Introduction to Carbohydrates and Carbohydrate Metabolism

Vocabulary flashcards covering the chemical classification, structure, types, biological significance, digestion, and metabolic traits of carbohydrates.

Carbohydrates

Polyhydric alcohols with potentially active aldehyde or ketone groups that serve as the main source of energy in the body and are the most abundant organic molecules in nature.

Monosaccharides

Simple sugars containing only one sugar unit that serve as the building blocks of all carbohydrates and cannot be hydrolyzed into simpler forms.

Trioses

Monosaccharides containing three carbon atoms, such as glyceraldehydes and dihydroxyacetone.

Tetroses

Monosaccharides containing four carbon atoms.

Pentoses

Monosaccharides containing five carbon atoms, such as ribose, deoxyribose, xyloses, ribulose, and arabinose.

Hexoses

Monosaccharides containing six carbon atoms, including glucose, galactose, mannose, and fructose.

Heptoses

Monosaccharides containing seven carbon atoms.

Aldose

A monosaccharide that contains an aldehyde functional group.

Ketose

A monosaccharide that contains a ketone functional group.

Disaccharides

Carbohydrates consisting of two sugar units, such as sucrose, lactose, maltose, and isomaltose.

Oligosaccharides

Carbohydrates composed of $3$ to $10$ sugar units.

Polysaccharides

The most complex carbohydrates, composed of more than $10$ sugar units.

Isomers

Compounds sharing the exact same chemical formula (such as glucose, fructose, galactose, and mannose, which share $C_6H_{12}O_6$) but having different structures.

Stereoisomers

Compounds identical in chemical composition that differ only in their spatial configuration, such as L-glucose and D-glucose.

Epimers

Two sugars that differ from one another only in the spatial configuration around a single carbon atom.

Epimerase

An enzyme that catalyzes epimerization in tissues, such as converting galactose into glucose in the liver.

Ribose

The most important pentose sugar, derived from nucleic acids, which acts as a structural element of nucleic acids and coenzymes like $ATP$, $NAD$, and $NADP$.

Deoxyribose

A pentose sugar produced when a hydroxyl group is removed from carbon number two of a ribose sugar.

Ribulose

A pentose sugar formed in metabolic processes that acts as an intermediate in direct oxidative pathways of glucose breakdown, such as the pentose phosphate pathway.

Glucose

A hexose monosaccharide that serves as the main metabolic fuel for the brain, red blood cells, renal medulla, cornea, retina, and testis, and is the primary sugar present in human blood.

Glucuronic Acid

An acid formed when glucose undergoes oxidation in the body.

Sorbitol

An alcohol produced when glucose undergoes reduction.

Fructose

A hexose monosaccharide found in fruits, vegetables, and honey; it is the sweetest of all sugars and accumulates in fructose intolerance.

Galactose

A hexose sugar obtained from dairy products, synthesized in the mammary glands to form lactose, and found as part of galactolipids in nervous tissues.

Mannose

A hexose sugar obtained by hydrolyzing plant manosans and gums, serving as a constituent of prosthetic polysaccharides of albumin and globulins.

Sucrose

A key dietary disaccharide found in carrots and pineapples that hydrolyzes in the intestinal tract into glucose and fructose.

Maltose

A disaccharide (malt sugar) that yields two units of glucose upon hydrolysis by enzymes or acids.

Lactose

Milk sugar disaccharide that hydrolyzes into one unit of glucose and one unit of galactose.

Amylose

A constituent of plant starch granules that accounts for $20\%$ of starch.

Amylopectin

A constituent of plant starch granules that accounts for $80\%$ of starch.

Inulin

A polysaccharide found in onion and garlic bulbs used clinically in the evaluation of renal function because it is readily excreted through the kidneys.

Glycogen

The main storage polysaccharide in animals (animal starch), stored in the liver and muscles, containing alpha 1-4 linkages linearly and alpha 1-6 linkages at branch points.

Dextrins

Intermediary products of starch hydrolysis that form sticky, gummy masses used as mucilage.

Cellulose

The most abundant organic compound, making up $50\%$ or more of carbon vegetation, which acts as dietary roughage to promote bowel evacuation in humans.

Dextrans

Polysaccharides produced by microorganisms such as Leuconostoc dextranicum when grown on sugar media, recommended for use as blood extenders.

Salivary Amylase

An enzyme in the mouth that initiates carbohydrate digestion by breaking starches down into smaller sugar molecules.

Pancreatic Amylase

An enzyme produced by the pancreas that breaks down starches into simpler sugars inside the small intestine.

Cellulase

A bacterial enzyme capable of breaking down cellulose.

Peristalsis

The movement or contraction of intestinal muscles, stimulated by organic acids, alcohol, and carbon dioxide resulting from bacterial hydrolysis of pentosans.

Normal Blood Glucose Level

The physiological concentration of blood glucose ranging from $80\text{ to }120\,mg$ per $100\,ml$ of blood.

Hypoglycemia

A clinical state defined by blood glucose levels falling below $80\,mg$ per $100\,ml$ of blood.

Hyperglycemia

A clinical state defined by blood glucose levels exceeding $120\,mg$ per $100\,ml$ of blood.