2. Condensation reactions of carbohydrates

Question 1

When two monosaccharides undergo a condensation reaction, a what is formed?

Answer 1

Disaccharide.

Question 2

During this reaction, the hydroxy group of one monosaccharide combines with the hydrogen of another monosaccharide.

This covalent bond is called a what?

Answer 2

Glycosidic bond, and can be of the alpha (⍺) or beta (β) type.

Question 3

The three monosaccharides (glucose, fructose and galactose) can all undergo condensation reactions with each other to form which three common types of disaccharides?

Answer 3

Maltose, sucrose and lactose.

Question 4

Maltose is the end-product of starch digestion in the human gut.

It is also found in malted barley. Maltose is formed from a condensation reaction between two what?

Answer 4

Glucose monomers.

Question 5

Sucrose is also known as what?

Answer 5

Table sugar.

Question 6

How is sucrose formed?

Answer 6

Sucrose is formed from a condensation reaction between a glucose and fructose monomer.

Question 7

You might already know that lactose is found in milk, and that some people are intolerant to this disaccharide.

Lactose is formed from a condensation reaction between what?

Answer 7

A galactose and glucose monomer.

Question 8

Condensation reactions between monosaccharides doesn’t necessarily end with the formation of a disaccharide.

Reactions with further monosaccharides can produce a type of polymer called a polysaccharide. Large numbers of monosaccharides undergo condensation reactions to form a polysaccharide.

Polysaccharides are often called what?

Answer 8

Complex carbohydrates.

Question 9

Unlike monosaccharides and disaccharides, polysaccharides are generally what?

Answer 9

Insoluble and tasteless.

Question 10

What are 3 common types of polysaccharides?

Answer 10

Starch, glycogen and cellulose.

Question 11

What do plants produce as a mechanism to store glucose?

Answer 11

Starch.

Question 12

Starch is found in the seeds and fleshy part of fruit and vegetables. Plants are able to produce and polymerise ⍺-glucose molecules to produce the condensation polymer, starch.

All plants store starch so that it can be metabolised to produce energy. When required, plants are able to break down starch into what?

Answer 12

Glucose.

Question 13

Two forms of starch exist. These are what?

Are they soluble in water?

Answer 13

Amylose and amylopectin. Amylopectin is soluble in water.

Question 14

What is formed from excess glucose stored in the liver and muscle tissues of animals?

Answer 14

Glycogen.

Question 15

When energy is depleted (such as when you forget to have breakfast), glycogen can be broken back down to glucose, which can then be used in what?

Answer 15

Cellular respiration.

Question 16

What is the main structural component of plant cell walls?

Answer 16

Cellulose.

Question 17

Cellulose is the most common carbohydrate and organic molecule, formed from a condensation reaction between ꞵ-glucose monomers.

We are unable to digest cellulose, since we lack the enzyme that breaks down the ꞵ-glucose C1-C4 glycosidic link. Only a few animals, such as what, contain bacteria that are able to digest cellulose.

Answer 17

Horses and cows.