This document discusses the structure and replication of DNA. Some key points:
- DNA is composed of sugars, phosphates, and nitrogen bases. Its double-helix structure was discovered by Watson and Crick in 1953.
- Before cell division, the cell must replicate its DNA. Replication involves unwinding the DNA double helix and using each strand as a template to synthesize a new complementary strand.
- The process of DNA replication is semi-conservative, resulting in two DNA molecules each containing one original and one new strand.
- DNA polymerase and other enzymes are involved in replicating DNA. Occasionally DNA is damaged, but cells have repair mechanisms to correct errors.
“This structure has novel features which are of considerable biological interest.”
This may be the science most famous statement, which appeared in April 1953 in the scientific paper where James Watson and Francis Crick presented the structure of the DNA-helix.
“It has not escaped our notice that the specific pairing we have postulated immediately suggests a possible copying mechanism for the genetic material."
This document discusses several key aspects of DNA structure and function:
1) Chromosomes contain DNA, histone proteins, and some RNA. DNA contains a code made up of four nucleotide bases that determines the sequence of amino acids in proteins.
2) DNA replicates semi-conservatively, with each parent strand serving as a template to produce two new DNA double helices.
3) Replication requires DNA polymerase, nucleotides, and energy and proceeds through initiation, elongation, and termination steps at the replication fork.
DNA replication is a complex process that involves unwinding of the DNA double helix, synthesis of new strands that are complementary to the original strands, and enzymes such as DNA polymerase and helicase. There are multiple origins of replication in eukaryotes that allow bidirectional replication from many starting points along DNA molecules. Enzymes involved include DNA polymerase alpha that works with primase to initiate DNA synthesis, and DNA polymerases delta and epsilon that carry out leading and lagging strand elongation. Telomeres prevent shortening of chromosomes with each round of replication through the action of telomerase.
DNA replication in prokaryotes involves initiation, elongation, and termination phases. Initiation begins with the binding of initiator proteins to the origin of replication, unwinding the DNA helix to form replication forks. Elongation synthesizes the leading and lagging strands bidirectionally away from the origin using DNA polymerases. Termination occurs when the replication forks meet, completing duplication of the chromosome.
Dna replication, transcription and translationAshfaq Ahmad
DNA is made up of four nucleotides that form a double helix structure. Watson and Crick discovered that DNA replicates in a semi-conservative manner where each new DNA molecule contains one original and one new strand. DNA replication is highly regulated and involves several enzymes to ensure its accuracy and fidelity. Errors can occur but are typically corrected by DNA repair mechanisms. The information stored in DNA is used to make RNA and proteins through the central dogma of molecular biology which involves two key processes - transcription of DNA to RNA and translation of RNA to protein.
DNA replication is the process by which DNA copies itself to produce identical daughter molecules. It involves separation of the DNA double helix into two strands, each serving as a template for synthesis of a new partner strand. In prokaryotes, replication occurs at a single origin of replication and proceeds bidirectionally. The two strands are replicated simultaneously in a semiconservative manner. Eukaryotes have multiple origins of replication and utilize several DNA polymerases and other proteins. DNA replication must occur with high fidelity to preserve genetic information between generations.
Multiple proteins are required for DNA replication, including DNA polymerases, helicases, primase, topoisomerases, ligase and single-stranded DNA binding proteins. Helicases unwind DNA at replication forks using ATP while primase synthesizes RNA primers and DNA polymerases use the primers to replicate DNA in the 5' to 3' direction. DNA gyrase introduces negative supercoils to relieve positive supercoiling formed during unwinding while ligase seals nicks between Okazaki fragments to complete replication.
Initiation: recognize the starting point, separate dsDNA, primer synthesis, …
Elongation: add dNTPs to the existing strand, form phosphoester bonds, correct the mismatch bases, extending the DNA strand, …
Termination: stop the replication
The replication starts at a particular point called origin.
The origin of E. coli, ori C, is at the location of 82.
The structure of the origin is 248 bp long and AT-rich.
DnaA recognizes ori C.
DnaB and DnaC join the DNA-DnaA complex, open the local AT-rich region, and move on the template downstream further to separate enough space.
DnaA is replaced gradually.
SSB protein binds the complex to stabilize ssDNA.
Primase joins and forms a complex called primosome.
Primase starts the synthesis of primers on the ssDNA template using NTP as the substrates in the 5´- 3´ direction at the expense of ATP.
The short RNA fragments provide free 3´-OH groups for DNA elongation.
dNTPs are continuously connected to the primer or the nascent DNA chain by DNA-pol III.
The core enzymes (、、and ) catalyze the synthesis of leading and lagging strands, respectively.
The nature of the chain elongation is the series formation of the phosphodiester bonds.
The synthesis direction of the leading strand is the same as that of the replication fork.
The synthesis direction of the latest Okazaki fragment is also the same as that of the replication fork.
Link for Replication video, https://www.youtube.com/watch?v=I9ArIJWYZHI
Primers on Okazaki fragments are digested by RNase.
The gaps are filled by DNA-pol I in the 5´→3´direction.
The nick between the 5´end of one fragment and the 3´end of the next fragment is sealed by ligase.
The replication of E. coli is bidirectional from one origin, and the two replication forks must meet at one point called ter at 32.
All the primers will be removed, and all the fragments will be connected by DNA-pol I and ligase.
§3.2 Replication of Eukaryotes
DNA replication is closely related with cell cycle.
Multiple origins on one chromosome, and replications are activated in a sequential order rather than simultaneously.
The eukaryotic origins are shorter than that of E. coli.
Requires DNA-pol (primase activity) and DNA-pol (polymerase activity and helicase activity).
Needs topoisomerase and replication factors (RF) to assist.
DNA replication and nucleosome assembling occur simultaneously.
Overall replication speed is compatible with that of prokaryotes.
The terminal structure of eukaryotic DNA of chromosomes is called telomere.
Telomere is composed of terminal DNA sequence and proteins.
The sequence of typical telomeres is rich in T and G.
The telomere structure is crucial to keep the termini of chromosomes in the cell from becoming entangled and sticking to each other.
The eukaryotic cells use telomerase to maintain the integrity of DNA telomere.
The telomerase is composed of
telomerase RNA
telomerase association protein
telomerase reverse trans
“This structure has novel features which are of considerable biological interest.”
This may be the science most famous statement, which appeared in April 1953 in the scientific paper where James Watson and Francis Crick presented the structure of the DNA-helix.
“It has not escaped our notice that the specific pairing we have postulated immediately suggests a possible copying mechanism for the genetic material."
This document discusses several key aspects of DNA structure and function:
1) Chromosomes contain DNA, histone proteins, and some RNA. DNA contains a code made up of four nucleotide bases that determines the sequence of amino acids in proteins.
2) DNA replicates semi-conservatively, with each parent strand serving as a template to produce two new DNA double helices.
3) Replication requires DNA polymerase, nucleotides, and energy and proceeds through initiation, elongation, and termination steps at the replication fork.
DNA replication is a complex process that involves unwinding of the DNA double helix, synthesis of new strands that are complementary to the original strands, and enzymes such as DNA polymerase and helicase. There are multiple origins of replication in eukaryotes that allow bidirectional replication from many starting points along DNA molecules. Enzymes involved include DNA polymerase alpha that works with primase to initiate DNA synthesis, and DNA polymerases delta and epsilon that carry out leading and lagging strand elongation. Telomeres prevent shortening of chromosomes with each round of replication through the action of telomerase.
DNA replication in prokaryotes involves initiation, elongation, and termination phases. Initiation begins with the binding of initiator proteins to the origin of replication, unwinding the DNA helix to form replication forks. Elongation synthesizes the leading and lagging strands bidirectionally away from the origin using DNA polymerases. Termination occurs when the replication forks meet, completing duplication of the chromosome.
Dna replication, transcription and translationAshfaq Ahmad
DNA is made up of four nucleotides that form a double helix structure. Watson and Crick discovered that DNA replicates in a semi-conservative manner where each new DNA molecule contains one original and one new strand. DNA replication is highly regulated and involves several enzymes to ensure its accuracy and fidelity. Errors can occur but are typically corrected by DNA repair mechanisms. The information stored in DNA is used to make RNA and proteins through the central dogma of molecular biology which involves two key processes - transcription of DNA to RNA and translation of RNA to protein.
DNA replication is the process by which DNA copies itself to produce identical daughter molecules. It involves separation of the DNA double helix into two strands, each serving as a template for synthesis of a new partner strand. In prokaryotes, replication occurs at a single origin of replication and proceeds bidirectionally. The two strands are replicated simultaneously in a semiconservative manner. Eukaryotes have multiple origins of replication and utilize several DNA polymerases and other proteins. DNA replication must occur with high fidelity to preserve genetic information between generations.
Multiple proteins are required for DNA replication, including DNA polymerases, helicases, primase, topoisomerases, ligase and single-stranded DNA binding proteins. Helicases unwind DNA at replication forks using ATP while primase synthesizes RNA primers and DNA polymerases use the primers to replicate DNA in the 5' to 3' direction. DNA gyrase introduces negative supercoils to relieve positive supercoiling formed during unwinding while ligase seals nicks between Okazaki fragments to complete replication.
Initiation: recognize the starting point, separate dsDNA, primer synthesis, …
Elongation: add dNTPs to the existing strand, form phosphoester bonds, correct the mismatch bases, extending the DNA strand, …
Termination: stop the replication
The replication starts at a particular point called origin.
The origin of E. coli, ori C, is at the location of 82.
The structure of the origin is 248 bp long and AT-rich.
DnaA recognizes ori C.
DnaB and DnaC join the DNA-DnaA complex, open the local AT-rich region, and move on the template downstream further to separate enough space.
DnaA is replaced gradually.
SSB protein binds the complex to stabilize ssDNA.
Primase joins and forms a complex called primosome.
Primase starts the synthesis of primers on the ssDNA template using NTP as the substrates in the 5´- 3´ direction at the expense of ATP.
The short RNA fragments provide free 3´-OH groups for DNA elongation.
dNTPs are continuously connected to the primer or the nascent DNA chain by DNA-pol III.
The core enzymes (、、and ) catalyze the synthesis of leading and lagging strands, respectively.
The nature of the chain elongation is the series formation of the phosphodiester bonds.
The synthesis direction of the leading strand is the same as that of the replication fork.
The synthesis direction of the latest Okazaki fragment is also the same as that of the replication fork.
Link for Replication video, https://www.youtube.com/watch?v=I9ArIJWYZHI
Primers on Okazaki fragments are digested by RNase.
The gaps are filled by DNA-pol I in the 5´→3´direction.
The nick between the 5´end of one fragment and the 3´end of the next fragment is sealed by ligase.
The replication of E. coli is bidirectional from one origin, and the two replication forks must meet at one point called ter at 32.
All the primers will be removed, and all the fragments will be connected by DNA-pol I and ligase.
§3.2 Replication of Eukaryotes
DNA replication is closely related with cell cycle.
Multiple origins on one chromosome, and replications are activated in a sequential order rather than simultaneously.
The eukaryotic origins are shorter than that of E. coli.
Requires DNA-pol (primase activity) and DNA-pol (polymerase activity and helicase activity).
Needs topoisomerase and replication factors (RF) to assist.
DNA replication and nucleosome assembling occur simultaneously.
Overall replication speed is compatible with that of prokaryotes.
The terminal structure of eukaryotic DNA of chromosomes is called telomere.
Telomere is composed of terminal DNA sequence and proteins.
The sequence of typical telomeres is rich in T and G.
The telomere structure is crucial to keep the termini of chromosomes in the cell from becoming entangled and sticking to each other.
The eukaryotic cells use telomerase to maintain the integrity of DNA telomere.
The telomerase is composed of
telomerase RNA
telomerase association protein
telomerase reverse trans
This document discusses DNA replication. It begins by defining replication and describing the main types (conservative, dispersive, semiconservative). It then discusses the key proteins and enzymes involved like DNA polymerase, helicase, topoisomerase, primase, and ligase. The main stages of replication - initiation, elongation, and termination - are outlined. Initiation involves unwinding the DNA and forming a replication fork. Elongation describes continuous synthesis of the leading strand and discontinuous synthesis of the lagging strand in short Okazaki fragments.
Replication fork in prokaryotic replicationAnam Tariq
The document describes the steps in prokaryotic DNA synthesis. It discusses:
1) Separation of the two complementary DNA strands through unwinding at the origin of replication, aided by DnaA protein and helicases.
2) Formation of the replication fork as a Y-shaped structure as the strands separate, allowing bidirectional replication.
3) Various proteins involved in strand separation and maintaining the replication fork, including single-stranded DNA binding proteins and DNA polymerase.
1) DNA replication begins with the unwinding of the DNA double helix at an origin of replication site.
2) This forms a replication fork with leading and lagging strands that are copied semi-conservatively to produce two identical copies of DNA.
3) RNA primers, DNA polymerases, helicase and single-strand binding proteins work together to separate the strands and synthesize new DNA in the 5’-3’ direction along the template.
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.
DNA replication is the process by which DNA makes a copy of itself during cell division.The separation of the two single strands of DNA creates a 'Y' shape called a replication 'fork'. The two separated strands will act as templates for making the new strands of DNA.
DNA replication involves separating the two strands of the DNA double helix to serve as templates for producing two new DNA molecules. Each new molecule contains one old strand and one newly synthesized strand. This process of semiconservative replication ensures that each cell receives a complete copy of the genome upon division. DNA polymerases are the key enzymes that catalyze DNA replication by adding nucleotides to the 3' end of a growing DNA strand in a 5' to 3' direction. Replication occurs bidirectionally from an origin of replication.
A reaction in which daughter DNAs are synthesized using the parental DNAs as the template.
Transferring the genetic information to the descendant generation with a high fidelity
Semi-conservative replication
Bidirectional replication
Semi-continuous replication
High fidelity
Replication starts from unwinding the dsDNA at a particular point (called origin), followed by the synthesis on each strand.
The parental dsDNA and two newly formed dsDNA form a Y-shape structure called replication fork.
Replication of DNA involves the semi-conservative duplication of DNA during the S phase of the cell cycle. It requires enzymes like DNA polymerase, helicase, primase, ligase and single-stranded DNA binding proteins. Meselson and Stahl's experiment provided evidence that replication is semi-conservative, with the parental DNA strands serving as templates for the production of two new double helix DNA molecules. Replication differs between prokaryotes and eukaryotes in terms of location, enzymes involved, and speed.
DNA replication uses a semi-conservative method that results in two double-stranded DNA molecules, each with one old parental strand and one new daughter strand. Replication occurs through the theta and rolling circle mechanisms in prokaryotes. The theta mechanism involves unwinding DNA at the origin of replication and creating replication forks that allow bidirectional synthesis of new strands. The rolling circle mechanism involves nicking one strand at the origin, allowing it to be replicated unidirectionally as it "rolls" off the parental strand.
DNA replication requires unwinding of the DNA double helix by helicases. Single-stranded DNA binding proteins prevent rewinding. DNA polymerases then synthesize new strands by adding nucleotides to the 3' end of the existing strand. In eukaryotes, the leading strand is continuously extended while the lagging strand is synthesized in fragments. Proofreading by exonuclease activity increases the fidelity of replication.
DNA replication occurs semi-conservatively to produce two identical copies of DNA before cell division. It involves unwinding of the DNA double helix by helicase, followed by synthesis of new strands complementary to the original strands. RNA primers are required for DNA polymerase to begin DNA synthesis. The leading strand is synthesized continuously while the lagging strand is synthesized in fragments called Okazaki fragments. DNA polymerase proofreads and repairs any errors with its exonuclease activity to maintain high fidelity of DNA replication.
DNA replication involves three main steps - initiation, elongation, and termination. Initiation begins with unwinding of the DNA double helix by helicase. RNA primers are then added by primase to serve as starting points for DNA polymerase. During elongation, DNA polymerase adds nucleotides to the 3' end of the primers on both the leading and lagging strand. The lagging strand is synthesized in fragments called Okazaki fragments. Proofreading ensures high fidelity by removing mismatched nucleotides. Termination occurs when a termination protein binds to stop unwinding and replication.
DNA replication in prokaryotes occurs through three main steps: initiation, elongation, and termination. Initiation begins at the origin of replication when DnaA and other proteins help separate the DNA strands. Elongation then uses DNA polymerases and other enzymes to bidirectionally copy the DNA in a semiconservative manner, producing both a leading and lagging strand. Termination occurs when the replication forks meet at the terminus region, utilizing proteins like Tus to stop replication.
DNA replication is the process by which a cell makes an identical copy of its DNA. There are three proposed models of replication: conservative, semi-conservative, and dispersive. Meselson-Stahl experiments provided evidence supporting the semi-conservative model. DNA replication involves unwinding of the DNA double helix, synthesis of an RNA primer, and elongation of the DNA strands by DNA polymerase. Telomeres protect chromosome ends from degradation during replication. Cancer cells maintain telomere length through expression of telomerase. Maintaining healthy lifestyle habits can help lengthen telomeres and delay aging.
1. DNA replication is the process where parental DNA is used as a template to produce identical copies of DNA or daughter DNA. It ensures faithful transmission of genetic material to offspring.
2. Replication starts at specific origins of replication and involves initiation, elongation, and termination phases. Enzymes involved include DNA polymerases, helicases, primases, ligases and more.
3. Eukaryotic replication is more complex, with multiple polymerases and regulated initiation. Telomerase is required for end-replication and chromosome integrity.
4. DNA repair mechanisms include base excision, nucleotide excision, mismatch and double-strand break repair to fix errors and damage via pathways like non-homologous
DNA, RNA, and proteins are the basic components of molecular biology. DNA stores genetic information and is replicated for cell division, while RNA acts as an intermediary to help synthesize proteins according to the genetic code. Molecular biologists study the interactions between these molecules to understand how life processes like DNA replication, transcription, and translation work at the cellular level.
DNA replication is the process by which a cell makes an identical copy of its DNA before cell division. It involves unwinding the double helix, synthesizing new strands using existing strands as templates, and joining fragments together. Several enzymes are required, including DNA helicase to unwind the strands, DNA primase to add primers for synthesis, DNA polymerase to extend the new strands, and DNA ligase to join fragments. Replication proceeds bidirectionally from an origin of replication and results in two new DNA molecules that each contain one original and one new strand.
DNA replication is the process where a cell makes an identical copy of its DNA before cell division. It occurs in S phase of the cell cycle. DNA polymerase enzymes add nucleotides to each DNA strand based on complementary base pairing. This results in two identical DNA double helices, each with one original strand and one newly synthesized strand. In eukaryotes, DNA replication is more complex, involving multiple origins of replication and DNA polymerases. Mechanisms like proofreading and DNA repair help ensure high-fidelity copying of the genome.
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
This document discusses replicons and the enzymes involved in DNA replication. It defines a replicon as a DNA molecule containing an origin of replication essential for initiating replication. Replicons can be linear or circular and contain initiator and termination sequences. The number of replicons per chromosome depends on its size. Various enzymes involved in replication include helicases to unwind DNA, primase to create RNA primers, DNA polymerases for DNA synthesis, ligase to join DNA fragments, and topoisomerases to relieve torsional stress. Replication proceeds bidirectionally from origins in prokaryotes and from multiple origins in eukaryotes in a tightly regulated process.
This document discusses DNA replication. It begins by defining replication and describing the main types (conservative, dispersive, semiconservative). It then discusses the key proteins and enzymes involved like DNA polymerase, helicase, topoisomerase, primase, and ligase. The main stages of replication - initiation, elongation, and termination - are outlined. Initiation involves unwinding the DNA and forming a replication fork. Elongation describes continuous synthesis of the leading strand and discontinuous synthesis of the lagging strand in short Okazaki fragments.
Replication fork in prokaryotic replicationAnam Tariq
The document describes the steps in prokaryotic DNA synthesis. It discusses:
1) Separation of the two complementary DNA strands through unwinding at the origin of replication, aided by DnaA protein and helicases.
2) Formation of the replication fork as a Y-shaped structure as the strands separate, allowing bidirectional replication.
3) Various proteins involved in strand separation and maintaining the replication fork, including single-stranded DNA binding proteins and DNA polymerase.
1) DNA replication begins with the unwinding of the DNA double helix at an origin of replication site.
2) This forms a replication fork with leading and lagging strands that are copied semi-conservatively to produce two identical copies of DNA.
3) RNA primers, DNA polymerases, helicase and single-strand binding proteins work together to separate the strands and synthesize new DNA in the 5’-3’ direction along the template.
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.
DNA replication is the process by which DNA makes a copy of itself during cell division.The separation of the two single strands of DNA creates a 'Y' shape called a replication 'fork'. The two separated strands will act as templates for making the new strands of DNA.
DNA replication involves separating the two strands of the DNA double helix to serve as templates for producing two new DNA molecules. Each new molecule contains one old strand and one newly synthesized strand. This process of semiconservative replication ensures that each cell receives a complete copy of the genome upon division. DNA polymerases are the key enzymes that catalyze DNA replication by adding nucleotides to the 3' end of a growing DNA strand in a 5' to 3' direction. Replication occurs bidirectionally from an origin of replication.
A reaction in which daughter DNAs are synthesized using the parental DNAs as the template.
Transferring the genetic information to the descendant generation with a high fidelity
Semi-conservative replication
Bidirectional replication
Semi-continuous replication
High fidelity
Replication starts from unwinding the dsDNA at a particular point (called origin), followed by the synthesis on each strand.
The parental dsDNA and two newly formed dsDNA form a Y-shape structure called replication fork.
Replication of DNA involves the semi-conservative duplication of DNA during the S phase of the cell cycle. It requires enzymes like DNA polymerase, helicase, primase, ligase and single-stranded DNA binding proteins. Meselson and Stahl's experiment provided evidence that replication is semi-conservative, with the parental DNA strands serving as templates for the production of two new double helix DNA molecules. Replication differs between prokaryotes and eukaryotes in terms of location, enzymes involved, and speed.
DNA replication uses a semi-conservative method that results in two double-stranded DNA molecules, each with one old parental strand and one new daughter strand. Replication occurs through the theta and rolling circle mechanisms in prokaryotes. The theta mechanism involves unwinding DNA at the origin of replication and creating replication forks that allow bidirectional synthesis of new strands. The rolling circle mechanism involves nicking one strand at the origin, allowing it to be replicated unidirectionally as it "rolls" off the parental strand.
DNA replication requires unwinding of the DNA double helix by helicases. Single-stranded DNA binding proteins prevent rewinding. DNA polymerases then synthesize new strands by adding nucleotides to the 3' end of the existing strand. In eukaryotes, the leading strand is continuously extended while the lagging strand is synthesized in fragments. Proofreading by exonuclease activity increases the fidelity of replication.
DNA replication occurs semi-conservatively to produce two identical copies of DNA before cell division. It involves unwinding of the DNA double helix by helicase, followed by synthesis of new strands complementary to the original strands. RNA primers are required for DNA polymerase to begin DNA synthesis. The leading strand is synthesized continuously while the lagging strand is synthesized in fragments called Okazaki fragments. DNA polymerase proofreads and repairs any errors with its exonuclease activity to maintain high fidelity of DNA replication.
DNA replication involves three main steps - initiation, elongation, and termination. Initiation begins with unwinding of the DNA double helix by helicase. RNA primers are then added by primase to serve as starting points for DNA polymerase. During elongation, DNA polymerase adds nucleotides to the 3' end of the primers on both the leading and lagging strand. The lagging strand is synthesized in fragments called Okazaki fragments. Proofreading ensures high fidelity by removing mismatched nucleotides. Termination occurs when a termination protein binds to stop unwinding and replication.
DNA replication in prokaryotes occurs through three main steps: initiation, elongation, and termination. Initiation begins at the origin of replication when DnaA and other proteins help separate the DNA strands. Elongation then uses DNA polymerases and other enzymes to bidirectionally copy the DNA in a semiconservative manner, producing both a leading and lagging strand. Termination occurs when the replication forks meet at the terminus region, utilizing proteins like Tus to stop replication.
DNA replication is the process by which a cell makes an identical copy of its DNA. There are three proposed models of replication: conservative, semi-conservative, and dispersive. Meselson-Stahl experiments provided evidence supporting the semi-conservative model. DNA replication involves unwinding of the DNA double helix, synthesis of an RNA primer, and elongation of the DNA strands by DNA polymerase. Telomeres protect chromosome ends from degradation during replication. Cancer cells maintain telomere length through expression of telomerase. Maintaining healthy lifestyle habits can help lengthen telomeres and delay aging.
1. DNA replication is the process where parental DNA is used as a template to produce identical copies of DNA or daughter DNA. It ensures faithful transmission of genetic material to offspring.
2. Replication starts at specific origins of replication and involves initiation, elongation, and termination phases. Enzymes involved include DNA polymerases, helicases, primases, ligases and more.
3. Eukaryotic replication is more complex, with multiple polymerases and regulated initiation. Telomerase is required for end-replication and chromosome integrity.
4. DNA repair mechanisms include base excision, nucleotide excision, mismatch and double-strand break repair to fix errors and damage via pathways like non-homologous
DNA, RNA, and proteins are the basic components of molecular biology. DNA stores genetic information and is replicated for cell division, while RNA acts as an intermediary to help synthesize proteins according to the genetic code. Molecular biologists study the interactions between these molecules to understand how life processes like DNA replication, transcription, and translation work at the cellular level.
DNA replication is the process by which a cell makes an identical copy of its DNA before cell division. It involves unwinding the double helix, synthesizing new strands using existing strands as templates, and joining fragments together. Several enzymes are required, including DNA helicase to unwind the strands, DNA primase to add primers for synthesis, DNA polymerase to extend the new strands, and DNA ligase to join fragments. Replication proceeds bidirectionally from an origin of replication and results in two new DNA molecules that each contain one original and one new strand.
DNA replication is the process where a cell makes an identical copy of its DNA before cell division. It occurs in S phase of the cell cycle. DNA polymerase enzymes add nucleotides to each DNA strand based on complementary base pairing. This results in two identical DNA double helices, each with one original strand and one newly synthesized strand. In eukaryotes, DNA replication is more complex, involving multiple origins of replication and DNA polymerases. Mechanisms like proofreading and DNA repair help ensure high-fidelity copying of the genome.
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
This document discusses replicons and the enzymes involved in DNA replication. It defines a replicon as a DNA molecule containing an origin of replication essential for initiating replication. Replicons can be linear or circular and contain initiator and termination sequences. The number of replicons per chromosome depends on its size. Various enzymes involved in replication include helicases to unwind DNA, primase to create RNA primers, DNA polymerases for DNA synthesis, ligase to join DNA fragments, and topoisomerases to relieve torsional stress. Replication proceeds bidirectionally from origins in prokaryotes and from multiple origins in eukaryotes in a tightly regulated process.
Similar to structure of DNA and replication.pdf (20)
A Strategic Approach: GenAI in EducationPeter Windle
Artificial Intelligence (AI) technologies such as Generative AI, Image Generators and Large Language Models have had a dramatic impact on teaching, learning and assessment over the past 18 months. The most immediate threat AI posed was to Academic Integrity with Higher Education Institutes (HEIs) focusing their efforts on combating the use of GenAI in assessment. Guidelines were developed for staff and students, policies put in place too. Innovative educators have forged paths in the use of Generative AI for teaching, learning and assessments leading to pockets of transformation springing up across HEIs, often with little or no top-down guidance, support or direction.
This Gasta posits a strategic approach to integrating AI into HEIs to prepare staff, students and the curriculum for an evolving world and workplace. We will highlight the advantages of working with these technologies beyond the realm of teaching, learning and assessment by considering prompt engineering skills, industry impact, curriculum changes, and the need for staff upskilling. In contrast, not engaging strategically with Generative AI poses risks, including falling behind peers, missed opportunities and failing to ensure our graduates remain employable. The rapid evolution of AI technologies necessitates a proactive and strategic approach if we are to remain relevant.
This presentation was provided by Steph Pollock of The American Psychological Association’s Journals Program, and Damita Snow, of The American Society of Civil Engineers (ASCE), for the initial session of NISO's 2024 Training Series "DEIA in the Scholarly Landscape." Session One: 'Setting Expectations: a DEIA Primer,' was held June 6, 2024.
A review of the growth of the Israel Genealogy Research Association Database Collection for the last 12 months. Our collection is now passed the 3 million mark and still growing. See which archives have contributed the most. See the different types of records we have, and which years have had records added. You can also see what we have for the future.
Strategies for Effective Upskilling is a presentation by Chinwendu Peace in a Your Skill Boost Masterclass organisation by the Excellence Foundation for South Sudan on 08th and 09th June 2024 from 1 PM to 3 PM on each day.
Exploiting Artificial Intelligence for Empowering Researchers and Faculty, In...Dr. Vinod Kumar Kanvaria
Exploiting Artificial Intelligence for Empowering Researchers and Faculty,
International FDP on Fundamentals of Research in Social Sciences
at Integral University, Lucknow, 06.06.2024
By Dr. Vinod Kumar Kanvaria
How to Manage Your Lost Opportunities in Odoo 17 CRMCeline George
Odoo 17 CRM allows us to track why we lose sales opportunities with "Lost Reasons." This helps analyze our sales process and identify areas for improvement. Here's how to configure lost reasons in Odoo 17 CRM
it describes the bony anatomy including the femoral head , acetabulum, labrum . also discusses the capsule , ligaments . muscle that act on the hip joint and the range of motion are outlined. factors affecting hip joint stability and weight transmission through the joint are summarized.
How to Build a Module in Odoo 17 Using the Scaffold MethodCeline George
Odoo provides an option for creating a module by using a single line command. By using this command the user can make a whole structure of a module. It is very easy for a beginner to make a module. There is no need to make each file manually. This slide will show how to create a module using the scaffold method.
Executive Directors Chat Leveraging AI for Diversity, Equity, and InclusionTechSoup
Let’s explore the intersection of technology and equity in the final session of our DEI series. Discover how AI tools, like ChatGPT, can be used to support and enhance your nonprofit's DEI initiatives. Participants will gain insights into practical AI applications and get tips for leveraging technology to advance their DEI goals.
5. Cell division and DNA replication
• Cells divide
Growth, Repair, Replacement
• Before cells divide they have to double cell
structures, organelles and their genetic
information
7. Site and function of nucleic
acids
• DNA
• RNA
• site of DNA
• IN eukaryoytes: cellsDNA is found in the nucleus(chromosomes) and in
the mitochondria.
• In prokaryotes: there is a single chromosome which contain DNA
.There may be also a non chromosomal DNA in the form of plasmid.
• Functions of DNA ; replications(cell division)
expression of genetic information and protein synthesis(through RNA’s)
8. Site of RNA’s
• 1. RNA’s that synthesized in the mitochondria remain within this
organelle.
• 2. RNA’s that synthesized in the nucleus perform their function in the
cytoplasm.
• Function of RNA’s
• 1. RNA’s participate in the process of expression of genetic information
that stored in DNA (protein synthesis).
• Some viruses use RNA in their its single or double stranded form as a
genetic material i.e RNA is used instead of DNA.
9. Steps of DNA replication
• Replication folk
• chain elongation reverse transcriptase
• DNA repair
• regulation of DNA synthesis
• inhibitor of replication.
10. Semiconservative
• The process by which DNA is copied is
called semiconservative. This mean
that after replication ,each of daughter
DNA mol. Will of daughter DNA mol.
Will contain :
• 1. one old strand: one parental strand is
conserved.
• 2.one new strand which is synthesized
from free nucleotide present in the
11. Cont.
• During replication , the double strand
DNA mol.I(duplex) that is to be copied
is separated into two strands and each
is used as a template for the synthesis
of a new complementary strand.
12.
13. In prokaryotes
• DNA polymerase I catalyzes DNA
repair.
• DNA polymerases II is unknown
function.
• DNA polymerases III catalyses mostly
replication of DNA.
14. In eukaryotes
• DNA pol- alpha catalyses replication of
nuclear DNA.
• DNA pol –beta catalyses replication
DNA repair.
• DNA pol gamma catalyses replication of
mtochondria DNA.
• DNA pol delta responsible for leading
strand of DNA replication.
15. Cont.
• DNA pol ε responsible for synthesis of
lagging strand and repair.
16. A. Strand separation
• For replication: strands of DNA
separated, polymerase use only single
stranded DNA as template.
• IN prokaryotes.E.coli – ORIC –
initiation of replication.
• IN eukaryotes :multiple site for
replication along the DNA helix.
17. Replication folk
• As strands unwind and separate , they
form the ‘V’’ shape where synthesis
occur.This region is called repliction
folk.
• 1. RF moves along the DNA mol. As
synthesis occur.
• 2. replication of double stranded DNA is
bidirectional.
18. Proteins responsible
• A. helix –destabilizing (HD) proteins:
they bind nonenzymatically to a single
stranded DNA,without interfering with
the ability of the nucleotides serve as a
template
• Functions:
• 1wo strands separated.
• Protect DNA from nuclease enzyme
that cleave single stranded DNA.
19. Cont.
• B. Helix unwinding proteins: also called
helicase.or rep proteins.
• 1. bind single stranded DNA near the
replication fork and then move into the
neighbouring double stranded region.
• 2.Requires energy. 2ATP mol. Are
consumed to separate each base pair.
• 3. once the strand separated
destabilizing proteins binds.
20.
21. Topo I and II
• “Swivels”
• Prevents formation of supertwinsting
and rotation of the entire chromosome
ahead of replication folk. Super twisting
makes further separation more difficult
and entire chromosome consume more
energy.
22. Topoisomerase I (DNA
swivelases
• They cut and rejoin a single of double
helix .
• This process does not require ATP as
the energy released from the cleavage
(cutting ) of phosphodiester bond is
reused to reseal (rejoin) the strand.
• By creating transient “nick”the DNA
helix on either side of the nick is
allowed to rotate at the phosphodiester
23. Topoisomerase II (DNA
gyrase)
• It binds to both strand of the DNA and
make transient breaks in both strands
of DNA helix to pass through the break
and finally reseal the break .
• A negative supertwists can be
introduced that allow the break
unwinding of the DNA double helix.
24. Formation of RNA primer
• 1. polymerase III is unable to assemble
the first few nucleotides of a new strand
using the parent DNA strand as a
template.
• 2.This assembly require RNA primer:
• A. a short fragment of RNA . 10
nucleotides.
• B.Complementary and antiparallel to
the DNA strand.
25. Cont.
• C. free -OH group at 3’end . This Oh
serves as a the acceptor of the first
nucleotide from DNA polymerase III.
• 3.synthesis of RNA primer requires
primosome which is a complex of an
protein called :RNA pol and protein
called DNA B protein.
• Primosome binds with single stranded
DNA and enable the initiation of
27. Synthesis of new DNA
• The substrate of DNA are:
dATP,dGTP,dTTp,and dCTP. If one of
four nucleotide is not available , DNA
synthesis will blocked.
• Using the free 3ÓH group of the RNA
primer as the acceptor of the first
nucleotide , DNA polymerase III begins
to add subsequent nucleotide.
28. Chain elongation
• DNA pol lII moves along the template
strand , substrate nucleotide pair with
the pairing rule. A=T, G=C,thus
complementary to the parent strand.
• New strand runs in 5’-3’ direction while template strand runs 3’-5’. The
daughter strand chain must grow in opposite directions, one towards
replication fork and the other away from it.
29. Cont.
• Leading strand is the strand that being copied in the direction towards
replication fork . It is synthesized almost continuously
• Lagging strand : is the strand being copied in the direction away from
replication fork . It is synthesized discontinuously by forming small
fragment of DNA called : OKAZAKI fragments.
• They are joined to become a single , continuous strand.
30. Excision of RNA primers and their replacement with DNA
• 1. DNA polymerase III continues to synthesize DNA un till it is
blocked by a fragment of the RNA primer.
• 2.The RNA primer is excised by DNA polymerase I
• 3. Gaps resulting from the excised RNA primers are filled by DNA pol I.
• 4. Nicks are sealed by DNA ligase.
• 5. final phosphodiester linkage between the 5’ phosphate group on the
DNA chain synthesized by DNA polymerase III and 3’ hydroxyl group
on the chain made by DNA polymerase I is catalyzed by DNA ligase
.The energy required for this joint is provided by cleavage of ATP tp
AMP and Ppi.
31. Reverse transcriptase
• Also called RNA dependent DNA polymerase :
• DNA – RNA - protein
• Retroviruses has a mechanism for reversing the first step in this flow
form RNA to DNA.
• The retrovirus contain ss RNA nucleic acid and a viral enzyme called
reverse transcriptase.
32. Mechanism of replication
• 1.Ss RNA ds DNA
• 2.This enzyme synthesize a DNA –RNA hybride mol. Using
• A) RNA genome as template.
• B) dATP ,dGTP and dCTP gTTP as substrates.
• 3. RNA degraded by Rnase H .
• The remaining DNA strand in turn serve as a template to form a double
stranded genome of the virus.
• The newly synthesized viral double stranded DNA enters the nucleus of
the infected cell and can integrate by recombination into host
chromosome.
• Eg: HIV(AIDS) ,hepatitis A virus and some tumor viruse.
• RT are important in recombinant DNA technolongy.
33. DNA repair
• A)Causes of DNA damage:
• Physical agent e.g x-ray , ultraviolet light.
• Chemical agent e.g alkylating agent
• Ionizing radiation
• B) single base alteration:
• 1. depurination i.e removal of purine.
• 2.deamination of cytosine to uracil
• 3. deamination of adenine to hypoxathine.
• 4.Alkylation of base i.e addition of alkyl group.
• 5. Insertion or deletion of nucleotide.
• Base analog incorporation.
35. Cont.
• Chain break: e.g phosphodiester bonds can be broken.
• Cross linkage:
• A. between bases in same or opposite strands.
• B. between DNA and protein molecule e.g histones
36. fate of damaged DNA
• 1.Repaired
• 2. Replaced by DNA recombination
• 3. Retained : retention leads to mutation and cell death.
37. Mechanism of DNA repair
Excision repair : damaged only one strand e;g thymine dimers and
missing base.
Repair of pyrimidine-pyrimidine dimer:
1. The dimers result form covalent joining of two adjacent pyrimidine.
2. Caused by uv rays
3. Thymine dimers prevent DNA pol from replicating the DNA strand
beyond the site of dimer formation.
4. Dimer is excised and repair:
a. Uv –specific endonuclease recognises the dimer and makes a nick
near it ,at 5’ end
b. gap is filled by polymerase I ,in the direction of 5’ to 3’.Other strand acts
as template.
c. Thymine dimer region is excised by the 5’-3’ exonuclease activity of
DNA pol I and sealed by DNA ligase.
38. Xeroderma pigmentosum
• It is an autosomal recessive disease, is an e.g of a defective
mechanism for the repair of pyrimidine dimers in DNA.
• Absence of uv specific endonucleases require for the recognition of the
dimers is the cause of this disease.
• Individuals are sensitive to uv light which causes extensive
accumulation of thymine dimers in skin cells with malignant
transformation.
39.
40. Some of the most common symptoms are:
An unusually severe sunburn after a short sun exposure. The
sunburn may last for several weeks. The sunburn usually
occurs during a child’s first sun exposure.
development of many freckles at an early age.
Irregular dark spots.
Thin skin.
Excessive dryness.
Rough-surfaced growths (solar keratoses), and skin cancers.
Eyes that are painfully sensitive to the sun and may easily
become irritated, bloodshot, and clouded.
Blistering or freckling on minimum sun exposure.
Premature aging of skin, lips, eyes, mouth and tongue
41. Repair of cytosine deamination to uracil
• Abnormal uracil is recognized by glycosylase that cleaves the base .
• Endonuclease cuts the phosphodiester bond on 5’side.
• DNA pol I fills the gap.
• DNA ligase seals the breaks.
42. Photoreactivation or light repair
• Thymine repair
• Use visible light (300-600nm) for activating specific enzyme called
photoactivating enzyme which directly cleave and correct the dimer in
its place.
43. Recombination repair(sister strand exchange)
• In prokaryotes (E.coli) , the cell deal with DNA replication at the dimer
and reinitiating it on the other side of the dimer . This leaves gap in the
newly synthesized strand b.
• By sister strand exchange , the unmutated single stranded segment
from homologous DNA excised form good strand (d strand) and
inserted into the gap present in b strand opposite the dimer.
• The gap in d strand is next filled by polymerase I.