Biochemistry Chapter on Carbohydrates

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Questions and Answers

Which of the following is classified as a ketose?

Glucose

Mannose

Galactose

Ribulose (correct)

What is the metabolic role of D-ribose?

Intermediate in glycolysis

Sugar of milk

Component of RNA (correct)

Major energy source

Which monosaccharide is primarily found in fruits and honey?

D-mannose

D-galactose

D-fructose (correct)

D-glucose

What is the chemical formula for a pentose monosaccharide?

C5H10O5 Signup and view all the answers

Which of the following is an aldotriose?

Glyceraldehyde Signup and view all the answers

What is the role of D-mannose in the body?

Component of mucopolysaccharides Signup and view all the answers

Which monosaccharide is known as the sugar of milk?

D-galactose Signup and view all the answers

What is the formula for a heptose monosaccharide?

C7H14O7 Signup and view all the answers

What type of reaction occurs during the cyclization of hexoses?

Intramolecular condensation Signup and view all the answers

Which of the following sugars is specifically a component of DNA?

2-D-deoxyribose Signup and view all the answers

Which type of glucose polymer is primarily responsible for the energy storage in plant sources?

Amylopectin Signup and view all the answers

What type of linkage primarily connects the D-glucose units in α-amylose?

α(1→4) glycosidic bond Signup and view all the answers

What is the main storage polysaccharide found in animal cells?

Glycogen Signup and view all the answers

How is glycogen primarily produced in the body?

Glycogenesis Signup and view all the answers

What is a key difference between glycogen and amylopectin?

Glycogen has branch points every 8 to 14 glucose residues Signup and view all the answers

At what stage does starch digestion begin in mammals?

In the mouth Signup and view all the answers

Which enzyme is primarily responsible for hydrolyzing the α-1,4-glycosidic bonds during starch digestion?

Amylase Signup and view all the answers

What primarily influences the amount of glycogen stored in the body?

Physical training and eating habits Signup and view all the answers

What are proteoglycans primarily composed of?

Glycosaminoglycans linked to proteins Signup and view all the answers

Which of the following is NOT a function of glycosaminoglycans?

Storing genetic information Signup and view all the answers

What type of structure do glycosaminoglycans have?

Long unbranched polysaccharides Signup and view all the answers

Which modified sugar is found in the disaccharide units of glycosaminoglycans?

N-acetylgalactosamine Signup and view all the answers

In which body structure is hyaluronan primarily found?

Synovial fluid of joints Signup and view all the answers

What role does heparin serve in the body?

An anticoagulant Signup and view all the answers

Which of the following locations is NOT associated with glycosaminoglycans?

Corneal epithelium Signup and view all the answers

What type of acid is commonly present in the disaccharide units of glycosaminoglycans?

Uronic acid Signup and view all the answers

What type of bond is formed between two monosaccharides in a disaccharide?

Glycosidic bond Signup and view all the answers

Which disaccharide is composed of galactose and glucose linked by a β-(1→4) glycosidic bond?

Lactose Signup and view all the answers

Which disaccharide is characterized by an α-(1→4) glycosidic bond and is a major degradation product of starch?

Maltose Signup and view all the answers

What is the correct nomenclature for a glycoside made from β-D-glucose?

b-D-glucopyranoside Signup and view all the answers

Which type of bond in disaccharides is resistant to cleavage by base?

Glycosidic bond Signup and view all the answers

What is the primary sugar found in milk, consisting of galactose and glucose?

Lactose Signup and view all the answers

Which disaccharide is made of glucose and fructose connected by an α-(1→2)β-glycosidic bond?

Sucrose Signup and view all the answers

What occurs when a monosaccharide hemiacetal reacts with a second molecule of alcohol?

Formation of an acetal Signup and view all the answers

What is the basic unit of carbohydrates?

Monosaccharides Signup and view all the answers

Which of the following is a function of carbohydrates in animal cells?

Temporary stores of glucose as glycogen Signup and view all the answers

Which type of carbohydrate serves as structural components in cell walls of bacteria and plants?

Polysaccharides Signup and view all the answers

What role do glycosaminoglycans play in the body?

Lubrication and adhesion in connective tissues Signup and view all the answers

How do carbohydrates contribute to the composition of nucleic acids?

As components of nucleotides in DNA and RNA Signup and view all the answers

Which of the following is NOT a function of carbohydrates?

Rapid nucleic acid replication Signup and view all the answers

Which process produces carbohydrates in plants?

Photosynthesis Signup and view all the answers

What is the significance of carbohydrate components in cell membranes?

To serve as recognition sites for cell communication Signup and view all the answers

Which of the following is a function of hyaluronate?

Shock absorber and lubricant Signup and view all the answers

What is the primary biological role of heparin?

Anticoagulation Signup and view all the answers

What type of bond links the disaccharide units in hyaluronate?

β(1 4) Signup and view all the answers

Chondroitin sulfate is primarily found in which type of tissue?

Connective tissue Signup and view all the answers

Which of the following explains why heparin must be administered parenterally?

It has a high negative charge and large size. Signup and view all the answers

What causes osteoarthritis in relation to chondroitin sulfate?

Loss of chondroitin sulfate from cartilage Signup and view all the answers

What is the role of activated antithrombin III in the action of heparin?

Inactivates thrombin and other proteases Signup and view all the answers

Which of the following GAGs is primarily a copolymer of D-glucuronic acid and N-acetyl-D-glucosamine?

Hyaluronate Signup and view all the answers

Study Notes

Carbohydrates

Carbohydrates, also known as saccharides, are "hydrated carbons" (CH₂O)ₙ, where n ≥ 3.
Monosaccharides are the basic units.
Monosaccharides are classified based on the number of carbon atoms (trioses, tetroses, pentoses, hexoses, heptoses, octoses, etc) and the type of carbonyl group (aldose or ketose).
Key examples of monosaccharides include glucose, fructose, galactose, ribose, and deoxyribose.
Important monosaccharides play roles in metabolic pathways, forming components of nucleic acids, and providing energy.
Disaccharides are formed when two monosaccharides link together via a glycosidic bond.
Common disaccharides include sucrose (table sugar), lactose (milk sugar), and maltose.
Polysaccharides are polymers of monosaccharides.
Polysaccharides serve as energy storage (starch, glycogen) and structural components (cellulose, chitin).
Starch is a storage polysaccharide in plants composed of amylose and amylopectin.
Glycogen is a storage polysaccharide in animals.
Cellulose is a structural polysaccharide in plants.
Chitin is a structural polysaccharide found in the exoskeletons of insects and fungi.
Heteropolysaccharides are made up of two or more different types of monosaccharides(eg. Glycosaminoglycans or GAGs).
GAGs are usually found in extracellular space and act as lubricant and structural support.
Examples of GAGs include hyaluronate, heparin, chondroitin sulfates, keratan sulfate and dermatan sulfate.
Proteoglycans are glycoproteins with covalently attached GAG chains.

Sugar Derivatives

D-gluconic acid, D-glucuronic acid, D-glucitol, sorbitol, ascorbic acid, ribital, myo-inositol, and xylitol are examples of sugar derivatives.
B-D-2-deoxyribose, D-glucosamine, and D-galactosamine are also sugar derivatives.

Monosaccharides - Classification

Monosaccharides are classified by the carbonyl group and number of carbon atoms.
A carbon atom double bonded to oxygen is called a carbonyl group. Monosaccharides with an aldehyde group are called aldoses, and those with a ketone group are called ketoses.
The most abundant monosaccharide is D-glucose. Other important monosaccharides include fructose and galactose.
Glyceraldehyde and dihydroxyacetone are examples of trioses.

Other

Carbohydrate analysis/glucose assay (different methods)
The analytical procedure most often performed in the clinical chemistry laboratory is the determination of glucose in blood, urine, or other biological fluid.
Vitamin C is not a monosaccharide and is crucial for maintaining health of tissue, cartilage, connective tissue and bone, and collagen formation.
Recommended daily allowance: ~45mg for adults (60mg if pregnant, 80mg if lactating).
Glycoproteins – Proteoglycans, are heavily glycosylated glycoproteins with a core protein with one or more glycosaminoglycan chains. There are different types.
Glycomics.
Bacterial cell walls, glycoproteins, glycolipids are other glyco-conjugates.

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Description

Test your knowledge on carbohydrates with this quiz that covers ketoses, pentoses, and their various roles in metabolism. Questions include the identification of monosaccharides and the functions of polysaccharides in biological systems. Brush up on your understanding of sugar classification and enzymatic reactions involved in carbohydrate digestion.