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Week 2
Carbohydrate dig./Reg. of metabolic path/ Overview of Met. Ana & Cat States/Energy Gen. in Mitoch./Electron Transport & Oxidative Phosph, TCA cycle, non mend inheritance/mitoch myopahties
53
Biochemistry
Graduate
08/15/2011

Additional Biochemistry Flashcards

 


 

Cards

Term

 

 

 

 

What enzyme cleaves the non-reducing end of maltose?

Definition

 

 

 

 

 α-1,4- glucoamylase

Term

 

 

 

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

Definition

 

 

 

 

 α-1,6-isomaltase

Term

 

 

 

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

Definition

 

 

 

 

Trehalase

Term

 

 

 

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

Definition

 

 

 

 

Lactase

Term

 

 

 

 

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

Definition

 

 

 

 

Glucose and Galactose

Term

 

 

 

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

Definition

 

 

 

 

Lactase

Term

 

 

 

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

Definition

 

 

 

 

α-Dextrins

Term

 

 

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

Definition

 

 

 

 

Pancreatic α-amylase

Term

 

 

 

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

Definition

 

 

 

 

The brush border membrane of the intestinal mucosal cells

Term

 

 

 

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

Definition

 

 

 

 

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

Term

 

 

 

 

What does maltase break down maltose to?

Definition

 

 

 

 

2 Glucose units

Term

 

 

 

 

What are the products of sucrase?

Definition

 

 

 

 

fructose and glucose

Term

 

 

 

 

What's similar about trehalase and isomaltase?

Definition

 

 

 

 

They both produce 2 units of glucose

Term

 

 

 

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

Definition

 

 

 

 

Cellulose

Term

 

 

 

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

Definition

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.

Term

 

 

 

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

Definition

 

 

 

 

Digestion of fiber by Colon microbes

Term

 

 

 

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

Definition

 

 

 

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

Term

 

 

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?

Definition

 

 

 

 

Colon Diverticulae disease

Term

 

 

 

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

Definition

 

 

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)

Term

 

 

 

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

Definition

 

 

 

 

Salivary α-amylase

Term

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

Definition

 

 

 

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

Term

 

 

 

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

Definition

 

 

 

α-dextrins

Term

 

 

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?

Definition

 

 

 

 

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

Term

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

Definition

 

 

 

 

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

Term

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

Definition

 

 

 

 

D. CCK activates the relaxation of the
sphincter of Oddi

Term

 

 

 

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

Definition

 

 

 

 

Maltotriose

Term

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

Definition

 

 

 

 

B. Amylose

Term

 

 

 

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

Definition

 

 

 

 

The Duodenum (after release of pancreatic α-amylase)

Term

 

 

 

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

Definition

 

 

 

 

The Brush border membrane of teh Intestinal Villi

Term
An enzyme complex of the brush border is acting as an exoglucosidase (i.e., it begins from the non-reducing end of oligosaccharide). It digests limit dextrin to isomaltose, which is subsequently digested by isomaltase of the sucrase-isomaltase complex. It can also cleave a-1,4 bonds in maltose by acting as maltase. What enzyme complex is this?
Definition

 

 

 

 

The glucoamylase complex

Term

 

 

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

Definition

 

 

 

 

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

Term

 

 

 

Beta-glycosidase complex hydrolyzes _____
linkages in what carbohydrate?

Definition

 

 

 

 

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

Term

 

 

 

 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?

Definition

 

 

 

 

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

Term

 

 

 

 

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

Definition

 

 

 

 

α-dextrins

Term

 

 

 

 

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

Definition

 

 

 

 

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

Term

 

 

 

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

Definition

 

 

1. Limit dextrins

2. Maltotriose

3. Maltose

Term

 

 

 

 

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

Definition

 

 

 

 

Glucose

Term

 

 

 

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

Definition

 

 

 

1. Glucose

2. Maltose
3. Maltotriose

Term

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

 

Definition

 

 

 

 

D.

Term

 

 

 

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

Definition

 

 

 

 

Lactose Intolerance

Term

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.

Definition
Term

 

 

 

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

Definition

 

 

 

 

Epithelial cells of the kidney

Term

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

Definition

 

 

 

 

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

Term

 

 

 

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

Definition

 

 

 

 

Na+/K+-ATPase

Term

 

 

 

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

Definition

 

 

 

 

Cytocholasin B

Term

 

 

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.

Definition

 

 

 

 

Glucose transport; mucosal surface

Term

 

 

 

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

Definition

 

 

 

 

GLUT-4

Term

 

 

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?

Definition

 

 

 

 

Human erythrocytes & blood-brain barrier

Term

 

 

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?

Definition

 

 

 

 

GLUT-2

Term

 

 

 

 

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

Definition

 

 

 

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

Term

 

 

 

 

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

Definition

 

 

 

 

GLUT-7

Term

 

 

"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?

Definition

 

 

 

 

GLUT-4 in skeletal muscle and adipose tissue

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