Carbohydrates – Lecture Vocabulary

A vocabulary set covering major carbohydrate terms, structures, reactions, and examples discussed in the lecture.

Carbohydrate

Organic molecule composed of carbon, hydrogen, and oxygen in an approximate 1:2:1 ratio; serves as an energy source or structural material.

Lipid

Biomolecule rich in carbon and hydrogen with relatively little oxygen; functions mainly in long-term energy storage and membrane structure.

Monosaccharide

Simple sugar and monomer of carbohydrates containing 3–7 carbons; examples include glucose, fructose, and galactose.

Disaccharide

Dimer formed when two monosaccharides join via dehydration synthesis (e.g., sucrose, lactose, maltose).

Polysaccharide

Polymer consisting of many monosaccharides linked together (e.g., starch, glycogen, cellulose, chitin).

Glucose

Six-carbon sugar (C6H12O6) produced by photosynthesis; immediate energy source in blood and cells, also called dextrose.

Fructose

Fruit sugar (C6H12O6) found in many plants and honey; sweeter than glucose and used in high-fructose corn syrup.

Galactose

Hexose sugar (C6H12O6) obtained from hydrolysis of lactose; least sweet of the common monosaccharides.

Ribose

Five-carbon sugar (C5H10O5) that forms part of the sugar-phosphate backbone of RNA.

Deoxyribose

Five-carbon sugar (C5H10O4) lacking one oxygen atom; component of the DNA backbone.

Hexose

Monosaccharide containing six carbons, such as glucose, fructose, or galactose.

Pentose

Monosaccharide containing five carbons, such as ribose or deoxyribose.

Hydrophilic

Having an affinity for water; sugars are hydrophilic because their many hydroxyl (–OH) groups form hydrogen bonds with water.

Dehydration Synthesis

Chemical reaction that joins two monomers by removing a molecule of water; forms disaccharides and polysaccharides.

Hydrolysis

Reaction that breaks polymers into monomers by adding water; splits disaccharides like sucrose into their component sugars.

Lactase

Enzyme that hydrolyzes lactose into glucose and galactose; deficiency results in lactose intolerance.

Sucrose

Table sugar disaccharide composed of glucose and fructose; primary transport sugar in plants.

Lactose

Milk sugar disaccharide composed of galactose and glucose; requires lactase for digestion.

Maltose

Disaccharide consisting of two glucose units; produced during starch digestion and malting of grains.

Starch

Plant storage polysaccharide of glucose consisting of amylose (unbranched) and amylopectin (branched) chains.

Glycogen

Highly branched glucose polysaccharide serving as carbohydrate storage in animal liver and muscle tissue.

Cellulose

Structural glucose polysaccharide in plant cell walls; indigestible by humans due to its β-glucose bonds.

Chitin

Structural polysaccharide of N-acetyl glucosamine forming arthropod exoskeletons and fungal cell walls.

N-acetyl Glucosamine

Amino sugar monomer of chitin that contains an acetylated amino group.

Isomer

Compounds with the same molecular formula but different structural arrangements, e.g., glucose, fructose, and galactose.

1 : 2 : 1 Ratio

Characteristic proportion of carbon, hydrogen, and oxygen atoms in many carbohydrate formulas (C:H:O).

Photosynthesis

Process in plants that produces glucose from carbon dioxide and water using light energy, releasing oxygen as a by-product.