are generally slower and more reversible. Acid catalysis is sometimes employed to increase the rate of addition.
This presentation explores a brief idea about the structural and functional attributes of nucleotides, the structure and function of genetic materials along with the impact of UV rays and pH upon them.
Current Ms word generated power point presentation covers major details about the micronuclei test. It's significance and assays to conduct it. It is used to detect the micronuclei formation inside the cells of nearly every multicellular organism. It's formation takes place during chromosomal sepration at metaphase.
hematic appreciation test is a psychological assessment tool used to measure an individual's appreciation and understanding of specific themes or topics. This test helps to evaluate an individual's ability to connect different ideas and concepts within a given theme, as well as their overall comprehension and interpretation skills. The results of the test can provide valuable insights into an individual's cognitive abilities, creativity, and critical thinking skills
Travis Hills' Endeavors in Minnesota: Fostering Environmental and Economic Pr...Travis Hills MN
Travis Hills of Minnesota developed a method to convert waste into high-value dry fertilizer, significantly enriching soil quality. By providing farmers with a valuable resource derived from waste, Travis Hills helps enhance farm profitability while promoting environmental stewardship. Travis Hills' sustainable practices lead to cost savings and increased revenue for farmers by improving resource efficiency and reducing waste.
ANAMOLOUS SECONDARY GROWTH IN DICOT ROOTS.pptxRASHMI M G
Abnormal or anomalous secondary growth in plants. It defines secondary growth as an increase in plant girth due to vascular cambium or cork cambium. Anomalous secondary growth does not follow the normal pattern of a single vascular cambium producing xylem internally and phloem externally.
2. 2
History of DNA
• Early scientists thought protein was
the cell’s hereditary material because
it was more complex than DNA
• Proteins were composed of 20
different amino acids in long
polypeptide chains
3. 3
The Genetic Material
Frederick Griffith, 1928
studied Streptococcus pneumoniae, a
pathogenic bacterium causing pneumonia
there are 2 strains of Streptococcus:
- S strain is virulent
- R strain is nonvirulent
Griffith infected mice with these strains
hoping to understand the difference
between the strains
4. 4
Griffith’s results:
- live S strain cells killed the mice
- live R strain cells did not kill the mice
- heat-killed S strain cells did not kill
the mice
- heat-killed S strain + live R strain
cells killed the mice
6. 6
Griffith’s conclusion:
- information specifying virulence passed
from the dead S strain cells into the live R
strain cells
- Griffith called the transfer of this information
transformation
7. 7
The Genetic Material
Avery, MacLeod, & McCarty, 1944
repeated Griffith’s experiment using purified
cell extracts and discovered:
- removal of all protein from the
transforming material did not destroy its
ability to transform R strain cells
- DNA-digesting enzymes destroyed all
transforming ability
- the transforming material is DNA
8. 8
The Genetic Material
Hershey & Chase, 1952
- investigated bacteriophages: viruses that
infect bacteria
- the bacteriophage was composed of only
DNA and protein
- they wanted to determine which of these
molecules is the genetic material that is
injected into the bacteria
9. 9
The Genetic Material
- Bacteriophage DNA was labeled with
radioactive phosphorus (32P)
- Bacteriophage protein was labeled with
radioactive sulfur (35S)
- radioactive molecules were tracked
- only the bacteriophage DNA (as indicated
by the 32P) entered the bacteria and was
used to produce more bacteriophage
- conclusion: DNA is the genetic material
11. 11
DNA Structure
DNA is a nucleic acid.
The building blocks of DNA are
nucleotides, each composed of:
–a 5-carbon sugar called deoxyribose
–a phosphate group (PO4)
–a nitrogenous base
• adenine, thymine, cytosine, guanine
13. 13
DNA Structure
The nucleotide structure consists of
–the nitrogenous base attached to the 1’
carbon of deoxyribose
–the phosphate group attached to the 5’
carbon of deoxyribose
–a free hydroxyl group (-OH) at the 3’
carbon of deoxyribose
15. 15
DNA Structure
Nucleotides are connected to each other to
form a long chain
phosphodiester bond: bond between
adjacent nucleotides
–formed between the phosphate group of
one nucleotide and the 3’ –OH of the
next nucleotide
The chain of nucleotides has a 5’ to 3’
orientation.
17. 17
DNA Structure
Determining the 3-dimmensional structure of
DNA involved the work of a few scientists:
–Erwin Chargaff determined that
• amount of adenine = amount of thymine
• amount of cytosine = amount of guanine
This is known as Chargaff’s Rules
18. 18
DNA Structure
Rosalind Franklin and Maurice Wilkins
–Franklin performed X-ray diffraction
studies to identify the 3-D structure
–discovered that DNA is helical
–discovered that the molecule has a
diameter of 2nm and makes a complete
turn of the helix every 3.4 nm
19. 19
James Watson and Francis Crick, 1953
– deduced the structure of DNA using evidence
from Chargaff, Franklin, and others
– proposed a double helix structure
The double helix consists of:
– 2 sugar-phosphate backbones
– nitrogenous bases toward the interior of the
molecule
– bases form hydrogen bonds with
complementary bases on the opposite
sugar-phosphate backbone
20. 20
DNA Structure
The two strands of nucleotides are
antiparallel to each other
–one is oriented 5’ to 3’, the other 3’ to 5’
The two strands wrap around each other to
create the helical shape of the molecule.
22. 22
Replication Facts
• DNA has to be copied before a cell divides
• DNA is copied during the S or synthesis
phase of interphase
• New cells will need identical DNA strands
23. 23
Synthesis Phase (S phase)
• S phase during interphase of the cell cycle
• Nucleus of eukaryotes
Mitosis
-prophase
-metaphase
-anaphase
-telophase
G1 G2
S
phase
interphase
DNA replication takes
place in the S phase.
24. 24
DNA Replication
Matthew Meselson & Franklin Stahl, 1958
investigated the process of DNA replication
considered 3 possible mechanisms:
– conservative model
– semiconservative model
– dispersive model
26. 28
DNA Replication
Meselson and Stahl concluded that the
mechanism of DNA replication is the
semiconservative model.
Each strand of DNA acts as a template for
the synthesis of a new strand.
27. 29
•DNA replication is the process of copying a DNA molecule. Replication is
semiconservative, with each strand of the original double helix (parental molecule)
serving as a template (mold or model) for a new strand in a daughter molecule. This
process consists of:
•Unwinding (initiation): old strands of the parent DNA molecule are unwound as
weak hydrogen bonds between the paired bases are “unzipped” and broken by the
enzyme helicase.
•Complementary base pairing (elongation): free nucleotides present in the nucleus
bind with complementary bases on unzipped portions of the two strands of DNA; this
process is catalyzed by DNA polymerase.
•Joining (elongation): complementary nucleotides bond to each other to form new
strands; each daughter DNA molecule contains an old strand and a new strand; this
process is also catalyzed by DNA polymerase.
•Termination – replication is terminated differently in prokaryotes and eukaryotes
Ends in prokaryotes when origin is reached
Ends in eukaryotes when telomere is reached
telomeres – repeated DNA sequence on the ends of eukaryotic
chromosomes
•DNA replication must occur before a cell can divide; in cancer, drugs with molecules
similar to the four nucleotides are used to stop replication.
DNA Replication
29. How is a Repl. origin selected?
Priming at the oriC (Bacterial)
Origin
Initiation
30. + Hu on the origin
+ ATP
Ready to bind primase!
31. 1. Many copies of dnaA bind the four 9-mers; DNA wraps
around dnaA forming “Initial Complex”. This requires ATP
and a protein Hu that is already bound to the DNA.
3. Two copies of dnaB (helicase) bind the 13-mers. This
requires dnaC (which does not remain with the
Prepriming Complex) and ATP.
4. Primase binds to dnaB (helicase) and the DNA.
2. This triggers opening of the 13-mers (Open complex).
5. dnaB:primase complex moves along the template 3’>5’
synthesizing RNA primers 5’>3’ for Pol III to extend.
Order of events at OriC
33. Enzymes Involved in
Elongation:
1. DNA-dependent DNA polymerases
– synthesize DNA from dNTPs
– require a template strand and a primer strand with
a 3’-OH end
– all synthesize from 5’ to 3’ (add nt to 3’ end only)
36. Proofreading Activity
Insertion of the wrong nucleotide causes the DNA
polymerase to stall, and then the 3’-to-5’ exonuclease
activity removes the mispaired A nt. The polymerase then
continues adding nts to the primer.
37. If DNA polymerases only synthesize 5’ to 3’, how
does the replication fork move directionally?
38. • Lagging strand synthesized as small (~100-1000 bp)
fragments - “Okazaki fragments” .
• Okazaki fragments begin as very short 6-15 nt RNA
primers synthesized by primase.
2. Primase - RNA polymerase that synthesizes the
RNA primers (11-12 nt that start with pppAG) for both
lagging and leading strand synthesis
40. Pol III extends the RNA primers until the 3’ end of an
Okazaki fragment reaches the 5’ end of a downstream
Okazaki fragment.
Lagging strand synthesis (continued)
Then, Pol I degrades the RNA part with its 5’-3’
exonuclease activity, and replaces it with DNA. Pol I
is not highly processive, so stops before going far.
41. At this stage, Lagging strand is a series of DNA
fragments (without gaps).
Fragments stitched together covalently by DNA
Ligase.
3. DNA Ligase - joins the 5’ phosphate of one DNA
molecule to the 3’ OH of another, using energy in the
form of NAD (prokaryotes) or ATP (eukaryotes). It
prefers substrates that are double-stranded, with only
one strand needing ligation, and lacking gaps.
42. Ligase will join these two G--G--A--T--C--C--T--T--G--A--T--C--C
| | | | | | | | | | | | |
C--C--T--A--G G--A--A--C--T--A--G--G
Ligase will NOT join these
two.
G--G--A--T--C--C--T--T--G--A--T--C--C
| | | | | | | | | | | |
C--C--T--A--G C--A--A--C--T--A--G--G
Ligase will NOT join these
two.
G--G--A--T--C--C--T--T--G--A--T--C--C
| | | | | | | | | | | |
C--C--T--A--A G--A--A--C--T--A--G--G
Ligase will NOT join these
two.
G--G--A--T--C--C--T--T--G--A--T--C--C
| | | | | | | | | | | |
C--C--T--A--G G--T--A--C--T--A--G--G
Ligase will NOT join these
two. C--C--T--A--G C--T--A--C--T--A--G--G
DNA Ligase Substrate Specificity
43. HO
P
3'
5'
2
1
+ AMP
3'
P
AMP
P
AMP
+
HO
3'
P
5'
Ligase
NAD
1 2
1
3'
NMN
P
Ligase
NAD NMN
+AMP
Mechanism of
Prokaryotic
DNA Ligase-
Ligase binds NAD,
cleaves it, leaving AMP
attached to it.
Ligase-AMP binds and
attaches to 5’ end of a
DNA molecule (1) via the
AMP.
The DNA fragment with
the 3’ OH end (2) reacts
with the phosphodiester,
displacing the AMP-
ligase.
(Eukaryotic
DNA ligase
uses ATP
as AMP
donor,
instead of
NAD).
44. Replisome - DNA and protein machinery at a
replication fork.
Other proteins needed for DNA replication:
4. DNA Helicase (dnaB gene) – hexameric protein,
unwinds DNA strands, uses ATP.
5. SSB – single-strand DNA binding protein, prevents
strands from re-annealing and from being degraded,
stimulates DNA Pol III.
6. Gyrase – Topoisomerase II, keeps DNA ahead of
fork from over winding (i.e., relieves torsional strain).
46. Rubber Band Model
of Supercoiling DNA
DNA Gyrase relaxes positive
supercoils by breaking and
rejoining both DNA strands.
47. 5'
3'
3'
5'
5'
5'
DNA Polymerase III
actshere
DNA Polymerase I extends
one Okazaki fragment and
removes the RNA from
another.
DNA Ligase then joins
fragmentstogether.
ssDNA binding
protein(SSB)
Helicase (DnaB)
Primase
3'
Gyrase
Sp in n in g
at 10,000
r p m
A p ro k ary o tic fo rk is trav ellin g at 50 to 100 k b / m in u te.
Eu k ary o tic fo rk s trav el at 0.5 - 5 k b / m in u te.
Primosome
A Replisome
48. What about the ends (or telomeres) of linear chromosomes?
DNA polymerase/ligase cannot fill gap at end of chromosome after RNA
primer is removed. this gap is not filled, chromosomes would
become shorter each round of replication!
Solution:
1. Eukaryotes have tandemly repeated sequences at the ends of their
chromosomes.
2. Telomerase (composed of protein and RNA complementary to the
telomere repeat) binds to the terminal telomere repeat and
catalyzes the addition of of new repeats.
3. Compensates by lengthening the chromosome.
4. Absence or mutation of telomerase activity results in chromosome
shortening and limited cell division.
50. Final Step - Assembly into Nucleosomes:
• As DNA unwinds, nucleosomes must disassemble.
• Histones and the associated chromatin proteins must be duplicated
by new protein synthesis.
• Newly replicated DNA is assembled into nucleosomes almost
immediately.
• Histone chaperone proteins control the assembly.
Fig. 3.17
51. 53
Proofreading New DNA
• DNA polymerase initially makes about 1 in
10,000 base pairing errors
• Enzymes proofread and correct these
mistakes
• The new error rate for DNA that has been
proofread is 1 in 1 billion base pairing
errors
53. •Prokaryotic Replication
•Bacteria have a single loop of DNA that must
replicate before the cell divides.
•Replication in prokaryotes may be bidirectional
from one point of origin or in only one direction.
•Replication only proceeds in one direction, from 5'
to 3'.
•Bacterial cells are able to replicate their DNA at a
rate of about 106 base pairs per minute.
•Bacterial cells can complete DNA replication in 40
minutes; eukaryotes take hours.
54. 56
•Eukaryotic Replication
•Replication in eukaryotes starts at many
points of origin and spreads with many
replication bubbles—places where the DNA
strands are separating and replication is
occurring.
•Replication forks are the V-shape ends of
the replication bubbles; the sites of DNA
replication.
•Eukaryotes replicate their DNA at a slower
rate – 500 to 5,000 base pairs per minute.
•Eukaryotes take hours to complete DNA
replication.
58. 60
•Replication Errors
•A genetic mutation is a permanent change in the sequence
of bases.
•Base changes during replication are one way mutations
occur.
•A mismatched nucleotide may occur once per 100,000
base pairs, causing a pause in replication.
•Proofreading is the removal of a mismatched nucleotide;
DNA repair enzymes perform this proofreading function
and reduce the error rate to one per billion base pairs.
•Incorrect base pairs that survive the proofreading process
contribute to gene mutations.