Carbohydrates Flashcards
What are simple carbohydrates?
Sugars composed of a single sugar molecule (a monosaccharide) or two joined sugar molecules (a disaccharide)
Simple carbohydrates are the most basic form of carbohydrates.
Define monosaccharides.
Sugars that are not broken down further during digestion with the general formula CnH2nO, where n = 3 to 7
Common monosaccharides include glucose, fructose, and galactose.
What are disaccharides?
Carbohydrates composed of two monosaccharide units linked by a glycosidic bond
Examples include sucrose, lactose, and maltose.
What is glucose?
A common monosaccharide containing six carbons, also known as dextrose or blood sugar
It is a component of sucrose, lactose, and maltose.
What is fructose?
A common monosaccharide containing six carbons, naturally present in honey and many fruits
Also referred to as levulose or fruit sugar.
What is galactose?
A monosaccharide containing six carbons that can be converted into glucose in the body
It usually joins with other monosaccharides in foods and living systems.
What are pentoses?
Sugar molecules containing five carbon atoms.
What are sugar alcohols?
Compounds formed from monosaccharides by replacing a hydrogen atom with a hydroxyl group (–OH)
Commonly used as nutritive sweeteners, also called polyols.
Define condensation in chemistry.
A reaction in which a covalent bond is formed between two molecules by removal of a water molecule.
What is sucrose?
A disaccharide composed of one molecule of glucose and one molecule of fructose
Commonly known as table sugar.
What is lactose?
A disaccharide composed of glucose and galactose, also known as milk sugar.
What is maltose?
A disaccharide composed of two glucose molecules, sometimes called malt sugar
Maltose is formed whenever long molecules of starch break down.
Define complex carbohydrates.
Chains of more than two monosaccharides, which may be oligosaccharides or polysaccharides.
What are oligosaccharides?
Short carbohydrate chains composed of 3 to 10 sugar molecules.
What are prebiotics?
Group of compounds that promote growth and activity of beneficial bacteria in the host organism.
Define microbiota.
Community of beneficial and pathogenic microorganisms that inhabit the body.
What are polysaccharides?
Long carbohydrate chains composed of more than 10 sugar molecules
They can be straight or branched.
What is starch?
The major storage form of carbohydrate in plants, composed of long chains of glucose molecules.
Define amylose.
A straight-chain polysaccharide composed of glucose units.
What is amylopectin?
A branched-chain polysaccharide composed of glucose units.
What is resistant starch?
A starch that is not digested.
Define glycogen.
A highly branched polysaccharide composed of multiple glucose units, the primary storage form of glucose in animals.
What is dietary fibre?
Carbohydrates and lignins that are non-digestible and not absorbed in the human small intestine.
What is functional fibre?
Isolated non-digestible carbohydrates with beneficial effects in humans.
Define total fibre.
The sum of dietary fibre and functional fibre.
What is soluble fibre?
Non-digestible carbohydrates that dissolve in water.
What is insoluble fibre?
Non-digestible carbohydrates that do not dissolve in water.
Define cellulose.
A straight-chain polysaccharide composed of hundreds of glucose units linked by beta bonds
It is non-digestible by humans and a component of dietary fibre.
What are hemicelluloses?
A group of large polysaccharides in dietary fibre that are fermented more easily than cellulose.
What are pectins?
Type of dietary fibre found in fruits.
What are gums?
Dietary fibres found between plant cell walls and contain galactose and other monosaccharides.
What are mucilages?
Gelatinous soluble fibres found in seaweed.
What is psyllium?
The dried husk of the psyllium seed.
Define lignins.
Insoluble fibres composed of multi-ring alcohol units, the only noncarbohydrate component of dietary fibre.
What are β-glucans?
Functional fibre consisting of branched polysaccharide chains of glucose, helping lower blood cholesterol levels.
What is chitin?
A long-chain structural polysaccharide of slightly modified glucose found in the hard exterior skeletons of insects and fungi.
What is chitosan?
Polysaccharide derived from chitin.
What is pancreatic amylase?
Starch-digesting enzyme secreted by the pancreas.
True or False: Alpha (α) bonds can be broken by human intestinal enzymes.
True.
True or False: Beta (β) bonds can be broken by human intestinal enzymes.
False.
Where does carbohydrate digestion primarily take place?
In the small intestine.
What are ketone bodies?
Molecules formed when insufficient carbohydrate is available to completely metabolise fat.
Define ketosis.
Abnormally high concentration of ketone bodies in body tissues and fluids.
What is the function of insulin?
Stimulates the uptake of blood glucose into muscle and adipose cells and the synthesis of glycogen in the liver.
What does glucagon do?
Promotes the breakdown of liver glycogen to glucose, increasing blood glucose levels.
What is the glycemic index?
A measure of the effect of food on blood glucose levels.
What is diabetes mellitus?
A chronic disease in which uptake of blood glucose by body cells is impaired, resulting in high glucose levels in the blood and urine.
