What enzyme cleaves the non-reducing end of maltose?

 α-1,4- glucoamylase

What enzyme acts on the α-1,6 bonds of isomaltose?

 α-1,6-isomaltase

What enzyme acts on an unusual bond between the  anomeric carbons of two glucose residues?

Trehalase

What β-galactosidase cleaves the bond β-1,4 bond between glucose and galactose?

Lactase

Lactase is formed by a β-1,4 linkage of what two sugars?

Glucose and Galactose

What enzyme has levels that are high in infants but decline in the age of most populations except for northern europeans?

Lactase

Salivary and pancreatic amylase break down starch into several products. Oligosaccharides with α-1,6 branches are known as what?

α-Dextrins

What initiates digestion of starch and
glycogen in the duodenum and randomly produces maltose, isomaltose, maltotriose, and a limited number of dextrins?

Pancreatic α-amylase

Isomaltase, maltase, trehalase, sucrase, and lactase are all semi-specific or specific disaccharidase complexes that are located where?

The brush border membrane of the intestinal mucosal cells

What is the bond and what are the products of isomaltase?

Isomaltase breaks down an α(1,6) bond in isomaltose to 2 glucose units

What does maltase break down maltose to?

2 Glucose units

What are the products of sucrase?

fructose and glucose

What's similar about trehalase and isomaltase?

They both produce 2 units of glucose

What predominant polymer in fiber is made up of mostly β-1,4 linkages?

Cellulose

Dietary fibers such as pectins can have what positive effect in humans? What disorder is this beneficial for?

Pectins can increase gastric emptying and delay entry of digestional components into the small intestine where absorption occurs.

Pectins may be beneficial to diabetic mellitus patients by slowing the the rate of absorption of simple sugars and preventing blood glucose levels after meals.

Acetate, propionate, and butyrate are products of what component of digestion?

Digestion of fiber by Colon microbes

How does fiber reduce pressure on the colonic wall (aka "softening of the stool")?

Undigested fiber and the osmotically active anions increase the size and wetness of
stools because they attract water and form gels

Undigested fiber and the osmotically active anions increase the size and wetness of stools because they attract water and form gels. What disease is this beneficial effect especially important to?

Colon Diverticulae disease

How does β-glucan (obtained from oats) reduce cholesterol levels?

By reducing bile acid reabsorption in the intestine (more bile acid is excreted due to β-glycan and the body compensates by dipping into the available cholesterol pool, thus lowering serum cholesterol levels)

What type of α-amylase is an endoglycosidase, acting on internal bonds?

Salivary α-amylase

Which statement is incorrect?

A. Salivary amylase randomly hydrolyzes internal alpha 1,4 glycocidic bonds between glucosyl residues within amylopectin, amylose and glycogen

B. Salivary α-Amylase is an exoglucosidase acting on external bonds as opposed to internal bonds cleaved by endoglucosidases
 

C. End product of action of alpha amylase is α-dextrin (branched oligosaccharide with 5-9 glucosyl residues)

D. Salivary amylase acts on mylopectin and amylose; both are converted to α-dextrins that together with undigested food move to stomach

B. Salivary Alpha Amylase is an endoglycosidase acting on internal bonds as opposed to external bonds cleaved by exoglucosidases

Amylopectin and amylose are converted to ______ that
together with undigested food move to stomach

α-dextrins

The Duodenum produces and secretes two hormones that travel in the blood stream to the pancreas and regulate pancreatic secretion of compounds that play a role in
carbohydrate metabolism. What activates the release of these hormones?

The presence of acid chyme from the stomach activates the duodenum to release CCK and Secretin

Which statement about Secretin is false?

A. Secretin stimulates the pancreas to release pancreatic juice rich in alkaline bicarbonate (pH 7.6 to 7.9)

B. Secretin increases the the acidity of the the stomach

C. Pancreatic juice contains several digestive
enzymes one of which is pancreatic α-amylase

D. The Duodenum produces and secretes Secretin

B. Secretin neutralizes the acidity of the bolus of the stomach

Which statement about CCK is INCORRECT?

A. CCK is secreted as a result of stimuli caused by
products of digestion of mainly proteins and lipids but not carbohydrates.
B. CCK stimulates contraction of the
gallbladder 

C. CCK stimulates secretion of pancreatic juice rich in digestive enzymes one of which is pancreatic a-amylase, D. CCK activates the relaxation of the
upper esophageal sphincter

D. CCK activates the relaxation of the
sphincter of Oddi

What end product of carbohydrate digestion by pancreatic α-amylase in the duodenum is a trisaccharride with α-1,4 linkages?

Maltotriose

Which of the following is not a main end product of Carbohydrate Digestion by Pancreatic α-amylase in the Duodenum?

A. Maltose
B. Amylose

C. Maltotriose

D. Limit Dextrin

E. Isomaltose

B. Amylose

Where would be a good place to find Tri- & Disaccharides with both α-1,4 and α-1,6 bonds in the human body?

The Duodenum (after release of pancreatic α-amylase)

What portion of the small intestine releases 4 enzymes (glycosidases) to continue carbohydrate
digestion in the small intestines?

The Brush border membrane of teh Intestinal Villi

The glucoamylase complex

Sucrase hydrolyzs _________ bonds
in sucrose to produce fructose and glucose while Isomaltase cleaves
_____ bonds in isomaltose

Sucrase hydrolyzs α-(1, 2) bonds and Isomaltase cleaves
α-1,6 bonds in isomaltose

Beta-glycosidase complex hydrolyzes _____
linkages in what carbohydrate?

Beta-glycosidase complex (mainly lactase): hydrolyzes the β-(1,4) linkages in lactose

 Trehalase, found mainly in young mushrooms and insects, catalyzes the hydrolysis of bonds between two glucosyl units in trehalose. What type of linkage does trehalase act on?

α-(1,1) bonds between the anomeric carbons

Salivary α-amylase in the mouth acts on starch. What is the major product of Salivary α-amylase?

α-dextrins

What are the major products of carbohydrate digestion that occurs in the stomach?

There are none; carbohydrate digestion occurs in the mouth and the small intestine

In the lumen of the small intestine, pancreatic α-amylase acts on dextrins to form what 3 products?

1. Limit dextrins

2. Maltotriose

3. Maltose

What is a product of every brush border intestinal villi enzyme?

Glucose

Dextrinase, producing limit dextrins in the brush border, makes what three specific products?

1. Glucose

2. Maltose
3. Maltotriose

What is incorrect about a condition of pain, nausea, and flatulence after ingestion of food containing lactose?

A. Likely symptoms include Intestinal Irritation, Discomfort, and Bloating

B. Production of lactic acid and release of terrible gases
(CH₄ & H₂) via GI bacterial fermentation of lactose

C. Caused by low levels of lactase or Intestinal Injury

D. Caused by an allergy to Lactose

D.

Inability to digest milk (fresh milk) leads to the formation of Short Chain Fatty Acids and Natural Gases. These conditions are some evidence of ________.

Lactose Intolerance

Which statement is false?

A. Order of absorption of monosaccharides through the capillary blood vessels of the intestine villi is: Galactose>Glucose>Fructose

B. There is a single transport mechanisms responsible for absorption of monosaccharides across the intestinal epithelial cell

C. Non-energy dependent facilitated diffusion carried out by facilitated transporters for fructose, mannose and sorbitol

D. Na+-dependent Facilitated Transport (Na+-dependent active transport). Also known as Carrier-mediated transport, which is energy-driven.

Sodium (Na+)-dependent GLUcose Transporter (SGLT) and Non-sodium-coupled facilitative transporters are in intestinal epithelial cells and what other cell type?

Epithelial cells of the kidney

Which statement below is INCORRECT?

A. Both glucose and fructose are transported by facilitated transporters on the luminal and serosal sides of absorptive cells

B. Glucose and galactose are transported by the Na+-
Glucose –cotransporter (SGLT) on the luminal (mucosal) side of the absorptive cells

C. SGLT is present in the epithelial cells of the liver

D. Na⁺ drives the absorption of galactose, glucose, and fructose from intestinal lumen through absorptive cells and into capillaries

C. C. SGLT is present in the epithelial cells of the kidney

Certain cardiotonic drugs, notably the steroids
such as ouabain and digitoxigenin (digoxin)
inhibit glucose absorption. What do they inhibit specifically?

Na+/K+-ATPase

What is a fungal alkaloid that inhibits
Na⁺-independent glucose transport?

Cytocholasin B

Phlorizin (phloretin-2’-beta-glucoside) is a plant
glycoside that inhibits ______ by acting on
the _________, competing with the
substrates although it does not enter the cell.

Glucose transport; mucosal surface

Found in adipose tissue and skeletal muscle, the only insulin-stimulated glucose-uptake transporter is what?

GLUT-4

GLUT-1, which is insulin insensitive and has a high affinity for glucose, can be found in the blood-retinal barrier as well as the blood-placental barrier. What other two cell types contain GLUT-1?

Human erythrocytes & blood-brain barrier

A glucose transporter isoform can be found in Liver, kidney, and pancreatic β-cells. Uptake and release is seen in the liver as well as β-cell glucose sensing in the pancreas. A low affinity for glucose (Km is 15 mM) confirms that this is which isoform?

GLUT-2

GLUT-5 in the intestinal epithelium is a ___________ transporter.

GLUT-5 in the intestinal epithelium is a fructose transporter.

Which GLUT isoform specializes in moving glucose out of the endoplasmic reticulum?

GLUT-7

"Binding of insulin to its cell membrane receptor causes vesicles containing glucose transport proteins to move from inside the cell to the cell membrane" probably describes which glucose transporter? What tissue(s) can this be found in?

GLUT-4 in skeletal muscle and adipose tissue