Carbohydrates Flashcards
(13 cards)
What is NSP?
Non-starch polysaccharide, (dietary fibre)
Cellulose - long B-1,4 linked chains of glucosyl units.
What is resistant starch?
Polymers of amylose and amylopectin in a semi-crystalline state - can’t be digested in SI as binds inaccessible to enzymes, fully digested in LI.
How is Starch digested?
At different rates
Produce different postprandial rises in blood glc, insulin etc.
More slowly digested produce small peaks in blood Glc and insulin.
What is the future of carbohydrate research?
Understand its structure and properties at DIFFERENT sites of GI tract and effects on metabolism
FUNCTIONAL FOODS - health benefits for T2DM & CVD.
what is the generic form of carbs?
Cn(H2O)n
Carry aldehyde or ketone gp (or substances yielding them on hydrolysis).
what are the significant features of carbs?
most abundant biomolecules dietary staple and fibre industrial uses green polymers biofuels
what type of links are found in maltose and lactose?
1–> 4
what are the molecular weights of glycogen? How does it differ from starch?
400,000 for proglycogen
10E7 for macroglycogen
highly branched
Why do beta glucans increase gut viscosity?
B1–>3 linkages make them water soluble.
Why is hydrolysis minimal in saliva?
acidic pH in stomach inhibits aloha-amylase (optimal pH is 6.7).
which enzymes are present on the intestinal mucosa?
maltase
alpha-limit dextrinase
lactase
sucrase
what is the traditional view concerning sugar absorption?
Glc and hexoses removed before remains of meal (digesta and chyme) reach terminal ileum.
Evidence accumulating that not all starch digested at same rate so above unlikely.
How does temperature affect alpha amylases?
Increased T;
decreased Km (substrate more accessible)
Increased Kcat/Km (hydrolysis rate increases).
- proportion of amorphous material = double helices in raw form so don’t fit into active sites - decreases.
