Nucleic acid carries genetic material- part-2
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Hershey and Chase conducted an experiment in 1952 using bacteriophages (viruses that infect bacteria) to determine whether DNA or protein is the genetic material. They labeled phage particles with either radioactive phosphorus or sulfur and allowed them to infect E. coli bacteria. They found that the radioactive phosphorus from the DNA entered the bacterial cells and was incorporated into the next generation of phages, while the radioactive sulfur from the protein coat did not. This established that DNA, not protein, carries the genetic information required for reproduction.
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Nucleic acid carries genetic material part-1
Nucleic acid carries genetic material (Griffith’s Hershey & Chase and Avery- Macleod-McCarty Experiment)
Introdution of dna as genetic material
Frederick Griffith discovered a "transforming principle" in 1928 when live S strain bacteria developed in mice injected with a mixture of heat-killed S strain and live R strain bacteria. Later, Avery, MacLeod and McCarty determined that this transforming principle was DNA through experiments treating bacteria with enzymes that broke down DNA, RNA, and proteins. In 1952, Hershey and Chase conclusively showed through experiments with radioactive labeling of bacteriophages that DNA is the genetic material transferred from viruses to bacteria during infection, not proteins.
Nucleic acid carries genetic material
Nucleic acid carries genetic material (Griffith’s Hershey & Chase Experiment, Avery- Macleod-McCarty Experiment, Hershey- Chase Experiment and Fraenkel-Conrat’s Experiment)
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The document summarizes several key experiments that helped establish DNA as the genetic material:
- Griffith's experiment showed a "transforming principle" in dead bacteria could change live bacteria;
- Avery, McCarty and MacLeod purified and identified this principle as DNA;
- Hershey and Chase showed that DNA, not protein, was injected by viruses into infected bacteria;
- Fraenkel-Conrat's experiment proved that RNA could also act as genetic material.
Rosalind Franklin's X-ray crystallography work provided evidence of DNA's double-helix structure, though she did not receive full credit due to gender biases of the time.
DNA as genetic material
Frederick Griffith's experiments in 1928 showed that a transforming principle could pass from dead virulent pneumonia bacteria to live avirulent bacteria, making them deadly. Oswald Avery later purified this principle and through chemical and enzymatic tests determined it was DNA, not protein as previously believed. In 1952, Hershey and Chase used radioactive labeling to track the entry of DNA and proteins from bacteriophages into infected bacteria. They found that only the labeled DNA entered the bacterial cells, providing definitive evidence that DNA is the genetic material.
DNA as genetic material
1) Griffith discovered a "transforming principle" that allowed non-virulent bacteria to become virulent after exposure to heat-killed virulent bacteria.
2) Avery, MacLeod, and McCarty determined that the transforming principle was DNA through experiments treating components with DNAses, RNAses, and proteases.
3) Hershey and Chase provided definitive evidence that DNA is the genetic material through experiments using bacteriophages containing radioactive DNA or protein to infect bacteria, showing that only DNA was transferred.
Evidences to prove DNA as genetic material
Frederick Griffith conducted experiments in 1928 using two strains of Streptococcus pneumoniae bacteria - R strain bacteria that were harmless, and S strain bacteria that were virulent and caused pneumonia. When Griffith combined heat-killed S bacteria with live R bacteria and injected them into mice, the mice unexpectedly developed pneumonia and died, with their blood containing live S bacteria. Griffith concluded the R bacteria must have taken on a "transforming principle" from the S bacteria that allowed them to become virulent. In 1944, Avery, McCarty and MacLeod purified this principle from heat-killed S cells and determined through various tests that it was DNA. However, debate continued until 1952 when Hershey and Chase conclusively identified DNA
DNA as a Genetic Material
DNA as a Genetic Material - Dr. P. Saranraj, Assistant Professor, Department of Microbiology, Sacred Heart College (Autonomous), Tirupattur, Vellore District, Tamil Nadu, India.
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Nucleic acid carries genetic material part-1
Nucleic acid carries genetic material (Griffith’s Hershey & Chase and Avery- Macleod-McCarty Experiment)
Introdution of dna as genetic material
Frederick Griffith discovered a "transforming principle" in 1928 when live S strain bacteria developed in mice injected with a mixture of heat-killed S strain and live R strain bacteria. Later, Avery, MacLeod and McCarty determined that this transforming principle was DNA through experiments treating bacteria with enzymes that broke down DNA, RNA, and proteins. In 1952, Hershey and Chase conclusively showed through experiments with radioactive labeling of bacteriophages that DNA is the genetic material transferred from viruses to bacteria during infection, not proteins.
Nucleic acid carries genetic material
Nucleic acid carries genetic material (Griffith’s Hershey & Chase Experiment, Avery- Macleod-McCarty Experiment, Hershey- Chase Experiment and Fraenkel-Conrat’s Experiment)
DNA as genetic material
The document summarizes several key experiments that helped establish DNA as the genetic material:
- Griffith's experiment showed a "transforming principle" in dead bacteria could change live bacteria;
- Avery, McCarty and MacLeod purified and identified this principle as DNA;
- Hershey and Chase showed that DNA, not protein, was injected by viruses into infected bacteria;
- Fraenkel-Conrat's experiment proved that RNA could also act as genetic material.
Rosalind Franklin's X-ray crystallography work provided evidence of DNA's double-helix structure, though she did not receive full credit due to gender biases of the time.
DNA as genetic material
Frederick Griffith's experiments in 1928 showed that a transforming principle could pass from dead virulent pneumonia bacteria to live avirulent bacteria, making them deadly. Oswald Avery later purified this principle and through chemical and enzymatic tests determined it was DNA, not protein as previously believed. In 1952, Hershey and Chase used radioactive labeling to track the entry of DNA and proteins from bacteriophages into infected bacteria. They found that only the labeled DNA entered the bacterial cells, providing definitive evidence that DNA is the genetic material.
DNA as genetic material
1) Griffith discovered a "transforming principle" that allowed non-virulent bacteria to become virulent after exposure to heat-killed virulent bacteria.
2) Avery, MacLeod, and McCarty determined that the transforming principle was DNA through experiments treating components with DNAses, RNAses, and proteases.
3) Hershey and Chase provided definitive evidence that DNA is the genetic material through experiments using bacteriophages containing radioactive DNA or protein to infect bacteria, showing that only DNA was transferred.
Evidences to prove DNA as genetic material
Frederick Griffith conducted experiments in 1928 using two strains of Streptococcus pneumoniae bacteria - R strain bacteria that were harmless, and S strain bacteria that were virulent and caused pneumonia. When Griffith combined heat-killed S bacteria with live R bacteria and injected them into mice, the mice unexpectedly developed pneumonia and died, with their blood containing live S bacteria. Griffith concluded the R bacteria must have taken on a "transforming principle" from the S bacteria that allowed them to become virulent. In 1944, Avery, McCarty and MacLeod purified this principle from heat-killed S cells and determined through various tests that it was DNA. However, debate continued until 1952 when Hershey and Chase conclusively identified DNA
DNA as a Genetic Material
DNA as a Genetic Material - Dr. P. Saranraj, Assistant Professor, Department of Microbiology, Sacred Heart College (Autonomous), Tirupattur, Vellore District, Tamil Nadu, India.
Transforming principle..
Frederick Griffith discovered the principle of transformation through experiments with Streptococcus pneumoniae bacteria. He found that heat-killed virulent S-strain bacteria could make non-virulent R-strain bacteria transform and become virulent. Later, Oswald Avery, Colin MacLeod and Maclyn McCarty discovered that DNA alone from S bacteria could transform R bacteria. Alfred Hershey and Martha Chase provided conclusive evidence that DNA, not protein, is the genetic material through experiments using bacteriophages infecting E. coli bacteria. They found that radioactive DNA, but not protein, passed from the bacteriophages into the bacterial cells.
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Gregor Mendel discovered genes in 1866. Friedrich Miescher isolated DNA in 1868. In the 1940s, Avery, MacLeod and McCarty conducted experiments showing that DNA is the genetic material. They found that only DNA from one type of pneumonia bacteria could transform another type of the bacteria. Similarly, Hershey and Chase showed in 1952 that when viruses infect bacteria, only the viral DNA, not proteins, enters the host cell, proving DNA is the genetic material in viruses too. These experiments established DNA as the universal genetic material.
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The document discusses evidence that DNA is the genetic material:
1) Griffith's experiment showed bacterial transformation from non-virulent to virulent strains upon uptake of DNA from heat-killed bacteria.
2) Avery, MacLeod and McCarty's experiment showed transformation only occurred when DNA was present, as DNase treatment prevented transformation.
3) Hershey and Chase's experiment using radioactive labels showed that only bacteriophage DNA, not protein, entered bacteria to produce new phage particles.
Discovery of DNA as genetic material
Three key experiments helped resolve the question of whether DNA or protein served as the genetic material. Griffith's transformation experiment showed that heat-killed bacteria could transform live bacteria, indicating a heritable factor. Avery, MacLeod and McCarty's experiments showed that the transforming principle was destroyed by DNAase, showing it was DNA. Hershey and Chase used radioactively labeled bacteriophage to infect bacteria, finding that only the label in the phage's DNA entered the bacterial cells, demonstrating that DNA rather than protein transfers genetic information. These experiments established DNA as the genetic material.
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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
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Genetic engineering involves the direct manipulation of genes through techniques like gene cloning and transfer. Key tools include restriction enzymes, plasmids, and the creation of DNA libraries which allow genes to be identified and isolated. Techniques like PCR, gel electrophoresis, and blotting allow analysis and study of DNA, RNA, and proteins. Restriction mapping uses restriction enzymes to cut DNA into fragments which can then be used to identify genes and construct maps of DNA sequences.
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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
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DNA as genetic material.pptx
The document discusses the hierarchy of knowledge in biochemistry, molecular biology, and biotechnology. It begins by explaining how biochemistry initially focused on proteins and enzymes, while molecular biology focused on nucleic acids and the structure and function of genes. Biotechnology emerged due to advances in molecular biology and recombinant DNA techniques. The key areas of each discipline are defined, including how molecular biology studies how organisms are made from simple molecules at the cellular level.
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details of all the steps and conclusion done by Griffith in his experiment and further research by Avery, Macleod, McCarty on the same.
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1) Griffith's experiment showed bacterial transformation from non-virulent to virulent strains upon uptake of DNA from heat-killed bacteria.
2) Avery, MacLeod and McCarty's experiment showed transformation only occurred when DNA was present, as DNase treatment prevented transformation.
3) Hershey and Chase's experiment using radioactive labels showed that only bacteriophage DNA, not protein, entered bacteria to produce new phage particles.
Discovery of DNA as genetic material
Three key experiments helped resolve the question of whether DNA or protein served as the genetic material. Griffith's transformation experiment showed that heat-killed bacteria could transform live bacteria, indicating a heritable factor. Avery, MacLeod and McCarty's experiments showed that the transforming principle was destroyed by DNAase, showing it was DNA. Hershey and Chase used radioactively labeled bacteriophage to infect bacteria, finding that only the label in the phage's DNA entered the bacterial cells, demonstrating that DNA rather than protein transfers genetic information. These experiments established DNA as the genetic material.
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Hershey and chase experiment-the blender experiment
It was performed by Alfred Hershey and Martha Chase in 1952.
It led to confirmation of the genetic nature of DNA came from an experiment with E.coli phage T2.
for more details visit our youtube channel.
The hershey chase experiment
The Hershey-Chase experiment proved that DNA is the genetic material transferred from viruses to bacteria. They labeled the DNA of some bacteriophages with radioactive phosphorus and the protein of others with radioactive sulfur. When the labeled phages infected bacteria, only the bacteria infected with phages containing radioactive DNA became radioactive, showing the DNA entered the bacteria while the labeled proteins did not. This provided evidence that DNA rather than protein carries genetic information.
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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
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This study examined how aging affects AICD gene expression in zebrafish. The researchers analyzed AICD RNA levels in the gut tissue of 5-, 11-, and 13-month old zebrafish using qPCR and found no significant difference, indicating that AICD expression is not altered during this period. They also found that changing the zebrafish housing conditions did not affect AICD levels. Future work will involve analyzing AICD and Tcf3a gene expression in 20-month old zebrafish to further study the effects of aging, requiring the isolation of B-cells from the zebrafish.
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Bacterial conjugation is a form of horizontal gene transfer that requires physical contact between bacteria. During conjugation, genetic material is transferred from a "donor" bacteria to a "recipient" bacteria via a pilus. The F plasmid contains genes necessary for conjugation and is present in the donor cell. Conjugation results in the donor cell transferring a segment of its DNA to the recipient cell, integrating it into the recipient's genome and allowing for genetic recombination between the two bacterial cells. This transfer of antibiotic resistance and other genes between bacteria through conjugation contributes to the spread of multidrug resistance.
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Genetic engineering
Genetic engineering involves the direct manipulation of genes through techniques like gene cloning and transfer. Key tools include restriction enzymes, plasmids, and the creation of DNA libraries which allow genes to be identified and isolated. Techniques like PCR, gel electrophoresis, and blotting allow analysis and study of DNA, RNA, and proteins. Restriction mapping uses restriction enzymes to cut DNA into fragments which can then be used to identify genes and construct maps of DNA sequences.
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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.
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Fredrick Griffith discovered that heat-killed pneumonia bacteria could transform harmless bacteria into deadly disease-causing bacteria when mixed together and injected into mice. This led researchers like Oswald Avery to determine that DNA was the molecule responsible for transformation. Further experiments by Hershey and Chase showed that the genetic material of viruses that infect bacteria is DNA. Together, these findings established DNA as the genetic material that gets passed from parents to offspring and controls inheritance.
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1. In the early 1950s, scientists including Rosalind Franklin, Maurice Wilkins, James Watson, and Francis Crick were working to determine the structure of DNA. Franklin's X-ray crystallography photos provided key evidence of a double helix structure.
2. In 1953, Watson and Crick published a paper proposing that DNA consists of two intertwined strands coiled around each other in the shape of a double helix, with bases on the inside pairing according to Chargaff's rules. This successfully described DNA's structure and how it can replicate.
3. Their model built upon prior discoveries including Griffith's transformation experiments, Avery's finding that DNA is the genetic material, Chargaff
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The document summarizes key experiments that helped discover that DNA is the genetic material:
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- Avery, McCarty, and MacLeod's experiment showed that DNA is the transforming factor by destroying other molecules.
- Hershey and Chase's experiment using radioactively labeled viruses demonstrated that DNA enters host bacteria cells during infection.
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HistoryofDNA.ppt
The document summarizes key experiments that helped discover that DNA is the genetic material:
- Griffith's experiment showed that DNA carries genetic information that can transform bacteria from harmless to deadly.
- Avery, McCarty, and MacLeod's experiment showed that DNA is the transforming factor by destroying other molecules.
- Hershey and Chase's experiment using radioactively labeled viruses demonstrated that DNA enters the host bacteria cell during infection.
- The structure of DNA was discovered in 1953 by Watson and Crick using data from prior scientists like Chargaff and Franklin. They built a double-helix model that explained DNA replication. The Meselson-Stahl experiment supported the semi-conservative model of replication.
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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.
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Frederick Griffith conducted experiments in 1928 using two strains of Streptococcus pneumoniae bacteria - R strain and S strain. The R strain was non-virulent while the S strain was virulent. Griffith found that when he injected a mixture of heat-killed S bacteria and live R bacteria into mice, the mice became sick, showing that something from the S bacteria had transformed the R bacteria. Later experiments by Avery, McCarty, and MacLeod in 1944 identified this transforming substance as DNA. Further experiments by Hershey and Chase in the 1950s using bacteriophage viruses provided more evidence that DNA, not protein, was the genetic material being transferred from viruses to bacteria to cause infection.
DNA as genetic material
The genetic material of a cell refers to materials like DNA, RNA, and proteins that play a fundamental role in determining cell structure and heredity. Early experiments suggested DNA, RNA, or proteins could be the genetic material. However, later experiments provided strong evidence that DNA is the primary genetic material:
1. Frederick Griffith's experiments in 1928 with pneumococcus bacteria showed that genetic information could be transferred between bacteria.
2. In 1944, Avery, Macleod, and McCarty proved that the transforming principle in pneumococcus was DNA, not RNA or proteins.
3. In 1952, Hershey and Chase's experiment with bacteriophage T2 virus showed that only DNA entered bacterial cells
research done to prove DNA a genetic material
1. Genetic inheritance refers to the transmission of traits from parents to offspring through genetic material. DNA was identified as the genetic material based on its ability to stably replicate and mutate over generations.
2. Experiments in the early 20th century identified DNA as the substance within chromosomes that determines inheritance. Key experiments included Avery, MacLeod and McCarty demonstrating transformation is caused by DNA.
3. The structure of DNA was elucidated in 1953 when Watson and Crick proposed the double helix model based on X-ray crystallography data from Franklin and Chargaff's rules regarding nucleotide base ratios. This established DNA as the molecule of heredity.
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1) Bacterial transformation experiments by Griffith and Avery's team showed that DNA is the genetic material that can be transferred between bacteria to alter traits like disease-causing ability.
2) Hershey and Chase's experiments with bacteriophages demonstrated that viral DNA, not the protein coat, enters bacterial cells to transmit the viral genes.
3) DNA functions to store, copy, and transmit genetic information from parent to daughter cells and between generations through its molecular structure and role in heredity.
1663966397774_SANI.pptx
Hershey and Chase conducted an experiment in 1952 using radioactive phosphorus and sulfur to label the DNA and proteins of bacteriophage viruses. They found that when the viruses infected bacteria, only the bacteria exposed to viruses containing radioactive DNA became radioactive, not those exposed to viruses with radioactive proteins. This led to the conclusion that DNA, not protein, is the genetic material transferred from viruses to bacteria during infection.
DNA Structure and Function..pptx
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).
DNA.pptx
The document summarizes key evidence and discoveries that led to the acceptance of DNA as the genetic material:
1) Chargaff's rule showed equal amounts of certain DNA base pairs and hinted at DNA's structure.
2) Franklin and Wilkins' X-ray crystallography provided clues to Watson and Crick, whose 1953 double helix model explained DNA's structure.
3) Griffith's experiment showed one type of bacteria could transform another through some "transforming principle," later shown by Avery, MacLeod and McCarty to be DNA. Hershey and Chase's experiment confirmed DNA is the genetic material of viruses.
Similar to Nucleic acid carries genetic material- part-2 (20)
MOLECULAR BASIS OF INHERITANCE -DNA AS GENETIC MATERIAL
MOLECULAR BASIS OF INHERITANCE -DNA AS GENETIC MATERIAL
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Rolling Circle Replication
Rolling circle replication is a form of DNA replication that occurs in circular DNA like plasmids, bacteriophages, and viroids. It involves five key steps: 1) a circular double-stranded DNA template is nicked at a single origin site, 2) the exposed 3' end is used to initiate replication of the leading strand while displacing the 5' end, 3) the displaced single-stranded DNA acts as the lagging strand and is replicated through Okazaki fragments, 4) both the displaced and unnicked strands are fully replicated, and 5) the displaced strand is rejoined to form a circular DNA product.
S1 Nuclease Mapping
S1 nuclease mapping is a laboratory technique used to locate the 5' end of an RNA transcript within a mixture by using the S1 nuclease. The S1 nuclease is an endonuclease that degrades single-stranded DNA and RNA but does not degrade double-stranded DNA or RNA-DNA hybrids. In S1 mapping, a transcript is hybridized to a DNA template and treated with S1 nuclease, which degrades any unhybridized RNA. This allows mapping the 5' end of the transcript to the DNA template. S1 nuclease mapping can determine the exact locations of start and end points of transcription and any splice points within transcripts.
Ramachandran Plot
The document summarizes the Ramachandran plot, which is a plot of the phi and psi dihedral angles of amino acid residues in protein structures. It was originally developed in 1963 to show possible conformations of phi and psi angles for amino acid residues and the empirical distribution of these angles observed in protein structures. The plot takes advantage of the circular nature of dihedral angles, with edges wrapping from right to left and bottom to top. It can be used to determine amino acid preferences and how the presence or absence of groups like a methylene group at C-beta affect the angles.
Ascent of sap (plant physiology)
The document discusses the mechanism of ascent of sap in plants. It describes several experiments that were conducted to study this process, including the eosin experiment and ringing experiment. It also discusses and rejects several proposed theories for the ascent of sap, such as the root pressure theory, vital theories, and imbibition theory. The document concludes that the transpiration pull and cohesive properties of water theory provides the most convincing explanation for how water moves upwards in plants. According to this theory, transpiration from leaves creates tension in the xylem vessels that pulls water upwards through the plant.
Transport in plant (Plant physiology)
Transport in plants occurs over long distances through the vascular system or within cells. Materials move in and out of cells by diffusion, facilitated diffusion, or active transport. Diffusion is a passive, slow movement along a concentration gradient without energy expenditure. Facilitated diffusion uses helper proteins like porins and aquaporins to selectively transport hydrophilic substances without expending energy. Active transport moves substances against a concentration gradient faster than passive transport by utilizing ATP as an energy source.
Methods of illustrating evolutionary relationship
Phylogenetic trees illustrate evolutionary relationships between individuals or species. There are several methods to construct phylogenetic trees, including distance-matrix methods like Neighbor Joining and UPGMA, as well as Maximum Parsimony, Maximum Likelihood, and Bayesian Inference. These methods analyze genetic distances and sequences to determine which individuals or species share a common evolutionary ancestor based on their similarities and differences. Accurately depicting evolutionary relationships is important for fields like medicine to discover new treatments from closely-related species.
Co-evolution of angiosperms and animals
The document discusses several examples of coevolution between species:
1. Predator-prey relationships like between predators and their prey lead to an evolutionary arms race as each evolves adaptations to hunt or avoid being caught.
2. Herbivores and the plants they eat also coevolve, as seen with lodgepole pine cones adapting differently depending on whether squirrels or crossbills are present.
3. Acacia ants and acacia plants have a mutualistic relationship where the ants protect the plants and the plants provide food and shelter for the ants.
4. Flowering plants and their pollinators like bees, birds and insects have coevolved mutual adaptations - flowers attract
Angiosperms
This document summarizes key aspects of angiosperms including their evolution, life cycle, and the field of systematic botany. It discusses how angiosperms evolved diversified forms and efficient reproduction mechanisms. Their life cycle involves an alternation between a dominant sporophyte generation and a reduced parasitic gametophyte generation. Systematic botany aims to classify and name all plant species based on their morphology and relationships, which is important for fields like agriculture, forestry, and ecology.
Operational taxonomic unit (OTUs)
An operational taxonomic unit (OTU) is a pragmatic definition used to group closely related organisms or unknown microbes based on DNA sequence similarity. OTUs cluster sequences of a marker gene, like 16S rRNA for prokaryotes, according to a similarity threshold chosen by the researcher, usually 97%. This operational definition allows the study and classification of microbes lacking traditional taxonomy and serves as a proxy for "species" when analyzing sequence datasets.
Numerical taxonomy
Numerical taxonomy refers to the application of mathematical and computational methods to analyze taxonomic data and evaluate the similarities between organisms. It involves assigning numerical values to characterize similarities between organisms based on many descriptive characters. The taxa are then organized based on their calculated affinities. Numerical taxonomy aims to provide more objective and data-driven classifications compared to traditional taxonomy.
Data mining
Cluster analysis is an unsupervised machine learning technique used to group similar objects together. It partitions data into clusters where objects within a cluster are as similar as possible to each other, and as dissimilar as possible to objects in other clusters. There are several clustering methods including partitioning, hierarchical, density-based, grid-based, and model-based. Clustering is widely used in applications such as market segmentation, document classification, and fraud detection.
Cladistic
Cladistics is a biological classification system that groups organisms based on shared traits and evolutionary relationships. It aims to trace ancestry back to common ancestors by constructing phylogenetic trees based on morphological and molecular data. Key terms in cladistics include plesiomorphy (ancestral traits), apomorphy (derived traits that define groups), and homoplasy (traits that evolved separately in different groups). Together, analysis of character states helps determine evolutionary relationships between taxa.
Functional aspects of ecosystem
This document discusses energy flow and nutrient cycling in ecosystems. It can be summarized as follows:
1. Energy from the sun enters ecosystems through photosynthesis, where it is converted to chemical energy in plants. This energy then passes through food chains to consumers, with some energy lost as heat at each trophic level.
2. Nutrients cycle through ecosystems, moving between biotic and abiotic components. Major nutrient cycles include carbon, nitrogen, and phosphorus, which cycle globally or locally between organisms, soils, water, and the atmosphere.
3. Energy and matter transfer with low efficiencies between trophic levels, with around 10% of energy typically transferred between each level according to Lindeman's law
Cot curve
Cot value and Cot Curve analysis is a technique for measuring DNA complexity based on renaturation kinetics. DNA is denatured and allowed to reanneal, with larger DNA taking longer. Cot value accounts for DNA concentration, time, and buffer effects, representing repetitive sequences - lower Cot means more repeats. Examples show bacteria have nearly all single-copy DNA, while mouse has varying proportions of single-copy, middle repetitive, and highly repetitive sequences. Cot curve analysis provides information on genome size, complexity, and proportions of sequence types.
Semiconservative DNA replication
DNA replicates through a process called semiconservative replication, where each parental DNA strand serves as a template to produce two identical daughter double helices, each with one parental and one new strand. The Meselson-Stahl experiment demonstrated this by growing E. coli in heavy nitrogen, then transferring to light nitrogen and analyzing DNA density over generations, finding bands matching semiconservative replication but not other models like conservative or dispersive replication.
Various model of DNA replication
1. There are four main models of DNA replication: rolling circle replication, theta replication, bidirectional replication of linear DNA, and telomere replication.
2. Rolling circle replication involves nicking circular DNA and using one strand as a template to produce multiple copies of the original circular DNA.
3. Theta replication occurs in prokaryotes and involves unwinding circular DNA at an origin of replication and replicating bi-directionally to form a theta-shaped structure.
4. Bidirectional replication of linear DNA involves unwinding DNA at origins of replication and using leading and lagging strand synthesis to replicate in both directions until the ends of the linear genome are reached.
Replication of DNA
DNA replication is the process by which a cell makes an identical copy of its DNA. It begins at specific locations in the genome called origins of replication. Enzymes such as helicase unwind and separate the double helix, while DNA polymerase adds complementary nucleotides to each strand to synthesize new daughter strands. The two resulting DNA molecules are identical to the original. Replication occurs through three coordinated steps - initiation, elongation, and termination. Initiation involves binding of proteins to origins of replication to form complexes. Elongation is catalyzed by DNA polymerase adding nucleotides to growing strands. There are two mechanisms for elongation - continuous synthesis of the leading strand and discontinuous synthesis of the lagging strand in fragments called Okazaki fragments.
Semiconservative replication
DNA replicates through a process called semiconservative replication, where each parental DNA strand serves as a template to produce two identical daughter double helices, each with one parental and one new strand. The Meselson-Stahl experiment demonstrated this by growing E. coli in heavy nitrogen, then transferring to light nitrogen and analyzing DNA density over generations, finding bands matching semiconservative replication.
Telomere replication
Telomeres are repetitive non-coding sequences at the ends of chromosomes that protect genes from being deleted during DNA replication. In humans, the telomere sequence is TTAGGG repeated 100 to 1000 times. With each cell division, some telomeric sequences are lost but this does not initially harm the cell. However, telomeres cannot be replicated indefinitely and will eventually be completely lost without a mechanism to maintain their length. The enzyme telomerase was discovered to attach to chromosome ends and uses its internal RNA template to add telomeric repeats to the 3' end of DNA strands, allowing chromosome ends to be fully replicated.
DNA replication
This document summarizes DNA replication in eukaryotic cells. It begins with an overview of DNA replication, including that it occurs during S phase and produces two identical DNA molecules from one original. It then describes the process of initiation, elongation, and termination of DNA replication. Initiation involves unwinding of DNA and formation of replication forks. Elongation involves continuous synthesis of the leading strand and discontinuous synthesis of the Okazaki fragments on the lagging strand. The document discusses several models of replication, including rolling circle replication, theta replication in prokaryotes, and replication of linear and telomeric DNA. It highlights key aspects like semiconservative replication being shown by Meselson-Stahl experiments. In
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Nucleic acid carries genetic material- part-2
- 1. Nucleic Acid- Carries genetic material Part-2 Hershey- Chase Experiment Dr. Emasushan Minj Assistant Professor Department of Botany
- 2. Introduction • Hershey-chase experiment was conducted in 1952, by Alfred Hershey & Martha Chase using Phage and identified DNA to be the genetic material. • A phage is a virus that infects bacteria. • It consists of a protein coat that encloses the dsDNA. • Since phage consist only of nucleic acid surrounded by protein, it is easy to determine whether the protein or the nucleic acid is the genetic material.
- 3. Experiment- • Radioactive isotopes of sulfur and phosphorus such as 35S and 32P were used. • T2- bacteriophage and the bacterium Escherichia coli were taken for the experiment. • The phages were labeled with radioactive isotopes 35S and 32P and infect the bacterium growing in culture medium. • Further to identify the material infected into the cell by phages attached to the bacterial wall.
- 5. * E. coli was infected by 32P labeled DNA phage. 32P entered and next generation of phages that burst from the infected bacterium results significant amount of 32P label. *E. coli was infected by 35S labeled protein coat phage. There was no radioactive 35S in the next generation of phage. *Experiment proved that genetic material in DNA not the protein. • Hershey shared the 1969 Nobel Prize in Physiology or Medicine for his discoveries concerning the genetic structure of virus.
- 6. Thank you