carbs Flashcards
What are the classes of carbohydrates based on the number of sugar units?
Monosaccharides, Oligosaccharides, Polysaccharides.
What are monosaccharides?
Single sugars that are freely soluble in water and have a sweet taste.
What are oligosaccharides?
Short chains of single sugars covalently linked.
What are polysaccharides?
Long chains (hundreds or thousands) of single sugars covalently linked.
What does the term ‘saccharide’ derive from?
‘Saccharide’ is derived from the Latin word ‘sacchararum’ due to the sweet taste of mono/disaccharides.
Are monosaccharides chiral?
All monosaccharides (except dihydroxyacetone) are chiral, having one or more asymmetric carbon atoms.
What notation is used to differentiate between enantiomers of monosaccharides?
Fisher notation [D- L-] is used, determined relative to glyceraldehyde.
What are epimers?
Epimers are a special subset of diastereoisomers where two sugars differ only in the configuration around one carbon.
What happens during the cyclization of glucose and fructose?
When the ring forms: OH up = α and OH down = β. These isomers are called anomers.
What is the anomeric carbon?
The new chiral hemiacetal/hemiketal carbon formed during cyclization.
What are modified sugars?
Modified sugars include amino sugars and deoxy sugars, e.g., 2’-deoxy ribose seen in DNA.
What are disaccharides?
Disaccharides consist of two monosaccharides joined covalently by an O-glycosidic bond/linkage.
What are examples of disaccharides?
- Maltose, 2. Cellobiose, 3. Lactose (milk sugar), 4. Sucrose (cane sugar, table sugar).
What are the chemical and physical properties of mono/disaccharides?
Almost all taste sweet, undergo hydrogen bonding, are solids at room temperature, and are very soluble in water.
What is notable about concentrated solutions of monosaccharides?
Highly concentrated solutions like honey, maple syrup, and molasses are very viscous liquids.
