Flashcards in Biochem - macronutrients digestions Deck (54)
bonds in proteins? in fats?
proteins have peptide bonds
fats have ester bonds
class of enzymes that perform hydrolysis?
2 main disaccharides in diet?
lactose and sucrose
galactose + glucose
fructose + glucose
polysaccharides of glucose; contains amylose and amylopectin
spiral chain, unbranched, alpha 1,4 linked starch components
branched polymer of starch with alpha 1,4 chains and 1,6 branches; similar to glycogen
what enzyme works in mouth? what does it do?
salivary alpha amylase
cleaves starch by breaking the 1,4 linkages between glucose --> this creates dextrins
linear and branched oligosaccharides that enter stomach after salivary amylase cleaves starch
digestion that started in the stomach is continued ...
in the intestines by pancreatic alpha amylase
salivary and pancreatic alpha amylases are...
both endo-glucosidases found in the brush border
intestinal absorption : aa vs fats
aa absorbed by villi and enter portal vein --> liver
fats dont go through portal vein - they go into lymph as chylomicrons
what neutralizes stomach acid in the small intestine
bicarbonate from the pancreas
products of pancreatic alpha amylase on glucose
disaccharides maltose and isomaltose, trisaccharides, and small oligosaccharides
what is digested at brush border?
sucrose, lactose, and starch products
4 brush border enzymes...
hydrolyze di, tri, and oligo saccharides into monosaccharides
also called alpha glucosidase
cleaves glucose from nonreducing ends of oligosaccharides
converts sucrose into glucose and fructose
also called beta galactosidase
cleaves lactose into galactose and glucose
transport in intestines
glucose and Na+ are transported by secondary active transport
lactose cannot be digested and is oxidized instead by gut bacteria which produces gas and causes bloating and watery diarrhea due to increased osmotic pressure
-common in asians
carbs that cannot be digested
=cellulose, carragennan, raffinose, lignin, hemicelluloses
B 1,4 linked glucose - cannot be cleaved by human enzymes
sucrose + galactose
trisaccharide in beans, cause gas
alpha glucosidase breaks the B1,4 linkage in raffinose/trisaccharide in beans
fate of indigestible food...
fermentation by colon bacteria producing
-lactic acid, short chain FAs, and gases (H2, CO2, and CH4)
-osmotic effect --> watery stool
protein digestion pathway
starts in stomach -- pepsin converts proteins to smaller polypeptides -- in small intestine proteolytic enzymes from the pancreas cleave polypeptides into oligopeptides and AA -- intestinal enzymes cleave the oligopeptides into AA --finally AA are absorbed by epithelium into blood
proteolytic enzymes made by pancreas
trypsin, chymotrypsin, elastase, and carboxypeptidases