Nucleic acids are macromolecules that store genetic information and enable protein production. Nucleic acids include DNA and RNA. These molecules are composed of long strands of nucleotides. Nucleotides are composed of a nitrogenous base, a five-carbon sugar, and a phosphate group.
The document contains sample questions about nucleic acids and enzymes. For nucleic acids, it asks about nucleosides, the difference between RNA and DNA sugars, gel electrophoresis of DNA fragments, light absorption of nucleotides and proteins, components found in RNA but not DNA, and base pairing rules. It also includes questions about translating mRNA and forming codon-anticodon interactions. For enzymes, it discusses them as catalysts, mechanisms of catalysis including transition states and active sites, classes of enzymes, coenzymes, and factors affecting enzyme activity. Sample multiple choice questions test understanding of enzyme function, naming, components, effects of temperature, and catalytic mechanisms.
The genetic code is the sequence of nitrogenous bases in mRNA that encodes information for protein synthesis. It has several key properties: it is a triplet code where each codon consists of 3 nucleotides; it is non-overlapping so codons are read sequentially; it is comma-less so there is no wasted space between codons. The code is also non-ambiguous, polar, and degenerate meaning some codons can specify the same amino acid. Certain codons act as start or stop signals. The genetic code was deciphered using both theoretical approaches and experimental techniques like using homopolymers and random copolymers in cell-free protein synthesis systems. The genetic code proved to be nearly universal across living organisms.
DNA is composed of nucleotides that contain nitrogen bases, sugars, and phosphates. The order of these nucleotides determines the genetic code. DNA exists as a double helix structure with two complementary strands joined by hydrogen bonds between nitrogen bases on each strand. This double helix structure allows DNA to efficiently store and replicate genetic information.
DNA is a double-helix molecule that carries genetic instructions. It is composed of two strands of polynucleotides made up of nucleotides, each containing a nitrogenous base, sugar, and phosphate. The strands are stabilized by hydrogen bonds between complementary bases and base-stacking interactions. DNA can be denatured into single strands by elevated temperature, extreme pH, low salt concentrations, or chemicals that disrupt hydrogen bonding between strands. Denaturation temperature depends on factors like base composition and length. Renaturation occurs when double-stranded DNA is cooled under conditions that allow the strands to re-form hydrogen bonds and complementary base pairing.
CBCS 4TH SEM ,
CHARGING, STRUCTURE AND FUNCTION OF tRNA,
AMINOACYL RNA SYNTHETASE(ASR) PROOFREADING AND EDITING
https://www.youtube.com/watch?v=YzOVMWYLiCE
There are three main forms of DNA structure: A-DNA, B-DNA, and Z-DNA. B-DNA is the most common form found under physiological conditions, having a right-handed double helix with 10.5 base pairs per turn. A-DNA forms under dehydrating conditions and has a wider helix with 11 base pairs per turn. Z-DNA is a left-handed helix that forms with alternating purine-pyrimidine sequences, containing 12 base pairs per turn in a narrow, zig-zag structure. While B-DNA is most prevalent, the structure can vary depending on sequence and environmental conditions.
The document discusses transcription in prokaryotes and eukaryotes. In prokaryotes, RNA polymerase binds to promoter sequences and transcribes DNA into RNA through initiation, elongation, and termination. Transcription requires RNA polymerase and proceeds similarly in eukaryotes but involves multiple RNA polymerases and occurs in the nucleus. Eukaryotic transcription is more complex, utilizing regulatory sequences, transcription factors, and RNA processing to modify pre-mRNA into mature mRNA through splicing, capping, polyadenylation, and other modifications. Mutations can affect splicing and cause genetic disorders like beta-thalassemia.
The document contains sample questions about nucleic acids and enzymes. For nucleic acids, it asks about nucleosides, the difference between RNA and DNA sugars, gel electrophoresis of DNA fragments, light absorption of nucleotides and proteins, components found in RNA but not DNA, and base pairing rules. It also includes questions about translating mRNA and forming codon-anticodon interactions. For enzymes, it discusses them as catalysts, mechanisms of catalysis including transition states and active sites, classes of enzymes, coenzymes, and factors affecting enzyme activity. Sample multiple choice questions test understanding of enzyme function, naming, components, effects of temperature, and catalytic mechanisms.
The genetic code is the sequence of nitrogenous bases in mRNA that encodes information for protein synthesis. It has several key properties: it is a triplet code where each codon consists of 3 nucleotides; it is non-overlapping so codons are read sequentially; it is comma-less so there is no wasted space between codons. The code is also non-ambiguous, polar, and degenerate meaning some codons can specify the same amino acid. Certain codons act as start or stop signals. The genetic code was deciphered using both theoretical approaches and experimental techniques like using homopolymers and random copolymers in cell-free protein synthesis systems. The genetic code proved to be nearly universal across living organisms.
DNA is composed of nucleotides that contain nitrogen bases, sugars, and phosphates. The order of these nucleotides determines the genetic code. DNA exists as a double helix structure with two complementary strands joined by hydrogen bonds between nitrogen bases on each strand. This double helix structure allows DNA to efficiently store and replicate genetic information.
DNA is a double-helix molecule that carries genetic instructions. It is composed of two strands of polynucleotides made up of nucleotides, each containing a nitrogenous base, sugar, and phosphate. The strands are stabilized by hydrogen bonds between complementary bases and base-stacking interactions. DNA can be denatured into single strands by elevated temperature, extreme pH, low salt concentrations, or chemicals that disrupt hydrogen bonding between strands. Denaturation temperature depends on factors like base composition and length. Renaturation occurs when double-stranded DNA is cooled under conditions that allow the strands to re-form hydrogen bonds and complementary base pairing.
CBCS 4TH SEM ,
CHARGING, STRUCTURE AND FUNCTION OF tRNA,
AMINOACYL RNA SYNTHETASE(ASR) PROOFREADING AND EDITING
https://www.youtube.com/watch?v=YzOVMWYLiCE
There are three main forms of DNA structure: A-DNA, B-DNA, and Z-DNA. B-DNA is the most common form found under physiological conditions, having a right-handed double helix with 10.5 base pairs per turn. A-DNA forms under dehydrating conditions and has a wider helix with 11 base pairs per turn. Z-DNA is a left-handed helix that forms with alternating purine-pyrimidine sequences, containing 12 base pairs per turn in a narrow, zig-zag structure. While B-DNA is most prevalent, the structure can vary depending on sequence and environmental conditions.
The document discusses transcription in prokaryotes and eukaryotes. In prokaryotes, RNA polymerase binds to promoter sequences and transcribes DNA into RNA through initiation, elongation, and termination. Transcription requires RNA polymerase and proceeds similarly in eukaryotes but involves multiple RNA polymerases and occurs in the nucleus. Eukaryotic transcription is more complex, utilizing regulatory sequences, transcription factors, and RNA processing to modify pre-mRNA into mature mRNA through splicing, capping, polyadenylation, and other modifications. Mutations can affect splicing and cause genetic disorders like beta-thalassemia.
1. Mutations can occur through errors in DNA replication, repair, or recombination which can cause substitutions, insertions or deletions of DNA bases. Environmental mutagens like radiation and chemicals can also directly interact with DNA and cause mutations.
2. Some mutations involve changes to a single DNA base pair, while others are larger scale mutations affecting longer DNA segments. Point mutations may substitute one base for another, while insertions or deletions can disrupt the DNA reading frame.
3. Cells have mechanisms like direct repair and photoreactivation to correct some mutations, but errors in these pathways can also lead to mutations if not repaired properly.
Abzymes, also known as catalytic antibodies, are monoclonal antibodies that exhibit enzymatic activity. They are able to bind to transition states of enzyme-catalyzed reactions with high specificity and affinity, stabilizing the transition state and increasing reaction rates. Abzymes can be artificially produced by immunizing animals with transition state analogs of reactions. They have potential applications in drug development, cancer treatment, and developing therapies for viral infections like HIV. Researchers have engineered an abzyme that can degrade an essential region of the HIV envelope protein, rendering the virus unable to infect cells.
eukaryotic translation initiation and its regulationnida rehman
The document summarizes eukaryotic translation initiation. It describes how the 43S preinitiation complex is formed and recruits to the 5' end of mRNA with the help of initiation factors. The complex then scans the 5' UTR until it recognizes the start codon, after which the 60S subunit joins to form the 80S ribosome. Initiation factors are regulated by phosphorylation and proteolysis. Translation can also be controlled by RNA-binding proteins and the length of the poly-A tail.
Frederick Sanger developed two important methods for protein sequencing: 1) using fluorodinitrobenzene to determine the N-terminal amino acid, and 2) cleaving proteins into fragments and piecing their sequences together. The standard strategy involves separating chains, identifying terminal residues, cleaving the protein, sequencing fragments, and reconstructing the full sequence. The Edman degradation method allows sequential removal of residues from the N-terminus. Mass spectrometry techniques like peptide mass fingerprinting and tandem mass spectrometry now dominate protein sequencing.
Histone proteins package DNA into nucleosomes and facilitate chromatin formation. There are two main classes of histones - core histones like H2A, H2B, H3, and H4 which assemble around DNA, and linker histone H1 which binds nucleosomes. Post-translational modifications of histone tails like acetylation and methylation regulate gene expression by altering chromatin structure. Genomic imprinting is an epigenetic process where gene expression depends on parental origin through histone modifications and other epigenetic markers without changing DNA sequence.
DNA and RNA have similar structures but differ in key ways. DNA contains deoxyribose and is usually double stranded, carrying genetic information in cells as DNA. Its classic double helix structure contains paired bases (A-T and C-G) connected by hydrogen bonds. RNA is usually single stranded and contains ribose. There are three main types of RNA - mRNA, tRNA, and rRNA - that have different roles like transcribing DNA instructions and transporting amino acids for protein synthesis. tRNA and other RNAs fold into cloverleaf secondary structures stabilized by hydrogen bonding within their nucleotide sequences.
Gene expression involves two main steps - transcription and translation. During transcription, DNA is copied into mRNA with the help of RNA polymerase. Translation then uses the mRNA to assemble amino acids into proteins with the help of tRNA and rRNA. Though genes code for traits, there is not a simple one-to-one relationship due to various regulatory factors.
Regulation of eukaryotic gene expressionMd Murad Khan
The document discusses various mechanisms of regulating gene expression in eukaryotes. It explains that regulation can occur at multiple levels, including DNA, transcription, mRNA processing, and protein synthesis. Key points include: (1) Regulation allows adaptation and cellular differentiation; (2) In eukaryotes, transcription and translation are separated, allowing more complex regulation; (3) Regulation mechanisms include controlling chromatin structure, transcription initiation, mRNA splicing/stability, and protein modifications. Environmental factors like heat and hormones can also induce gene expression changes through transcription factors.
The document discusses the Ramachandran plot, which shows statistically probable combinations of the phi and psi backbone torsion angles in proteins. It describes how these two angles describe rotations around bonds in the polypeptide backbone and influence protein folding. The plot reveals allowed and disallowed regions based on steric clashes between atoms at different angle combinations. Common structures like alpha helices and beta sheets correspond to allowed regions in the plot.
The document summarizes the process of translation in cells. It describes how the genetic code on mRNA is translated into a sequence of amino acids with the help of tRNA and ribosomes. There are several steps involved: 1) amino acids are activated by attaching to tRNA, 2) initiation begins with formation of initiation complexes on ribosomes, 3) elongation occurs as new amino acids are added one by one to the growing polypeptide chain through movement of tRNA between ribosomal sites, and 4) termination releases the full protein when a stop codon is reached. The entire process requires energy in the form of GTP hydrolysis at several steps.
Post-translational modifications (PTMs) refer to any alterations made to proteins after their initial synthesis, such as modification of amino acid side chains. PTMs influence protein structure, stability, activity, and more. Common PTMs include phosphorylation, glycosylation, methylation, and hydroxylation. PTMs are important for proper protein folding, conferring stability, and regulating protein activity and function. They increase proteome diversity and complexity.
DNA and RNA are nucleic acids that play important roles in cells. DNA contains the genetic instructions used in the development and functioning of living organisms. It has a double helix structure formed by base pairing between adenine and thymine, and cytosine and guanine. RNA is usually single-stranded and exists in several forms that help carry out the instructions specified by genes, including messenger RNA, transfer RNA, and ribosomal RNA. Messenger RNA carries copies of instructions from DNA to the sites of protein synthesis. Transfer RNA transfers amino acids to the ribosome during protein synthesis according to the mRNA sequence. Ribosomal RNA is a component of ribosomes and helps in protein synthesis.
Transcription definition
steps of transcription
general structure of gene
RNA polymerase structure
Transcription in prokaryotes in detail (initiation, elongation and termination)
Post-transcriptional modifications are important processes that convert primary transcript RNA into mature RNA. These modifications include 5' capping, 3' polyadenylation, and splicing of introns in eukaryotes. The modifications help make RNA molecules recognizable for translation and increase protein synthesis efficiency by removing non-coding regions. Different types of RNA undergo specific processing pathways involving nucleases, snoRNAs and other protein complexes.
This document discusses three forms of DNA: A-DNA, B-DNA, and Z-DNA. A-DNA has a more compact helical structure than B-DNA, with the basepairs closer to the helix axis. It occurs under dehydrated conditions. Z-DNA has a left-handed helical structure and is formed by alternating purines and pyrimidines, especially GC stretches. The major differences between A, B, and Z-DNA involve the sugar conformation, placement of basepairs, and helical geometry.
Classification of amino acid by KK Sahu sirKAUSHAL SAHU
Introduction of amino acid
Common structure of amino acid
History
Classification of amino acid basis on R-group
Non polar aliphatic R group
Aromatic R group
Uncharged polar R group
Positive Charge R group
Negative charge R group
Properties of amino acids
Conclusions
References
This document discusses various chromatography techniques including paper chromatography, thin layer chromatography, partition chromatography, adsorption chromatography, ion-exchange chromatography, gel filtration chromatography, affinity chromatography, high performance liquid chromatography, and gas chromatography. The different techniques separate molecules based on properties like size, charge, and affinity. They have various applications in biochemistry like purifying proteins, antibodies, and separating biological compounds.
There are three main levels of control to ensure DNA replication is initiated only once per cell cycle in bacteria:
1. ATP hydrolysis by beta-clamp protein
2. Sequestration of hemimethylated DNA by SeqA protein
3. Titration of DnaA protein levels through its regulatory locus
In eukaryotes, licensing factors like ORC, Cdc6, Cdt1 and MCM proteins bind to origins of replication and license them for a single round of replication. After replication begins, these factors dissociate from origins preventing re-replication. Geminin protein also prevents re-licensing of newly synthesized DNA in G2 phase.
DNA polymerase proofreads
DNA contains the genetic instructions for all living organisms. It exists as a double helix composed of nucleotides with a phosphate-sugar backbone and nitrogenous bases of adenine, cytosine, guanine and thymine. DNA undergoes replication to make copies for new cells, and is transcribed and translated to make proteins for cell functions. It can also undergo recombination during cell division to increase genetic variation.
1. Mutations can occur through errors in DNA replication, repair, or recombination which can cause substitutions, insertions or deletions of DNA bases. Environmental mutagens like radiation and chemicals can also directly interact with DNA and cause mutations.
2. Some mutations involve changes to a single DNA base pair, while others are larger scale mutations affecting longer DNA segments. Point mutations may substitute one base for another, while insertions or deletions can disrupt the DNA reading frame.
3. Cells have mechanisms like direct repair and photoreactivation to correct some mutations, but errors in these pathways can also lead to mutations if not repaired properly.
Abzymes, also known as catalytic antibodies, are monoclonal antibodies that exhibit enzymatic activity. They are able to bind to transition states of enzyme-catalyzed reactions with high specificity and affinity, stabilizing the transition state and increasing reaction rates. Abzymes can be artificially produced by immunizing animals with transition state analogs of reactions. They have potential applications in drug development, cancer treatment, and developing therapies for viral infections like HIV. Researchers have engineered an abzyme that can degrade an essential region of the HIV envelope protein, rendering the virus unable to infect cells.
eukaryotic translation initiation and its regulationnida rehman
The document summarizes eukaryotic translation initiation. It describes how the 43S preinitiation complex is formed and recruits to the 5' end of mRNA with the help of initiation factors. The complex then scans the 5' UTR until it recognizes the start codon, after which the 60S subunit joins to form the 80S ribosome. Initiation factors are regulated by phosphorylation and proteolysis. Translation can also be controlled by RNA-binding proteins and the length of the poly-A tail.
Frederick Sanger developed two important methods for protein sequencing: 1) using fluorodinitrobenzene to determine the N-terminal amino acid, and 2) cleaving proteins into fragments and piecing their sequences together. The standard strategy involves separating chains, identifying terminal residues, cleaving the protein, sequencing fragments, and reconstructing the full sequence. The Edman degradation method allows sequential removal of residues from the N-terminus. Mass spectrometry techniques like peptide mass fingerprinting and tandem mass spectrometry now dominate protein sequencing.
Histone proteins package DNA into nucleosomes and facilitate chromatin formation. There are two main classes of histones - core histones like H2A, H2B, H3, and H4 which assemble around DNA, and linker histone H1 which binds nucleosomes. Post-translational modifications of histone tails like acetylation and methylation regulate gene expression by altering chromatin structure. Genomic imprinting is an epigenetic process where gene expression depends on parental origin through histone modifications and other epigenetic markers without changing DNA sequence.
DNA and RNA have similar structures but differ in key ways. DNA contains deoxyribose and is usually double stranded, carrying genetic information in cells as DNA. Its classic double helix structure contains paired bases (A-T and C-G) connected by hydrogen bonds. RNA is usually single stranded and contains ribose. There are three main types of RNA - mRNA, tRNA, and rRNA - that have different roles like transcribing DNA instructions and transporting amino acids for protein synthesis. tRNA and other RNAs fold into cloverleaf secondary structures stabilized by hydrogen bonding within their nucleotide sequences.
Gene expression involves two main steps - transcription and translation. During transcription, DNA is copied into mRNA with the help of RNA polymerase. Translation then uses the mRNA to assemble amino acids into proteins with the help of tRNA and rRNA. Though genes code for traits, there is not a simple one-to-one relationship due to various regulatory factors.
Regulation of eukaryotic gene expressionMd Murad Khan
The document discusses various mechanisms of regulating gene expression in eukaryotes. It explains that regulation can occur at multiple levels, including DNA, transcription, mRNA processing, and protein synthesis. Key points include: (1) Regulation allows adaptation and cellular differentiation; (2) In eukaryotes, transcription and translation are separated, allowing more complex regulation; (3) Regulation mechanisms include controlling chromatin structure, transcription initiation, mRNA splicing/stability, and protein modifications. Environmental factors like heat and hormones can also induce gene expression changes through transcription factors.
The document discusses the Ramachandran plot, which shows statistically probable combinations of the phi and psi backbone torsion angles in proteins. It describes how these two angles describe rotations around bonds in the polypeptide backbone and influence protein folding. The plot reveals allowed and disallowed regions based on steric clashes between atoms at different angle combinations. Common structures like alpha helices and beta sheets correspond to allowed regions in the plot.
The document summarizes the process of translation in cells. It describes how the genetic code on mRNA is translated into a sequence of amino acids with the help of tRNA and ribosomes. There are several steps involved: 1) amino acids are activated by attaching to tRNA, 2) initiation begins with formation of initiation complexes on ribosomes, 3) elongation occurs as new amino acids are added one by one to the growing polypeptide chain through movement of tRNA between ribosomal sites, and 4) termination releases the full protein when a stop codon is reached. The entire process requires energy in the form of GTP hydrolysis at several steps.
Post-translational modifications (PTMs) refer to any alterations made to proteins after their initial synthesis, such as modification of amino acid side chains. PTMs influence protein structure, stability, activity, and more. Common PTMs include phosphorylation, glycosylation, methylation, and hydroxylation. PTMs are important for proper protein folding, conferring stability, and regulating protein activity and function. They increase proteome diversity and complexity.
DNA and RNA are nucleic acids that play important roles in cells. DNA contains the genetic instructions used in the development and functioning of living organisms. It has a double helix structure formed by base pairing between adenine and thymine, and cytosine and guanine. RNA is usually single-stranded and exists in several forms that help carry out the instructions specified by genes, including messenger RNA, transfer RNA, and ribosomal RNA. Messenger RNA carries copies of instructions from DNA to the sites of protein synthesis. Transfer RNA transfers amino acids to the ribosome during protein synthesis according to the mRNA sequence. Ribosomal RNA is a component of ribosomes and helps in protein synthesis.
Transcription definition
steps of transcription
general structure of gene
RNA polymerase structure
Transcription in prokaryotes in detail (initiation, elongation and termination)
Post-transcriptional modifications are important processes that convert primary transcript RNA into mature RNA. These modifications include 5' capping, 3' polyadenylation, and splicing of introns in eukaryotes. The modifications help make RNA molecules recognizable for translation and increase protein synthesis efficiency by removing non-coding regions. Different types of RNA undergo specific processing pathways involving nucleases, snoRNAs and other protein complexes.
This document discusses three forms of DNA: A-DNA, B-DNA, and Z-DNA. A-DNA has a more compact helical structure than B-DNA, with the basepairs closer to the helix axis. It occurs under dehydrated conditions. Z-DNA has a left-handed helical structure and is formed by alternating purines and pyrimidines, especially GC stretches. The major differences between A, B, and Z-DNA involve the sugar conformation, placement of basepairs, and helical geometry.
Classification of amino acid by KK Sahu sirKAUSHAL SAHU
Introduction of amino acid
Common structure of amino acid
History
Classification of amino acid basis on R-group
Non polar aliphatic R group
Aromatic R group
Uncharged polar R group
Positive Charge R group
Negative charge R group
Properties of amino acids
Conclusions
References
This document discusses various chromatography techniques including paper chromatography, thin layer chromatography, partition chromatography, adsorption chromatography, ion-exchange chromatography, gel filtration chromatography, affinity chromatography, high performance liquid chromatography, and gas chromatography. The different techniques separate molecules based on properties like size, charge, and affinity. They have various applications in biochemistry like purifying proteins, antibodies, and separating biological compounds.
There are three main levels of control to ensure DNA replication is initiated only once per cell cycle in bacteria:
1. ATP hydrolysis by beta-clamp protein
2. Sequestration of hemimethylated DNA by SeqA protein
3. Titration of DnaA protein levels through its regulatory locus
In eukaryotes, licensing factors like ORC, Cdc6, Cdt1 and MCM proteins bind to origins of replication and license them for a single round of replication. After replication begins, these factors dissociate from origins preventing re-replication. Geminin protein also prevents re-licensing of newly synthesized DNA in G2 phase.
DNA polymerase proofreads
DNA contains the genetic instructions for all living organisms. It exists as a double helix composed of nucleotides with a phosphate-sugar backbone and nitrogenous bases of adenine, cytosine, guanine and thymine. DNA undergoes replication to make copies for new cells, and is transcribed and translated to make proteins for cell functions. It can also undergo recombination during cell division to increase genetic variation.
Nucleic acids are polymeric macromolecules essential for life. They include DNA and RNA and are made of nucleotides. DNA contains the genetic instructions in cells and is organized into chromosomes. It exists as a double helix held together by base pairing between purines and pyrimidines. RNA has several types and functions in protein synthesis or regulation. Nucleotides are the monomers of nucleic acids and also have important roles in metabolism. DNA is tightly packaged in the nucleus through winding around histone proteins to form nucleosomes and higher-order chromatin structures.
DNA is the molecule that stores genetic information. It is composed of nucleotides containing nitrogenous bases, sugars, and phosphates. The four bases in DNA are adenine, guanine, cytosine, and thymine. DNA exists as two strands coiled around each other in the shape of a double helix. Each strand acts as a template for the other. DNA is replicated through a semi-conservative process where each original strand acts as a template for a new partner strand. This ensures each new cell contains an exact copy of the original DNA.
Structure of dna, its organization & functions, july 2020enamifat
DNA is made up of two strands that wind around each other in a double helix structure. Each strand is a polymer of deoxyribonucleotides connected by phosphodiester bonds. The bases on one strand form hydrogen bonds with complementary bases on the other strand according to base pairing rules. DNA carries the genetic instructions for growth, development, functioning and reproduction of living organisms. DNA is organized within the cell through coiling and folding with histone proteins to form nucleosomes and chromatin, and ultimately chromosomes.
The document summarizes key aspects of DNA structure and function. It describes the central dogma of molecular biology whereby DNA is transcribed into RNA and then translated into protein. It explains gene expression and the genetic code using codons. It discusses the structures of nucleic acids, nucleotides, and their polymerization to form DNA and RNA. It also summarizes DNA replication, the different forms of DNA/RNA, and their complementary base pairing.
Nucleic Acid Chemistry Of Purine and Pyrimidine Ribonucleotide Part I MD1 By ...princeprefa
This document discusses nucleic acid structure and gene expression. It begins by introducing nucleotides, which are the monomers that make up nucleic acids like DNA and RNA. They consist of a nitrogenous base, a 5-carbon sugar, and phosphate groups. The document then summarizes the central dogma of molecular biology, which states that DNA is transcribed into RNA which is translated into protein. It describes the structure of DNA as a double helix with complementary base pairing, and RNA as generally single-stranded. The document concludes by discussing DNA replication and the cell cycle.
The document provides an overview of key concepts in molecular biology including:
- DNA and RNA structure, including nucleotides, bases, sugars, and single vs double stranded forms.
- Key cellular components like genes, chromosomes, and genomes of prokaryotes and eukaryotes.
- Central processes like transcription, translation, and the central dogma.
- Differences between prokaryotic and eukaryotic cells, including bacterial vs human DNA organization and composition.
It also includes diagrams of DNA structure, the genetic code, and tRNA structure to illustrate these concepts. The document concludes with sample review questions.
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.
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)
A brief introduction to human genetics. Relevant to medical students i.e biochem, anatomy and physiology students.
It might be very short but it is also helpful.
DNA is composed of nucleotides that contain nitrogenous bases, sugars, and phosphates. DNA stores and transmits genetic information through genes located on chromosomes in the cell nucleus. DNA is transcribed into RNA and translated into proteins. Genetic traits are passed from parents to offspring through dominant and recessive genes according to patterns of inheritance. DNA is highly condensed and organized within the nucleus to fit inside cells.
DNA and RNA are nucleic acids that store and help express genetic information. DNA is composed of nucleotides containing deoxyribose, phosphates, and one of four nitrogenous bases (adenine, guanine, cytosine, thymine). RNA is similar but contains ribose and uracil instead of thymine. The genetic code is stored in DNA as base pair sequences in chromosomes. During cell division, DNA replicates and genes direct protein production through transcription of DNA to mRNA and translation of mRNA to proteins.
The document discusses nucleic acids and their role in genetics. It begins by defining nucleic acids as important biopolymers that contain genetic information and facilitate its transfer between generations. It then describes the two main types of nucleic acids: DNA and RNA. DNA contains the full genetic code and resides in the nucleus, while RNA carries messages from DNA and has various functions. The document proceeds to discuss the composition, structure, and functions of nucleic acids in more detail.
The document discusses the structure and properties of DNA and its role as the genetic material. Some key points:
- DNA is composed of nucleotides containing nitrogenous bases, sugars, and phosphate groups. The bases adenine and thymine and cytosine and guanine form base pairs between two anti-parallel DNA strands.
- Experiments by Griffith, Avery, Hershey and Chase provided evidence that DNA, not protein, is the genetic material based on its ability to transform phenotypes and be taken up by bacteria.
- DNA replication is semi-conservative and uses DNA polymerases to copy the parental strands. Meselson-Stahl experiments confirmed the semi-conservative model.
- Mutations
Chromatin, which contains DNA and proteins, is found in the nucleus of eukaryotic cells. Histone proteins help package DNA into chromatin and condense it further into chromosomes during cell division. DNA is a double-stranded polymer composed of nucleotides containing a sugar, phosphate, and one of four nitrogenous bases. It forms the twisted ladder-shaped structure known as a double helix and carries the genetic instructions that are passed from parents to offspring. DNA replication is the process where DNA copies itself before cell division, involving unwinding of the DNA strands, formation of a replication fork, and synthesis of new strands along the original templates.
The document provides an overview of molecular biology and discusses several key topics:
1) It discusses how cells organize and package DNA within the nucleus and replicate it during cell division.
2) Genome organization, including introns, exons, satellites and repetitive DNA is covered. Chromatin structure and packaging is also discussed.
3) DNA interacts with proteins through specific and non-specific binding. DNA is organized into chromatin through interactions with histone proteins in eukaryotes and other proteins in prokaryotes.
This document discusses DNA structure and replication. It begins by describing the structure of DNA as a double helix with two antiparallel strands held together by hydrogen bonds between complementary nucleotide base pairs. DNA replication is then summarized as a semi-conservative process where the parental DNA strands separate and each acts as a template for new complementary strands to be synthesized, resulting in two new DNA molecules each with one original and one new strand. The key steps of replication including initiation, unwinding of the strands, primer formation, elongation of new strands, and ligation are also outlined.
Nucleic acids are macromolecules made of nucleotides that contain three components: a 5-carbon sugar, phosphate group, and nitrogenous base. DNA and RNA are the two main types of nucleic acids. DNA contains the sugar deoxyribose and has a double helix structure, while RNA contains the sugar ribose and is single-stranded. Both are composed of nucleotides joined by phosphodiester bonds and function to carry genetic information for protein synthesis. Their primary differences are that DNA contains the base thymine while RNA contains uracil, and DNA is generally found in the nucleus while RNA has additional roles in the cytoplasm.
Viruses are obligate intracellular parasites that infect all types of cells. They consist of nucleic acid surrounded by a protein coat and in some cases an envelope. Viruses hijack the host cell's machinery to replicate themselves and are then released to infect new host cells. There are many variations in the viral life cycle depending on whether the virus has DNA or RNA as its genome and whether it is enveloped. Viruses are classified based on their structure, composition and genetics.
Mycology is the branch of biology concerned with the study of fungi, including their genetic and biochemical properties, their taxonomy and their use to humans as a source for tinder, traditional medicine, food, and entheogens, as well as their dangers, such as toxicity or infection.
In the late 16th century several Dutch lens makers designed devices that magnified objects, but in 1609 Galileo Galilei perfected the first device known as a microscope. Dutch spectacle makers Zaccharias Janssen and Hans Lipperhey are noted as the first men to develop the concept of the compound microscope.
In the late 16th century several Dutch lens makers designed devices that magnified objects, but in 1609 Galileo Galilei perfected the first device known as a microscope. Dutch spectacle makers Zaccharias Janssen and Hans Lipperhey are noted as the first men to develop the concept of the compound microscope.
Microbial Spoilage include the contamination of Pharmaceutical products with the microbes which lead to spoilage of the product affecting Drug safety and quality, and is not intended for use. Shortly Microbial Spoilage is defined as deterioration of pharmaceutical products by the contaminant microbe.
In the late 16th century several Dutch lens makers designed devices that magnified objects, but in 1609 Galileo Galilei perfected the first device known as a microscope. Dutch spectacle makers Zaccharias Janssen and Hans Lipperhey are noted as the first men to develop the concept of the compound microscope.
Bacteria are a type of biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a number of shapes, ranging from spheres to rods and spirals. Bacteria were among the first life forms to appear on Earth, and are present in most of its habitats
Microbiology is the study of organisms that are usually too small to be seen by the unaided eye; it employs techniques—such as sterilization and the use of culture media—that are required to isolate and grow these microorganisms.
Louis Pasteur in 1859 used swan-necked flasks to disprove the theory of spontaneous generation by showing that liquids in the flasks did not grow microbes due to being protected from dust and microbes in the air. Edward Jenner developed the first vaccine for smallpox in the late 1700s by inoculating people with material from cowpox lesions. Alexander Fleming discovered penicillin in 1928 after observing a mold that produced a chemical clearing surrounding bacteria on a culture plate.
Bacteria are microscopic, single-celled organisms that thrive in diverse environments. These organisms can live in soil, the ocean and inside the human gut. Humans' relationship with bacteria is complex. Sometimes bacteria lend us a helping hand, such as by curdling milk into yogurt or helping with our digestion
Bacteria are microscopic, single-celled organisms that thrive in diverse environments. These organisms can live in soil, the ocean and inside the human gut. Humans' relationship with bacteria is complex. Sometimes bacteria lend us a helping hand, such as by curdling milk into yogurt or helping with our digestion
Diuretics, also called water pills, are medications designed to increase the amount of water and salt expelled from the body as urine. There are three types of prescription diuretics. They're often prescribed to help treat high blood pressure, but they're used for other conditions as well.
The main site of diuretic action is well established for the different groups of diuretics: carbonic anhydrase inhibitors act on the proximal tubulus, loop diuretics on the diluting segment, thiazides on the cortical diluting segment/distal tubulus, and potassium-sparing agents on distal tubulus/collecting ducts.
Diuretics, also called water pills, are medications designed to increase the amount of water and salt expelled from the body as urine. There are three types of prescription diuretics. They’re often prescribed to help treat high blood pressure, but they’re used for other conditions as well.
Proton-pump inhibitors are a group of medications whose main action is a pronounced and long-lasting reduction of stomach acid production. Within the class of medications, there is no clear evidence that one agent works better than another. They are the most potent inhibitors of acid secretion available.
Synthesis of Naproxen, Ketoprofen, Ketorolac, Diclofenac and IbuprofenPharmacy Universe
This document summarizes the synthesis of several common nonsteroidal anti-inflammatory drugs (NSAIDs) including naproxen, ketoprofen, ketorolac, diclofenac, and ibuprofen. It outlines the key reaction steps for producing each compound, starting from various aromatic precursors and involving reactions such as acylation, alkylation, hydrolysis, bromination, reduction, chlorination, and hydrolysis.
The main site of diuretic action is well established for the different groups of diuretics: carbonic anhydrase inhibitors act on the proximal tubulus, loop diuretics on the diluting segment, thiazides on the cortical diluting segment/distal tubulus, and potassium-sparing agents on distal tubulus/collecting ducts.
In conclusion, the present study found that esomeprazole 40 mg daily may be more effective than either omeprazole 20 mg daily, pantoprazole 40 mg daily or lansoprazole 30 mg daily for the rapid relief of heartburn symptoms in patients with endoscopically proven reflux esophagitis.
Mechanisms of diuretic drugs. Diuretic drugs increase urine output by the kidney (i.e., promote diuresis). This is accomplished by altering how the kidney handles sodium. If the kidney excretes more sodium, then water excretion will also increase.
These lecture slides, by Dr Sidra Arshad, offer a quick overview of the physiological basis of a normal electrocardiogram.
Learning objectives:
1. Define an electrocardiogram (ECG) and electrocardiography
2. Describe how dipoles generated by the heart produce the waveforms of the ECG
3. Describe the components of a normal electrocardiogram of a typical bipolar lead (limb II)
4. Differentiate between intervals and segments
5. Enlist some common indications for obtaining an ECG
6. Describe the flow of current around the heart during the cardiac cycle
7. Discuss the placement and polarity of the leads of electrocardiograph
8. Describe the normal electrocardiograms recorded from the limb leads and explain the physiological basis of the different records that are obtained
9. Define mean electrical vector (axis) of the heart and give the normal range
10. Define the mean QRS vector
11. Describe the axes of leads (hexagonal reference system)
12. Comprehend the vectorial analysis of the normal ECG
13. Determine the mean electrical axis of the ventricular QRS and appreciate the mean axis deviation
14. Explain the concepts of current of injury, J point, and their significance
Study Resources:
1. Chapter 11, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 9, Human Physiology - From Cells to Systems, Lauralee Sherwood, 9th edition
3. Chapter 29, Ganong’s Review of Medical Physiology, 26th edition
4. Electrocardiogram, StatPearls - https://www.ncbi.nlm.nih.gov/books/NBK549803/
5. ECG in Medical Practice by ABM Abdullah, 4th edition
6. Chapter 3, Cardiology Explained, https://www.ncbi.nlm.nih.gov/books/NBK2214/
7. ECG Basics, http://www.nataliescasebook.com/tag/e-c-g-basics
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3. Nucleosides: The addition of pentose sugar to a base produces
a nucleoside, if the sugar is ribose, a riboncleoside is produced,
if the sugar is 2-deoxyribose, a deoxyribonucleoside is produced.
Adenosine
Guanosine
Deoxyadenosine
Deoxyguanosine
5. Nucleotides are phosphate esters of nucleosides. Most commonly, the
phosphoryl group is attached to the oxygen of the 5'-hydroxyl group
In nucleic acids, the 5'
phosporyl is esterified to
the 3' OH of the next
sugar, forming a sugar
phosphate backbone, from
which the purine and
pyrimidine bases extend.
Nucleotides:
6. G - C
A - T
Crucial property: Nitrogenous bases form pairs between purine and
pyrimidine, Adenine must pair with Thymine, and Guanine must pair
with Cytosine. The bases form weak hydrogen bonds.
• In a body or somatic cell:
A = 30.3%
T = 30.3%
G = 19.5%
C = 19.9%
7. Structure of DNA and RNA
“Legs of ladder”
Phosphate &
Sugar Backbone
Nitrogenous
Base (A,T,G or C)
“Rungs of ladder”
8.
9. DNA: DNA is a double helical strand consists of nucleotides that
contains the genetic information used in the development and
functioning of all known living organisms with the exception of some
viruses where RNA carries the genetic information. The main role of
DNA molecule is storage of information in the long term.
The DNA segment that caries this information are called genes (in
other Word the structural and functional unit of DNA is gene), but
other part of DNA sequences have structural purposes or are
involved in regulating the use of this genetic information.
DNA consists of two long polymers of simple units called nucleotides
with backbones of sugars and phosphate group joined by ester bonds.
These two strands ran in opposite directions to each other and are
therefore antiparallel (one is 5’ – 3’ and the other one is 3’ – 5’).
10. Organization of DNA:
Within cells, DNA is organized into long structures called
chromosomes, these chromosomes are duplicated before cell division in
a process called DNA replication. The largest human chromosome is
chromosome number 1 and is about 220million base pairs long. Human
genome has approximately 3 billion base pairs of DNA arranged into 46
chromosomes. Eukaryotic organisms store most of their DNA inside
the cell nucleus and some of their DNA locates in mitochondria or
chloroplast. In contrast prokaryotes store their DNA only in the
cytoplasm.
In eukaryotic cells, DNA is packaged with proteins to form chromatin
fibers that make up chromosomes. This organization allows eukaryotic
DNA to be accurately replicated and sorted into daughter cells
without much error during cell division. Prokaryotic cells usually contain
circular DNA molecules called plasmids, which are stored within the
cell's cytoplasm. Eukaryotic chromosomes, on the other hand, have
several levels of organization.
11. Eukaryotic DNA coil around histone
proteins to form histone-DNA
complexes called nucleosomes, which
are organized into large, coiled loops
held together by scaffolding proteins.
Nucleosomes are octamer with 2
copies of each of H2A, H2B, H3 and
H4 histones. About 147 bp of DNA
wrapped around histone core particle.
Linker DNA between core particles
gives total of about 200 bp per
nucleosome. Histone H1 is works as
linker between octamers. Humans have
about 25 million nucleosomes/cell.
12.
13.
14. Use of DNA:
Genetic Engineering: The genetically modified organisms can be used
to produce products such as recombinant protein, used in medical
research, or be grown in agriculture.
Forensics / Criminal identification: DNA in blood, skin, saliva or hair
found in crime scene can be used for criminal identification. The
method is called DNA profiling or genetic finger printing.
Parental identification: there are some segments in the DNA which
are identical with DNA of parents
Medical diagnosis: genetic disease diagnosis
History / Anthropology:
15. Genetic Code:
Only one of the two strands of DNA codes for proteins, so scientists
write the genetic code as a sequence of bases. The genetic code is
read in groups of three bases / nucleotides, each group representing
one amino acid. Each trinucleotide sequence is called a codon. A gene
includes a series of codons that is read sequentially from a starting
point at one end to a termination point at the other end (5’ – 3’
direction). There are 64 codons, each of these codons has a specific
meaning in protein synthesis. 61 codons represents amino acids, three
codons cause the termination of protein synthesis.
Phe: UUU UUC; Leu: UUA, UUG, CUU, CUC, CUA, CUG;
Met: AUG
Stop codon: UAA, UAG, UGA; when one of these codons appears in an
mRNA, it stops transcription.
16.
17. Mutations: Alterations in the DNA sequence called mutations.
Silent mutation: Changed base may code for the same amino
acid.
Missense mutation: changed base code for different amino
acid.
Non sense mutation: Changed base may become a termination
codon.
Frameshift mutation: If one or two nucleotides are either
deleted or added to the coding region of a sequence.
Transition mutation: substitution of one pyrimidine by the
other, G-C to A-T
Transversion mutation: Substitution of purine by pyrimidine
or vice versa: A-T to T-A or C-G
18. Central dogma: The flow of information from DNA to RNA to protein is
termed as the central dogma of molecular biology and is descriptive of all
organisms with the exception of some viruses that have RNA as the
repository of their genetic information. Central dogma includes replication,
transcription and translation.
Replication: A double-stranded nucleic acid is duplicated to give identical
copies during cell division.
Transcription: Generation of single-stranded RNA which is identical in
sequence with one of the strands of the duplex DNA. There are three types
of RNA: messenger RNA (mRNA), transfer RNA (tRNA) and ribosomal RNA
(rRNA).
Translation: Its a process through which converts the nucleotide sequence
of RNA into the sequence of amino acids comprising a protein. An mRNA is
translated into a protein sequence. The entire length of an mRNA is not
translated, but each mRNA contains at least one coding region (exon) that is
related to protein sequence, the non-coding sequence of the mRNA is known
as intron.
19. DNA replication is
semiconservative:
The genetic material is
reproduced accurately. The
parental duplex is replicated to
form two daughter duplexes,
each of which consists of one
parental strand and one newly
synthesized daughter strand.
This behaviour is called
semiconservative replication.
20. E coli were grown in a
medium containing 15N heavy
isotope of nitrogen in
ammonium chloride (NH4Cl).
Thus all the nitrogenous
components in cells including
bases in their DNA became
highly enriched in heavy
nitrogen. The DNA isolated
from such cells have a
density 1% greater than
that of normal DNA and can
be separated by
centrifugation in cesium
chloride solution. DNA
duplexes at lower position
are heavy, normal duplexes
are at upper position and
mixed duplexes are at
middle position.
21. DNA Replication:
Replication of DNA is a complex system which involves in the stages of
initiation, elongation and termination.
Initiation involves recognition of an origin by a complex of proteins.
Before DNA synthesis begins, the parental strands must be separated
and stabilized in the single stranded state. Then synthesis of daughter
strands can be initiated at the replication fork. Initiation in E. Coli is
accomplished by a protein complex called the primosome.
Elongation is undertaken by another complex of proteins called replisome
and assembled from its components at the onset of replication. As the
replisome moves along DNA, the parental strand unwind and daughter
strands are synthesized with the help of DNA Polymerase.
Termination: At the end of replicon, joining and or termination reactions
are necessary. Following termination, the duplicate chromosomes must be
separated from one another.
22. Mammalian DNA Polymeases:
DNA pol I ----- Priming
DNA pol III -------DNA synthesis
DNA pol II ------- Repair
DNA pol ------ Repair
DNA pol γ -----Replication (mitochondrial)
DNA Polymerases:
An enzyme that can synthesize a new DNA strand on a template
strand is called a DNA polymerase. Both prokaryotic and eukaryotic
cells contain multiple DNA polymerases.
23. DNA synthesis is semidiscontinuous:
The antiparallel structure of the two strand of duplex DNA poses a problem
for replication. As the replication fork advances, daughter strand must be
synthesized on both the exposed parental single strands. The fork moves in
the direction from 5’ – 3’ on one strand, and in the direction from 3’ – 5’ on
the other strand. Nucleic acids are synthesized only from a 5’ end toward a
3’ end.
Two of the newly synthesized strands have different properties:
Leading strand: On the leading strand DNA synthesis can proceed
continuously in the 5’ to 3’ direction as the parental duplex is unwound.
Lagging strand: On the lagging strand a stretch of single stranded parental
DNA must be exposed, and then a segment is synthesized in the reverse
direction. A series of these fragments are synthesized, each 5’ to 3’, then
they are joined together to create an intact lagging strand. These
fragments are also known as Okazaki fragments. Thus the lagging strand is
synthesized discontinuously and the leading strand is synthesized
continuously. This mode of synthesis is called semidiscontinuous replication.
24. DNA polymerase can not initiate a DNA chain, a priming activity is
required to provide 3’-OH ends to start the DNA chain on both the
leading and lagging strand. The leading strand requires only one
primer at the origin but there must be a series of initiation events
on the lagging strand, since each Okazaki fragments require its own
start. Each Okazaki fragment starts with a primer of ~10 bases of
RNA. At the end, RNA has been removed and replaced, Okazaki
fragments are then linked with the enzyme DNA ligase.
Helicase: A helicase is an enzyme that separates
the strands of DNA, usually using the hydrolysis of
ATP to provide the necessary energy.
Replication
Fork
Parental DNA Molecule
3’
5’
3’
5’
25. • The Leading Strand is synthesized as a single strand from the
point of origin toward the opening replication fork
• The Lagging Strand is synthesized discontinuously against overall
direction of replication
• This strand is made in many short segments It is replicated from
the replication fork toward the origin
RNA Primer
Leading Strand
DNA Polymerase
5
’
5’
3’
3’
Lagging Strand
5’
5’
3’
3’
26. • Okazaki Fragments - series of short segments on the lagging strand
• Must be joined together by an enzyme, ligase.
Lagging Strand
RNA
Primer
DNA
Polymerase
3’
3’
5’
5’
Okazaki Fragment
27. 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
DNA Damage & Repair
• Chemicals & ultraviolet radiation damage the DNA in our
body cells
• Cells must continuously repair damaged DNA
• Excision repair occurs when any of over 50 repair enzymes
remove damaged parts of DNA
• DNA polymerase and DNA ligase replace and bind the new
nucleotides together
28. RNA: RNA contain ribose instead of deoxyribose in DNA, and
uracil instead of thymine. RNA exists as single strand and are
capable of folding into complex structures.
RNA is the working copies of DNA, the copying process during which
a DNA strand serves as a template for the synthesis of RNA is
called transcription. The synthesis of RNA molecules using DNA
strands as the templates so that the genetic information can be
transferred from DNA to RNA.
There are three types of RNA:
i) Ribosomal RNA (rRNA): rRNA make up about 80% of the total
RNA in the cell, rRNA associates with ribosomes and serves as the
sites for protein synthesis.
29. ii) Transfer RNA (tRNA): tRNA make up about 15% of the total
RNA in the cell. There is at least one specific type of tRNA for
each of the 20 amino acids found in proteins. Each tRNA serves
as an adaptor molecule at the 3’ end that carries its specific
amino acid. It recognizes the genetic code on an mRNA.
iii) Messenger RNA (mRNA): mRNA comprises only about 5% of
the total RNA in the cell. It is most heterogenous type of RNA
in size and base sequence. The mRNA carries genetic information
from the nuclear DNA to the cytosol where it used for protein
synthesis.
30. • Both processes use DNA as the template.
• Phosphodiester bonds are formed in both cases.
• Both synthesis directions are from 5´ to 3´.
Similarity between replication and transcription
Replication Transcription
template double strands single strand
substrate dNTP NTP
primer yes no
Enzyme DNA polymerase RNA polymerase
product dsDNA ssRNA
Differences between replication and transcription
31. • The whole genome of DNA needs to be replicated, but only small
portion of genome is transcribed in response to the development
requirement, physiological need and environmental changes.
• DNA regions that can be transcribed into any RNA or protein product
other than regulatory factor or proteins are called structural genes.
The template strand is the strand from which the RNA is actually
transcribed or new strand of DNA is synthesized during replication.
It is also termed as antisense strand.
The coding strand is the strand whose base sequence specifies the
sequence of RNA or amino acid sequence of the encoded protein.
Therefore, it is also called as sense strand.
G C A G T A C A T G T C5' 3'
3' C G T C A T G T A C A G 5' template
strand
coding
strand
transcription
RNAG C A G U A C A U G U C5' 3'
32. Transcription of prokaryotic genes:
In bacteria one type of RNA polymerase synthesizes all of the RNA
except for the short RNA primers which needs primase.
RNA polymerase is a multisubunit enzyme:
a) Core enzyme: consists of four peptide subunits, 2, 1 and 1
/
and are
responsible for 5’ to 3’ RNA polymerase activity.
b) Holoenzyme: the sigma (σ) subunit recognize the promoter region on the
DNA. The sigma (σ) subunit plus the core enzyme make up the holoenzyme.
subunit MW function
36512 Determine the DNA to be transcribed
150618 Catalyze polymerization
155613 Bind & open DNA template
70263
Recognize the promoter
for synthesis initiation
33. Steps in the RNA synthesis:
Initiation, Elongation, Termination,
Initiation: RNA polymerase holoenzyme binds to the promoter region
of the DNA and starts transcription, the prokaryotic promoter
contains characteristic consensus sequences; pribnow box (six
nucleotides) at ~-10 position, and a special sequence at -35 region.
• Each transcriptable region is called operon.
• One operon includes several structural genes and upstream
regulatory sequences (or regulatory regions).
• The promoter is the DNA sequence where RNA-polymerase
can bind. It is the key point for the transcription control.
Promoter exists in the upstream region of each gene.
34. 5'
3'
3'
5'
-50 -40 -30 -20 -10 1 10
start-10
region
T A T A A T
A T A T T A
(Pribnow box)
-35
region
T T G A C A
A A C T G T
Prokaryotic promoter
35. Elongation: Once the promoter region has been recognized by RNA Pol,
local unwinding of the DNA occurs and begins to synthesize a transcript
of the DNA sequence.The elongation phase is said to begin when the
tanscript exceeds 10 nucleotides in length. Sigma factor is then
released and the core enzyme is able to move and synthesize RNA using
NTP as substrate. RNA polymerase does not require a primer and has
no proofreading activity.
Termination: Termination factor requiers for termination, eg, ρ (Rho)
factor for E coli. Elongation continues until a termination signal is
reached. Termination may be spontaneous or dependent on ρ (Rho)
factor.
36. Transcription of Eukaryotic genes:
Three types of RNA polymerase:
i) RNA Polymerase I: Synthesizes rRNA
ii) RNA Polymerase II: Synthesizes mRNA,
iii) RNA polymerase III: Produces tRNA and other small RNAs
structural gene
GCGC CAAT TATA
intronexon exon
CAAT box
GC box
TATA box (Hogness box)
Promoter Region of Eukaryotic genes:
(~-25bp position)
(~-70 - 80bp position)
(~-90bp position)
37. Initiation: Transcription initiation needs promoter and upstream
regulatory regions. RNA-pol does not bind the promoter directly.
RNA-pol II associates with six transcription factors, TFII A, TFIIB,
TFIID, TFIIE, TFIIF and TFII H to make a pre-initiation complex
and then starts transcription.
Elongation: Elongation is similar to that of prokaryotes and continues
up to termination codon.
Pre-initiation complex
(PIC)RNA pol II
TF II F
TATA
DNA
TF II
A
TF II
B
TF II E
TF II H
TFIID
39. Exon and intron:
Exons are the coding sequences that appear on split genes
and primary transcripts, and found in matured mRNA.
Introns are the non-coding sequences that are transcript
into primary mRNAs, and will be spliced out in the later
cleavage process.