Carb Metabolism Flashcards
Name the 4 hexoses
Glucose (aldose)
Galactose
Mannose
Fructose (ketose)
C1 is the _____ . _____ reacts with C1 to make a ring? ___, ___ are the enzymes that break these linkages
Reactive aldehyde/keytone.
C5,
glycosidases
Glycogen 1-4 linkage chain is called; 1,6? Name 2 indigestible carbs?
Amylose, 1-6, fiber/cellulose.
List the composition of Dissacharides? What monosaccharides do we eat?
M: Glucose & Fructose (eaten)
Sucrose (Glc+Fru)
Lactose (Gal+Glc)
Maltose - (Glu+Glu)
What happens to PS in the Oral Cavity - a-Amylase?
Use Starch
Cleavage
Starch ==> Maltose, Isomaltose, and Starch Dextrin (8 saccaride unit w/1-6 linkages)
Pancreas: a-Amylase? (SI) What is unique?
Cleavage of polysaccharides into disaccharides.
Starch Dextrin brokend down (extratime) ==> Maltose (1-4), Isomaltose (1-6)
Name some Glucosidases (in SI) remember they are bound to epithelial cells. What do the do in the SI?
*what enzyme is missing w/ lactose intolerance?
disaccharide cleavage into monosaccharides
Maltase, Isomaltase, *Lactase, and Sucrase
Where do the monosaccharides go? Where to the undigested carbohydrates go?
MS: hepatic portal circulation to Liver
UC: go to colon; bacteria degradation and production of gas
What causes high H2 concentration in Hydrogen Breath Test?
1) Lactose intolerance
2) Bacterial Overgrowth
3) Rapid Passage of Food through small intestine.
SI - Absorption of Monosaccharides:
⁃ Active Transport System
Think whole enterocyte
(SGLT): 1 Galactose and Glucose for 2 Na+
⁃ ATP mediated co-transporter
⁃ Na+ concentration gradient maintained by ATP Na/K
pump
Absorption of Monosaccharides:
⁃ Facilitated Transport System
Glucose Transporters:
⁃ GLUT-5: Fructose (In from lumen)
⁃ GLUT-2: All monosaccarides to hepatic circulation.
Steps of Glycolysis (investment)
3
Glucose –> Glucose-6-Phosphate
Hexokinase (-1ATP)
G6P –> Fructose-6-Phosphate
Phosphoglucose Isomerase
F6P --> Fructose 1,6 BisPhosphate phosphofructose kinase (PFK)**(-1ATP)
Steps of Glycolysis (Splitting) (2)
** which goes further in glycolysis
1) Fructose 1,6, BisPhosphate split by aldolase –> **glyceraldehyde-3- phosphate & Dihydroxyacetone phosphate.
Triphosphate isomerase converts dihydroxyacetone phosphate to glyceraldehyde-3-phosphate.
Step 1 of Glycolysis (ORP)
(GAPDH) producing NADH
*why do RBC’s take ups more glucose than needed for energy?
Glyceraldehyde-3-phosphate –>
1, 3 Bisphosphoglycerate (adds (P))
BY: Glyceraldehyde-3-phosphate dehydrogenase ( +1NADH)
RBC SHUNT –> mutase to give 2,3 BPG
Steps 2-5 of Glycolysis (ORP)
**third regulated step.
1, 3 Bisphosphoglycerate --> 3 phosphoglycerate Phoshoglycerate kinase (takes (P))
3 –> 2 phosphoglycerate
phosphoglycerate mutase
2-phosphoglycerate –> phosphoenolpyruvate
Enolase - (-H20)
**Phosphoenolpyruvate --> Pyruvate Pyruvate kinase (takes (P))
