1. Biological Molecules

Question 1

Name three disaccharides

Answer 1

Maltose sucrose and lactose

Question 2

What monosaccharides make up sucrose

Answer 2

Glucose + fructose

Question 3

What monosaccharides make up maltose

Answer 3

Glucose + glucose

Question 4

What monosaccharides make up lactose

Answer 4

Glucose + galactose

Question 5

Describe a hydrogen bond

Answer 5

A weak electrostatic force between two dipolar molecules

Question 6

What is the primary structure of a protein. What type of bond is involved

Answer 6

The order of specific amino acids, held by peptide bonds

Question 7

What is the secondary structure of a protein

Answer 7

When H-bonds form between the amino causing either:
an alpha-helix shape
or a beta-pleated sheet

Question 8

what is the territory structure of a protein? what bonds are involved

Answer 8

The 3d shape of the polypeptide is dependent on the secondary structure
- h bonds
- ionic
- di sulfide

Question 9

What does hydrophilic mean

Answer 9

Molecule has a charge, so it’s attracted to water

Question 10

Describe the differences in alpha and beta glucoses

Answer 10

A-glucose has H group on top and OH bottom

B-glucose has H group on bottom and OH on top

Question 11

Draw the structure of a protien

Answer 11

R
|
H2N——C—-COOH
|
H

Question 12

What are the 4 uses of lipids

Answer 12

• Waterproofing
• Energy source
• Insulation
• Protection

Question 13

Why are triglycerides better at storing energy than carbohydrates

Answer 13

High ratio of c-h (stores energy)

Question 14

Give three properties of triglycerides relating to its function

Answer 14

Low energy to mass ratio, good for storage, storing a lot in small masses

Large, non polar = insoluble in water. Do not effect osmosis or water potential of cell

High ratio of h:o = source of water when oxidised

Question 15

Describe the test for lipids

Answer 15

• 2cm of sample, 5cm of ethanol, shake
• Add water and shake
• Milky white emulsion indicates the presence of a lipid
  Repeat with control, water instead of sample

Question 16

What is the difference between reducing and non-reducing sugars?

Answer 16

a reducing sugar is able to donate electrons.

Question 17

Describe structure of glycogen

Answer 17

• a-glucose polymer
• 1-4 glycosidic + 1-6
• ## highly branched

Question 18

what is cellulose, and how does its structure help its function

Answer 18

Single, unbranched chain of alternating b glucoses
H bonds form between rows, tensile strength
Makes up microfibril in plant walls

Question 19

what are the 5 components of an amino acid?

Answer 19

central carbon, R group, hydrogen, carboxyl group (COOH), amino group (HNH)

Question 20

describe the test for NON-reducing sugars

Answer 20

• Add dilute hydrochloride acid to sample
• Neutralise solution with sodium hydrogen-carbonate
• Use litmus paper to identify when the solution has been neutralised,
• add a little more sodium hydrogen-carbonate
• Then carry out Benedict’s test as normal;
• positive = brick red

Question 21

describe the INDUCED-FIT MODEL

Answer 21

active site and substrate have complementary shapes, active site must change slightly to bind to fit substrate and bind to form ENZYME-SUBSTRATE COMPLEX.

Question 22

what bond is formed between two monosaccharides?

Answer 22

glycosidic.

Question 23

what is an isomer? apply to glucose.

Answer 23

• molecule with same molecular formula but structurally different
• ## a-glucose, b-glucose

Question 24

draw the structures of a-glucose and b-glucose.

Answer 24

OH on bottom of a-glucose, top on b

Question 25

structure of starch

Answer 25

• amylose, 1-4 glycosidic
• amylopectin, 1-4 + 1-6

Question 26

What is the function of starch? give three features that help function.

Answer 26

Store of glucose in plants
- helix, fit a lot in small space
- branched molecule, SA for hydrolysis
- insoluble, no effect on water pot.

Question 27

How does glycogens structure help its function?

Answer 27

Store of glucose in animals, muscle and liver cells.
- Branched structure, SA for hydrolysis
- insoluble, no effect on water pot

Question 28

Structure of cellulose (4)

Answer 28

• b-glucose
• long, straight chains
• every other molecule inverted 180
• chains held together in parallel by hydrogen bonds to form fibrils

Question 29

Role of cellulose.

Answer 29

• Provide strength to cell wall

Question 30

Describe the use of benedict’s reagent to test for the presence of REDUCING SUGARS.

Answer 30

• 2cm of
• equal volume of benedict’s reagent
• water bath for 5 mins

Question 31

Benedict’s test for NON-REDUCING SUGARS

Answer 31

• add dilute HCL to sample and heat in a water bath, close to boil
• neutralise with sodium hydrogen carbonate.
• use litmus paper to test that solution is slightly alkaline
• benedict’s solution as normal

Question 32

triglycerides are made up of…

Answer 32

One glycerol molecule and three molecule of fatty acids.

Question 33

What reaction and bond joins a glycerol and a fatty acid?

Answer 33

• condensation
• ester bond

Question 34

Describe the quaternary structure of proteins.

Answer 34

Association of multiple polypeptide chains and non-protein (prosthetic) groups.

Question 35

Describe the biuret test

Answer 35

• Equal volumes sample and sodium hydroxide at room temp.
• Add a few drops of copper2 sulfate, mix
• purple coloration indicates presence of peptide bonds, blue if negative.

Question 36

Name the bond that joins amino acids together

Answer 36

Peptide

Question 37

amino acids are joint by…

Answer 37

condensation reaction.

Question 38

Role of enzymes

Answer 38

lowers activation energy of the reaction it catalyses.

Question 39

Explain the effect that a high PH has on an enzyme controlled reaction

Answer 39

• PH alters charges of amino acids, substrate cannot bind to active site
• Tertiary structure may be changed, active site changed shape (ionic bonds)