Biological Molecules

Question 1

What are monomers

Answer 1

Molecules that ca be linked together to form long chains.

Question 2

What are polymers

Answer 2

Long chains of monomer sub-units.

Question 3

What are the properties of carbon

Answer 3

• Forms long chains
• 4 covalent bonds
• Can bond with other chain/rings of carbon and gain other properties

Question 4

What are the monomers of carbohydrates

Answer 4

Monosacchrides such as
glucose
fructose
galactose

Question 5

What are polymers of carbohydrates

Answer 5

Polysacchrides such as
starch
cellulose

Question 6

How many forms of carbohydrates are there

Answer 6

3
Monosacchrides
Disacchrides ( sucrose, maltose and lactose)
Polysacchrides

Question 7

What are isomers

Answer 7

Compounds with the same molecular formula but different molecular arrangement

Question 8

What are the isomers of glucose

Answer 8

Alpha glucose

Beta glucose

Question 9

What are the structures of alpha and beta glucose

Answer 9

.

Question 10

Product of condensation of alpha glucose molecules

Answer 10

Starch and Glycogen

Question 11

Properties of starch

Answer 11

• Made of 80% amylopectin and 20% amylose
• Insoluble (doesnt affect water potential)
• Metabolically inactive
• Branches to give easy access to glucose
• Amylose makes it compact which makes it more suitable for storage

Question 12

Glycosidic bonds for amylose and amylopectin

Answer 12

• 1,4

Question 13

Properties of glycogen

Answer 13

• Condensation of Alpha glucose molecules
• Same structure as starch
• Insoluble (doesn’t affect water potential)
• Higher metabolic rate than starch which means that the respiratory rate can increase. it is therefore broken down more rapidly that starch

Question 14

Cellulose

Answer 14

• Condensation of Beta glucose moleules
• Glucose molecules forms straight chains of 10,000 of glucose molecules
• The chains form hydrogen bonds which form cross links.
• Provides strength
• Grouped to form microfibrils to provide more strength

Question 15

What are the monomers of lipids

Answer 15

monomer: fatty acid and glycerol
polymers: fats

Question 16

Properties of lipids

Answer 16

• Insoluble in water
• Soluble in ethanol
• Stores energy
• Used for insulation
• Used for making biological membranes
• Acts as a hormone

Question 17

What does a triglyceride look like

Answer 17

1 glycerol molecule and 3 fatty acids

Question 18

What bond does it form?

Answer 18

Ester bond

Question 19

Why are polyunsaturated chains more liqiud

Answer 19

The double bonds push the carbon atoms apart which alter their shape; making it more liquid

Question 20

What are the properties of triglycerides

Answer 20

• Excellent energy storage
• Low mass to energy ratio ( much energy can be stored in a small volume)
• Non-polar (insoluble)
• Release water when oxidised (important source of water

Question 21

What does a phospholipid look like

Answer 21

phosphate group, 2 fatty acids and 1 glycerol
hydrophilic head
hydrophobic tail

Question 22

What are the properties of phospholipids

Answer 22

• Combine with carbohydrates to form glycolipids. This is important for cell recognition
• Hydrophilic head hold the surface membrane together
• They are polar

Question 23

What is the test for lipids

Answer 23

Emulsion test

1. Put food sample into a test tube
2. Add ethanol to the sample
3. Shake the test tube thoroughly
4. Add water and shake gently
5. Cloudy white colour indicates the presence of lipids

Question 24

What are the monomers of proteins

Answer 24

Amino acids

Question 25

What is the polymer of proteins

Answer 25

Polypeptide

Question 26

What are the products of the condensation reaction of 2 polypeptides

Answer 26

Dipeptide+water

Question 27

What bond holds the dipeptides together

Answer 27

peptide bonds

Question 28

Explain the primary structure of a protein

Answer 28

It is a sequence of amino acids in a polypeptide chain formed by enzyme catalysed condensation reactions. it decides the ultimate shape and hence its function . A single change can give it a complete different function.

Question 29

Explain the secondary structure of a protein

Answer 29

Hydrogen bonds start to form between the amino acids. This automatically makes the chain coil into a alpha helix or a beta pleated sheet.

Question 30

Explain the teriary structure of a protein

Answer 30

The chain is coiled or pleated even further and more bonds form between different parts of the polypeptide chain. This forms a 3D structure. The chain is held together by 4 bonds *ionic bonds hydrogen bonds *hydrophilic and hydrophobic bonds *disulphid bond ( 2 cysteine amino acids form a strong double bond between the sulfur atoms)

Question 31

Explain the tertiary structure of a protein

Answer 31

The chain is coiled or pleated even further and more bonds form between different parts of the polypeptide chain. This forms a 3D structure. The chain is held together by 4 bonds *ionic bonds hydrogen bonds *hydrophilic and hydrophobic bonds *disulphid bond ( 2 cysteine amino acids form a strong double bond between the sulfur atoms)

Question 32

Explain the Quaternary structure of a protein

Answer 32

It arises from a combination of number of different polypeptide chains and some non protein groups to form a large complex protein molecule. e.g haemoglobin

Question 33

What is the test for proteins

Answer 33

Biuret test 1 1. Add biurets regent to a food sample 2. Observe colour change 3. Purple means that protein is present

Question 34

What is a Globular protein

Answer 34

Globular proteins are ball shaped proteins with a compact structure. Examples include enzymes, storage proteins and receptors. They contain hydrophobic parts which face towards the center and hydrophilic parts which face the edges.This makes them soluble.

Question 35

Fibrous proteins

Answer 35

They have a very thin and long structure. They tend to have structural functions such as collagen, keratin and actin. They are always composed of many polypeptide chains . They are also insoluble in water.