Carbohydrates

Question 1

What are monosaccharides?

Answer 1

Monosaccharides are the basic sub-units (i.e. monomers) of carbohydrates

Question 2

What is the main function of monosaccharides?

Answer 2

Monosaccharides are sources of energy. For example, glucose is broken down in the human body to produce ATP.

Question 3

What are three examples of monosaccharides

Answer 3

1. Glucose
2. Fructose
3. Galactose

Question 4

What are disaccharides?

Answer 4

Pairs of monosaccharides linked together by condensation are known as disaccharides.

Question 5

What is the main function of disaccharides?

Answer 5

Provide a quick source of energy as they can be easily digested. Thus, it can be said that disaccharides are the transport form of carbohydrates.

Question 6

What are three examples of disaccharides?

Answer 6

1. Glucose + Glucose => Maltose + H2O
2. Glucose + Galactose => Lactose + H2O
3. Glucose + Fructose => Sucrose + H2O

Question 7

What are polysaccharides?

Answer 7

Long chains of monosaccharides; the polymer form of carbohydrates

Question 8

What is cellulose?

Answer 8

• Cellulose is a structural polysaccharide found in cells
• It is a linear molecules composed of beta-glucose subunits
• Beta-glucose alternates (adjacent monomers are flipped 180 degrees) to form cellulose, thereby forming a straight chain
• Indigestible for most animals as they lack the enzyme to break it down

Question 9

Where is cellulose used?

Answer 9

Since they are unbranched, they can bundle up (cellulose microfibrils) giving cellulose a high tensile strength. Due to high tensile strength, cellulose is used as the basis of plant cell walls (prevents cell from bursting)

Question 10

What is starch?

Answer 10

• Starch is an energy storage polysaccharide found in plant cells
• It is a helical molecules (as adjacent subunits do not alternate in orientation) composed of alpha-glucose subunits

Question 11

What are the 2 forms of starch?

Answer 11

1. Amylose is the unbranched form of starch and has 1,4 linkages
2. Amylopectin has some 1,6 linkages and so is a branched molecules

Question 12

What is glycogen?

Answer 12

• Energy storage polysaccharide formed in animals

- Similar in structure to amylopectin, except it is more branched

Question 13

What are the 2 main functions of polysaccharides?

Answer 13

1. Structural Components
   
   • Example: Cellulose
2. Energy Storage
   
   • Glucose is stored as starch in plants and glycogen
     in animals
   • Starch and glycogen are insoluble due to their
     large nature, thereby preventing excess water to
     enter the cells by osmosis