Biochemistry: Monosaccharides and Disaccharides

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Questions and Answers

What is the role of the anomeric carbon in monosaccharides?

It is always the last carbon in the chain.

It is the C that is part of the C=O group. (correct)

It determines the sweetness of the sugar.

It is the carbon that forms a double bond with oxygen.

Which statement correctly describes the formation of ring structures in hexose sugars?

The C=O group reacts with the OH group to form a ring. (correct)

The ring structures can only be 6-sided.

The ring structure cannot stabilize in aqueous solutions.

Anomeric carbon remains part of the carbon chain.

What distinguishes alpha (α) and beta (β) glucose isomers?

The orientation of the -OH group on carbon 1. (correct)

The number of oxygen atoms in the molecule.

The type of glycosidic linkage formed.

The carbon chain length in the molecule.

Which disaccharide is formed from two glucose molecules?

Maltose Signup and view all the answers

What type of bond is formed between monosaccharides during condensation reactions?

Glycosidic linkage Signup and view all the answers

What type of bond links glucose monomers in starch?

α-1,4-glycosidic bond Signup and view all the answers

Which statement best describes lactose intolerance?

It leads to symptoms such as diarrhea and gas after consuming milk products. Signup and view all the answers

What is the main function of glycogen in the human body?

To serve as a source of energy during strenuous activity Signup and view all the answers

Which sugar molecule is considered the major form of sugar in milk?

Lactose Signup and view all the answers

What distinguishes amylopectin from amylose?

Amylopectin has α-1,4 and α-1,6 linkages; amylose only has α-1,4 linkages. Signup and view all the answers

In plants, where is starch primarily stored?

In plastids (chloroplasts) Signup and view all the answers

What type of linkage is prominent in the main chain of glycogen?

α-1,4-glycosidic bond Signup and view all the answers

What is the primary component of sucrose?

Glucose and Fructose Signup and view all the answers

What role does insulin play in glucose management?

It helps the body convert excess glucose into glycogen. Signup and view all the answers

What is the effect of dietary starch on animals?

It provides energy through hydrolysis of its glucose monomers. Signup and view all the answers

Study Notes

Linear Monosaccharides

Carbon 1 is the anomeric carbon, located at the C=O (carbonyl) carbon.
In aqueous solutions, hexose sugars form rings.

Ring Structures

Anomeric carbon (C=O group) reacts with an OH group to form stable 5- or 6-sided rings.
No atoms are lost during ring formation.

Alpha and Beta Orientation

When glucose forms a ring, the -OH group on carbon 1 can be in two orientations: alpha (α) or beta (β).
Alpha (α): The -OH group is below the ring, opposite to the -CH2OH group.
Beta (β): The -OH group is above the ring, on the same side as the -CH2OH group.
These are isomers; same composition but different arrangement.

Disaccharides

Disaccharides are two monosaccharides joined through a condensation reaction.
The bond formed is a glycosidic linkage.
Examples:
- Glucose + Glucose = Maltose
- Glucose + Galactose = Lactose
- Glucose + Fructose = Sucrose

Disaccharide Linkage Naming

To name the linkage, identify the anomeric carbon's α or β position.
Number the carbons and determine which two are linked.
Examples: α-1,4 linkage.

Maltose

Glucose + Glucose = Maltose + H₂O
Found in malted products (e.g., beer).

Lactose

Glucose + Galactose = Lactose + H₂O
Major sugar in milk.
Lactose intolerance: Individuals have low lactase enzyme (small intestine), resulting in diarrhea, gas, and bloating after dairy consumption.

Sucrose

Glucose + Fructose = Sucrose + H₂O
Table sugar; major transport form of sugars in plants.

Polysaccharides

Polymers of monosaccharides joined by glycosidic linkages.
Two main types:
- Storage: Energy storage molecules, hydrolyzed as needed.
- Structural: Building materials for cells.

Starch

Storage polysaccharide in plants.
Stored in plastids (chloroplasts).
Hydrolyzed by animals for energy.
Composed of two forms:
- Amylose: Unbranched, α-1,4 glycosidic bonds.
- Amylopectin: Branched, α-1,4 and α-1,6 glycosidic bonds.
Major sources: Potatoes and grains.

Glycogen

Storage polysaccharide in animal liver and muscle cells.
Similar to amylopectin, but with more branching.
Hydrolyzed when the body needs more glucose.
Main chain linkage: α-1,4 glycosidic bond.
Branch linkage: α-1,6 glycosidic bond.

Insulin

Insulin helps the body store excess glucose.
It enables glucose conversion into energy and glycogen storage in the liver and muscles.
Glycogen is produced and stored in muscle cells as well, and used for energy during strenuous activity. Glucose is converted into lactic acid.

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Description

This quiz explores the concepts of linear monosaccharides and the formation of ring structures. It covers the anomeric carbon, alpha and beta orientation of glucose, and the formation of disaccharides through glycosidic linkages. Test your understanding of carbohydrate chemistry and the different types of sugars.