This document discusses the Central Dogma of Biology and the discovery of DNA as the genetic material. It summarizes that:
1) Early experiments showed that chromosomes behaved like Mendel's hereditary factors and were linked to specific traits. The Hershey-Chase experiment provided definitive evidence that DNA, not protein, was the genetic material.
2) Watson and Crick discovered the double helix structure of DNA in 1953, explaining Chargaff's rules of base pairing. Semiconservative replication of DNA was demonstrated by Meselson and Stahl in 1957.
3) DNA replication requires several enzymes including DNA polymerase, helicase, ligase and primase to unwind and copy the DNA, adding
Chapter 6. Molecular basis of inheritance.mohan bio
Nucleic acids like DNA and RNA are the genetic material found in living cells. DNA carries genetic information from one generation to the next and is made up of deoxyribose, phosphate groups, and nitrogenous bases. DNA replication is semi-conservative and produces two identical DNA molecules, each with one old and one new strand. Transcription produces mRNA from a DNA template, and translation reads mRNA to produce proteins according to the central dogma of biology.
DNA replication is semi-conservative, with each new DNA molecule containing one old and one new strand. Several enzymes are involved, including DNA polymerase, helicase, and ligase. The leading strand is replicated continuously while the lagging strand involves discontinuous replication of Okazaki fragments that are later joined. Primers of RNA are required to initiate synthesis, with DNA polymerase then adding complementary nucleotides to the 3' end to extend the DNA chain. Chargaff's rules and the double helix model of DNA provided evidence that DNA is the genetic material.
1) The document provides an overview of DNA structure and function. It describes DNA as the genetic material that carries hereditary information from one generation to the next in the form of genes.
2) The key experiments that proved DNA is the genetic material are described, including Griffith's transformation experiment, Avery's work showing the transforming principle is DNA, and Hershey and Chase's experiment using radioactive labeling of DNA and proteins in bacteriophages.
3) Watson and Crick are credited with discovering the double helix structure of DNA in 1953 based on Chargaff's rules of base pairing and X-ray crystallography data. Their model explained DNA's ability to self-replicate semiconserv
The Hershey-Chase experiment helped confirm that DNA is the genetic material by showing that the DNA, but not the proteins, of bacteriophages enters host bacterial cells during infection. They uniquely labeled the DNA and proteins of bacteriophages with different radioactive isotopes, then showed that the progeny of infected bacteria contained the radioactivity from the original phage DNA but not proteins. This provided strong evidence that DNA, rather than protein, carries the genetic information required for reproduction.
The document summarizes the central dogma of biology and the discovery of DNA as the genetic material. It describes key experiments that showed DNA replicates in a semiconservative manner, with each parental strand serving as a template for a new complementary daughter strand. The process of DNA replication requires several enzymes including DNA polymerase, helicase, ligase and primase to unwind, copy and join new DNA strands.
This document provides an overview of the discovery of DNA as the genetic material. It discusses early evidence from experiments transforming bacteria and showing that viral DNA enters bacterial cells. It also describes Rosalind Franklin's X-ray crystallography work that provided insights into DNA's structure and allowed Watson and Crick to deduce the double helix model with paired nitrogenous bases. Their model resolved the structure and showed how DNA could store and replicate the genetic information required for inheritance.
Chapter 6. Molecular basis of inheritance.mohan bio
Nucleic acids like DNA and RNA are the genetic material found in living cells. DNA carries genetic information from one generation to the next and is made up of deoxyribose, phosphate groups, and nitrogenous bases. DNA replication is semi-conservative and produces two identical DNA molecules, each with one old and one new strand. Transcription produces mRNA from a DNA template, and translation reads mRNA to produce proteins according to the central dogma of biology.
DNA replication is semi-conservative, with each new DNA molecule containing one old and one new strand. Several enzymes are involved, including DNA polymerase, helicase, and ligase. The leading strand is replicated continuously while the lagging strand involves discontinuous replication of Okazaki fragments that are later joined. Primers of RNA are required to initiate synthesis, with DNA polymerase then adding complementary nucleotides to the 3' end to extend the DNA chain. Chargaff's rules and the double helix model of DNA provided evidence that DNA is the genetic material.
1) The document provides an overview of DNA structure and function. It describes DNA as the genetic material that carries hereditary information from one generation to the next in the form of genes.
2) The key experiments that proved DNA is the genetic material are described, including Griffith's transformation experiment, Avery's work showing the transforming principle is DNA, and Hershey and Chase's experiment using radioactive labeling of DNA and proteins in bacteriophages.
3) Watson and Crick are credited with discovering the double helix structure of DNA in 1953 based on Chargaff's rules of base pairing and X-ray crystallography data. Their model explained DNA's ability to self-replicate semiconserv
The Hershey-Chase experiment helped confirm that DNA is the genetic material by showing that the DNA, but not the proteins, of bacteriophages enters host bacterial cells during infection. They uniquely labeled the DNA and proteins of bacteriophages with different radioactive isotopes, then showed that the progeny of infected bacteria contained the radioactivity from the original phage DNA but not proteins. This provided strong evidence that DNA, rather than protein, carries the genetic information required for reproduction.
The document summarizes the central dogma of biology and the discovery of DNA as the genetic material. It describes key experiments that showed DNA replicates in a semiconservative manner, with each parental strand serving as a template for a new complementary daughter strand. The process of DNA replication requires several enzymes including DNA polymerase, helicase, ligase and primase to unwind, copy and join new DNA strands.
This document provides an overview of the discovery of DNA as the genetic material. It discusses early evidence from experiments transforming bacteria and showing that viral DNA enters bacterial cells. It also describes Rosalind Franklin's X-ray crystallography work that provided insights into DNA's structure and allowed Watson and Crick to deduce the double helix model with paired nitrogenous bases. Their model resolved the structure and showed how DNA could store and replicate the genetic information required for inheritance.
Chapter 16: Molecular Basis of InheritanceAngel Vega
KEY CONCEPTS
16.1 DNA is the genetic material
16.2 Many proteins work together in
DNA replication and repair
16.3 A chromosome consists of a DNA molecule packed together with proteins
DNA is the genetic material present in all living cells. It is a double-stranded molecule composed of deoxyribose, phosphate groups, and nitrogenous bases. DNA replicates semi-conservatively to produce two identical copies of itself during cell division. It carries genetic information that is transcribed into mRNA which is then translated into proteins.
- Griffith's experiment in 1928 showed that genetic material from heat-killed pathogenic bacteria could transform harmless bacteria into pathogenic ones, which he called the "transforming principle".
- Avery, Macleod, and McCarty's experiment in 1944 proved that DNA is the genetic material by showing that only DNA, and not other molecules, was able to transform bacteria.
- Hershey and Chase's experiment in 1952, using radioactive isotopes, demonstrated that DNA, not protein, enters a bacterial cell during viral infection, proving that DNA is the genetic material.
This document discusses the structure and replication of DNA. It provides details on:
1. The key components of DNA including deoxyribose sugar, phosphate groups, and nitrogenous bases. It also describes how nucleotides and polynucleotide strands are formed.
2. The double helix structure of DNA proposed by Watson and Crick, including how the strands are antiparallel and connected through complementary base pairing.
3. Semiconservative replication of DNA, where each old DNA strand acts as a template for a new complementary strand, resulting in two identical double-stranded DNA molecules after replication.
4. Experiments by Meselson and Stahl using isotopes that provided evidence supporting the
This document discusses microbial genetics and genetic recombination in bacteria. It explains that genetic recombination produces genetic variation through the processes of meiosis, fertilization, and crossing over. In bacteria, genetic transfer can occur through transformation, transduction, or conjugation. Transformation involves uptake of naked DNA from the environment. Transduction involves transfer of DNA between bacteria via bacteriophages. Conjugation requires an F plasmid and involves transfer of DNA through direct contact between bacterial cells. These processes of genetic transfer and recombination generate genetic diversity in bacterial populations.
This document discusses bacterial genetics and various mechanisms of genetic variation in bacteria. It describes the basic structure of DNA and RNA, and how genetic information is stored and transferred between generations in bacteria via chromosomes, plasmids, and transposons. The key mechanisms of genetic variation discussed are mutation, transformation, transduction, conjugation, and transposition. Mutation can occur via point mutations, frameshift mutations, or through exposure to mutagens. Transformation, transduction, and conjugation allow for the lateral transfer of genetic material between bacteria.
The document discusses various artificial transformation methods for improving the efficiency of plasmid DNA transformation in bacteria. It describes chemical transformation using calcium chloride, electroporation using electric pulses, physical transformation using nanomaterials and friction, and combined transformation methods that integrate multiple approaches. The conclusion states that while artificial methods increase transformation effectiveness over natural processes, simpler and more universal techniques are still needed that can transform a wide range of bacterial species.
DNA was discovered to be the genetic material through a series of experiments in the 1900s. Griffith's experiments with bacteria showed that DNA carries genetic information that can transform non-virulent bacteria strains into virulent ones. Further experiments by Avery, Macleod and McCarty isolated the heat-killed bacteria and found that only the DNA fraction could induce this transformation, not other components like proteins. Hershey and Chase's experiments with bacteriophage also showed that viral DNA, not proteins, entered the bacterial host cell and was responsible for replication. These experiments conclusively demonstrated that DNA is the carrier of genetic information in living organisms.
Transformation and transfection allow the genetic alteration of cells through the introduction of foreign DNA. Transformation refers specifically to bacteria, where naked DNA fragments can be taken up through natural competence or artificial methods like heat shock or electroporation. Transfection applies to eukaryotic cells, using techniques like lipofection to introduce DNA through membrane pores. Common methods to transform plants include Agrobacterium infection, particle bombardment, and electroporation. These techniques generate genetically modified cells and organisms.
This document provides an overview of genetic engineering and its applications to microorganisms. It defines genetic engineering as the direct manipulation of an organism's genome using biotechnology. The key steps involved are isolating the gene of interest, inserting it into a vector, introducing the vector into a host cell, and harvesting the gene product from the clone. Common hosts used are bacteria, yeast, plant and animal cells. The document also discusses some tools used in genetic engineering like restriction enzymes and DNA ligase. It outlines several applications of genetic engineering in medicine, research, agriculture and industry. It concludes by noting some ethical and safety concerns regarding genetically modified organisms.
Sexual reproduction in bacteria involves the transfer of genetic material between bacterial cells through three main mechanisms: transformation, transduction, and conjugation. Transformation involves the uptake of naked DNA by competent bacterial cells. Transduction occurs when bacterial DNA is transferred by bacteriophages. Conjugation is the transfer of DNA through direct cell-to-cell contact via conjugation pili. Gram staining is a technique used to differentiate between Gram-positive and Gram-negative bacteria based on differences in cell wall structure.
The document provides an overview of DNA structure and function. It discusses early experiments that established DNA as the genetic material, including Griffith's experiments showing transformation in bacteria and Avery, Macleod and McCarty's experiments proving that DNA is the transforming principle. It describes Chargaff's rules, Watson and Crick's proposal of the double helix model based on X-ray diffraction data, and semiconservative DNA replication demonstrated by Meselson and Stahl's experiment using nitrogen isotopes.
This power point presentation is an attempt to present some direct and some indirect evidences in favour of DNA as genetic material. Very few organisms have RNA as genetic material for example plant virus and some bacteriophages
Genetics is the science of heredity and the transmission of biological traits from parents to offspring. For centuries, the mechanism of heredity was unknown. Early theories proposed various substances or vital forces that were transmitted between generations. The development of the microscope led to the identification of chromosomes and their role in heredity. Later, DNA and RNA were identified as the genetic material contained in chromosomes. DNA is made of nucleotides with a sugar-phosphate backbone linked by nitrogenous bases. Its double helix structure allows for replication and transmission of genes from parents to offspring. This established DNA as the physical carrier of heredity.
Transduction is a mode of genetic transfer between bacteria mediated by bacteriophages. During viral replication, fragments of bacterial DNA can become packaged within viral particles. These particles may then infect other bacteria and insert the donor DNA into the recipient genome. There are two types of transduction - generalized, where any bacterial DNA fragment can be transferred, and specialized, where only DNA near the site of viral integration is transferred. Cotransduction frequencies can also be used to map the relative locations of bacterial genes, as genes closer together are more likely to be cotransferred within the same viral particle. Transduction is useful for genetic engineering and mapping bacterial chromosomes.
Bacteria may engage in genetic exchange through natural transformation where they take up environmental DNA. While this was initially thought to be a mechanism for recombination, evidence shows it primarily functions to obtain nutrients. The DNA uptake sequence preferences seen in some bacteria likely evolved through passive accumulation driven by the uptake machinery's bias rather than serving recombination. Any recombination in bacteria likely occurs accidentally during DNA repair. In contrast, sexual reproduction in eukaryotes evolved to solve a problem unique to their complexity that is nearly universal among eukaryotes.
The document discusses different types of cloning technologies including DNA cloning, reproductive cloning, and therapeutic cloning. DNA cloning involves transferring a DNA fragment from one organism to a self-replicating vector like a bacterial plasmid to generate multiple copies. Reproductive cloning aims to generate an animal with the same nuclear DNA as another through somatic cell nuclear transfer, while therapeutic cloning seeks to produce human embryos for stem cell research. Both cloning techniques are controversial due to safety and ethical concerns.
All living things share DNA as their genetic code, which contains the instructions that determine an organism's characteristics. DNA evidence shows that all life on Earth evolved from a common ancestor, as organisms with more similar DNA are more closely related evolutionarily. Mutations in DNA over time led to the diversity of life we see today. Comparative anatomy, embryology, fossils, and DNA/protein evidence all support the theory of evolution through common descent.
Bacterial recombination refers to the exchange of genes between DNA molecules, contributing to genetic diversity in bacteria. There are three main ways bacteria undergo genetic recombination: transformation, conjugation, and transduction. Transformation involves the uptake of naked DNA from the environment. Conjugation requires direct cell-to-cell contact and plasmid transfer. Transduction involves the transfer of bacterial genes between cells using bacteriophages. Both generalized and specialized transduction can occur depending on how the bacterial DNA is packaged into the phage particle. Overall, these processes increase genetic variation in bacterial populations.
This document provides an overview of DNA and genetics. It discusses how DNA was established as the genetic material through experiments in the 1900s and 1950s. It describes the structure of DNA as a double helix based on the work of Watson, Crick, Wilkins and Franklin. It also summarizes Mendel's laws of inheritance and how chromosomes package and transmit genetic information from one generation to the next. The document traces the history of genetics from early Greek philosophers through modern discoveries that have revolutionized our understanding of heredity and molecular biology.
1. Frederick Griffith discovered in 1928 that a "rough" non-pathogenic strain of pneumonia bacteria could be transformed into a "smooth" pathogenic strain through exposure to heat-killed pathogenic bacteria.
2. Hershey and Chase provided evidence in 1952 that DNA, not protein, was the genetic material through experiments using radioactive labeling of bacteriophages.
3. Watson and Crick deduced the double-helix structure of DNA in 1953 based on Chargaff's rules of DNA composition and Rosalind Franklin's X-ray crystallography photos of DNA.
Chapter 16: Molecular Basis of InheritanceAngel Vega
KEY CONCEPTS
16.1 DNA is the genetic material
16.2 Many proteins work together in
DNA replication and repair
16.3 A chromosome consists of a DNA molecule packed together with proteins
DNA is the genetic material present in all living cells. It is a double-stranded molecule composed of deoxyribose, phosphate groups, and nitrogenous bases. DNA replicates semi-conservatively to produce two identical copies of itself during cell division. It carries genetic information that is transcribed into mRNA which is then translated into proteins.
- Griffith's experiment in 1928 showed that genetic material from heat-killed pathogenic bacteria could transform harmless bacteria into pathogenic ones, which he called the "transforming principle".
- Avery, Macleod, and McCarty's experiment in 1944 proved that DNA is the genetic material by showing that only DNA, and not other molecules, was able to transform bacteria.
- Hershey and Chase's experiment in 1952, using radioactive isotopes, demonstrated that DNA, not protein, enters a bacterial cell during viral infection, proving that DNA is the genetic material.
This document discusses the structure and replication of DNA. It provides details on:
1. The key components of DNA including deoxyribose sugar, phosphate groups, and nitrogenous bases. It also describes how nucleotides and polynucleotide strands are formed.
2. The double helix structure of DNA proposed by Watson and Crick, including how the strands are antiparallel and connected through complementary base pairing.
3. Semiconservative replication of DNA, where each old DNA strand acts as a template for a new complementary strand, resulting in two identical double-stranded DNA molecules after replication.
4. Experiments by Meselson and Stahl using isotopes that provided evidence supporting the
This document discusses microbial genetics and genetic recombination in bacteria. It explains that genetic recombination produces genetic variation through the processes of meiosis, fertilization, and crossing over. In bacteria, genetic transfer can occur through transformation, transduction, or conjugation. Transformation involves uptake of naked DNA from the environment. Transduction involves transfer of DNA between bacteria via bacteriophages. Conjugation requires an F plasmid and involves transfer of DNA through direct contact between bacterial cells. These processes of genetic transfer and recombination generate genetic diversity in bacterial populations.
This document discusses bacterial genetics and various mechanisms of genetic variation in bacteria. It describes the basic structure of DNA and RNA, and how genetic information is stored and transferred between generations in bacteria via chromosomes, plasmids, and transposons. The key mechanisms of genetic variation discussed are mutation, transformation, transduction, conjugation, and transposition. Mutation can occur via point mutations, frameshift mutations, or through exposure to mutagens. Transformation, transduction, and conjugation allow for the lateral transfer of genetic material between bacteria.
The document discusses various artificial transformation methods for improving the efficiency of plasmid DNA transformation in bacteria. It describes chemical transformation using calcium chloride, electroporation using electric pulses, physical transformation using nanomaterials and friction, and combined transformation methods that integrate multiple approaches. The conclusion states that while artificial methods increase transformation effectiveness over natural processes, simpler and more universal techniques are still needed that can transform a wide range of bacterial species.
DNA was discovered to be the genetic material through a series of experiments in the 1900s. Griffith's experiments with bacteria showed that DNA carries genetic information that can transform non-virulent bacteria strains into virulent ones. Further experiments by Avery, Macleod and McCarty isolated the heat-killed bacteria and found that only the DNA fraction could induce this transformation, not other components like proteins. Hershey and Chase's experiments with bacteriophage also showed that viral DNA, not proteins, entered the bacterial host cell and was responsible for replication. These experiments conclusively demonstrated that DNA is the carrier of genetic information in living organisms.
Transformation and transfection allow the genetic alteration of cells through the introduction of foreign DNA. Transformation refers specifically to bacteria, where naked DNA fragments can be taken up through natural competence or artificial methods like heat shock or electroporation. Transfection applies to eukaryotic cells, using techniques like lipofection to introduce DNA through membrane pores. Common methods to transform plants include Agrobacterium infection, particle bombardment, and electroporation. These techniques generate genetically modified cells and organisms.
This document provides an overview of genetic engineering and its applications to microorganisms. It defines genetic engineering as the direct manipulation of an organism's genome using biotechnology. The key steps involved are isolating the gene of interest, inserting it into a vector, introducing the vector into a host cell, and harvesting the gene product from the clone. Common hosts used are bacteria, yeast, plant and animal cells. The document also discusses some tools used in genetic engineering like restriction enzymes and DNA ligase. It outlines several applications of genetic engineering in medicine, research, agriculture and industry. It concludes by noting some ethical and safety concerns regarding genetically modified organisms.
Sexual reproduction in bacteria involves the transfer of genetic material between bacterial cells through three main mechanisms: transformation, transduction, and conjugation. Transformation involves the uptake of naked DNA by competent bacterial cells. Transduction occurs when bacterial DNA is transferred by bacteriophages. Conjugation is the transfer of DNA through direct cell-to-cell contact via conjugation pili. Gram staining is a technique used to differentiate between Gram-positive and Gram-negative bacteria based on differences in cell wall structure.
The document provides an overview of DNA structure and function. It discusses early experiments that established DNA as the genetic material, including Griffith's experiments showing transformation in bacteria and Avery, Macleod and McCarty's experiments proving that DNA is the transforming principle. It describes Chargaff's rules, Watson and Crick's proposal of the double helix model based on X-ray diffraction data, and semiconservative DNA replication demonstrated by Meselson and Stahl's experiment using nitrogen isotopes.
This power point presentation is an attempt to present some direct and some indirect evidences in favour of DNA as genetic material. Very few organisms have RNA as genetic material for example plant virus and some bacteriophages
Genetics is the science of heredity and the transmission of biological traits from parents to offspring. For centuries, the mechanism of heredity was unknown. Early theories proposed various substances or vital forces that were transmitted between generations. The development of the microscope led to the identification of chromosomes and their role in heredity. Later, DNA and RNA were identified as the genetic material contained in chromosomes. DNA is made of nucleotides with a sugar-phosphate backbone linked by nitrogenous bases. Its double helix structure allows for replication and transmission of genes from parents to offspring. This established DNA as the physical carrier of heredity.
Transduction is a mode of genetic transfer between bacteria mediated by bacteriophages. During viral replication, fragments of bacterial DNA can become packaged within viral particles. These particles may then infect other bacteria and insert the donor DNA into the recipient genome. There are two types of transduction - generalized, where any bacterial DNA fragment can be transferred, and specialized, where only DNA near the site of viral integration is transferred. Cotransduction frequencies can also be used to map the relative locations of bacterial genes, as genes closer together are more likely to be cotransferred within the same viral particle. Transduction is useful for genetic engineering and mapping bacterial chromosomes.
Bacteria may engage in genetic exchange through natural transformation where they take up environmental DNA. While this was initially thought to be a mechanism for recombination, evidence shows it primarily functions to obtain nutrients. The DNA uptake sequence preferences seen in some bacteria likely evolved through passive accumulation driven by the uptake machinery's bias rather than serving recombination. Any recombination in bacteria likely occurs accidentally during DNA repair. In contrast, sexual reproduction in eukaryotes evolved to solve a problem unique to their complexity that is nearly universal among eukaryotes.
The document discusses different types of cloning technologies including DNA cloning, reproductive cloning, and therapeutic cloning. DNA cloning involves transferring a DNA fragment from one organism to a self-replicating vector like a bacterial plasmid to generate multiple copies. Reproductive cloning aims to generate an animal with the same nuclear DNA as another through somatic cell nuclear transfer, while therapeutic cloning seeks to produce human embryos for stem cell research. Both cloning techniques are controversial due to safety and ethical concerns.
All living things share DNA as their genetic code, which contains the instructions that determine an organism's characteristics. DNA evidence shows that all life on Earth evolved from a common ancestor, as organisms with more similar DNA are more closely related evolutionarily. Mutations in DNA over time led to the diversity of life we see today. Comparative anatomy, embryology, fossils, and DNA/protein evidence all support the theory of evolution through common descent.
Bacterial recombination refers to the exchange of genes between DNA molecules, contributing to genetic diversity in bacteria. There are three main ways bacteria undergo genetic recombination: transformation, conjugation, and transduction. Transformation involves the uptake of naked DNA from the environment. Conjugation requires direct cell-to-cell contact and plasmid transfer. Transduction involves the transfer of bacterial genes between cells using bacteriophages. Both generalized and specialized transduction can occur depending on how the bacterial DNA is packaged into the phage particle. Overall, these processes increase genetic variation in bacterial populations.
This document provides an overview of DNA and genetics. It discusses how DNA was established as the genetic material through experiments in the 1900s and 1950s. It describes the structure of DNA as a double helix based on the work of Watson, Crick, Wilkins and Franklin. It also summarizes Mendel's laws of inheritance and how chromosomes package and transmit genetic information from one generation to the next. The document traces the history of genetics from early Greek philosophers through modern discoveries that have revolutionized our understanding of heredity and molecular biology.
1. Frederick Griffith discovered in 1928 that a "rough" non-pathogenic strain of pneumonia bacteria could be transformed into a "smooth" pathogenic strain through exposure to heat-killed pathogenic bacteria.
2. Hershey and Chase provided evidence in 1952 that DNA, not protein, was the genetic material through experiments using radioactive labeling of bacteriophages.
3. Watson and Crick deduced the double-helix structure of DNA in 1953 based on Chargaff's rules of DNA composition and Rosalind Franklin's X-ray crystallography photos of DNA.
The document provides a history of discoveries related to DNA and genetics. It describes experiments in the 1940s-1950s that proved DNA is the genetic material responsible for inheritance. It details discoveries such as DNA's double helix structure and base pairing rules. The document also summarizes the mapping of the human genome and benefits of understanding the genome sequence.
This document provides an overview of DNA and genetics. It discusses how DNA was established as the genetic material through experiments in the 1940s-1950s, including Griffith's transformation experiments, Avery et al.'s work demonstrating the transforming principle was DNA, and Hershey and Chase's experiments with bacterial viruses. It also summarizes the discovery of the DNA double helix structure by Watson and Crick in 1953, based on Chargaff's rules and X-ray crystallography data. The key properties of DNA structure, including specific base pairing and semiconservative replication, are briefly outlined.
Molecular basis of inheritance by mohanbiomohan bio
Nucleic acids are macromolecules found in all living cells that carry genetic information. Friedrich Miescher first isolated nucleic acids from white blood cells in 1869. There are two main types of nucleic acids: DNA and RNA. DNA is the genetic material found in the nuclei of cells and in organelles like mitochondria. It has a double-helix structure formed by pairing of nitrogenous bases. RNA is also found in cells and is involved in protein synthesis. The flow of genetic information goes from DNA to RNA to protein, as described by the central dogma of molecular biology.
Historical development of genetics finalHotaru Imai
This document summarizes the historical development of genetics from early concepts to modern understanding. It describes key figures and their contributions, including:
- Mendel who established basic laws of inheritance through pea plant experiments.
- Watson and Crick who discovered the double helix structure of DNA.
- Chargaff who found regular proportions of DNA bases between species.
- Nirenberg who helped discover the genetic code.
- Berg who created the first recombinant DNA molecules.
The document traces the progression of genetics from early theories to establishing DNA as the molecule of inheritance and cracking the genetic code.
This document discusses nucleic acids and their structure and function. It begins by introducing the two types of nucleic acids - DNA and RNA. It then describes the structure of DNA in detail, including that DNA is composed of nucleotides containing nitrogenous bases, pentose sugars, and phosphate groups. It explains that DNA exists as a double helix with the bases pairing between the two strands. The document also discusses the structure and function of RNA, as well as the roles of DNA and RNA in heredity and protein synthesis.
The document provides information about nucleic acids and DNA structure. It defines nucleic acids as macromolecules present in living cells that were first isolated by Miescher. The two types are DNA and RNA, with DNA serving as the genetic material that is found in the nucleus of eukaryotic cells in the form of chromosomes. It then describes the double helix structure of DNA proposed by Watson and Crick, including that it consists of two anti-parallel polynucleotide chains held together by hydrogen bonds between complementary nucleotide base pairs. The document also discusses DNA replication and how experiments by Meselson and Stahl supported the semi-conservative model.
1. DNA encodes genetic information and is made up of nucleotides containing a sugar, phosphate, and nitrogenous base. DNA exists as a double helix structure with two complementary strands bonded together.
2. Watson and Crick discovered the double helix structure of DNA in 1953 using evidence from Franklin's X-ray diffraction images of DNA fibers showing the molecule consisted of two strands twisted around each other.
3. DNA has three main functions - storing genetic information through protein coding genes, duplicating itself through DNA replication, and transmitting genetic information between generations during cellular reproduction.
This document provides information on genetics and DNA. It discusses that DNA is found coiled in chromatin in the nucleus of cells. During cell division, chromatin coils tightly to form chromosomes which are duplicated so each new cell contains a full set. DNA is made of nucleotides containing a sugar, phosphate, and one of four nitrogenous bases. The bases bond with each other to form the sides of the DNA double helix structure. Experiments by Griffith, Hershey and Chase provided evidence that DNA is the genetic material. Watson and Crick used evidence from Franklin and others to develop the first model of the DNA double helix structure. DNA holds the instructions for development and reproduction and can replicate itself through semiconservative replication.
This document provides information on genetics and DNA. It discusses that DNA is found coiled in chromatin in the nucleus of cells. During cell division, chromatin coils tightly to form chromosomes which are duplicated so each new cell contains a full set. DNA is made of nucleotides containing a sugar, phosphate, and one of four nitrogenous bases. The bases bond with each other to form the DNA double helix structure. Experiments by Griffith, Hershey and Chase provided evidence that DNA is the genetic material. Watson and Crick deduced the DNA structure is a double helix with specific base pairing between A-T and G-C. DNA holds the code for inheritance and protein production. It can replicate through semiconservative replication to make
CH- 6 MOLECULAR BASIS OF INHERITANCE (1).pdfSunitaKumar24
DNA is made up of two polynucleotide chains that are coiled together in a double helix structure. Each chain contains deoxyribonucleotides joined by phosphodiester bonds. The nucleotides consist of a pentose sugar, phosphate group, and one of four nitrogenous bases - adenine, guanine, cytosine, or thymine. The bases on each chain pair up through hydrogen bonds to form base pairs between adenine and thymine or cytosine and guanine. DNA replicates semiconservatively, with each new DNA molecule containing one original and one newly synthesized strand.
1. Nucleic acids DNA and RNA act as genetic material in living organisms, with DNA serving as the primary genetic material that is faithfully copied and passed on to offspring.
2. Early experiments established that DNA, not protein, was the genetic material through transformation and infection experiments.
3. DNA was shown to be stable and able to replicate, with base-pairing allowing for the duplication of genetic information. While RNA also replicates, it is less stable than DNA due to its structure.
This document provides information on genetics and DNA. It discusses that DNA is found coiled in chromatin in the nucleus of cells. Chromosomes contain duplicated DNA and genes. DNA is made of nucleotides containing nitrogenous bases and sugars. Watson and Crick discovered that DNA has a double helix structure with adenine bonding with thymine and guanine bonding with cytosine. DNA replicates semi-conservatively before cell division. Genes can be cloned using recombinant DNA technology or PCR to produce proteins like insulin for medical use.
This document provides an overview of genetics and DNA. It discusses the location of DNA in cells, DNA structure including the double helix model, DNA replication, and gene expression. Key events covered include Griffith's experiments demonstrating transformation, Hershey and Chase's experiments showing DNA is the genetic material in viruses, and Watson and Crick's discovery of DNA's double helix structure. The roles of DNA, including inheritance and protein coding, are described. DNA cloning techniques like recombinant DNA and PCR are also summarized.
This document provides an overview of genetics and DNA. It discusses the location of DNA in cells, DNA structure including its double helix formation, the discovery of DNA as the genetic material through experiments in the 1900s, DNA replication and repair, techniques like cloning and PCR, and applications of biotechnology including producing insulin through recombinant DNA and genetically modified crops. The key roles of DNA in inheritance and providing genetic instructions for life processes are also summarized.
DNA is made of two linked strands that wind around each other to resemble a twisted ladder — a shape known as a double helix. Each strand has a backbone made of alternating sugar (deoxyribose) and phosphate groups. Attached to each sugar is one of four bases: adenine (A), cytosine (C), guanine (G) or thymine (T).
The document summarizes several key experiments that helped establish DNA as the genetic material:
1) Griffith's transforming principle experiment in 1928 demonstrated that something from heat-killed bacteria could transform live bacteria, indicating the presence of a "transforming principle."
2) Avery, McCarty, and MacLeod purified this principle in 1944 and showed that it was DNA through a series of tests.
3) Hershey and Chase's 1952 experiment using bacteriophage proved that the genetic material injected into bacteria was DNA, not protein.
4) Chargaff formulated his rules in 1950 showing equal concentrations of DNA bases adenine and thymine and guanine and cytosine.
5) Mesel
This document discusses gene regulation in prokaryotes and eukaryotes. It explains that gene regulation allows cells to only express genes when they are needed. In prokaryotes, gene regulation typically occurs through operons at the transcriptional level. Eukaryotic gene regulation is more complex and can occur through epigenetic, transcriptional, post-transcriptional, translational and post-translational mechanisms. Key methods of regulation include chromatin remodeling, transcription factor binding, RNA processing, mRNA degradation, and protein degradation.
Ribosomes are sub-microscopic organelles found in all living cells that are the sites of protein synthesis. They are composed of ribosomal RNA and proteins. Ribosomes exist in two types - 70S ribosomes in prokaryotes and 80S ribosomes in eukaryotes. 70S ribosomes are composed of a 50S and 30S subunit while 80S ribosomes have a 60S and 40S subunit. Ribosomes contain three functional sites - the mRNA binding site, the aminoacyl-tRNA site (A site), and the peptidyl-tRNA site (P site) where protein synthesis occurs through the joining of amino acids. Ribosomes provide enzymes and factors to facilitate the
Vacuoles are membrane-bound organelles found in plant and fungal cells that function to store waste, nutrients, and water to regulate pressure within the cell. The cell wall is located outside the plasma membrane in plant, fungal, and some bacterial and algal cells and provides structure, protection, and allows for cell growth and communication. The nucleus houses the cell's genetic material and has a surrounding membrane with pores to allow transport of molecules in and out. Peroxisomes are spherical organelles found in all eukaryotic cells that contain enzymes for metabolic processes. The cytosol is the liquid within the cell and cytoplasm but outside organelles, and serves functions of transport, metabolism, and signaling.
Biotechnology has been used for millennia to improve agriculture, food production, and medicine through techniques like animal husbandry and fermentation. Modern biotechnology applies scientific principles to processing materials through biological agents. It has applications in medicine like drug development, agriculture like developing pest-resistant crops, and industry like producing chemicals. Biotechnology's scope continues expanding in fields such as genetic engineering, stem cell research, and environmental remediation.
unit 1 cytoskeletal structures ECM docx.pdf sh.pdfMSCW Mysore
The cytoskeleton is made up of three main components - microtubules, microfilaments, and intermediate filaments. Microtubules are hollow tubes made of tubulin dimers that help maintain cell shape and transport vesicles. Microfilaments are made of actin and enable cell movement and division. Intermediate filaments provide structural support and anchor organelles. The extracellular matrix of animal cells contains collagen, fibronectin and proteoglycans, while plant cells have a cell wall made of cellulose and pectin.
Biotechnology III sem Practical manual MSCW Mysore
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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.
2. What is a Genetic “Factor”?
• From Mendel:
– we now accepted that there was genetic
transmission of traits.
• Traits are transmitted by “factors”
– Organisms carry 2 copies of each “factor”
• The question now was: what is the factor
that carries the genetic information?
3. Requirements of Genetic Material
• Must be able to replicate, so it is reproduced in each
cell of a growing organism.
• Must be able to control expression of traits
– Traits are determined by the proteins that act within us
– Proteins are determined by their sequences
• Therefore, the genetic material must be able to
encode the sequence of proteins
• It must be able to change in a controlled way, to
allow variation, adaptation, thus survival in a
changing environment.
4. Chromosomes – The First
Clue
• First ability to visualize chromosomes in the
nucleus came at the turn of the century
– construction of increasingly powerful
microscopes
– the discovery of dyes that selectively colored
various components of the cell
• Scientists examined cellular nuclei and
observed nuclear structures, which they
called chromosomes
• Observation of these structures suggested
their role in genetic transmission
5. Chromosome Observations
• Variety of chromosome types found in the nucleus
• 2 copies of each type of chromosome in most cells.
• All of the cells of an organism, except gametes and
rbc’s, have the same number of chromosomes.
• All organisms of the same species have the same
number of chromosomes.
• The number of chromosomes in a cell doubles
immediately prior to cell division
• Gametes have exactly half of the number of
chromosomes as the somatic cells of any organism.
– Gametes have just one copy of each chromosome type.
– Fertilization produces a diploid cell (a zygote), with the same
number of chromosomes as somatic cells of that organism.
6. Implications
• Chromosomes behaved like Mendel’s “factors”
– Mendel's hereditary factors were either located on
the chromosomes or were the chromosomes
themselves.
• Proof chromosomes were hereditary factors – 1905:
• The first physical trait was linked to the presence of
specific chromosomal material
– conversely, the absence of that chromosome meant
the absence of the particular physical trait.
• Discovery of the sex chromosomes
– "X" and "Y."
– distinguished from other chromosomes and from
each other
7. Importance of Sex Chromosomes
• Somatic cells taken from female donors always
contained 2 copies of the X chromosome
• Somatic cells taken from male donors always
contained one copy of the X chromosome and one
copy of the Y chromosome
• All of the other chromosomes in the nucleated cells
of both male and female donors appeared identical
• Thus, gender was shown to be the direct result of a
specific combination of chromosomal material
– The first phenotype (physical characteristic) to be
assigned a chromosomal location
– Specifically the X and Y chromosomes.
8.
9. What Carries the Genetic Information?
• Chromosomes are about 40% DNA & 60% protein.
– Protein is the larger component
• Protein molecules are composed of 20 different
subunits
• DNA molecules are composed of only four
• Therefore protein molecules could encode more
information, and a greater variety of information
– protein had the possibility for much more diversity than in
DNA
• Therefore, scientists believed that the protein in
chromosomes must carry the genetic information
10. The Discovery of DNA
• First identified in 1868 by Friedrich
Miescher, a Swiss biologist, in the
nuclei of pus cells obtained from
discarded surgical bandages.
• He called the substance nuclein
• Noted the presence of phosphorous
11. The Transforming Principle
• Fredrick Griffith - 1928
• Discovered that different strains of the bacterium
Strepotococcus pneumonae had different effects on
mice
– One strain could kill an injected mouse (virulent)
– Another strain had no effect (avirulent)
– When the virulent strain was heat-killed and injected into
mice, there was no effect.
– But when a heat-killed virulent strain was co-injected with the
avirulent strain, the mice died.
• Concluded that some factor in the heat killed bacteria
was transforming the living avirulent to virulent?
• What was the transforming principle and was this the
genetic material?
12.
13. The Transforming Principle is DNA
• Avery, Macleod, & McCarty – 1943
• Attempted to identify Griffith’s “transforming
principle”
• Separated the dead virulent cells into fractions
– The protein fraction
– DNA fraction
• Co-injected them with the avirulent strain.
– When co-injected with protein fraction, the mice lived
– with the DNA fraction, the mice died
• Result was IGNORED
– Most scientists believed protein was the genetic material.
– They discounted this result and said that there must have
been some protein in the fraction that conferred virulence.
14. The Hershey-Chase Experiment
• Hershey & Chase – 1952
• Performed the definitive experiment that
showed that DNA was the genetic
material.
• Bacteriphages = viruses that infect
bacteria
• Bacteriphage is composed only of
protein & DNA
• Inject their genetic material into the host
15.
16. The Experiment
• Prepared 2 cultures of bacteriophages
• Radiolabeled sulphur in one culture
– there is sulphur in proteins, in the amino acids methionine
and cysteine
– there is no sulphur in DNA
• Radiolabeled phosphorous in the second culture
– there is phosphorous in the phosphate backbone of DNA
– none in any of the amino acids.
• So this one culture in which only the phage protein
was labeled, and one culture in which only the phage
DNA was labeled.
17. Experiment Summary
• Performed side by side experiments with separate
phage cultures in which either the protein capsule
was labeled with radioactive sulfur or the DNA
core was labeled with radioactive phosphorus.
• The radioactively labeled phages were allowed to
infect bacteria.
• Agitation in a blender dislodged phage particles
from bacterial cells.
• Centrifugation pelleted cells, separating them from
the phage particles left in the supernatant.
18. Results Summary
• Radioactive sulfur was found predominantly in the
supernatant.
• Radioactive phosphorus was found predominantly
in the cell fraction, from which a new generation of
infective phage was generated.
• Thus, it was shown that the genetic material that
encoded the growth of a new generation of phage
was in the phosphorous-containing DNA.
19.
20. Chargaff’s Rule
• Once DNA was recognized as the genetic material,
scientists began investigating its mechanism and
structure.
• Erwin Chargaff – 1950
– discovered the % content of the 4 nucleotides was the
same in all tissues of the same species
– percentages could vary from species to species.
• He also found that in all animals (Chargaff’s rule):
%G = %C
%A = %T
• This suggested that the structure of the DNA was
specific and conserved in each organism.
• The significance of these results was initially
overlooked
21. Base Pairing in DNA
• Not understood ‘til Watson &
Crick described double helix
• Adenine & guanine are purines
– 2 organic rings
• Cytosine & guanine are
pyrimidines
– 1 organic ring
• Pairing a purine & a pyrimidine
creates the correct 2 nm distance
in the double helix
• A – T joined by 2 hydrogen
bonds
• G – C joined by 3 hydrogen
bonds
22. The Double Helix
• James Watson and Francis Crick – 1953
• Presented a model of the structure of DNA.
• It was already known from chemical studies
that DNA was a polymer of nucleotide
(sugar, base and phosphate) units.
• X-ray crystallographic data obtained by
Rosalind Franklin, combined with the
previous results from Chargaff and others,
were fitted together by Watson and Crick
into the double helix model.
23. Watson and Crick shared the 1962 Nobel Prize for
Physiology and Medicine with Maurice Wilkins.
Rosalind Franklin died before this date.
24. DNA Structure
• The double helix is formed from two strands of DNA
• DNA strands run in opposite directions
• They are complementary
– attached by hydrogen bonds between complimentary
base pairs:
– A - T and G - C
• This complementary pairing of the bases suggests
that, when DNA replicates, an exact duplicate of the
parental genetic information is made.
– The polymerization of a new complementary strand takes
place using each of the old strands as a template.
25.
26. Messelson and Stahl
• How does DNA replicate?
• Matthew Meselson and Franklin Stahl - 1957
• Did an experiment to determine which model best
represented DNA replication:
• semiconservative replication
– the two strands unwind and each acts as a template for
new strands
– each new strand is half comprised of molecules from
the old strand
• conservative replication
– the strands do not unwind, but somehow generate a
new double stranded DNA copy of entirely new
molecules
27.
28.
29. The Experiment
• The original DNA strand was labeled with the
heavy isotope of nitrogen, N-15.
• This DNA was allowed to go through one
round of replication with N-14 (non-labeled)
• the mixture was centrifuged so that the
heavier DNA would form a band lower in the
tube
• the intermediate (one N-15 strand and one N-
14 strand) and light DNA (all N-14) would
appear as a band higher in the tube
31. The actual results were as expected for the
semiconservative model and thus Watson and
Crick's suspicion was borne out.
32. Enzymes & Replication
• DNA replication is not a passive, spontaneous
process.
• More than a dozen enzymes & other proteins are
required to unwind the double helix & to synthesize
& finalize a new strand of DNA.
• The molecular mechanism of DNA replication can
best be understood from the point of view of the
machinery required to accomplish it.
• The unwound helix, with each strand being
synthesized into a new double helix, is called the
replication fork.
33. The Enzymes of DNA Replication
• Topoisomerase
– Responsible for initiation of unwinding of DNA.
– The tension holding the helix in its coiled and
supercoiled structure is broken by nicking a single
strand of DNA.
• Helicase
– Accomplishes unwinding of the original double
strand, once supercoiling is eliminated by
topoisomerase.
– The two strands want to bind together because of
hydrogen bonding affinity for each other, so
helicase requires energy (ATP) to break the
strands apart.
34. Single-stranded Binding Proteins
• Important to maintain the stability of the
replication fork.
• Line up along unpaired DNA strans,
holding them apart
• Single-stranded DNA is very unstable,
so these proteins bind bind to it while it
remains single stranded and keep it
from being degraded.
35. Beginning: Origins of Replication
• Replication begins at specific sites called origins of
replication
• In prokaryotes, the bacterial chromosome has a
specific origin
• In eukaryotes, replication begins at many sites on
the large molecule
– 100’s of origins
• Proteins that begin replication recognize the origin
sequence
• These enzymes attach to DNA, separating the
strands, and opening a replication bubble
• The end of the replication bubble is the “Y” shaped
replication fork, where new strands of DNA elongate
36.
37. Elongation
• Elongation of the new DNA strands is catalyzed by
DNA polymerase
• Nucleotides align with complimentary bases on the
template strand, and are added by the polymerase,
one by one, to the growing chain
– DNA polymerase proceeds along a single-stranded DNA
molecule, recruiting free nucleotides to H-bond with the
complementary nucleotides on the single strand
• Forms a covalent phosphodiester bond with the
previous nucleotide of the same strand
– The energy stored in the triphosphate is used to covalently
bind each new nucleotide to the growing second strand
• Replication proceeds in both directions
40. DNA Polymerase
• There are different forms of DNA
polymerase
– DNA polymerase III is responsible for the
synthesis of new DNA strands
• DNA polymerase is actually an aggregate
of several different protein subunits, so it is
often called a holoenzyme.
• Primary job is adding nucleotides to the
growing chain
• Also has proofreading activities
41. Proofreading & Repair
• DNA polymerase proofreads each
nucleotide added against its’ template
as it is added
• Removes incorrectly paired nucleotides
& corrects
42. DNA Strands are Anti-parallel
• The sugar phosphate backbones of the 2
parent strands run in opposite directions
– “upside down” to each other
• DNA is polar
– There is a 3’ end and a 5’ end
– At the 3’ end, a OH is attached to the 3’ C of the
last deoxyribose
– At the other end a phosphate group is attached to
the 5’ C of the last nucleotide
• DNA polymerase adds nucleotides only to the
3’ end of the growing chain
– So new DNA strand elongates only in the 5’ 3”
direction
43.
44. Why 5’ 3’?
• Why can DNA polymerase only add nucleotides to
the 3’ end ?
• Needs a triphosphate to provide energy for the
bond between an added nucleotide & the growing
DNA strand.
• This triphosphate is very unstable
– can easily break into a monophosphate and an inorganic
pyrophosphate
• At the 5' end, this triphosphate can easily break
– It is not be able to attach new nucleotides to the 5' end
once the phosphate has broken off
• The 3' end only has a hydroxyl group
– As long as new nucleotide triphosphates are brought by
DNA polymerase, synthesis of a new strand continues,
no matter how long the 3' end has remained free.
45. Leading & Lagging Strands
• The new strand made by adding to the 3’ end =
leading strand
– Parent strand is 3’ 5’
– New strand is 5’ 3’
• How can DNA polymerase synthesize new copies
of the 5' 3' strand, if it can only travel in one
direction?
• To elongate in the other direction, the process must
work away from the replication fork
• The new strand formed on the 5’ 3’ parent strand
is called the lagging strand
46. Building the Lagging Strand
• DNA polymerase makes a second copy
in an overall 3’ 5’ direction
• First, it produces short segments,
called Okazaki fragments
– These are built in a 5’ –3’ direction
• Okazaki fragments are joined together
by ligase to produce the new 3’5’
lagging strand
47. Ligase
• Catalyzes the formation of a
phosphodiester bond given an
unattached adjacent 3‘ OH and 5‘
phosphate.
• This can join Okazaki fragments
• This can also fill in the unattached gap
left when an RNA primer is removed
• DNA polymerase can organize the bond
on the 5' end of the primer, but ligase is
needed to make the bond on the 3' end.
48.
49. Primers
• DNA polymerase cannot start synthesizing on
a bare single strand.
– It only adds to an existing chain
• It needs a primer with a 3'OH group on which
to attach a nucleotide.
• The start of a new chain is not DNA, but a
short RNA primer
– Only one primer is needed for the leading strand
– One primer for each Okazaki fragment on the
lagging strand
50. Primase
• Part of an aggregate of proteins called
the primeosome.
• Attaches the small RNA primer to the
single-stranded DNA which acts as a
substitute 3'OH so DNA polymerase
can begin synthesis
• This RNA primer is eventually removed
by RNase H
– the gap is filled in by DNA polymerase I.
51.
52. Ending the Strand
• DNA polymerase only adds to the 3’ end
• There is no way to complete the 5’ end of the new
strand
• A small gap would be left at the 5’ end of each new
strand
• Repeated replication would then make the strand
shorter and shorter, eventually losing genes
• Not a problem in prokaryotes, because the DNA is
circular
– There are no “ends”
53. Telomeres
• Eukaryotes have a special sequence of
repeated nucleotides at the end, called
telomeres
• Multiple repititions of a short nucleitide sequence
– Can be repeated hundreds, or thousands of times
– In humans, TTAGGG
• Do not contain genes
• Protects genes from erosion thru repeated
replication
• Precvents unfinished ends from activating DNA
monitoring & repair mechanisms
54. Telomerase
• Catalyzes lengthening of telomeres
• Includes a short RNA template with the
enzyme
• Present in immortal cell lines and in the
cells that give rise to gametes
• Not found in most somatic cells
• May account for finite life span of
tissues
55.
56. Further Proofreading & Repair
• Some errors evade initial proofreading
or occur after synthesis
• DNA can be damaged by reactive
chemicals, x-rays, UV, etc
• Cells continually monitor DNA for
mutations & repair
• Contain 100’s of repair enzymes
57. Nucleotide Excision & Repair
• A segment of DNA containing damage is cut
out by a nuclease (a DNA cutting enzyme)
• The gap is filled & closed by DNA
polymerase and ligase
• Thymine dimers
• Covalent linking of thymine bases
• Causes DNA to “buckle”
• One common problem corrected this way