Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
13 Cards in this Set
- Front
- Back
|
What can be transported through the lining of the digestive system?
|
water
metals fatty acids (monoacylglycerol) monomeric sugars monomeric aa (di & tri-peptides) monomeric nucleotides |
|
|
Hydrolysis
|
"water breaking"
-polymers --> monomers -nucleophilic attack: nucleophile (lone pair of e- *usually on O or N) -attacks--> an electrophile (*usually C or P atam already in double bond w/ an O) -hydrolysis the lone pair of e- in the O on the water |
|
|
Dietary polysaccharides
|
Starches
-amylose: linear polysaccharide of <4000 glucose monomers linked by alpha(1,4) glycosidic bonds -Amylopectin: branched polysaccharide of <40,000 glucose monomers contain linear alpha (1,4) linked strands that branches at every 20-30 monomers thru alpha(1,6) -glycogen: storage form of glucose in human cells contain same branch patterns of amylopectin but more branch points (1 for every 8-10 monomer) |
|
|
Dietary Disaccharides.
What they hydrolyze into. |
Lactose: Galactose + Glucose
-from milk Maltose: Glucose + Glucose -from digestion of amylose, amylopectin, or glycogen Sucrose: Glucose + Fructose -released from candy |
|
|
What is contained in high fructose corn syrup?
What is it similar to? Significant difference? |
Glucose + Fructose
Sucrose: 50% glucose & 50% fructose HFCS: 45% glucose & 55% fructose (slightly slower becuase added glycosidic link) no significant difference |
|
|
Fructose in Diet
|
-equally harmful either from sucrose & HFCS, via excess calorie consumption
-bypasses most important regulatory enzyme of glycolysis (PFK) |
|
|
1. The Good Sugars
2. The Bad Sugars 3. The Really Bad Sugars |
1. Cellulose, Amylose, Amylopectin (starches don't cause carries)
2. Sucrose, Maltose, Lactose, Fructose, Glucose -absorbed/metabolized by strep mutans->lowers mouth pH) 3. sucrose - used to form dextran (facilitates plaque, makes teetch sticky) -alpha(1,6) & (1,3) |
|
|
Starch Digestion in Mouth
|
-salivary alpha-amylase hydrolyzes only alpha (1,4) glycosidic links
-amylose, amylopectin, glycogen --> producing oligosaccharides (dextrans) |
|
|
Will salivary amylase hydrolyze dextrans?
Where else does starch digestion occur? Difference bw maltose & isomaltase? |
No bc alpha(1,6) links
-continues in lumen of small intestine -pancreatic alpha-amylaze hydrolyze alpha(1,4) links -linkage m=alpha(1,4) & i=alpha(1,6) |
|
|
Where are di- & tri-saccharides hydrolyzed?
|
by disaccharidase complexes attached to brush-border membrane of jejunum
-maltase-glucoamylase, sucrase-isomaltase, maltotriose, lactase-phorizin-hydrolase, sucrase-isomerase |
|
|
What is required to move Glucose across membrane?
|
SGLT (Na-dependent glucose cotransporter-1)
-moves thru mem using energy from a Na ion gradient (created by ATP-pump) -SGLT-1: transports glucose/galactose into mucosal cells -GLUT-5: transports fructose into mucosal cells -GLUT-2: all 3 monosaccharides from mucosal cells into portal circulation (passive transport: glucose, galactose, fructose) |
|
|
problems in carb digestion absorption
|
-only monosaccharides carbs that can be absorbed by intestines
-congenital lactase deficiency adverse at birth -sucrase-isomaltase deficiency rare: occur once child eats solid food (food w/ sugar) -maltase-glucoamylase defiency: once child starts consume startch |
|
|
Disaccharidase deficiencies
|
-cannot be absorbed in small intestine
-reaches large intestine -fermented by bacteria -unable to digest: bloat, diarrhea, dehydration |
