The majority of energy in the typical American diet comes from
carbohydrate.
A ketopentose is a carbohydrate containing
5 carbons and a ketone group.
When compounds with 1 or more chiral carbon atoms and the same formula are arranged as mirror images they are said to be _____.
enantiomers
What is the nutritional significance of stereoisomers?
Certain metabolic enzymes require a particular structure
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
What are the major dietary energy sources that are composed of two simple sugars?
disaccharides
What is the most common digestible homopolysaccharide existing as both amylose and amylopectin?
starch
Which of the following homopolysaccharides made of glucose contributes the most energy to the ordinary diet?
amylopectin
A homopolysaccharide that is important in human diets is _____ and the end product formed from the complete digestion of this homopolysaccharide is _____.
starch; glucose
In what form do carbohydrates enter the bloodstream?
monosaccharides
What is the key enzyme in digestion of polysaccharides?
α-amylase
Which of the following carbon bonds is digested by α-amylase?
α (1-4)
Which of the following is the predominant monosaccharide produced by the digestion of all dietary carbohydrates?
glucose
The enzyme needed to hydrolyze the α (1,6) bond of amylopectin is _____, which is secreted from the _____.
isomaltase, enterocyte
The disaccharidases are synthesized by the _____.
enterocyte
Sucrose digestion is initiated in the _____.
duodenum
The final molecules that are absorbed from the digestion of the carbohydrate in spaghetti (noodles) and a cream sauce are _____.
1. sucrose
2. glucose
3. maltose
4. galactose
5. lactose
6. fructose
d. 2, 4
Choose the best description of the main method of glucose absorption.
active transport with sodium
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What is a likely reason that large quantities of fructose may cause gut discomfort?
Facilitated diffusion is slower than active transport
The glucose transporter that is sensitive to insulin is
GLUT4.
Which hormonal changes occur in response to a fall in blood glucose concentration?
decreased insulin, increased glucagon
Glycemic load considers the _____ in the food.
quantity and quality of carbohydrate
People with type 1 diabetes have
below-normal glucokinase activity because of low insulin levels
Insulin is an anabolic hormone.
Which process does insulin stimulate
glycogenesis
Due to a lack of the enzyme glucose-6-phosphatase, which tissue capable of glycogenesis cannot contribute to blood glucose levels between meals?
muscle
Glycolysis is a process involving
reactions that convert glucose to pyruvate
The major end products of cellular oxidation of carbohydrate include
water, carbon dioxide, and energy
In what part of the cell does glycolysis occur
cytosol
In which cellular site is most of the energy released when carbohydrates are oxidized to carbon dioxide and water?
mitochondrion
Two hormones that stimulate glycogenolysis in the muscle and liver, respectively, are _____.
epinephrine and glucagon
In what organelle are the enzymes that catalyze the citric acid cycle located?
mitochondrion
In the _____ galactose is eventually converted to _____.
hepatocyte, glucose
Under anaerobic conditions within a cell, how many net ATPs are formed from one glucose molecule by substrate-level phosphorylation?
two
In the complete oxidation of 1 mol of glucose, how many ATPs are formed?
32-38
When oxygen is present in a tissue, less glucose is metabolized to pyruvate. Why?
ATP accumulates and inhibits phosphofructokinase.
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sdfs
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