Natural Polymers

Question 1

How many H bonds are formed between A and T?

Answer 1

2

Question 2

How many H bonds are formed between C and G?

Answer 2

3

Question 3

Differences between DNA and RNA

Answer 3

• double v single stranded
• deoxyribose vs ribose
• thymine vs uracil

Question 4

Examples of proteins (polymers of amides)

Answer 4

• enzymes
• haemoglobin
• collagen

polyamides

Question 5

Enzymes

Answer 5

natural catalysts - speeding up chemical processes

Question 6

Haemoglobin

Answer 6

carries oxygen in the blood

Question 7

Collagen

Answer 7

• strong/ tough material making up skin and nails, as well as hold internal organs in place
• it has great tensile strength
• three strands of amino acids interlock under tension

Question 8

What are the amide links between amino acid residues called?

Answer 8

peptide bonds

Question 9

Properties of amino acids

Answer 9

• optically active / chiral
• nature only uses left hand enantiomer of amino acids
• only one of two possible stereoisomers form so natural polypeptides form helical structures

Question 10

How are chains of amino acids stabilised?

Answer 10

the helical conformations increase stability of the polypeptides and the helix is stabilised by H bonding between amine and carbonyl groups of same polypeptide chain

Question 11

Primary protein structure

Answer 11

sequence of a chain of amino acids

Question 12

Secondary protein structure

Answer 12

local folding of the polypeptide chain into helices or sheets

Question 13

Tertiary protein structure

Answer 13

3D folding pattern of a protein due to side chain interactions

Question 14

Quaternary protein structure

Answer 14

protein consisting of more than one amino acid chain

Question 15

Denaturation of proteins

Answer 15

the disruption and possible destruction of both the secondary and tertiary structures

Question 16

How does denaturation work?

Answer 16

disrupts the normal α-helix and β-sheets in a protein and causes the unravelling into a random shape/coil

• it occurs because the intramolecular H bonding interactions are disrupted

Question 17

What causes denaturation?

Answer 17

• heat
• pH changes
• addition of salts
• changing solvent (it changes hydrogen bonding)

Question 18

What are examples of natural polymers?

Answer 18

• starch
• cellulose

(made up from sugar molecules) - polysaccharides

Question 19

What monomer is starch and cellulose formed from?

Answer 19

glucose

α-D-glucose = starch
β-D-glucose = cellulose

Question 20

What type of polymer is cellulose?

Answer 20

straight chain polymer - no coiling and molecule adopts an extended rod-like conformation

• optimises hydrogen bonding (intermolecular and intramolecular)
• completely insoluble in water

Question 21

What two type of molecules does starch consist of?

Answer 21

• amylose
• amylopectin

Question 22

What structure does an amylose fraction form?

Answer 22

a spiral due to H bonding

the spiral can bind to itself to form a double helix or bind to something else

Question 23

Properties of amylose

Answer 23

• pure amylose is insoluble in water (very strong inter- and intramolecular H bonding) so enzyme degradation is very slow
• often the minor component of starch

Question 24

Properties of amylopectin

Answer 24

• water soluble
• subject to rapid enzymatic degradation due to large number of chain ends and less chain packing

Question 25

How is starch broken down in the body?

Answer 25

amylase enzymes to break down starch into glucose to fuel the body