2.1.2 - Carbohydrates

Question 1

Glucose

Answer 1

• C6H12O6
• Hexose sugar
• 6 carbons

Question 2

Functions of glucose

Answer 2

• Source of energy in respiration

- Building block for larger carbohydrates

Question 3

Properties of glucose

Answer 3

• Small : Easily transported in and out of cells through carrier proteins
• Soluble : Easily transported around an organism through the blood
• Less reactive than other monosaccharides : Breakdown must be catalysed

Question 4

Isomers

Answer 4

Molecules which have the same chemical formula but a different arrangement of atoms in space

Question 5

Alpha glucose

Answer 5

OH on Carbon-1 below the plane of the ring

Question 6

Beta glucose

Answer 6

OH on Carbon-1 above the plane of the ring

Question 7

Monosaccharide

Answer 7

Monosaccharides are the simplest carbohydrates, consisting of only one sugar molecule

Question 8

Disaccharide

Answer 8

Disaccharides are sugars that are composed of two monosaccharides joined together in a condensation reaction

Question 9

Polysaccharide

Answer 9

Polysaccharides are polymers made up of many sugar monomers

Question 10

Ribose

Answer 10

• Pentose monosaccharide
• C5H10O5
• Found in RNA and ATP

Question 11

Maltose

Answer 11

Alpha glucose and alpha glucose

Question 12

Sucrose

Answer 12

Alpha glucose and fructose

Question 13

Lactose

Answer 13

Beta glucose and galactose

Question 14

Synthesis of disaccharides

Answer 14

• Joined together in a condensation reaction
• Produces water and a disaccharide
• Glycosidic bond formed in the disaccharide

Question 15

Condensation reaction

Answer 15

A chemical process in which two molecules combine to form a more complex molecule with the removal of water

Question 16

Glycosidic bond

Answer 16

Covalent bond formed between two monosaccharides through a condensation reaction

Question 17

Hydrolysis reaction

Answer 17

The breakdown of a molecule into two smaller molecules requiring the addition of a water molecule.

Question 18

Breakdown of disaccharides

Answer 18

• Broken down by hydrolysis reaction
• Forms a monosaccharide
• Water has to be added

Question 19

Starch (Structure)

Answer 19

• Consists of two different types of polysaccharides: amylose, amylopectin

Question 20

Amylose

Answer 20

• Source : Plant cells
• Subunit : Alpha glucose
• Bonds : 1-4 glycosidic bonds
• No branches

Question 21

Amylopectin

Answer 21

• Source : Plant
• Subunit : Alpha glucose
• Bonds : 1-4 and 1-6 glycosidic bonds
• Branches : Yes

Question 22

Starch (Function)

Answer 22

• The function of starch is to store energy in plants.
• It is helix shaped so it is compact and more energy can be stored in a small space
• It is branched, so starch can be readily hydrolysed back into glucose

Question 23

Glycogen (Structure)

Answer 23

• Source : Animal cells
• Subunits : Alpha glucose
• Bonds : 1-4 and 1-6 glycosidic bonds
• Branched : Yes

Question 24

Glycogen (Function)

Answer 24

• It is insoluble, branched and compact
• The function of glycogen is to store energy in animals and fungi
• It is more coiled than amylopectin. The coiling and branching makes it compact, so more energy can be stored.
• Branching means that there are many free ends where glucose molecules can be added or removed. Animals require quick release of energy, that is why glycogen is more branched than amylopectin

Question 25

Cellulose (Structure)

Answer 25

• Source : Plant cells
• Subunit : Beta glucose
• Bonds : 1-4 glycosidic bonds
• Branches : No
• Alternate beta glucose molecules are turned upside down
• Straight and unbranched

Question 26

Cellulose (Function)

Answer 26

• Cellulose is used to make cell walls
• Cellulose -> Microfibrils -> Macrofibrils -> Fibres
• Cellulose has a high tensile strength preventing plant cells from bursting