Quiz 2 chapters 3-4
Enzymes: Match the enzymes with the pathway in which they function in carbohydrate metabolism. -phosphofructokinase -pyruvate carboxylase -glycogen phosphorylase -glucose-6-phosphate dehydrogenase -branching enzyme
-glycolysis -gluconeogenesis -glycogenolysis -pentose phosphate -glyocogenesis
Fructose transport into enterocyte relies on the facilitative transporter GLUT5.
True
An individual whose diet is lacking in pectins and β-glucans might suffer with hypercholesterolemia.
True
Glucose phosphorylation in the liver is catalyzed by glucokinase.
True
Maintenance of normal blood glucose concentration is controlled by the small intestine, the liver, the kidneys, skeletal muscle, and adipose tissue.
True
Pectins, gums, inulin and resistant starches are structurally longer-chain, water-soluble fibers
True
Choose the best description of the main method of glucose absorption.
active transport with sodium
A good choice of a food to add to one's diet in an effort to increase fiber intake while not consuming large portions is ____.
almonds
People with type 1 diabetes have ___
below normal glucokinase activity because of low insulin levels
Which component of the cell wall contributes to the fiber content of foods?
bran layer
The majority of energy in the typical American diet comes from ____.
carbohydrate
Common food sources of fructans are ____.
chicory, onions, and Jerusalem artichokes
What type of bond holds two monosaccharides together?
covalent
In what part of the cell does glycolysis occur?
cytosol
Which hormonal changes occur in response to a fall in blood glucose concentration
decreased insulin, increased glucagon
Because fibers absorb primary bile acids to promote their excretion, they help to protect against ____.
diarrhea
What are the major dietary energy sources that are composed of two simple sugars?
disaccharides
Sucrose digestion is initiated in the ____.
duodenum
When compounds with one or more chiral carbon atoms and the same formula are arranged as mirror images they are said to be ____.
enantiomers
The disaccharidases are synthesized by the ____.
enterocyte
Two hormones that stimulate glycogenolysis in the muscle and liver, respectively, are ____.
epinephrine; glucagon
Pentose sugars provide more dietary energy than hexose sugars.
false
The muscle is an important tissue in gluconeogenesis because it can use amino acids from protein breakdown and convert them to glucose, which it then secretes into the circulation for other tissues.
false
The purpose of the pentose phosphate pathway is to generate ribose, for nucleic acid synthesis, and NAD, for oxidizing power.
fasle
A ketopentose is a carbohydrate containing ____.
five carbons and a ketone group
Glycemic load considers the ____ in the food.
quantity and quality of carbohydrate
Glycolysis is a process involving ____.
reactions that convert glucose to pyruvate
During the end reaction of the electron transport chain, molecular oxygen becomes _____
reduced to H2O
In skeletal muscle, hypercortisolism may lead to ____.
reduction in the size of muscle fibers
Which tissue has the least activity of the pentose phosphate pathway?
skeletal muscle
Viscous gel-forming fibers may contribute to satiety by ____.
slowing gastric emptying
Conversion of phosphorylase b to the active phosphorylase a is carried out by ____.
AMP
Which of the following homopolysaccharides made of glucose contributes the most energy to the ordinary diet?
Amylopectin
The enzyme ATP synthase is believed to catalyze the formation of ATP, as described by the ____ theory.
Chemiosmotic
All cells have mitochondria, which act as the main site for ATP production.
False
Because they do not have mitochondria, red blood cells generate a lot of lactate from glycolysis, which they in turn must convert into glucose to meet their energy needs.
False
Glycogenolysis in muscle cells provides glucose that can be transported through the bloodstream.
False
Hemicelluloses with acids in their side chains are fat soluble.
False
The abundance of GLUT4 is increased by induction in response to a high-CHO meal.
False
All of the following are substrates for gluconeogenesis EXCEPT ____.
Fatty acids
Name the model that depicts cyclized monosaccharides as lying in a horizontal plane with the hydroxyl groups pointing down or up from the plane
Haworth
People with type 1 diabetes have ____.
below-normal glucokinase activity because of low insulin levels
By what mechanism do soluble fibers decrease the absorption of lipids?
by adsorbing/interacting with lipids
Which substance is converted into glycogen in the process of glycogenesis?
glucose-1-phosphate
Insulin is an anabolic hormone. Which process does insulin stimulate?
glycogenesis
Dietary fibers are mainly provided by ____.
plant cell walls
Types of Fiber: Match the fiber with an appropriate description. -pectin -cellulose -gum -lignin -hemicellulose
-A group of polysaccharides with galacturonic acid as a primary constituent. It is soluble and gel forming; plentiful in many fruits -A long linear polymer that provides structure to the cell wall. Found in bran, legumes, root vegetables, and apples. -A hydrocolloid composed of sugar and sugar derivatives commonly used as a food additive that is secrete form plant injuries or can also be found in oats, barley, -The main noncarbohydrate component of fiber and a three-dimensional polymer of phenol. Found in carrots, berries, and wheat, and insoluble in water. -contains a number of sugars in its backbone and side chains. Some are water soluble and some are insoluble; found in bran and whole grains
Due to a lack of the enzyme glucose-6-phosphatase, which tissue capable of glycogenesis cannot contribute to blood glucose levels between meals?
Muscle
Chiral carbon atoms have ____.
four different atoms or groups attached to them
Which of the following fibers stimulates the growth of bifidobacteria and thus are considered prebiotics?
fructans
If an individual with no blood sugar abnormalities when eating regularly presented with severe hypoglycemia after 30 hours of fasting, which enzyme would you suspect might be malfunctioning?
fructose-1,6-biphosphatase
Which source of fiber would be the best to add to one's diet in order to lower serum lipid concentrations?
gar gum
Which process produces glucose-6-phosphate from noncarbohydrate sources?
gluconeogensis
Which substance is converted into glycogen in the process of glycogenesis?
glucose 1 phosphate
Gluconeogenesis is essentially the reversal of which pathway? TCA cycle
glycolysis
According to the USDA data for the year 2010, most of the carbohydrates in the American diet came from ____.
grain products
Diets low in fat and rich in high-fiber foods may reduce the risk of ____.
heart disease
most fibers are strongly _____
hydrophilic
Which scenario is NOT a typical gastrointestinal response to ingestion of dietary fiber?
increased absoption
Ingesting foods rich in gel-forming fibers is associated with ____.
increased gastric distention
Fiber-induced shifts in bile acid production from cholic acid toward chenodeoxycholic acid will act to ____.
inhibit cholesterol synthesis
α-dextrinase is also called ____
isomaltase
The poison, sodium cyanide, inhibits the enzyme cytochrome c oxidase. Why is ingestion of this poison usually fatal?
it blocks the production of ATP in the cells
which fiber type is slowly fermentable
lignin
In the ____, galactose is eventually converted to ____.
liver; glucose
In which cellular site is most of the energy released when carbohydrates are oxidized to carbon dioxide and water?
mitochondrion
Enterocytes absorb only one form of carbohydrate. This form is ____.
monosaccharides
In order to be absorbed by the body, all digestible carbohydrates must be broken down into ____.
monosaccharides
Which plant polysaccharides have a structure similar to gums?
mucilages
Which of the following high-fiber foods are most effective in lowering serum cholesterol?
oat bran
β-glucans are found in ____
oat products and barley
What is a water-soluble, gel-forming fiber that functions in the plant as intracellular cement and that is used commercially to make jellies and to provide fiber in enteral formulas?
pectin
The purpose of the hexose monophosphate shunt is to produce ____.
pentose phosphate and NADPH
A homopolysaccharide that is important in human diets is ____ and the end product formed from the complete digestion of this homopolysaccharide is ____.
starch; glucose
The occurrence of a molecule in different spatial configurations is ____.
stereoisomerism
The second most abundant food sources of carbohydrates are _____
sugars and sweetners
Which disaccharide is commonly found in mushrooms?
trehalose
Dietary fiber is defined as nondigestible carbohydrates and lignin that are intact and intrinsic in plants.
true
Glucose is transported from the lumen into the enterocyte by active transport using SGLT1 protein, which also requires Na as a co-transporter.
true
The process of gluconeogenesis occurs mainly in the liver and, in cases of starvation, in the kidneys as well.
true
Active transport requires energy for the Na-K pump to transport Na out of the cell, thereby driving the transport of another substance (e.g., glucose) when the Na re-enters the cell down its concentration gradient.
true
Pectins, gums, inulin and resistant starches are structurally longer-chain, water-soluble fibers.
true
β-glucans are effective in reducing serum cholesterol.
true
The health benefits of fiber are based on which two characteristics?
viscosity and fementability
An example of an RS1 starch is ____.
whole grains and seeds
