Polysaccharides and Carbohydrate Structure - Flashcards (Video Notes)

Flashcards covering polysaccharide types (starch, glycogen, cellulose, chitin), monosaccharides/disaccharides/polysaccharides, and polymerization processes (dehydration synthesis and hydrolysis) based on the provided notes.

What are the four major polysaccharides and their general roles?

Starch and glycogen store energy (plants and animals); cellulose and chitin are structural (cell walls and exoskeletons).

Which polysaccharide is the main storage form of glucose in plants?

Starch (composed mainly of alpha-glucose; includes amylose and amylopectin).

Which polysaccharide is the main storage form of glucose in animals?

Glycogen; highly branched storage polymer in liver and muscle.

Which polysaccharide forms the plant cell wall?

Cellulose; beta-1,4 linked beta-glucose; linear and unbranched.

Which polysaccharide forms arthropod exoskeletons and fungal cell walls?

Chitin; polymer of N-acetylglucosamine with beta linkages.

What type of glucose is used in starch and glycogen?

Alpha-glucose.

What type of glucose is used in cellulose and chitin?

Beta-glucose (cellulose); chitin is a beta-glucose derivative (N-acetylglucosamine).

What are the two forms of starch and how do they differ?

Amylose is unbranched; amylopectin is branched.

What are the glycosidic linkages in starch?

Alpha-1,4 linkages along chains with alpha-1,6 branches in amylopectin.

What are the glycosidic linkages in cellulose?

Beta-1,4 linkages; linear chains.

Why can't humans digest cellulose?

Because humans lack enzymes to hydrolyze beta-1,4 glycosidic bonds; beta glucose chains are indigestible.

Why is cellulose linear and unbranched?

Beta linkages cause every other glucose to be inverted, preventing helix formation and branching.

What is chitin composed of?

Polymer of N-acetylglucosamine (a beta-glucose derivative); structural exoskeleton for arthropods and fungal cell walls.

Which organisms digest cellulose in their gut?

Termites (with gut protozoa and bacteria) and ruminant animals (cows, sheep) with cellulolytic microbes.

What is a monosaccharide?

A simple sugar; 3–7 carbons; aldehyde or ketone; multiple hydroxyl groups.

What is a disaccharide?

A molecule of two monosaccharides covalently bonded (glycosidic linkage); examples maltose, lactose, sucrose.

What is a polysaccharide?

A polymer made of many monosaccharide units covalently linked.

What is polymerization?

The process of linking monomers to form a polymer.

What is dehydration synthesis (condensation)?

Bond formation between monomers with removal of a water molecule.

What is hydrolysis?

Breakdown of polymers into monomers by adding water.

How are carbohydrates classified?

By the number of sugar units: monosaccharides (1), disaccharides (2), polysaccharides (many).