Chargaff found a pattern in the ratios of nucleotide bases. In the DNA of each species he studied, the number of adenines approximately equaled the number of thymine, and the number of guanines approximately equaled the number of cytosine. In human DNA, the four bases are present in these percentages: A=30.9% and T=29.4%; G=19.9% and C=19.8%. The A=T and G=C equalities (Chargaff's rules) helped Watson and Crick to discover the structure of DNA.
Rosalind Franklin used X-ray diffraction to understand the physical structure of the DNA molecule. Franklin's famous "photograph 51" revealed the helical structure of DNA. This picture of DNA that had been crystallized under moist conditions shows a fuzzy X in the middle of the molecule, a pattern indicating a helical structure.
James Watson saw that the adenine-thymine bond was exactly as long as the cytosine-guanine bond. If the bases were paired in this way, each rung of the twisted ladder in the helix would be of equal length, and the sugar-phosphate backbone would be smooth.
James Watson and Francis Crick presented the structure of the DNA-helix, the molecule that carries genetic information from one generation to the other.
Chargaff's rules state that DNA from any cell of all organisms should have a 1:1 ratio (base Pair Rule)of pyrimidine and purine bases and, more specifically, that the amount of guanine is equal to cytosine and the amount of adenine is equal to thymine. This pattern is found in both strands of the DNA. The first rule holds that a double-stranded DNA molecule globally has percentage base pair equality: %A = %T and %G = %C.The rigorous validation of the rule constitutes the basis of Watson-Crick pairs in the DNA double helix. The second rule holds that both %A ~ %T and %G ~ %C are valid for each of the two DNA strands. This describes only a global feature of the base composition in a single DNA strand.
Franklin understood the physical structure of DNA using X ray diffraction. She used a photograph called "photograph 51" which revealed the helix structure of DNA. The picture was crystalized and showed a fuzzy X indicating the pattern of the helix.
Watson and Crick figured out that the guanine cytosine and thymine adenine bonds were the same length, and because they were paired this way, they would be part of the helical shape. They also presented the structure as helix, and that DNA carried genetic information to and fro.
In the 1940s, Chargaff studied samples of DNA taken from different sources and found the amount of adenine(A) was almost equal to the amount of thymine(T), and the amount of guanine (G) was almost equal to the amount of cytosine (C). The discovery of A=T and G=C became known as Chargaff's rule. Chargaff's rules state that DNA from any cell of all organisms should have a 1:1 ratio (base Pair Rule)of pyrimidine and purine bases and, more specifically, that the amount of guanine is equal to cytosine and the amount of adenine is equal to thymine. This pattern is found in both strands of the DNA. Rosalind Franklin worked with Maurice Wilkins. They used a technique called X-ray crystallography, in which a crystal is exposed to X-rays in order to produced a diffraction pattern. If the crystal is pure enough and the diffraction pattern is acquired very carefully, it is possible to reconstruct the positions of the atoms in the molecules that comprise the basic unit of the crystal called the unit cell. By the early 1950s, scientists were just learning how to do this for biological molecules as complex as DNA. Progress in discerning the structure of DNA was blocked because the A and B forms of DNA were mixed together in preparations, yielding impure crystals and "muddy" diffraction patterns that were near impossible to interpret.
After discovering the existence of the A and B forms of DNA, Rosalind Franklin also succeeded in developing an ingenious and laborious method to separate the two forms, providing the first DNA crystals pure enough to yield interpretable diffraction patterns. She then went on to obtain excellent X-ray diffraction patterns of crystalline B-form DNA and, using a combination of crystallographic theory and chemical reasoning, discovered important basic facts about its structure. She discovered that the sugar-phosphate backbone of DNA lies on the outside of the molecule, not the inside as was previously thought. She discovered the helical structure of DNA has two strands, not three as proposed in competing theories.
Watson and Crick showed that each strand of the DNA molecule was a template for the other. During cell division the two strands separate and on each strand a new "other half" is built, just like the one before. This way DNA can reproduce itself without changing its structure -- except for occasional errors, or mutations.
Chargaff's rules state that DNA from any cell of all organisms should have a 1:1 ratio of pyrimidine and purine bases and, more specifically, that the amount of guanine is equal to cytosine and the amount of adenine is equal to thymine. This pattern is found in both strands of the DNA. They were discovered by Austrian chemist Erwin Chargaff. The first rule holds that a double-stranded DNA molecule globally has percentage base pair equality: %A = %T and %G = %C. The exact validation of the rule constitutes the basis of Watson-Crick pairs in the DNA double helix. The second rule holds that both %A ~ %T and %G ~ %C are valid for each of the two DNA strands. This describes only a global feature of the base composition in a single DNA strand. The second of Chargaff's rules is that the composition of DNA varies from one species to another; in particular in the relative amounts of A, G, T, and C bases. Such evidence of molecular diversity, which had been presumed absent from DNA, made DNA a more credible candidate for the genetic material than protein.
Rosalind Franklin's most famous piece of evidence was the image called “Photo 51.” It depicts an X-ray diffraction of DNA. Taken in 1951, the image eventually led to the conclusion that DNA was composed of a double helix. Such a structure consists of two helices running in parallel.
James D. Watson and Francis Crick were the two co-discoverers of the structure of DNA in 1953. They used x-ray diffraction data collected by Rosalind Franklin and proposed the double helix or spiral staircase structure of the DNA molecule. Their article, Molecular Structure of Nucleic Acids: A Structure for Deoxyribose Nucleic Acid, is celebrated for its treatment of the B form of DNA (B-DNA), and as the source of Watson-Crick base pairing of nucleotides.
Chargaff's rule says that every DNA in each cell of any organism should have a one to one ratio . The ratio being G=C and A=T . G standing for guanine. C standing for cytosine. A standing for adenine. T standing for thymine .
Watson and Crick discover the structure of the DNA by using x-ray Diffraction found by Franklin. They also discovered that the DNA structure is a double helix.
Rosalind Franklin is best known for her X-ray diffraction of DNA . Her images of DNA helped Watson and crick discover the double helix structure of DNA. Franklins accomplishments are often overlooked
Chargaff, Rosalind Franklin, and Watson and Crick were scientists that had a major role in the discovery of the structure of DNA.
Chargaff was the scientist that figured out that the structure of DNA has organisms that create a 1:1 ratio. That ratio is Guanine = Cytosine and Adenine = Thymine. When he found this ratio he noticed that the ratio were quite equal to each other in percentages. The exact percentages were A=30.9% and T=29.4%; G=19.9% and C=19.8%. These percentages showed Chargaff that A is paired with T and G is paired with C.
Rosalind Franklin created an X-ray diffraction. This invention showed a structure of a DNA and the way it looks in our body. They also discovered that the structure of DNA is a double helix.
Watson and Crick were also the discovers of DNA being a double helix because when Rosalind Franklin discovered the double helix, the people did not believe her. They also discovered how the DNA splits in two parts. Those parts are A-DNA and B-DNA.
Chargaff found a pattern in the ratios of nucleotide bases. In the DNA of each species Chargaff studied, the number of adenines very closely almost equaled the number of thymine, and the number of guanines approximately equaled the number of cytosine. In human DNA, the four bases are present in these percentages: A=30.9% and T=29.4%; G=19.9% and C=19.8%. The A=T and G=C equalities (Chargaff's rules) helped Watson and Crick to discover the structure of DNA.
Rosalind Franklin used X-ray diffraction to understand the physical structure of the DNA molecule. Franklin's famous "photograph 51" revealed the helical structure of DNA. This picture of DNA that had been crystallized under moist conditions shows a fuzzy X in the middle of the molecule, a pattern indicating a helical structure.Chargaff found a pattern in the ratios of nucleotide bases. In the DNA of each species he studied, the number of adenines approximately equaled the number of thymine, and the number of guanines approximately equaled the number of cytosine. In human DNA, the four bases are present in these percentages: A=30.9% and T=29.4%; G=19.9% and C=19.8%. The A=T and G=C equalities (Chargaff's rules) helped Watson and Crick to discover the structure of DNA.
Rosalind Franklin(Zaven's mom) used X-ray diffraction to understand the physical structure of the DNA molecule. Franklin's famous "photograph 51" revealed the helical structure of DNA. This picture of DNA that had been crystallized under moist conditions shows a fuzzy X in the middle of the molecule, a pattern indicating a helix-likel structure.
James Watson saw that the adenine-thymine bond was exactly as long as the cytosine-guanine bond. If the bases were paired in this way, each rung of the twisted ladder in the helix would be of equal length, and the sugar-phosphate backbone would be smooth.
James Watson and Francis Crick presented the structure of the DNA-helix, the molecule that carries genetic information from one generation to the other.
Chargaff’s rule states that DNA should have a pyrimidine and purine base with a 1:1 ratio. He further states that the amount of guanine in a cell is equal to the amount of cytosine and the amount of adenine is equal to the amount of thymine. Chargaff’s first rule states that %A=%T and the %G=%C in a double-stranded DNA molecule. Chargaff’s second rule states that both %A ~ %T and %G ~ %C are valid for each of the two DNA strands.
Rosalind Franklin helped to make advancement towards the structure of the DNA. Rosalind Franklin was a crystallographer. She took an image of DNA; more specifically she took an X-ray diffraction image of the DNA. The diffraction pattern showed that DNA is helical, likely to be a double helix with antiparallel strands, and had a phosphate backbone on the outside.
Watson and Crick used the X-ray diffraction images taken by Rosalind Franklin to confirm that the DNA is in fact a double-helix.
Chargaff discovered that the percentages of guanine and cytosine are almost equal in any sample of DNA he observed. Also the same thing was true for adenine and thymine. The discovery of A=T and G=C became known as Chargaff's rules.
In the early 1950s British scientist Rosalind Franklin took a X-ray diffraction photograph of DNA. The X shaped pattern in the center of the photograph indicated that the structure of the DNA is helical. Franklin's X-ray pattern did not reveal the structure of the DNA. But it did carry important clues.
In 1953 Watson and Crick used the clues from Franklin's photograph to conclude that DNA is a double-helix.
Chargaff was the person who discovered the fact that guanine and cytosine had very close percentages in almost every DNA sample he had observed. By continuing the process, he saw the same thing for adenine and thymine. The percentages exactly were: A=30.9% and T=29.4%; G=19.9% and C=19.8%.So technically, A was equal to T, and G was equal to C. That became Chargaff's rule.
Later came Rosalind Franklin. She took an X-ray diffraction photograph of DNA. A pattern was formed in an X formation in the center of the photograph. This showed that DNA is helical. This did not reveal the structure of the DNA, but it helped with supporting us with important clues.
Finally came Watson and Crick. They used Franklins photographs, which showed how the X-ray displayed a X shaped pattern, to conclude the fact that DNA is a double-helix structure. This is how we know today that the DNA is a double helix with the nucleobases in between.
Chargaff’s rule states that DNA should have a pyrimidine and purine base with a 1:1 ratio. He further states that the amount of guanine in a cell is equal to the amount of cytosine and the amount of adenine is equal to the amount of thymine. Chargaff’s first rule states that %A=%T and the %G=%C in a double-stranded DNA molecule. Chargaff’s second rule states that both %A ~ %T and %G ~ %C are valid for each of the two DNA strands. Franklin understood the physical structure of DNA using X ray diffraction. She used a photograph called "photograph 51" which revealed the helix structure of DNA. The picture was crystalized and showed a fuzzy X indicating the pattern of the helix. James D. Watson and Francis Crick were the two co-discoverers of the structure of DNA in 1953. They used x-ray diffraction data collected by Rosalind Franklin and proposed the double helix or spiral staircase structure of the DNA molecule. Their article, Molecular Structure of Nucleic Acids: A Structure for Deoxyribose Nucleic Acid, is celebrated for its treatment of the B form of DNA (B-DNA), and as the source of Watson-Crick base pairing of nucleotides.
Chargaff found a pattern in the ratios of nucleotide bases. In the DNA of each species he studied, the number of adenines approximately equaled the number of thymine, and the number of guanines approximately equaled the number of cytosine. In human DNA, the four bases are present in these percentages: A=30.9% and T=29.4%; G=19.9% and C=19.8%. The A=T and G=C equalities (Chargaff's rules) helped Watson and Crick to discover the structure of DNA.
ReplyDeleteRosalind Franklin used X-ray diffraction to understand the physical structure of the DNA molecule. Franklin's famous "photograph 51" revealed the helical structure of DNA. This picture of DNA that had been crystallized under moist conditions shows a fuzzy X in the middle of the molecule, a pattern indicating a helical structure.
James Watson saw that the adenine-thymine bond was exactly as long as the cytosine-guanine bond. If the bases were paired in this way, each rung of the twisted ladder in the helix would be of equal length, and the sugar-phosphate backbone would be smooth.
James Watson and Francis Crick presented the structure of the DNA-helix, the molecule that carries genetic information from one generation to the other.
Chargaff's rules state that DNA from any cell of all organisms should have a 1:1 ratio (base Pair Rule)of pyrimidine and purine bases and, more specifically, that the amount of guanine is equal to cytosine and the amount of adenine is equal to thymine. This pattern is found in both strands of the DNA. The first rule holds that a double-stranded DNA molecule globally has percentage base pair equality: %A = %T and %G = %C.The rigorous validation of the rule constitutes the basis of Watson-Crick pairs in the DNA double helix. The second rule holds that both %A ~ %T and %G ~ %C are valid for each of the two DNA strands. This describes only a global feature of the base composition in a single DNA strand.
ReplyDeleteFranklin understood the physical structure of DNA using X ray diffraction. She used a photograph called "photograph 51" which revealed the helix structure of DNA. The picture was crystalized and showed a fuzzy X indicating the pattern of the helix.
Watson and Crick figured out that the guanine cytosine and thymine adenine bonds were the same length, and because they were paired this way, they would be part of the helical shape. They also presented the structure as helix, and that DNA carried genetic information to and fro.
In the 1940s, Chargaff studied samples of DNA taken from different sources and found the amount of adenine(A) was almost equal to the amount of thymine(T), and the amount of guanine (G) was almost equal to the amount of cytosine (C). The discovery of A=T and G=C became known as Chargaff's rule. Chargaff's rules state that DNA from any cell of all organisms should have a 1:1 ratio (base Pair Rule)of pyrimidine and purine bases and, more specifically, that the amount of guanine is equal to cytosine and the amount of adenine is equal to thymine. This pattern is found in both strands of the DNA.
ReplyDeleteRosalind Franklin worked with Maurice Wilkins. They used a technique called X-ray crystallography, in which a crystal is exposed to X-rays in order to produced a diffraction pattern. If the crystal is pure enough and the diffraction pattern is acquired very carefully, it is possible to reconstruct the positions of the atoms in the molecules that comprise the basic unit of the crystal called the unit cell. By the early 1950s, scientists were just learning how to do this for biological molecules as complex as DNA. Progress in discerning the structure of DNA was blocked because the A and B forms of DNA were mixed together in preparations, yielding impure crystals and "muddy" diffraction patterns that were near impossible to interpret.
After discovering the existence of the A and B forms of DNA, Rosalind Franklin also succeeded in developing an ingenious and laborious method to separate the two forms, providing the first DNA crystals pure enough to yield interpretable diffraction patterns. She then went on to obtain excellent X-ray diffraction patterns of crystalline B-form DNA and, using a combination of crystallographic theory and chemical reasoning, discovered important basic facts about its structure. She discovered that the sugar-phosphate backbone of DNA lies on the outside of the molecule, not the inside as was previously thought. She discovered the helical structure of DNA has two strands, not three as proposed in competing theories.
Watson and Crick showed that each strand of the DNA molecule was a template for the other. During cell division the two strands separate and on each strand a new "other half" is built, just like the one before. This way DNA can reproduce itself without changing its structure -- except for occasional errors, or mutations.
^ Lia
ReplyDeleteChargaff's rules state that DNA from any cell of all organisms should have a 1:1 ratio of pyrimidine and purine bases and, more specifically, that the amount of guanine is equal to cytosine and the amount of adenine is equal to thymine. This pattern is found in both strands of the DNA. They were discovered by Austrian chemist Erwin Chargaff. The first rule holds that a double-stranded DNA molecule globally has percentage base pair equality: %A = %T and %G = %C. The exact validation of the rule constitutes the basis of Watson-Crick pairs in the DNA double helix. The second rule holds that both %A ~ %T and %G ~ %C are valid for each of the two DNA strands. This describes only a global feature of the base composition in a single DNA strand. The second of Chargaff's rules is that the composition of DNA varies from one species to another; in particular in the relative amounts of A, G, T, and C bases. Such evidence of molecular diversity, which had been presumed absent from DNA, made DNA a more credible candidate for the genetic material than protein.
ReplyDeleteRosalind Franklin's most famous piece of evidence was the image called “Photo 51.” It depicts an X-ray diffraction of DNA. Taken in 1951, the image eventually led to the conclusion that DNA was composed of a double helix. Such a structure consists of two helices running in parallel.
James D. Watson and Francis Crick were the two co-discoverers of the structure of DNA in 1953. They used x-ray diffraction data collected by Rosalind Franklin and proposed the double helix or spiral staircase structure of the DNA molecule. Their article, Molecular Structure of Nucleic Acids: A Structure for Deoxyribose Nucleic Acid, is celebrated for its treatment of the B form of DNA (B-DNA), and as the source of Watson-Crick base pairing of nucleotides.
Chargaff's rule says that every DNA in each cell of any organism should have a one to one ratio . The ratio being G=C and A=T . G standing for guanine. C standing for cytosine. A standing for adenine. T standing for thymine .
ReplyDeleteWatson and Crick discover the structure of the DNA by using x-ray Diffraction found by Franklin. They also discovered that the DNA structure is a double helix.
Rosalind Franklin is best known for her X-ray diffraction of DNA . Her images of DNA helped Watson and crick discover the double helix structure of DNA. Franklins accomplishments are often overlooked
Chargaff, Rosalind Franklin, and Watson and Crick were scientists that had a major role in the discovery of the structure of DNA.
ReplyDeleteChargaff was the scientist that figured out that the structure of DNA has organisms that create a 1:1 ratio. That ratio is Guanine = Cytosine and Adenine = Thymine. When he found this ratio he noticed that the ratio were quite equal to each other in percentages. The exact percentages were A=30.9% and T=29.4%; G=19.9% and C=19.8%. These percentages showed Chargaff that A is paired with T and G is paired with C.
Rosalind Franklin created an X-ray diffraction. This invention showed a structure of a DNA and the way it looks in our body. They also discovered that the structure of DNA is a double helix.
Watson and Crick were also the discovers of DNA being a double helix because when Rosalind Franklin discovered the double helix, the people did not believe her. They also discovered how the DNA splits in two parts. Those parts are A-DNA and B-DNA.
Chargaff found a pattern in the ratios of nucleotide bases. In the DNA of each species Chargaff studied, the number of adenines very closely almost equaled the number of thymine, and the number of guanines approximately equaled the number of cytosine. In human DNA, the four bases are present in these percentages: A=30.9% and T=29.4%; G=19.9% and C=19.8%. The A=T and G=C equalities (Chargaff's rules) helped Watson and Crick to discover the structure of DNA.
ReplyDeleteRosalind Franklin used X-ray diffraction to understand the physical structure of the DNA molecule. Franklin's famous "photograph 51" revealed the helical structure of DNA. This picture of DNA that had been crystallized under moist conditions shows a fuzzy X in the middle of the molecule, a pattern indicating a helical structure.Chargaff found a pattern in the ratios of nucleotide bases. In the DNA of each species he studied, the number of adenines approximately equaled the number of thymine, and the number of guanines approximately equaled the number of cytosine. In human DNA, the four bases are present in these percentages: A=30.9% and T=29.4%; G=19.9% and C=19.8%. The A=T and G=C equalities (Chargaff's rules) helped Watson and Crick to discover the structure of DNA.
Rosalind Franklin(Zaven's mom) used X-ray diffraction to understand the physical structure of the DNA molecule. Franklin's famous "photograph 51" revealed the helical structure of DNA. This picture of DNA that had been crystallized under moist conditions shows a fuzzy X in the middle of the molecule, a pattern indicating a helix-likel structure.
James Watson saw that the adenine-thymine bond was exactly as long as the cytosine-guanine bond. If the bases were paired in this way, each rung of the twisted ladder in the helix would be of equal length, and the sugar-phosphate backbone would be smooth.
James Watson and Francis Crick presented the structure of the DNA-helix, the molecule that carries genetic information from one generation to the other.
Chargaff’s rule states that DNA should have a pyrimidine and purine base with a 1:1 ratio. He further states that the amount of guanine in a cell is equal to the amount of cytosine and the amount of adenine is equal to the amount of thymine. Chargaff’s first rule states that %A=%T and the %G=%C in a double-stranded DNA molecule. Chargaff’s second rule states that both %A ~ %T and %G ~ %C are valid for each of the two DNA strands.
ReplyDeleteRosalind Franklin helped to make advancement towards the structure of the DNA. Rosalind Franklin was a crystallographer. She took an image of DNA; more specifically she took an X-ray diffraction image of the DNA. The diffraction pattern showed that DNA is helical, likely to be a double helix with antiparallel strands, and had a phosphate backbone on the outside.
Watson and Crick used the X-ray diffraction images taken by Rosalind Franklin to confirm that the DNA is in fact a double-helix.
Chargaff discovered that the percentages of guanine and cytosine are almost equal in any sample of DNA he observed. Also the same thing was true for adenine and thymine. The discovery of A=T and G=C became known as Chargaff's rules.
ReplyDeleteIn the early 1950s British scientist Rosalind Franklin took a X-ray diffraction photograph of DNA. The X shaped pattern in the center of the photograph indicated that the structure of the DNA is helical. Franklin's X-ray pattern did not reveal the structure of the DNA. But it did carry important clues.
In 1953 Watson and Crick used the clues from Franklin's photograph to conclude that DNA is a double-helix.
Chargaff was the person who discovered the fact that guanine and cytosine had very close percentages in almost every DNA sample he had observed. By continuing the process, he saw the same thing for adenine and thymine. The percentages exactly were: A=30.9% and T=29.4%; G=19.9% and C=19.8%.So technically, A was equal to T, and G was equal to C. That became Chargaff's rule.
ReplyDeleteLater came Rosalind Franklin. She took an X-ray diffraction photograph of DNA. A pattern was formed in an X formation in the center of the photograph. This showed that DNA is helical. This did not reveal the structure of the DNA, but it helped with supporting us with important clues.
Finally came Watson and Crick. They used Franklins photographs, which showed how the X-ray displayed a X shaped pattern, to conclude the fact that DNA is a double-helix structure. This is how we know today that the DNA is a double helix with the nucleobases in between.
Chargaff’s rule states that DNA should have a pyrimidine and purine base with a 1:1 ratio. He further states that the amount of guanine in a cell is equal to the amount of cytosine and the amount of adenine is equal to the amount of thymine. Chargaff’s first rule states that %A=%T and the %G=%C in a double-stranded DNA molecule. Chargaff’s second rule states that both %A ~ %T and %G ~ %C are valid for each of the two DNA strands.
ReplyDeleteFranklin understood the physical structure of DNA using X ray diffraction. She used a photograph called "photograph 51" which revealed the helix structure of DNA. The picture was crystalized and showed a fuzzy X indicating the pattern of the helix.
James D. Watson and Francis Crick were the two co-discoverers of the structure of DNA in 1953. They used x-ray diffraction data collected by Rosalind Franklin and proposed the double helix or spiral staircase structure of the DNA molecule. Their article, Molecular Structure of Nucleic Acids: A Structure for Deoxyribose Nucleic Acid, is celebrated for its treatment of the B form of DNA (B-DNA), and as the source of Watson-Crick base pairing of nucleotides.