logging in or signing up HistBio06 DNA Jancis Download Post to : URL : Related Presentations : Share Add to Flag Embed Email Send to Blogs and Networks Add to Channel Uploaded from authorPOINTLite Insert YouTube videos in PowerPont slides with aS Desktop Copy embed code: (To copy code, click on the text box) Embed: URL: Thumbnail: WordPress Embed Customize Embed The presentation is successfully added In Your Favorites. Views: 856 Category: Entertainment License: All Rights Reserved Like it (0) Dislike it (0) Added: October 15, 2007 This Presentation is Public Favorites: 0 Presentation Description No description available. Comments Posting comment... By: oshjen (17 month(s) ago) this presentation looks amazing and very informative pls send me a copy through e-mail..this will be agreat help in teaching my subjects Saving..... Post Reply Close Saving..... Edit Comment Close By: samudayab (36 month(s) ago) Very good presentation.. Thank You.... Samu... Saving..... Post Reply Close Saving..... Edit Comment Close Premium member Presentation Transcript Slide1: The DNA StructureThree Major Approaches: Three Major Approaches Structural (architecture of the molecules) Biochemical (interactions between cell metabolism and heredity) Informational (transfer of information, translation of information)The Discovery of DNA: The Discovery of DNA Friedrich Miescher (Swiss, 1844-1895) Intelligent from early age but very shy His father was a professor of anatomy Studied at the University of Göttingen under Ernst Felix Immanuel Hoppe-Seyler, considered the father of biochemistrySlide4: He examined used bandages obtained from a hospital caring for the wounded of the Crimean War in hope of finding something interesting He discovered a substance containing both phosphorus and nitrogen, made up of molecules that were apparently very large, in the nuclei of white blood cells found in pusSlide5: Named the substance nuclein because it seemed to come from cell nuclei. In 1874 when Miescher separated it into a protein and an acid molecule. It is now known as deoxyribonucleic acid (DNA) This substance was so unusual that Hoppe-Seyler repeated the work himself before allowing Miescher to publish the paper on the discovery Slide6: He found an excellent (and more pleasant) source of nuclear material in the sperm of the salmon The nuclei are large in any sperm cells, remarkably so in the salmon’s From these he first extracted a pure DNA In 1889 a pupil of his, the German pathologist Richard Altmann (1852- 1900) introduced the term “nucleic acid”Inborn Errors of Metabolism: Inborn Errors of Metabolism Archibald Garrod (British, 1857-1936) His father was a physician Received his medical training at St. Bartholomew's Hospital, London Slide8: The relationship between genes and proteins was first proposed by Garrod in 1908 Garrod, a prominent physician at St. Bartholomew's Hospital in London, understood both the new science of biochemistry and the emerging discipline of genetics Slide9: He studied a harmless but rare disorder in the general population but frequent in children of first-cousin marriages: alkaptonuria A patient with this disorder produces urine that when exposed to air turns distinctively dark, because these people lack the enzyme found in normal individuals who are able to convert the reddening agent, alkapton, to another substanceSlide11: Following Mendel’s laws, Garrod concluded that alkaptonuria is a congenital disorder, not the result of a bacterial infection as was commonly thought Slide12: He observed that inherited diseases reflect a patient's inability to make a particular enzyme, which he referred to as “inborn errors of metabolism” Garrod's hypothesis was ahead of its time In the 1930s George Beadle and Boris Ephrussi linked the synthesis of pigments to eye color in fruit flies to specific mutations 1910-1925: Development of Cytological Genetics: 1910-1925: Development of Cytological Genetics Cytogenetics is the study of chromosomes and chromosome abnormalitiesX-ray Crystallography: X-ray Crystallography X-ray crystallography is a technique that exploits the fact that X-rays are diffracted by crystals It is not an imaging technique: X-rays have the proper wavelength to be scattered by the electron cloud of an atom of comparable size Based on the diffraction pattern obtained from X-ray scattering off the periodic assembly of molecules or atoms in the crystal, the electron density can be reconstructed Slide18: In 1912 Max von Laue reported the diffraction of X rays by a crystal (for which he received a Nobel Prize in physics in 1914)Slide19: For progress in pharmaceutical research the structure of complex organic molecules has to be understood By studying the chemical reactions that a compound and its degradation products could enter into with other compounds of known structure, chemists were able to deduce the structures of many complex organic moleculesSlide20: X-ray crystallography allowed to determine molecular structure from the compound itself. In this method, structural information is obtained by mathematical analysis of the intensity of X rays scattered (or diffracted) from parallel planes in a crystal, as recorded photographically or by an electronic detector In 1915 a unique father-son team, William Henry Bragg (1862–1942) and his son, William Lawrence Bragg (1890–1971), won the Nobel Prize in physics for their seminal roles in X-ray crystallography William Lawrence Bragg (left) and William Henry Bragg: William Lawrence Bragg (left) and William Henry BraggSlide22: William Henry's original interest was in what diffraction showed about the nature of X-rays, and he was a skilled experimenter and designer of instruments William Lawrence was more concerned with what X-rays revealed about the crystalline state, and he possessed a powerful ability to conceptualize physical problems and express them mathematically Until electronic computers were developed during World War II, these calculations were incredibly laborious “Transforming Principle”: “Transforming Principle” In 1928, Frederick Griffith (British, conducted an experiment that showed the transformation of living cells by a “transforming principle”, which was later discovered to be DNA Tetranucleotide Hypothesis: Tetranucleotide Hypothesis Phoebus Levene (Russian-American, 1869-1940) He worked with Albrecht Kossel and Emil Fischer, the nucleic acid and protein experts at the turn of the 20th. century Slide26: He conducted experiments that in 1931 suggested that the four components of DNA occur in approximately equal ratios He suggested the possibly that DNA was made of a repeating tetramer If so, the implication was that the structure of DNA was too simple and too regular to contribute to genetic variation: attention thereafter focused on protein as the probable hereditary substance One gene-One enzyme Hypothesis: One gene-One enzyme Hypothesis This proposal of the one gene-one enzyme hypothesis was developed by the Americans George Beadle (1903-1989) and George Wells Tatum (1909-1975) in 1938Slide29: Beadle and Tatum hypothesized that if there really was a one-to-one relationship between genes and specific enzymes, it should be possible to create genetic mutants that are unable to carry out specific enzymatic reactions They exposed spores of Neurospora crassa (a bread mold) to X-rays or UV radiation and studied the resulting mutations The mutant molds had a variety of special nutritional needs. Unlike their normal counterparts, they could not live without the addition of particular vitamins or amino acids to their food Normal Neurospora requires only one vitamin (biotin), but mutants were created that also required thiamine or cholineSlide30: Genetic analysis showed that each mutant differed from the original, normal type by only one gene Biochemical studies showed that the mutants seemed to be blocked at certain steps in the normal metabolic pathways Their cells contained large accumulations of the substance synthesized just prior to the blockage point, just as Garrod's patients had accumulated alkaptonSlide32: As Beadle and Tatum had predicted, they created single gene mutations that incapacitated specific enzymes, so that the molds with these mutations required an external supply of the substance that the enzyme normally produced, and the substance that the enzyme normally used, piled up in the cell These results confirmed their one gene-one enzyme hypothesis They received the 1958 Nobel Prize in Physiology and Medicine “Transforming Principle” identified as DNA: “Transforming Principle” identified as DNA In the early 1940s Oswald T. Avery and Maclyn McCarty, a colleague at the Rockefeller Institute Hospital, began concentrating on the problem of pneumococcal transformationSlide34: Avery's work focused first on purifying the transforming substance. Using refined versions of Colin M. MacLeod's preparation techniques, Avery and McCarty isolated biologically active “transforming principle” from samples of pneumococciSlide35: Then attention turned to its chemical analysis. Proteases (enzymes that deactivate proteins) and lipases (enzymes which destroy lipids) were found not to inactivate the transforming principle Avery concluded that the substance was essentially protein and lipid free. He found that the substance was rich in nucleic acids, but ribonuclease, an enzyme that destroys ribonucleic acid (RNA), did not inactivate the substance eitherSlide36: It was not a carbohydrate like the polysaccharide capsular material, as carbohydrates are not precipitated by alcohol (the “transforming principle” was) Alcohol was, however, a well-known precipitant for deoxyribonucleic acid (DNA). Further, the transforming substance had a high molecular weight, as did DNA, and gave a strong reaction to the Dische test for DNA. Thus, the transforming substance, producing permanent, heritable change in an organism, was DNA What is Life? : What is Life? By the end of WWII, many physicists, saddened by the prospects of atomic bombs, turned their attention toward biology One of them was Erwin Schrödinger (Austrian 1887-1961) Slide39: Schrödinger published in 1945 a book titled What is Life? that planted the idea for searching “the secret of life” This marked the beginning of reductionism in biologyBase Ratios: Base Ratios In 1951 Edwin Chagraff (1905-2002) noted “regularities” in the base composition of nucleic acids, which reflected the existence in all DNA preparations of certain structural principles In particular, for duplex DNA he identified the constant proportion of bases: %A = %T and %C = %G X-ray Crystallography Applied to Nucleic Acids: X-ray Crystallography Applied to Nucleic Acids Between 1940's and 1950's: Maurice Wilkins (1916-) and Rosalind Franklin (1920-1958) worked on X-ray/DNAThe Hershey-Chase Experiment: The Hershey-Chase Experiment The Americans Alfred Hershey (1908-1997) and Martha Chase (1930-2003) published in 1952 a now classical paper Slide43: They showed DNA to be the carrier of genetic information in virus reproduction, working with T2 phage They demonstrated by labeling the capsid proteins and nucleic acid of bacteriophage T2 with different radioactive isotopes that only the DNA of the phage had to enter the cell for virus replication to occurEnter Watson and Crick: Enter Watson and Crick James Watson (American, 1928-) Francis Crick (British, 1916-)What did Watson and Crick Really Contribute?: What did Watson and Crick Really Contribute? Major original breaks by W & C were the A-T and C-G having the same molecular shape That lead to understanding constancy for the diameter of the DNA molecule, the use of Chargaff’s ratios The application of model building which lead to the complementary model You do not have the permission to view this presentation. In order to view it, please contact the author of the presentation.
HistBio06 DNA Jancis Download Post to : URL : Related Presentations : Share Add to Flag Embed Email Send to Blogs and Networks Add to Channel Uploaded from authorPOINTLite Insert YouTube videos in PowerPont slides with aS Desktop Copy embed code: (To copy code, click on the text box) Embed: URL: Thumbnail: WordPress Embed Customize Embed The presentation is successfully added In Your Favorites. Views: 856 Category: Entertainment License: All Rights Reserved Like it (0) Dislike it (0) Added: October 15, 2007 This Presentation is Public Favorites: 0 Presentation Description No description available. Comments Posting comment... By: oshjen (17 month(s) ago) this presentation looks amazing and very informative pls send me a copy through e-mail..this will be agreat help in teaching my subjects Saving..... Post Reply Close Saving..... Edit Comment Close By: samudayab (36 month(s) ago) Very good presentation.. Thank You.... Samu... Saving..... Post Reply Close Saving..... Edit Comment Close Premium member Presentation Transcript Slide1: The DNA StructureThree Major Approaches: Three Major Approaches Structural (architecture of the molecules) Biochemical (interactions between cell metabolism and heredity) Informational (transfer of information, translation of information)The Discovery of DNA: The Discovery of DNA Friedrich Miescher (Swiss, 1844-1895) Intelligent from early age but very shy His father was a professor of anatomy Studied at the University of Göttingen under Ernst Felix Immanuel Hoppe-Seyler, considered the father of biochemistrySlide4: He examined used bandages obtained from a hospital caring for the wounded of the Crimean War in hope of finding something interesting He discovered a substance containing both phosphorus and nitrogen, made up of molecules that were apparently very large, in the nuclei of white blood cells found in pusSlide5: Named the substance nuclein because it seemed to come from cell nuclei. In 1874 when Miescher separated it into a protein and an acid molecule. It is now known as deoxyribonucleic acid (DNA) This substance was so unusual that Hoppe-Seyler repeated the work himself before allowing Miescher to publish the paper on the discovery Slide6: He found an excellent (and more pleasant) source of nuclear material in the sperm of the salmon The nuclei are large in any sperm cells, remarkably so in the salmon’s From these he first extracted a pure DNA In 1889 a pupil of his, the German pathologist Richard Altmann (1852- 1900) introduced the term “nucleic acid”Inborn Errors of Metabolism: Inborn Errors of Metabolism Archibald Garrod (British, 1857-1936) His father was a physician Received his medical training at St. Bartholomew's Hospital, London Slide8: The relationship between genes and proteins was first proposed by Garrod in 1908 Garrod, a prominent physician at St. Bartholomew's Hospital in London, understood both the new science of biochemistry and the emerging discipline of genetics Slide9: He studied a harmless but rare disorder in the general population but frequent in children of first-cousin marriages: alkaptonuria A patient with this disorder produces urine that when exposed to air turns distinctively dark, because these people lack the enzyme found in normal individuals who are able to convert the reddening agent, alkapton, to another substanceSlide11: Following Mendel’s laws, Garrod concluded that alkaptonuria is a congenital disorder, not the result of a bacterial infection as was commonly thought Slide12: He observed that inherited diseases reflect a patient's inability to make a particular enzyme, which he referred to as “inborn errors of metabolism” Garrod's hypothesis was ahead of its time In the 1930s George Beadle and Boris Ephrussi linked the synthesis of pigments to eye color in fruit flies to specific mutations 1910-1925: Development of Cytological Genetics: 1910-1925: Development of Cytological Genetics Cytogenetics is the study of chromosomes and chromosome abnormalitiesX-ray Crystallography: X-ray Crystallography X-ray crystallography is a technique that exploits the fact that X-rays are diffracted by crystals It is not an imaging technique: X-rays have the proper wavelength to be scattered by the electron cloud of an atom of comparable size Based on the diffraction pattern obtained from X-ray scattering off the periodic assembly of molecules or atoms in the crystal, the electron density can be reconstructed Slide18: In 1912 Max von Laue reported the diffraction of X rays by a crystal (for which he received a Nobel Prize in physics in 1914)Slide19: For progress in pharmaceutical research the structure of complex organic molecules has to be understood By studying the chemical reactions that a compound and its degradation products could enter into with other compounds of known structure, chemists were able to deduce the structures of many complex organic moleculesSlide20: X-ray crystallography allowed to determine molecular structure from the compound itself. In this method, structural information is obtained by mathematical analysis of the intensity of X rays scattered (or diffracted) from parallel planes in a crystal, as recorded photographically or by an electronic detector In 1915 a unique father-son team, William Henry Bragg (1862–1942) and his son, William Lawrence Bragg (1890–1971), won the Nobel Prize in physics for their seminal roles in X-ray crystallography William Lawrence Bragg (left) and William Henry Bragg: William Lawrence Bragg (left) and William Henry BraggSlide22: William Henry's original interest was in what diffraction showed about the nature of X-rays, and he was a skilled experimenter and designer of instruments William Lawrence was more concerned with what X-rays revealed about the crystalline state, and he possessed a powerful ability to conceptualize physical problems and express them mathematically Until electronic computers were developed during World War II, these calculations were incredibly laborious “Transforming Principle”: “Transforming Principle” In 1928, Frederick Griffith (British, conducted an experiment that showed the transformation of living cells by a “transforming principle”, which was later discovered to be DNA Tetranucleotide Hypothesis: Tetranucleotide Hypothesis Phoebus Levene (Russian-American, 1869-1940) He worked with Albrecht Kossel and Emil Fischer, the nucleic acid and protein experts at the turn of the 20th. century Slide26: He conducted experiments that in 1931 suggested that the four components of DNA occur in approximately equal ratios He suggested the possibly that DNA was made of a repeating tetramer If so, the implication was that the structure of DNA was too simple and too regular to contribute to genetic variation: attention thereafter focused on protein as the probable hereditary substance One gene-One enzyme Hypothesis: One gene-One enzyme Hypothesis This proposal of the one gene-one enzyme hypothesis was developed by the Americans George Beadle (1903-1989) and George Wells Tatum (1909-1975) in 1938Slide29: Beadle and Tatum hypothesized that if there really was a one-to-one relationship between genes and specific enzymes, it should be possible to create genetic mutants that are unable to carry out specific enzymatic reactions They exposed spores of Neurospora crassa (a bread mold) to X-rays or UV radiation and studied the resulting mutations The mutant molds had a variety of special nutritional needs. Unlike their normal counterparts, they could not live without the addition of particular vitamins or amino acids to their food Normal Neurospora requires only one vitamin (biotin), but mutants were created that also required thiamine or cholineSlide30: Genetic analysis showed that each mutant differed from the original, normal type by only one gene Biochemical studies showed that the mutants seemed to be blocked at certain steps in the normal metabolic pathways Their cells contained large accumulations of the substance synthesized just prior to the blockage point, just as Garrod's patients had accumulated alkaptonSlide32: As Beadle and Tatum had predicted, they created single gene mutations that incapacitated specific enzymes, so that the molds with these mutations required an external supply of the substance that the enzyme normally produced, and the substance that the enzyme normally used, piled up in the cell These results confirmed their one gene-one enzyme hypothesis They received the 1958 Nobel Prize in Physiology and Medicine “Transforming Principle” identified as DNA: “Transforming Principle” identified as DNA In the early 1940s Oswald T. Avery and Maclyn McCarty, a colleague at the Rockefeller Institute Hospital, began concentrating on the problem of pneumococcal transformationSlide34: Avery's work focused first on purifying the transforming substance. Using refined versions of Colin M. MacLeod's preparation techniques, Avery and McCarty isolated biologically active “transforming principle” from samples of pneumococciSlide35: Then attention turned to its chemical analysis. Proteases (enzymes that deactivate proteins) and lipases (enzymes which destroy lipids) were found not to inactivate the transforming principle Avery concluded that the substance was essentially protein and lipid free. He found that the substance was rich in nucleic acids, but ribonuclease, an enzyme that destroys ribonucleic acid (RNA), did not inactivate the substance eitherSlide36: It was not a carbohydrate like the polysaccharide capsular material, as carbohydrates are not precipitated by alcohol (the “transforming principle” was) Alcohol was, however, a well-known precipitant for deoxyribonucleic acid (DNA). Further, the transforming substance had a high molecular weight, as did DNA, and gave a strong reaction to the Dische test for DNA. Thus, the transforming substance, producing permanent, heritable change in an organism, was DNA What is Life? : What is Life? By the end of WWII, many physicists, saddened by the prospects of atomic bombs, turned their attention toward biology One of them was Erwin Schrödinger (Austrian 1887-1961) Slide39: Schrödinger published in 1945 a book titled What is Life? that planted the idea for searching “the secret of life” This marked the beginning of reductionism in biologyBase Ratios: Base Ratios In 1951 Edwin Chagraff (1905-2002) noted “regularities” in the base composition of nucleic acids, which reflected the existence in all DNA preparations of certain structural principles In particular, for duplex DNA he identified the constant proportion of bases: %A = %T and %C = %G X-ray Crystallography Applied to Nucleic Acids: X-ray Crystallography Applied to Nucleic Acids Between 1940's and 1950's: Maurice Wilkins (1916-) and Rosalind Franklin (1920-1958) worked on X-ray/DNAThe Hershey-Chase Experiment: The Hershey-Chase Experiment The Americans Alfred Hershey (1908-1997) and Martha Chase (1930-2003) published in 1952 a now classical paper Slide43: They showed DNA to be the carrier of genetic information in virus reproduction, working with T2 phage They demonstrated by labeling the capsid proteins and nucleic acid of bacteriophage T2 with different radioactive isotopes that only the DNA of the phage had to enter the cell for virus replication to occurEnter Watson and Crick: Enter Watson and Crick James Watson (American, 1928-) Francis Crick (British, 1916-)What did Watson and Crick Really Contribute?: What did Watson and Crick Really Contribute? Major original breaks by W & C were the A-T and C-G having the same molecular shape That lead to understanding constancy for the diameter of the DNA molecule, the use of Chargaff’s ratios The application of model building which lead to the complementary model