2.3 Carbohydrates and lipids

Question 1

Carbohydrates and lipids are organic compounds and are mostly composed of three types of atom:

Answer 1

carbon, hydrogen and oxygen

Question 2

What is Glucose?

Answer 2

Monosaccharides are the simplest types of carbohydrates. The number of carbon atoms can be from three to seven. The carbons are joined to a hydroxyl group (-OH). Some examples are: ribose, glucose, fructose and galactose.

Question 3

Condensation reaction

Answer 3

Condensation reaction refers to the reaction in which two smaller organic molecules combine to form a larger molecule and a molecule of water or some other simple molecule.

Question 4

hydrolysis.

Answer 4

This is a chemical reaction in which water is used to break down the bonds of big compounds.

Question 5

Two monosaccharide monomers are linked together by a ___ reaction which forms a ___ bond

Answer 5

Two monosaccharide monomers are linked together by a condensation reaction which forms a glycosidic bond

Question 6

Isomers definition

Answer 6

They have the same chemical formula but a slightly different arrangement of the atoms.

Question 7

Sucrose is

Answer 7

Disaccharide, glucose and fructose

Question 8

Maltose is

Answer 8

Disaccharide, glucose (2 units)

Question 9

Lactose is

Answer 9

Disaccharide, glucose and galactose

Question 10

Starch is

Answer 10

Polysaccharide, glucose

Question 11

Glycogen is

Answer 11

Polysaccharide, glucose

Question 12

Cellulose is

Answer 12

Polysaccharide, glucose

Question 13

Monosaccharides

polarity, example, source and use

Answer 13

They are polar and soluble in water.
Glucose, ribose, fructose and galactose
Fructose is a sugar found in fruits and honey.
Galactose is a sugar in milk.

Question 14

Disaccharides

polarity, example, source and use

Answer 14

They are polar and soluble in water.
Maltose, lactose, sucrose
Maltose (glucose + glucose) is found in grains.
Sucrose (glucose + fructose) is found in sugar cane and sugar beets.
Lactose (glucose + galactose) is found in mammalian milk.

Question 15

Polysaccharides

polarity, example, source and use

Answer 15

Not all are polar and soluble in water.
Cellulose is the structural component of plant cell walls.
Starch forms energy stores in plants (e.g potatoes and cassava).
Glycogen is the storage form of carbohydrate. It is found in animals in the liver and muscles.

Question 16

Arrangement of glucose molecules

two kinds

Answer 16

linear, which is called amylose

branched, which is called amylopectin

Question 17

Usage of Starch

Answer 17

used to store energy. Other than storing energy, polysaccharides can also be used as a structural component. (think of cellulose present in plant cells gives the walls extra strength and protects the cell from over-expanding and bursting, as well as storing enough energy to be a source for biofuels.)

Question 18

How do starch and cellulose differ?

Answer 18

Starch and cellulose are both made up of the same monomer, glucose, but they differ in the arrangement of glucose molecules and position of the glycosidic bonds.
-In starch molecules, all glucose monomers are oriented in the same direction. In contrast, cellulose molecules are made up of glucose monomers that rotate 180 degrees around the backbone chain.

Question 19

Triglycerides are formed by ___ reactions between one ___ and ____ fatty acids, creating ___ bonds.

Answer 19

Triglycerides are formed by condensation reactions between one glycerol and three fatty acids, creating ester bonds.

Question 20

saturated fatty acid

Answer 20

A saturated fatty acid has no double bonds between any of the carbon atoms that make up the hydrocarbon chain.

Question 21

unsaturated fatty acid

Answer 21

An unsaturated fatty acid can be monounsaturated if it has just one double bond and, logically, a polyunsaturated fatty acid has two or more double bonds in its hydrocarbon chain. Unsaturated fatty acids can be either cis or trans isomers depending on the position of the two hydrogen atoms around the carbon–carbon double bond (see below).

Question 22

Why is glycogen used in animals over glucose?

Answer 22

Glycogen is the carbohydrate used for energy storage in animals. It is stored in the liver and muscles, and can be easily broken down (compared to lipids) to glucose, a form in which it can be rapidly transported around the body for use in cellular respiration. Thus, energy stored in glycogen is more accessible than the energy stored in fat.

Question 23

Key properties of lipids

Answer 23

Energy Content: More energy per gram than carbohydrates or proteins. Carbohydrates 17   kJ/g. Fats 37   kJ/g.
Density: Less dense (specific gravity) than water; oil floats on water.
Solubility:Non-polar, so will dissolve other non-polar compounds, but does not affect the movement of water.
Insulation:Excellent heat insulation; think of whale blubber.
Waterproof: Lipids are water-insoluble and provide a waterproof layer in plants and animals.

Question 24

Capillary Action

Answer 24

which is defined as the movement of water molecules and all the things that are dissolved in it within thin spaces without relying on gravity.