CHMA11H3 Lecture Notes - Lecture 39: Monosaccharide, Cell Nucleus, Hydrolysis
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8 Apr 2019
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CHMA11 Lecture 36: Nucleic Acids and Carbohydrates
- Nucleic Acids
o Linking of nucleotides
▪ Phosphate connects third carbon of one sugar to the fifth carbon of the
next sugar
• It is a phosphate linkage that connects nucleotides
▪ Directionality is 5’ to 3’
• New nucleotides are added to the 3’ end
o 5’ end: phosphate group is attached to the fifth carbon
o 3’ end: Hydroxyl group is attached to the third carbon
• Therefore nucleotides are joined by chemical reactions between
the hydroxyl of the old nucleotide and the phosphate group of the
new nucleotide
▪ Polynucleotide: formed by joining multiple nucleotides together
o Double Helix: DNA exists as two complementary strands that run antiparallel to
each other
▪ the two polynucleotides chains are wrapped around in a coil shape
resembling a step ladder
• Hydrogen bonds exist between the bases of both adjacent strands
toward the inside
o Yields the theoretical rungs on the ladder
o These base pairings therefore give the DNA its helical
shape
• The sugar phosphate backbone makes up the outside of the
ladder
o Phosphate gives DNA a negative charge overall
- Carbohydrates: energy source of the cell
o Provides energy to do all reactions within cell
o Can be thought of as being either simple or complex
▪ Simple Carbs: monosaccharides or disaccharides
• One or two sugar monomers linked by glycosidic bonds
• Are often isomers
o Will have their hydroxyl groups in altering places
▪ Different locations of hydroxyl yields different
isomers
▪ These different isomers have different properties
when they come together to form complex
carbohydrates
• Monosaccharides: simple linear molecules composed of 3 atoms
o Composed of carbon, hydrogen and oxygen