30 Questions
What is the average molecular weight of cellulose?
400,000 g/mol
How many glucose units are typically present in a cellulose molecule?
2,200 glucose units
What type of glycosidic bonds are present in amylopectin?
α-1,4 and α-1,6 glycosidic bonds
What is the total amount of glycogen in the body of a well-nourished adult human?
350 g
What is the primary function of glycogen in animals?
Energy storage
Why is cellulose insoluble in water?
The cellulose molecules form numerous intermolecular hydrogen bonds
What is the primary function of D-glucose in the human body?
To act as a primary source of energy for cells
Which of the following statements about D-galactose is true?
It is a component of the disaccharide lactose
What is the normal range of glucose concentration in human blood?
70-100 mg/dL
How does the glucose concentration in blood change after eating a meal?
It increases in the first hour and then decreases over the next 2-3 hours
What is the relationship between D-glucose and D-galactose?
They are epimers (diastereomers) differing in one chiral center
Why is D-galactose sometimes called 'brain sugar'?
It is a component of glycoproteins found in brain and nerve tissue
Which of the following is NOT a characteristic of cyclic hemiacetals?
They are planar structures with all substituents in the same plane as the ring.
In carbohydrate chemistry, what does the term 'pyranose' refer to?
A six-membered cyclic hemiacetal ring.
What is the configuration of the anomeric carbon in the β-anomer of a cyclic hemiacetal?
The -OH group on the anomeric carbon is on the same side of the ring as the terminal -CH2OH.
Which carbon is considered the anomeric carbon in an aldopentose?
C-1
What is the purpose of representing cyclic hemiacetals as Haworth projections?
To clearly represent the substituents above and below the plane of the ring.
Which of the following statements about anomers is correct?
Anomers are stereoisomers that differ in configuration only at the anomeric carbon.
What type of compound are glycosides hydrolyzed to in aqueous acid?
An alcohol and a monosaccharide
How are glycosides named?
By listing the alkyl or aryl group followed by the carbohydrate name with '-ide' suffix
Which reagents can reduce the carbonyl group of a monosaccharide to an alcohol?
NaBH4 and H2/Pt
What are the reduction products of monosaccharides called?
Alditols
How are alditols named?
By changing the '-ose' suffix of the parent monosaccharide to '-itol'
Which statement about aldonic acids is true?
They are formed by oxidation of the aldehyde group of an aldose under basic conditions
What type of bond joins the D-glucose units in cellulose?
$\beta$-1,4-glycosidic bonds
Why can't humans digest cellulose?
Humans lack $\beta$-glucosidases
Which organisms can digest cellulose?
Both A and B
What type of polysaccharides do humans use as glucose sources?
Starch and glycogen
Which of the following is NOT an example of a connective tissue?
Skeletal muscle
What is the best known biological function of heparin?
Anticoagulant activity
Study Notes
- N-acetyl-D-glucosamine is an acetylated derivative of D-glucosamine.
- Cyclic hemiacetals form when aldehydes/ketones react with alcohols, creating a five- or six-membered ring.
- D-Glucose is the most abundant monosaccharide in nature, essential in human nutrition, with a sweet taste.
- Glucose is a primary energy source for cells; blood glucose concentration ranges from 70-100 mg/dL.
- D-Galactose, an epimer of D-glucose, is crucial for lactose synthesis and found in brain glycoproteins.
- Polysaccharides like amylopectin (branched D-glucose), glycogen, and cellulose (linear D-glucose) serve energy/storage roles.
- Alditols are reduction products of monosaccharides, e.g., sorbitol, used as sugar substitutes for diabetics.
Learn about the significance of D-glucose in nature, its nutritional importance for humans, and its different properties. Understand the differences between D-glucose and L-glucose, and discover its various names and normal concentration in human blood.
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