Exam 1: Carbohydrates Flashcards
Condensation Chemical Reaction
Covalent Bond is Formed
One Molecule of water is released
Hydrolysis
Chemical Reaction
Disaccaride splits into two monosaccharides
Requires a molecule of water
Monosaccharides
Glucose
Fructose
Galactose
Disaccharides
Sucrose
Maltose
Lactose
Sucrose
Glucose+Fructose (white or table sugar)
Refined from juice of sugar beets or sugar cane
Occurs naturally in many fruits and vegetables
Maltose
Glucose+ Glucose (Malt sugar)
Produced during breakdown of starch
Lactose
Glucose+ Galactose
Principle carbohydrate in milk
Glucose
Most cells rely on glucose for fuel
Brain& nervous system rely on it almost exclusively
Fructose
Sweetest of sugars
Naturally occurring in fruits, honey and saps
Along with glucose, the most common monosaccharide in nature
Galactose
Primarily occurs as part of lactose
known as “milk sugar”
Freed from lactose as single sugar during digestion
Monosaccharides- Pentoses
- Furnish little dietary energy
- Ribose/deoxyribose> RNA/DNA
Sugar Alcohols
Derived from monosaccharides
High Fructose Corn Syrup
Monosaccharide Mixture
Usually 55% Fructose & 45% glucose
Oligosaccharides
Made of 3-10 sugar molecules
Found in beans, peas, bran, whole grains
Not hydrolyzed in human digestive system
Gut bacteria can digest them
Examples:
Raffinose (tri)
Stachyoses (tetra)
Verbascose (penta)
Polysaccharides
composed almost entirely of glucose (in some cases, also other monosaccharides)
Examples of Major ones in nutrition:
Starch
Glycogen
Fiber
Polysaccharides: Starch
Storage form of glucose in plants
Giant chains of hundreds of glucose units- can be broken by human digestive system
All starchy foods are plants:
Grains-richest source of starch
Legumes
Root Vegetables
Resistant Starch
Starch that cannot be digested or absorbed by humans
Often considered a form of FIBER because they move through upper GI tract undigested then metabolized by bacteria in colon
Types:
Naturally occurring
Processed
Polysaccharides: Glycogen
Storage form of energy for humans and animals
Not found in plant sources
Composed of highly branched chains of glucose units
Stored in liver & Muscles
- In liver 90g
- In muscles 150g
Polysaccharides: Fibers
Provide structure in stems, trunks, roots, leaves & skins of plants
Provide little or no energy for body (cannot be broken by human digestive enzymes)
Dietary Fiber
Non digestible CHO’s & lignin that are intact and intrinsic in plants
Functional Fiber
Non digestible CHO’s that are isolated, extracted or manufactured & known to have physiological benefits
Total fiber
Dietary Fiber + Functional Fiber
What are the types of fiber?
Soluble
Insoluble
Soluble Fibers
Dissolve in water
Form gels which are easily digested by bacteria in large intestine
Associated with lower risks of chronic diseases
Insoluble Fibers
Do not dissolve in water
retain structure and texture
aid digestive system by easing elimination
Fibers in Foods
Cellulose Hemicelluloses Pectins Gums& Mucilages Lignins Beta-Glucans Chitin&Chitosan
What are carbohydrates’ role in wellness?
Source of energy, sweetened and dietary fiber
Where does the digestion of CHO start?
the mouth
What do CHO’s break down into in the SMALL INTESTINE
Monosaccharides:
Enzymes specific for the CHO (example: lactase for lactose)
What are disorders associated with digestion and absorption of CHO’s
Lactose Intolerance
Oligosaccarides
Lactose Intolerance
Most common disaccharides disorder:
Deficiency of lactase
Symptoms: Abdominal Cramping, flatulence, diarrhea
Low dairy intake increases risk for deficiencies of calcium, riboflavin and vitamin D
Lactose Intolerance Nutrition Therapy
- Determine individual tolerance
- Gradually add small amounts of lactose-containing foods to lactose-free diets
Oligosaccharide Digestion
Humans lack the enzyme
Nutrition Therapy: Food Enzyme Dietary Supplement such as “Beano”
Absorption Across Intestinal Mucosa: Monosaccharides
Glucose & Galactose: Active transport
Fructose: Facilitated Diffusion
Carbs in liver
glucose may be used immediately or stored
Liver conversion of fructose and galactose to glucose
Metabolism
Metabolism primarily maintenance of blood glucose homeostasis at 70 to 100 mg/dL
