carbohydrates

What is the general formula for monosaccharides?

(CH2O)n

What is the formula for all hexose sugars?

C6H12O6

Give an example of a triose sugar and the formula

Glyceraldehyde C3H6O3

Give 2 examples of pentose sugars and the formula

Ribose, deoxyribose C5H10O5

Give 4 examples of hexose sugars and formula

a-glucose, b-glucose, fructose and galactose C6H12O6

What are the two isomers of glucose?

Alpha (a) and beta glucose

What is the structure of alpha glucose?

What is the structure of beta glucose?

What is the structural difference between alpha and beta glucose

Alpha- OH group is below C1

Beta- OH group is above C1

ABBA to remember

What can be the functions of monosaccharides?

• Energy source in respiration

• Building blocks for larger molecules

• Intermediates in reactions

• Constituents of nucleotides

What bond is formed between glucose molecules?

Glycosidic bond

Between which carbons does a glycosidic bond form?

C1 and C4

Which two molecules make a maltose molecule in a condensation reaction

a-glucose + a-glucose

Which two molecules form a sucrose molecule in a condensation reaction?

Glucose + fructose

Which two molecules form a lactose molecule in a condensation reaction?

Glucose + galactose

What is the biological role of maltose?

In germinating seeds

What is the biological role of sucrose?

Transport in phloem of flowering plants

What is the biological role of lactose?

In mammalian milk

What monomers make up starch?

a-glucose

What is the main function of starch in plants?

Glucose store

What two polymers make up the polysaccharide starch?

Amylose and amylopectin

Describe the structure of amylose

Linear, unbranched

What bonds are present in amylose?

a-1-4 glycosidic only

What shape does amylose form?

A chain which coils into an alpha helix structure

Describe the structure of amylopectin

Branched

What bonds are present in amylopectin?

a-1-4 glycosidic bonds between adjacent glucose monomers and a-1-6 glycosidic bonds that cross-link monomers

What is the function of glycogen in animals?

Main glucose store

Where is cellulose found in a plant cell?

Cell walls

What monomers make up cellulose?

Beta glucose

Describe the structure of cellulose

Long, parallel chains (of b-glucose)

What bonds are present in cellulose?

B-1-4 glycosidic bonds

What happens to the glucose monomers in cellulose due to the b-link and what does this allow to happen?

They are rotated 180° and this allows hydrogen bonds to form between the -OH groups of adjacent parallel chains

What is the name for bundles of 60-70 cellulose molecules that are tightly cross-linked?

Microfibrils

What is the name for bundles of microfibrils?

Fibres

Describe the permeability of cellulose and why this is useful

Cellulose fibres are freely permeable, because there are spaces between the fibres. This allowed water and its solutes to penetrate the cell wall to the cell membrane.

What monomers make up chitin?

B-glucose with some -OH groups replaces by nitrogen- containing acetylamine groups

Where is chitin found in insects and fungi?

Insect exoskeletons and fungi cell walls

How are cellulose and chitin structurally similar?

Both consist of adjacent molecules twisted 180° which allows hydrogen bonds to form between chains and forms microfibrils