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37 Cards in this Set
- Front
- Back
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What did Friedrich Miescher do? |
Looked at the physiology of lymph cells. Began to study pus cells as these were more abundant Isolated small quantities of the nuclei of the white blood cells. From these nuclei he isolated a substance that he called NUCLEIN |
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What did Richard Altman do? |
Obtained the first protein-free samples of a substance he called NUCLEIC ACID. Biological samples were being stained with newly invented chemical dyes (William Perkin). Cell nuclei were seen to contain rod-like segments which were called CHROMOSOMES |
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What did Levene and Jacobs do? |
Studied the molecular structure of nucleic acids. Deduced that there were PENTOSE (RNA) and THYMUS NUCLEIC ACIDS (DNA). The pentose nucleic acid hydrolyses readily with aqueous pyridine The thymus nucleic acid is much more stable. The pentose nucleic acid was made up of ADENOSINE, CYTIDINE, GUANOSINE and URIDINE. Their structures had the wrong enolic forms (-OH in wrong place) for guanosine and uridine. They demonstrated the presence of 2-deoxy-D-ribose. |
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What did Griffith do? |
Identified the difference between virulent and non-virulent forms of a pneumonia bacterium. There is a protective sugar coat on the virulent form. Showed that the non-virulent form could be permanently and hereditably transformed into the virulent form by treatment with an extract of theheat-killed virulent form. |
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What did Takahashi do? |
It was believed that the four heterocyclic bases were present in equal amounts in the structure of DNA. This lead to the TETRANUCLEOTIDE HYPOTHESISfor the structure of DNA. |
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What were the flaws in Takahashi's structure of DNA? |
1) The molecular weight was far too low. DNA was known to have a molecular weight of at least 200,000. 2) There was no possibility if information storage in the regular structure. |
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What did Astbury do? |
Deduced that DNA had repeating units 3.4 Å (0.34 nm) along the fibre axis. These units seemed to correspond to a succession of a flat nucleotides standing out, perpendicular to the long axis of the molecule He suggested that the nucleotide bases are stacked on top of each other "like a pile of pennies". |
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What did Avery do? |
Avery set out to discover the molecular basis for the changes that Griffith had observed in 1923. He was able to show that “DNA is responsible for the transforming activity” of the bacterium. |
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What did Masson Gulland do? |
Outlined a revolutionary proposal that the nucleotides were HYDROGEN BONDED to each other. Unfortunately, he was using the incorrect enol-tautomers ofguanosine and uridine |
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What did Chargaff do? |
Was able to show conclusively that the ratio of the four nucleotides present in DNA does not correspond to 1:1:1:1. More importantly he showed that the ratio of A:T was always 1 and the ratio of C:G was always 1. This lead to the formulation of CHARGAFF’S RULES. |
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What is the Beer-Lambert Law |
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What did Todd do? |
Established the configuration for the mono-nucleosides present in DNA by chemical synthesis. Showed that the phosphate was on the 5’-hydroxylg group, confirming the that DNA was linked via the 5’ and the 3’hydroxyls. He also showed that the bases were linked to the sugars with the b-configuration and that the oligomer (polymer with few repeating units) was connected via phosphodiester linkages. |
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What did Pauling do? |
Proposed a helical structure for DNA. Three strands linked together via hydrogen bonds betweenthe PHOSPHATES. Phosphates on the INSIDE of the helix BASES on the OUTSIDE |
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What did Watson and Crick do? |
Proposed a structure for DNA BASESon the INSIDE and the PHOSPHATES on the OUTSIDE. Knew that the DNA changed its conformation depending upon thewater content of the sample. Reasoned that the groups that would interact with the water (i.e. the hydrophilic phosphates) would have to be solvent (water) exposed. Strands had to run inopposite directions in order to explain the local C2 symmetry of the molecule. The hydrogen bondingof the bases, was solved by using the keto- rather than the enol-tautomers of T and G. Allowed for self complimentarity , and the possibility of information storage, copying and transfer of the genetic information. The true nature of Chargaff’s Rule was thus resolved. |
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What is the was the original structure of DNA? |
A right handed double helix |
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What is the structure of Z-DNA? |
left handed double helix grooves of equal size bases stacked almost perpendicular star shaped gap narrowest helix |
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What is the structure of A-DNA? |
Bases inclined relative to helix axis (not perpendicular) Similar size grooves Shallow grooves Bigger gap Wider helix diameter |
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What is the structure of B-DNA? |
There is a clear major and minor groove Bases stack at 90 degrees to helix axis Small gap Narrower helix diameter |
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What do the different structures say about DNA? |
It is conformationally flexible
(under different conditions) |
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What is the 'central dogma' of life?
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DNA replication (DNA -> DNA) using DNA polymerase
Transcription (DNA->RNA) using RNA polymerase Translation (RNA->protein) using a ribosome |
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What is tRNA? |
transfer RNA
the link between RNA and proteins |
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What are the 20 amino acids? |
alanine arginine asparagine aspartic acid cysteine glutamine glutamic acid glycine histidine isoleucine leucine lysine methionine phenylalanine proline serine threonine tryptophan tyrosine valine |
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What are the letters for each amino acid? |
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What are amino acids? |
Compounds containing an amine and a carboxylic acid functional group |
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What bonds form between cysteine? |
Disulphide bonds
The basis of the perm |
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Why are amino acids important? |
They are the building blocks for proteins Proteins play a vital role in all cellular processes |
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What are some examples of proteins? |
Structural Proteins Enzymes Transport Proteins Contractile Proteins Protective Proteins Hormones Toxins |
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What other roles do amino acids have? |
Food (e.g. aspartame) Neurotransmitters (serotonin, dopamine) Taurine (used to make bile, inhibits neurotransmission) Drugs (antibiotics, antihypertensive, anti-inflammatory, anti-obesity) |
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What are essential amino acids? |
ones that the body cannot synthesise, so must be obtained through food |
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What are the essential amino acids? |
Arginine, Histidine, Isoleucine, Leucine, Tryptophan, Lysine, Methionine, Phenylalanine, Threonine, Valine (Any Help In Learning These Little Molecules Proves Truly Valuable) |
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Which amino acids contain alcohol groups? |
Threonine, serine and tyrosine |
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Which amino acids are basic? |
Histidine, arginine and lysine |
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Which amino acids are acidic? |
Aspartic acid and glutamic acid |
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Which amino acids are polar? |
Tryptophan, asparagine and glutamine |
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Which amino acids make proteins? |
Glycine, alanine, valine, isoleucine, leucine, phenylalanine and proline |
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Which amino acids contain sulphur? |
Cysteine and methionine |
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What amino acid is the 'START' codon? |
Methionine |
