CARBOHYDRATES AND PROTEINS Flashcards
What is the cheapest source of calories providing 50% or more of calories in most diets?
Carbohydrates
What is the general elemental composition of carbohydrates?
Cx(H2O)y
What is the recommended daily carbohydrate intake for males and females?
Males: 220-330 g/day, Females: 180-230 g/day
What are the principal dietary carbohydrates?
Polysaccharides, disaccharides, and monosaccharides
Which polysaccharides are primarily digested in the gastrointestinal tract?
Starches (glucose polymers) and their derivatives
What is the structure of amylopectin?
A branched molecule
What is the structure of amylose?
A straight chain with only α1,4 linkages
What are the common dietary disaccharides?
Lactose (milk sugar) and sucrose (table sugar)
What are the common dietary monosaccharides?
Fructose and glucose
What is sorbitol, and how does it affect blood sugar?
Sorbitol is formed when the aldehyde group of glucose is hydrogenated to an alcohol group, slowing its absorption and diminishing its effect on blood sugar concentration.
What is the major storage form of polysaccharides in animals?
Glycogen
What is the structural similarity between glycogen and amylose?
Both are straight-chain polymers.
What are examples of non-starch polysaccharides?
Cellulose, hemicellulose, pectins, gums, alginates
What makes cellulose indigestible by humans?
It is composed of beta-1,4-linked glucose molecules in straight chains.
What is the primary enzyme responsible for carbohydrate digestion in the mouth?
Salivary alpha-amylase
At what pH is salivary alpha-amylase deactivated?
pH of 4 or lower
Which enzyme is more efficient at digesting carbohydrates in the small intestine?
Pancreatic alpha-amylase
What are the end products of alpha-amylase digestion?
Maltose, maltotriose, and α-limit dextrins
What enzymes hydrolyze disaccharides and small glucose polymers into monosaccharides?
Lactase, sucrase, maltase, and α-dextrinase
What are the monosaccharide products of lactose digestion?
Glucose and galactose
What are the monosaccharide products of sucrose digestion?
Glucose and fructose
What is the enzyme responsible for breaking down maltose?
Maltase (glucoamylase)
What is the substrate and product of trehalase?
Substrate: Trehalose, Product: Glucose
What is the glycemic index range for ‘good’ carbohydrates?
≤ 55