Biological molecules

Monomer

The smaller units from which larger molecules are made

Polymer

Molecules made from a large number of monomers joined together

Condensation reaction

A reaction which joins two molecules together with the formation of a chemical bond; involves the elimination of water

Hydrolysis reaction

A reaction that breaks a chemical bond between two molecules; involves the use of a water molecule

How are polymers separated

Hydrolysis reaction

Which elements do all carbohydrates contain

C, H and O

3 functions of carbohydrates

1. Energy source (glucose in respiration)

2. Energy store ( starch in plants, glycogen in plants )

3. Structure (cellulose in cell walls of plants)

Bond formed between 2 monosaccharides by condensation reaction

Glycosidic

What is maltose made up of

Glucose + glucose

What is sucrose made up of

Glucose + fructose

What is lactose made up of

Glucose + galactose

How is a polysaccharide formed

When 2 or more monosaccharides are joined together by condensation reactions

Glycogen is formed by the condensation of

Alpha-glucose

Starch is formed by the condensation of

Alpha-glucose

Cellulose is formed by the condensation of

Beta-glucose

Polysaccharides present in starch

Amylose + amylopectin

How does the structure of glycogen relate to its function

• Long, highly branched chain of alpha-glucose (more branches than starch) - means that stored glucose can be released quickly, which is important for energy release

• Very compact molecule - can fit into a small space

• Insoluble - doesn't draw water into cells by osmosis and can't diffuse out of cells

How does the structure of amylose in starch relate to its function

Long, unbranched chain of alpha-glucose joined by 1-4 glycosidic bonds, which give it a coiled structure - compact, so good for storage

How does the structure of amylopectin in starch relate to its function

• Long, unbranched chain of alpha- glucose joined by 1-4 glycosidic bonds with branches formed by 1-6 glycosidic bonds

( branched structure rather than helical) - side branches create more ends to allow enzymes to access and hydrolyse glycosidic bonds easily, so glucose can be released quickly

• Insoluble in water - doesn't affect water potential, so cells don't swell

How is glycogen more highly branched than starch

• Glycogen found in animals, whereas starch found in plants

• Animals have a higher metabolic rate, and therefore a higher respiratory rate, than plants. This is because they are more active

• Lots of side branches mean enzymes can access more glycosidic bonds at the same time, meaning the glycogen is broken down to form glucose monomers more rapidly

How is the structure of cellulose suited to its function of providing support

• Cellulose is made up of beta-glucose and so forms straight, unbranched chains

• These cellulose chains run parallel to each other and are linked together by many hydrogen bonds, which add collective strength (hydrogen bonds aren't strong themselves)

• Cross-linked cellulose chains are grouped together to form microfibrils, which in turn are grouped to form fibrils, this provides more strength

Give ways in which the structure of starch is similar to cellulose

• Both polymers/polysaccharides / made of monomers

• Both contain glucose

• Both contain glycosidic bonds

• Both have hydrogen bonding within structure