B1.1B Carbohydrates and glycoproteins

Monosaccharides Are the Building Blocks of Carbohydrates

1. Monosaccharides are the simplest form of carbohydrate.
2. They form the building blocks for larger carbohydrates like disaccharides and polysaccharides.

Pentoses and Hexoses Are Grouped by Carbon Count

1. Pentoses (5-carbon sugars)
   1. Ribose (C₅H₁₀O₅) and deoxyribose (C₅H₁₀O₄) are the key pentoses.
   2. They form the sugar-phosphate backbone in nucleotides.
   3. Ribose is found in RNA, and deoxyribose is found in DNA.
2. Hexoses (6-carbon sugars)
   1. Glucose (C₆H₁₂O₆) is the most important hexose.
   2. Hexoses often exist in ring forms, which are more stable and biologically active than straight chains.

Glucose Forms Two Ring Isomers: Alpha and Beta

1. Glucose (C₆H₁₂O₆) is a hexose whose ring has 6 atoms: 5 carbon atoms and 1 oxygen atom.
2. Glucose exists as two isomers: α-glucose and β-glucose.
3. They differ only in the orientation of the hydroxyl group on carbon 1.

Which polymer forms from each isomer (starch and glycogen from α-glucose, cellulose from β-glucose) is covered in B1.1.5 and B1.1.6.

Ribose and Deoxyribose Build the Nucleic Acid Backbone