Carbs (1.12 & 1.13)

Question 1

Draw the structural formula for alpha glucose

Answer 1

CH2OH
|
H C——————O. H
| / |. \ |
C. H. C
|. . OH. H / |
OH. |. | /. OH
C—————C
|. |
H. OH

Question 2

Define the terms monosaccharide, disaccharides and polysaccharide

Answer 2

MONOSACCHARIDES: single molecule of simple sugars
DISACCHARIDES: two monosaccharides joined together by a glycosidic bond
POLYSACCHARIDES: multiple monosaccharides joined together by multiple glycosidic bonds

Question 3

Explain how the structure and properties of starch makes it a suitable storage molecule

Answer 3

Starch is a good energy storage molecule as due to its shape (amylopectin = branch and amylose =spiral) allows it to remain compact allowing large amounts to be stored. As well as this, amylose and amylopectin are not very soluble so doesn’t affect osmotic effect of cells.

Question 4

Explain how the structure and properties of glycogen makes it a suitable storage molecule

Answer 4

Glycogen has a structure adapted for storage and fast breakdown. Glycogen has more branches than amylopectin, with terminal glucoses on the ends, which can be easily broken down for glucose. It also doesn’t affect the osmotic balance of cells.

Question 5

Explain how monosaccharides react together to form disaccharides

Answer 5

A condensation reaction between two monosaccharides occurs in order for the formation of a disaccharide. This reaction forms a glycosidic bond between the two monosaccharides and removes water (a hydrogen from one molecule and a hydroxide from the other)

Question 6

Explain how monosaccharides react together to form polysaccharides, specifically amylose and amylopectin

Answer 6

Monosaccharides are joined with glycosidic bonds through a condensation reaction to form a polysaccharide chain. It is through the bonding of multiple a-glucose molecules are amylopectin and amylose formed.
Amylose hydrogen bonding = spiral shape (six glucose units per turn)
Amylopectin difference with a-1,4 and a-1,6 results in branching

Question 7

Explain how disaccharides/polysaccharides are broken down to form monosaccharides

Answer 7

Poly and disaccharides are broken down to form monosaccharides through a hydrolysis reaction in which water is added. This adds back the hydrogen and hydroxide that was taken out originally to form the glycosidic bond

Question 8

State the monomers that make up the following disaccharides: sucrose, lactose and maltose

Answer 8

SUCROSE: glucose + fructose
LACTOSE: glucose + galactose
MALTOSE: glucose + glucose