Carbohydrates and nucleic acids Chapters 24, 25

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Carbohydrates and nucleic acidsChapters 24, 25

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Outline 1. Classification of carbohydrates 2.
Stereochemistry of open monosaccharides 3. Cyclic
forms of monosaccharides 4. Base-catalyzed
isomerisation of monosaccharides 5.
Glycosides 6. Reactions of monosaccharides 7.
Synthesis of monosaccharides 8. Disaccharides and
polysaccharides 9. Pyrimidine and purine
bases 10. Nucleosides and nucleotides 11.
Structures of DNA and RNA 12. Fluorescent
detection of nucleic acids
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Required
background Stereochemistry Aldehydes,
ketones Heterocyclic compounds Carboxylic acid
derivatives
Essential for 1. Biochemistry and other
life science courses 2. Appreciation of life 3.
Feeling confident about you organic chemistry
knowledge
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Outline 1. Classification of carbohydrates 2.
Stereochemistry of open monosaccharides 3. Cyclic
forms of monosaccharides 4. Base-catalyzed
isomerisation of monosaccharides 5.
Glycosides 6. Reactions of monosaccharides 7.
Synthesis of monosaccharides 8. Disaccharides and
polysaccharides 9. Pyrimidine and purine
bases 10. Nucleosides and nucleotides 11.
Structures of DNA and RNA 12. Fluorescent
detection of nucleic acids
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Outline 1. Classification of carbohydrates 2.
Stereochemistry of open monosaccharides 3. Cyclic
forms of monosaccharides 4. Base-catalyzed
isomerisation of monosaccharides 5.
Glycosides 6. Reactions of monosaccharides 7.
Synthesis of monosaccharides 8. Disaccharides and
polysaccharides 9. Pyrimidine and purine
bases 10. Nucleosides and nucleotides 11.
Structures of DNA and RNA 12. Fluorescent
detection of nucleic acids
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L- and D-monosacharides are enantiomers
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Outline 1. Classification of carbohydrates 2.
Stereochemistry of open monosaccharides 3. Cyclic
forms of monosaccharides 4. Base-catalyzed
isomerisation of monosaccharides 5.
Glycosides 6. Reactions of monosaccharides 7.
Synthesis of monosaccharides 8. Disaccharides and
polysaccharides 9. Pyrimidine and purine
bases 10. Nucleosides and nucleotides 11.
Structures of DNA and RNA 12. Fluorescent
detection of nucleic acids
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All cyclic forms of monosaccharides are cyclic
hemiacetals. The cycle are preferred forms and
contain either 6 atoms (pyranoses) or 5 atoms
(furanoses)
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Example 2 Cyclization of ribose
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Example 3 Cyclization of fructose
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Outline 1. Classification of carbohydrates 2.
Stereochemistry of open monosaccharides 3. Cyclic
forms of monosaccharides 4. Base-catalyzed
isomerisation of monosaccharides 5.
Glycosides 6. Reactions of monosaccharides 7.
Synthesis of monosaccharides 8. Disaccharides and
polysaccharides 9. Pyrimidine and purine
bases 10. Nucleosides and nucleotides 11.
Structures of DNA and RNA 12. Fluorescent
detection of nucleic acids
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Outline 1. Classification of carbohydrates 2.
Stereochemistry of open monosaccharides 3. Cyclic
forms of monosaccharides 4. Base-catalyzed
isomerisation of monosaccharides 5.
Glycosides 6. Reactions of monosaccharides 7.
Synthesis of monosaccharides 8. Disaccharides and
polysaccharides 9. Pyrimidine and purine
bases 10. Nucleosides and nucleotides 11.
Structures of DNA and RNA 12. Fluorescent
detection of nucleic acids
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Outline 1. Classification of carbohydrates 2.
Stereochemistry of open monosaccharides 3. Cyclic
forms of monosaccharides 4. Base-catalyzed
isomerisation of monosaccharides 5.
Glycosides 6. Reactions of monosaccharides 7.
Synthesis of monosaccharides 8. Disaccharides and
polysaccharides 9. Pyrimidine and purine
bases 10. Nucleosides and nucleotides 11.
Structures of DNA and RNA 12. Fluorescent
detection of nucleic acids
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1. Alkylation at the glycoside position (see the
previous slide)
2. Complete alkylation
3. Complete acylation
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4. Oxidation to aldonic acids
5. Oxidation to aldaric acids
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6. Reduction to alditols
7. Oxidation by the Tolence reagent (Ag2O, NH3,
H2O), producing Ag (a silver mirror
reaction). Because of the basic conditions, the
reaction produces a messy mixture
of carbohydrate-based ammonium salts (mostly
ammonium gluconate).
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Outline 1. Classification of carbohydrates 2.
Stereochemistry of open monosaccharides 3. Cyclic
forms of monosaccharides 4. Base-catalyzed
isomerisation of monosaccharides 5.
Glycosides 6. Reactions of monosaccharides 7.
Synthesis of monosaccharides 8. Disaccharides and
polysaccharides 9. Pyrimidine and purine
bases 10. Nucleosides and nucleotides 11.
Structures of DNA and RNA 12. Fluorescent
detection of nucleic acids
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Outline 1. Classification of carbohydrates 2.
Stereochemistry of open monosaccharides 3. Cyclic
forms of monosaccharides 4. Base-catalyzed
isomerisation of monosaccharides 5.
Glycosides 6. Reactions of monosaccharides 7.
Synthesis of monosaccharides 8. Disaccharides and
polysaccharides 9. Pyrimidine and purine
bases 10. Nucleosides and nucleotides 11.
Structures of DNA and RNA 12. Fluorescent
detection of nucleic acids
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Disaccharides and polysaccharides are composed
from two or more cyclic monosaccharides. If the
saccharide contains at least one semi-acetal
group, it is a reducing sugar due to the
equilibrium with the open form, which actually
reacts with the Tolence reagent.
Saccharides-acetales do not react with Tolence
reagent, because they do not equilibrate with the
open form in the alkaline conditions. Examples
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Polysaccharides
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Outline 1. Classification of carbohydrates 2.
Stereochemistry of open monosaccharides 3. Cyclic
forms of monosaccharides 4. Base-catalyzed
isomerisation of monosaccharides 5.
Glycosides 6. Reactions of monosaccharides 7.
Synthesis of monosaccharides 8. Disaccharides and
polysaccharides 9. Pyrimidine and purine
bases 10. Nucleosides and nucleotides 11.
Structures of DNA and RNA 12. Fluorescent
detection of nucleic acids
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Complimentarity of pyrimidine and purine bases
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Outline 1. Classification of carbohydrates 2.
Stereochemistry of open monosaccharides 3. Cyclic
forms of monosaccharides 4. Base-catalyzed
isomerisation of monosaccharides 5.
Glycosides 6. Reactions of monosaccharides 7.
Synthesis of monosaccharides 8. Disaccharides and
polysaccharides 9. Pyrimidine and purine
bases 10. Nucleosides and nucleotides 11.
Structures of DNA and RNA 12. Fluorescent
detection of nucleic acids
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Outline 1. Classification of carbohydrates 2.
Stereochemistry of open monosaccharides 3. Cyclic
forms of monosaccharides 4. Base-catalyzed
isomerisation of monosaccharides 5.
Glycosides 6. Reactions of monosaccharides 7.
Synthesis of monosaccharides 8. Disaccharides and
polysaccharides 9. Pyrimidine and purine
bases 10. Nucleosides and nucleotides 11.
Structures of DNA and RNA 12. Fluorescent
detection of nucleic acids
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Individual polynucleotide chains interact due to
the H-bonding between complimentary
bases, forming double strained DNA and RNA. A
sequence of three nucleotides encodes
incorporation of a specific aminoacid to a
protein. The double strain DNA, discovered by
Watson, Wilkins and Crick (1962 Nobel Prize), is
the most common, but not the only form of DNA in
living organisms.
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Outline 1. Classification of carbohydrates 2.
Stereochemistry of open monosaccharides 3. Cyclic
forms of monosaccharides 4. Base-catalyzed
isomerisation of monosaccharides 5.
Glycosides 6. Reactions of monosaccharides 7.
Synthesis of monosaccharides 8. Disaccharides and
polysaccharides 9. Pyrimidine and purine
bases 10. Nucleosides and nucleotides 11.
Structures of DNA and RNA 12. Fluorescent
detection of nucleic acids
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Fluorescent detection of nucleic acids is base on
their ability to interact with certain dyes and
restrict internal rotation of chromophoric
fragments around conjugated bonds. It may reduce
rotational dissipation of the light energy
and initiate fluorescence. Example of a
DNA-sensitive dye