Digestion, Absorption, Transport Of Carbs Flashcards
Starch
Alpha-D-glucose
Alpha-1,4 and alpha-1,6 glycosidic bonds
Amylose and amylopectin
Storage in plants
Glycogen
Storage in animals
Alpha-D-glucose
Alpha-1,4 and alpha-1,6 glycosidic bonds
Cellulose
Beta-D-glucose
Beta-1,4 bonds
Unbranched
Sucrose
Glucose and Fructose
Alpha, beta-1,2 glycosidic bond
Non reducing
Lactose
Galactose and Glucose
Beta-1,4 bond
Reducing
Trehalose
Glucose and Glucose
Alpha, alpha-1,1
Non reducing
What does digestion do?
Turn poly and disaccharides into their monosaccharides
Where is amylase found?
Saliva and pancreas
Salivary alpha amylase
Hydrolyzes interior alpha 1 4 bonds, breaking down starch and glycogen into maltose, maltotriose, and alpha-dextrins
What does lactase do?
Cleave lactose into galactose and glucose
What does trehalase do?
Cleave trehalose into 2 glucoses
What does sucrase do?
Cleave sucrose into fructose and glucose
What does sucrose isoamylase do?
Cleave maltose into 2 glucoses
Sucrase site - hydrolyzes sucrose to glucose and fructose with maltase activity
Isomaltase site - hydrolyzes alpha 1-6 bt glucose residues with maltase activity
What does glucoamylase do?
Cleave maltose into 2 glucose
Cleaves at NR end, one glucose molecule at a time
What does isomaltase do?
Cleave isomaltose into 2 glucoses
How does fiber get broken down and what does it get broken down into?
Colonic bacteria make it more soluble by converting it to gas, short chain fatty acids, and lactase
Glycosidase does what?
Hydrolyze glycosidic bonds
Salivary alpha-amylases do what?
Hydrolyze interior alpha 1-4 bonds bt glucose in amylopectin, amylose, and glycogen into smaller entities
What happens in the luminal phase?
Intestinal epithelial cells produce cholecystokinin (releases pancreatic alpha amylase) and secretin (releases bicarbonate that neutralizes intestinal pH)
What happens in membrane phase?
Lactose, maltose, sucrose, maltotriose, and alpha dextrins are broken down from the NR end 1 monosaccharide at a time
Glycemic index
Indicates how fast blood glucose levels rise after consumption
What happens in lactose intolerant people’s intestines?
Undirected lactose get into large intestine, water is drawn into large intestine, bacteria ferments lactose to lactate and gas, causing symptoms
SGLT proteins
Sodium dependent transporter
Active transport
Galactose and glucose
Major carb constituents in U.S.
Starch, sucrose, lactose
Glut1
RBCs, blood brain barrier
Expressed in cell types with barrier functions
Glut2
Liver, pancreatic beta cells, contraluminal memb of intestinal cells
Accepts all 3 monosaccharides
Transfers from intestinal lumen to circulation
Glut3
Brain (neurons)
Transporter in CNS
Glut4
Adipose tissue, skeletal muscle, heart muscle
Insulin sensitive transporter
Glut5
Intestinal epithelial cells, sperm
Fructose transporter
Facilitated diffusion
Sglt1
Intestinal epithelial cells
Glucose and galactose
Active transport
Sglt2
Kidney
Difference between galactose and glucose
Galactose has hydroxyl in beta position, glucose has it in the alpha
Alpha position
Down
