Carbohydrates and Lipids (2.3)

Question 1

Monosaccharides

Answer 1

Carbohydrates composed of recurring monomers. One sugar unit.

Question 2

Examples of monosaccharides

Answer 2

Glucose C₆H₁₂O₆
Fructose C₆H₁₂O₆
Galactose C₆H₁₂O₆
Ribose C₅H₁₀O₅

Question 3

Disaccharides

Answer 3

Two monosaccharide monomers joined with a glycosidic bond form a disaccharide. Two sugar units.

Question 4

Examples of disaccharides

Answer 4

Sucrose (glucose + fructose)
Lactose (galactose + glucose)
Maltose (two glucose monosaccharides)

Question 5

Polysaccharides

Answer 5

Many monosaccharide monomers joined with a glycosidic bond form polysaccharides. Many sugar units.

Question 6

Examples of polysaccharides

Answer 6

Starch (alpha D glucose subunits)
Glycogen (alpha D glucose subunits)
Cellulose (beta D glucose subunits)

Question 7

What are condensation reactions and how do they work?

Answer 7

A reaction that joins together two monosaccharides.

A condensation reaction is where a molecule of water is removed. This joins the two glucose units together, forming the glycosidic bond. So a condensation reaction joins together two monosaccharides to form a disaccharide.

Question 8

What are hydrolysis reactions and how do they work?

Answer 8

A reaction that splits a disaccharide into two monosaccharides.

A hydrolysis reaction is where a molecule of water is added. This breaks the glycosidic bond, splitting the disaccharide into two monosaccharides. So a hydrolysis reaction splits a disaccharide into its monosaccharide units.

Question 9

Triglycerides

Answer 9

A type of lipid composed of three fatty acids joined to a glycerol. Triglycerides can be saturated or unsaturated depending on the composition of the fatty acid chains.

Question 10

Saturated fatty acids

Answer 10

All the covalent atoms in the chain are connected with single covalent bonds. Maximum number of hydrogen atoms. Solid at room temperature.

Question 11

Unsaturated fatty acids

Answer 11

There are one or more double bonds. Liquid at room temperature.

Mono-unsaturated (only one double bond)
Poly-unsaturated (two or more double bonds)

Question 12

Unsaturated fatty acids structural configuration

Answer 12

Cis: The hydrogen atoms attached to the carbon double bond are on the same side.
Trans: The hydrogen atoms attached to the carbon double bond are on different sides.

Question 13

Health effects of lipids

Answer 13

Saturated and trans unsaturated fats increase cholesterol in blood, which can result in coronary heart disease, the leading cause of death in the United States.

Cis unsaturated fats lower cholesterol in blood.

Question 14

Phospholipids

Answer 14

A type of lipid composed of two fatty acids, glycerol and a phosphate group. Partly hydrophobic.

Question 15

Energy storage

Answer 15

Carbohydrates are soluble in water and easy to digest but they store less energy per gram.

Lipids are insoluble in water and harder to digest but they store more energy per gram.

Question 16

Condensation and hydrolysis reactions in lipids

Answer 16

In condensation reactions, glycerol and fatty acids are joined by removing a molecule of water to make a glyceride (lipid).

In hydrolysis reactions, a water molecule is added and provides the hydrogen and hydroxyl group to break the bond.

Question 17

Body Mass Index (BMI)

Answer 17

Body mass index = weight (in kg) / height² (in m)