NP06 – Glycolysis
Carbohydrates
• Composed of carbon, hydrogen and oxygen only = CHO
• No dietary requirement since it can be made in the body! à but physiological requirement: brain
needs glucose. Glucose can be derived from other nutrients, such as amino acids
Simple carbohydrates (sugars) - Cn(H2O)n
§ Monosaccharides / disaccharides (sugars)
• Intrinsic sugars
• Extrinsic sugars in free solution
o Lactose in milk
o Non-milk extrinsic
§ Complex carbohydrates
• Polysaccharides (>10-100 sugars)
o Starch
o Non-starch polysaccharides (e.g. cellulose)
• Oligosaccharides: Dextrins (tens of monosaccharides), Trisaccharides, Tetrasaccharides
§ Sugar alcohols
Simple monosaccharides (linear or circular)
• Glucose
• Fructose à completely different in chemical structure, need other transport methods in comparison
to glucose and galactose
• Galactose (hydroxyl group on the other side, compared to glucose à same transporter)
C6H12O6 (n=6) à all share the same molecular formula à MW = 180 g/mole
Also, smaller saccharides exist, n=
§ 6: hexose
§ 5: pentose à ribose for RNA and deoxyribose for DNA
§ 4: tetrose
§ 3: triose
Disaccharides à 2 x monosaccharides (bond between 2-OH branches)
• Sucrose (saccharose: what we call sugar): glucose + fructose
• Trehalose: glucosyl + glucoside (2 glucoses), C1-C1 binding: this is switched compared to maltose
Causes a smaller blood glucose spike than glucose and reduced sweetness
used in prepared frozen foods, like ice cream because it lowers freezing point of foods
• Lactose: glucose + galactose (the only way we take galactose from our diet: lactose from milk)
• Maltose – Isomaltose: glucosyl-glucose, maltose has a α-1,4 binding and isomaltose (branched, not
linear) has a α-1,6 binding
Condensation reaction to form disaccharides and longer molecules
Condensation of 2 glucose molecules releases water. An OH group from one glucose and an H atom from another
glucose combine to create a molecule of H2O. The two glucose molecules bond together with a single O atom to
form the disaccharide maltose.
Hydrolysis of starch by amylase
Hydrolysis needs water. The disaccharide maltose splits into two glucose molecules with H added to one and
OH to the other (from water). à that’s why we have so much water in the GI tract
In saliva and pancreatic juice results in formation of dextrins, eventually broken down to:
§ Glucose
Carbohydrates
• Composed of carbon, hydrogen and oxygen only = CHO
• No dietary requirement since it can be made in the body! à but physiological requirement: brain
needs glucose. Glucose can be derived from other nutrients, such as amino acids
Simple carbohydrates (sugars) - Cn(H2O)n
§ Monosaccharides / disaccharides (sugars)
• Intrinsic sugars
• Extrinsic sugars in free solution
o Lactose in milk
o Non-milk extrinsic
§ Complex carbohydrates
• Polysaccharides (>10-100 sugars)
o Starch
o Non-starch polysaccharides (e.g. cellulose)
• Oligosaccharides: Dextrins (tens of monosaccharides), Trisaccharides, Tetrasaccharides
§ Sugar alcohols
Simple monosaccharides (linear or circular)
• Glucose
• Fructose à completely different in chemical structure, need other transport methods in comparison
to glucose and galactose
• Galactose (hydroxyl group on the other side, compared to glucose à same transporter)
C6H12O6 (n=6) à all share the same molecular formula à MW = 180 g/mole
Also, smaller saccharides exist, n=
§ 6: hexose
§ 5: pentose à ribose for RNA and deoxyribose for DNA
§ 4: tetrose
§ 3: triose
Disaccharides à 2 x monosaccharides (bond between 2-OH branches)
• Sucrose (saccharose: what we call sugar): glucose + fructose
• Trehalose: glucosyl + glucoside (2 glucoses), C1-C1 binding: this is switched compared to maltose
Causes a smaller blood glucose spike than glucose and reduced sweetness
used in prepared frozen foods, like ice cream because it lowers freezing point of foods
• Lactose: glucose + galactose (the only way we take galactose from our diet: lactose from milk)
• Maltose – Isomaltose: glucosyl-glucose, maltose has a α-1,4 binding and isomaltose (branched, not
linear) has a α-1,6 binding
Condensation reaction to form disaccharides and longer molecules
Condensation of 2 glucose molecules releases water. An OH group from one glucose and an H atom from another
glucose combine to create a molecule of H2O. The two glucose molecules bond together with a single O atom to
form the disaccharide maltose.
Hydrolysis of starch by amylase
Hydrolysis needs water. The disaccharide maltose splits into two glucose molecules with H added to one and
OH to the other (from water). à that’s why we have so much water in the GI tract
In saliva and pancreatic juice results in formation of dextrins, eventually broken down to:
§ Glucose
