1 Biological Molecules and Enzymes

Question 1

Polar Molecule

Answer 1

A molecule with an uneven distribution of charge

Question 2

Polymerisation

Answer 2

The process by which monomers join to form long molecules called polymers

Question 3

Monomer of a polysaccharide

Answer 3

monosaccharide or single sugar e.g. glucose

Question 4

Monomer of a polynucleotide

Answer 4

mononucleotide

Question 5

Monomer of polypeptides

Answer 5

amino acids

Question 6

Condensation reaction

Answer 6

reaction that produces water

Question 7

Hydrolysis reaction

Answer 7

breaking down a polymer with the addition of water

Question 8

Examples of monosaccharides

Answer 8

Glucose, galactose, fructose

Question 9

Draw isomers of glucose

Answer 9

Alpha = H at top, OH at the bottom

Beta OH at the top, H at the bottom

Question 10

Reducing sugar

Answer 10

All monosaccharides and some disaccharides with the ability to donate an electron to reduce another chemical

Question 11

Test for reducing sugar

Answer 11

-Add food sample.
-Add equal volume of Benedict’s reagent.
-Heat gently in water bath.
Blue - No sugar
yellow >orange > red - Increasing amount of sugar

Question 12

Bond between monosaccharides

Answer 12

Condensation reactions

GLYCOSIDIC bonds

Question 13

Glucose + Glucose

Answer 13

Maltose

Question 14

Glucose + Fructose

Answer 14

Sucrose

Question 15

Glucose + Galactose

Answer 15

Lactose

Question 16

Test for non reducing sugar

Answer 16

• Benedict’s test.
• then add 2cm of dilute HCl and heat in boiling water bath (hydrolysis)
• Add sodium hydrogencarbonate (neutralisation)
• Redo Benedict’s test
  Blue - No sugar
  yellow >orange > red - Increasing amount of sugar

Question 17

Test for starch

Answer 17

Iodine

Orange to Blue/Black

Question 18

Starch features

Answer 18

• found in plants
• straight or branched
• insoluble so doesn’t affect WP
• does not diffuse out of cells
• compact
• hydrolysed to form alpha glucose
• branched to release glucose quickly

Question 19

Glycogen features

Answer 19

• found in animals and bacteria
• insoluble so doesn’t affect WP
• does not diffuse out of cells
• compact
• hydrolysed to form alpha glucose
• highly branched to release glucose quickly

Question 20

Cellulose features

Answer 20

• Made of Beta glucose
• straight unbranched chains
• hydrogen bonding
• microfibrils to form fibres
• plant cell wall component
• strong

Question 21

Roles of lipids

Answer 21

• Energy source
• Waterproofing
• Insulation
• Protection

Question 22

Bonding in triglycerides

Answer 22

3 fatty acids joined to 1 glycerol molecule
condensation reactions
ESTER bonds

Question 23

Saturated
Mono-unsaturated
Polyunsaturated

Answer 23

No double bonds in the fatty acid
One double bond
More than one double bond

Question 24

Triglyceride properties

Answer 24

• High ratio of C-H energy storing bonds
• low mass to energy ratio (good for storage)
• Insoluble (do not affect WP)
• good source of water when oxidised

Question 25

Phospholipid structure

Answer 25

Hydrophilic phosphate head | Hydrophobic fatty acid tail

Question 26

Phospholipid properties

Answer 26

- polar molecules so form a bilayer / barrier around cells | - can form glycolipids important in cell recognition

Question 27

Test for lipids

Answer 27

- Add ethanol to food sample and shake thoroughly to dissolve lipid - Add water and shake gently Cloudy white precipitate - lipids present

Question 28

Draw an amino acid

Answer 28

- C in middle - Amine (-NH2) group - Opposite Carboxyl (-COOH) group - H - Opposite R (variable group)

Question 29

Bonds between amino acids

Answer 29

Condensation reaction Between -NH2 of one amino acid and -COOH of another PEPTIDE bonds

Question 30

Bonding in secondary protein structure

Answer 30

Hydrogen bonds between polar groups Negative C=O Positive N-H Alpha helix and Beta pleated sheets

Question 31

Bonding in tertiary protein structure

Answer 31

- Disulfide bonds between cysteine R groups - Weak Hydrogen bonds between polar molecules - Ionic bonds between amine and carboxyl groups not involved in peptide bonds - Van der waals, very weak bonds between non polar groups

Question 32

Structure of Quarternary proteins

Answer 32

More than one polypeptide chain Same bonds as in tertiary structure Can contain prosthetic (non protein) groups

Question 33

Test for proteins

Answer 33

Add Biurets solution (weak copper (II) sulphate and mix | Blue to purple change - presence of protein