Biochemistry Chapter 11 – Carbohydrates,
Glycosidic Bonds & Polysaccharides|Verified
Questions Provided with A+ Graded Rationales
Latest Updated 2026
Be able to recognize the structures of carbohydrates.
Carbohydrates have multiple hydroxyl (-OH) groups and either an aldehyde (-CHO) or ketone
(C=O) group. Monosaccharides exist in straight-chain (open-chain) or cyclic forms (pyranose or
furanose). Recognizing structures involves identifying the number of carbons, functional
groups, and ring size.
What are the common biological functions of carbohydrates?
They serve as energy sources (glucose), energy storage (starch, glycogen), metabolic
intermediates, structural components of nucleic acids (ribose and deoxyribose), structural
elements in plants, bacteria, and arthropods (cellulose and chitin), and as recognition
molecules on cell surfaces (glycoproteins and glycolipids).
Be able to classify monosaccharides as aldohexoses, etc.
Monosaccharides are classified by functional group (aldose or ketose) and number of carbons:
triose (3C), tetrose (4C), pentose (5C), hexose (6C), or heptose (7C). For example, glucose is an
aldohexose, and fructose is a ketohexose.
For the common monosaccharides glucose, galactose, fructose, ribose, deoxyribose, and
mannose, you should know their classification and biological functions.
Glucose: aldohexose, main blood sugar and energy source. Galactose: aldohexose, part of
lactose. Fructose: ketohexose, fruit sugar and part of sucrose. Ribose: aldopentose, in RNA.
Deoxyribose: aldopentose (missing one oxygen), in DNA. Mannose: aldohexose, involved in
protein glycosylation.
Be able to recognize D and L isomers and α and β isomers.
D and L isomers are mirror images determined by the configuration of the chiral carbon
farthest from the carbonyl group (D = OH on right, L = OH on left). α and β refer to the
orientation of the -OH group on the anomeric carbon in cyclic form (α = opposite to CH₂OH, β
= same side).
, Know the following terms as they relate to carbohydrates: enantiomers, diastereomers,
epimers, anomers, pyranose, furanose.
Enantiomers: mirror-image isomers (D and L forms). Diastereomers: non-mirror
stereoisomers. Epimers: differ at one chiral center (e.g., glucose and mannose). Anomers:
differ at anomeric carbon (α vs β). Pyranose: 6-membered ring. Furanose: 5-membered ring.
Be able to convert carbohydrates between open-chain forms and ring forms.
Cyclization occurs when a hydroxyl group attacks the carbonyl carbon forming a hemiacetal
(aldose) or hemiketal (ketose). The open-chain can reopen in solution, allowing
interconversion between α and β forms (mutarotation).
Be able to give names of carbohydrates in forms such as α-D-glucopyranose.
Carbohydrates are named by configuration (D or L), anomeric form (α or β), sugar name, and
ring size: e.g., α-D-glucopyranose = alpha anomer of D-glucose in pyranose (6-membered)
form.
What are reducing sugars? How are they identified?
Reducing sugars can open to form an aldehyde or ketone that reduces mild oxidizing agents
(Tollen's, Fehling's, or Benedict's reagents). They test positive by forming metallic silver
(Tollen's) or a red Cu₂O precipitate (Benedict's/Fehling's).
What are some of the common ways that carbohydrates are modified?
Carbohydrates can be modified by phosphorylation, oxidation, reduction, amination,
sulfation, acetylation, or glycosidic linkage to proteins/lipids. These modifications alter
solubility, reactivity, and recognition.
What are glycoside bonds? How do they form disaccharides and polysaccharides? Be able to
identify the type of glycoside bond.
Glycosidic bonds form when the anomeric -OH of one sugar reacts with another -OH,
releasing water. This covalent linkage joins monosaccharides into disaccharides and
polysaccharides. Bonds are classified as α or β depending on the anomeric configuration and
numbered by linked carbons (e.g., α(1→4)).
For maltose, lactose, sucrose, and cellobiose, you should know the monosaccharides that
make them, the type of glycoside bond, and where they are found in nature.
Maltose: glucose + glucose, α(1→4), starch breakdown product. Lactose: glucose + galactose,
β(1→4), milk sugar. Sucrose: glucose + fructose, α(1→2)β, table sugar. Cellobiose: glucose +
glucose, β(1→4), cellulose breakdown product.
Glycosidic Bonds & Polysaccharides|Verified
Questions Provided with A+ Graded Rationales
Latest Updated 2026
Be able to recognize the structures of carbohydrates.
Carbohydrates have multiple hydroxyl (-OH) groups and either an aldehyde (-CHO) or ketone
(C=O) group. Monosaccharides exist in straight-chain (open-chain) or cyclic forms (pyranose or
furanose). Recognizing structures involves identifying the number of carbons, functional
groups, and ring size.
What are the common biological functions of carbohydrates?
They serve as energy sources (glucose), energy storage (starch, glycogen), metabolic
intermediates, structural components of nucleic acids (ribose and deoxyribose), structural
elements in plants, bacteria, and arthropods (cellulose and chitin), and as recognition
molecules on cell surfaces (glycoproteins and glycolipids).
Be able to classify monosaccharides as aldohexoses, etc.
Monosaccharides are classified by functional group (aldose or ketose) and number of carbons:
triose (3C), tetrose (4C), pentose (5C), hexose (6C), or heptose (7C). For example, glucose is an
aldohexose, and fructose is a ketohexose.
For the common monosaccharides glucose, galactose, fructose, ribose, deoxyribose, and
mannose, you should know their classification and biological functions.
Glucose: aldohexose, main blood sugar and energy source. Galactose: aldohexose, part of
lactose. Fructose: ketohexose, fruit sugar and part of sucrose. Ribose: aldopentose, in RNA.
Deoxyribose: aldopentose (missing one oxygen), in DNA. Mannose: aldohexose, involved in
protein glycosylation.
Be able to recognize D and L isomers and α and β isomers.
D and L isomers are mirror images determined by the configuration of the chiral carbon
farthest from the carbonyl group (D = OH on right, L = OH on left). α and β refer to the
orientation of the -OH group on the anomeric carbon in cyclic form (α = opposite to CH₂OH, β
= same side).
, Know the following terms as they relate to carbohydrates: enantiomers, diastereomers,
epimers, anomers, pyranose, furanose.
Enantiomers: mirror-image isomers (D and L forms). Diastereomers: non-mirror
stereoisomers. Epimers: differ at one chiral center (e.g., glucose and mannose). Anomers:
differ at anomeric carbon (α vs β). Pyranose: 6-membered ring. Furanose: 5-membered ring.
Be able to convert carbohydrates between open-chain forms and ring forms.
Cyclization occurs when a hydroxyl group attacks the carbonyl carbon forming a hemiacetal
(aldose) or hemiketal (ketose). The open-chain can reopen in solution, allowing
interconversion between α and β forms (mutarotation).
Be able to give names of carbohydrates in forms such as α-D-glucopyranose.
Carbohydrates are named by configuration (D or L), anomeric form (α or β), sugar name, and
ring size: e.g., α-D-glucopyranose = alpha anomer of D-glucose in pyranose (6-membered)
form.
What are reducing sugars? How are they identified?
Reducing sugars can open to form an aldehyde or ketone that reduces mild oxidizing agents
(Tollen's, Fehling's, or Benedict's reagents). They test positive by forming metallic silver
(Tollen's) or a red Cu₂O precipitate (Benedict's/Fehling's).
What are some of the common ways that carbohydrates are modified?
Carbohydrates can be modified by phosphorylation, oxidation, reduction, amination,
sulfation, acetylation, or glycosidic linkage to proteins/lipids. These modifications alter
solubility, reactivity, and recognition.
What are glycoside bonds? How do they form disaccharides and polysaccharides? Be able to
identify the type of glycoside bond.
Glycosidic bonds form when the anomeric -OH of one sugar reacts with another -OH,
releasing water. This covalent linkage joins monosaccharides into disaccharides and
polysaccharides. Bonds are classified as α or β depending on the anomeric configuration and
numbered by linked carbons (e.g., α(1→4)).
For maltose, lactose, sucrose, and cellobiose, you should know the monosaccharides that
make them, the type of glycoside bond, and where they are found in nature.
Maltose: glucose + glucose, α(1→4), starch breakdown product. Lactose: glucose + galactose,
β(1→4), milk sugar. Sucrose: glucose + fructose, α(1→2)β, table sugar. Cellobiose: glucose +
glucose, β(1→4), cellulose breakdown product.
