Chapter 1- Biological Molecules

Question 1

Monomer

Answer 1

Smaller units used to make larger molecules

Question 2

Polymer

Answer 2

Molecules made from monomers joined together (complex + large)

Question 3

Condensation reaction

Answer 3

Joins 2 monosaccharides by forming a glycosidic bond and removing water

Question 4

Hydrolysis reaction

Answer 4

Water added to disaccharide to break the bond and release the monosaccharides.

Question 5

What are the 3 monosaccharides?

Answer 5

Glucose, galactose, fructose

Question 6

What are the two isomers of glucose?

Answer 6

Alpha and beta

Question 7

How are disaccharides formed?

Answer 7

In a condensation reaction

Question 8

Glucose + glucose ->

Answer 8

Maltose

Question 9

Glucose + fructose ->

Answer 9

Sucrose

Question 10

Glucose + galactose ->

Answer 10

Lactose

Question 11

Test for reducing sugars

Answer 11

1. Add equal volume of sample + Benedict’s to test tube
2. Heat in water bath
3. Turns red/orange

Question 12

Test for non-reducing sugars

Answer 12

1 . Negative Benedict’s test
2. + dilute HCl + gently boil =in water bath
3. Add sodium hydrogen carbonate to neutralise
4. Repeat Benedict’s
5. Colour change if positive

Question 13

Test for starch

Answer 13

1. Add 2 drops iodine solution + shake
2. Colour change to blue-black if present

Question 14

Monomer in starch

Answer 14

Alpha glucose

Question 15

Function of starch

Answer 15

Energy storage

Question 16

How does the structure of starch relate to its function?

Answer 16

-Insoluble = X affect water potential
-Large = X diffuse out
-Compact = a lot in small space
-Hydrolysed into alpha glucose = easily transported for respiration
-Branched = has many ends = enzymes act simultaneously = rapid energy release

Question 17

Monomer in glycogen

Answer 17

Alpha glucose

Question 18

Function of glycogen and in what organisms?

Answer 18

Carbohydrate store in animals + bacteria

Question 19

How does the structure of glycogen relate to its function?

Answer 19

-Insoluble = X affect osmosis
-Compact = lot in small space
-Highly branched = > ends to act on = rapid glucose release for respiration

Question 20

Monomer in cellulose

Answer 20

Beta glucose (every other one is inverted)

Question 21

Structure of cellulose

Answer 21

Straight, unbranched, parallel chains = H bonds for cross linkages for strength

Question 22

How are the cellulose chains grouped?

Answer 22

In microfibrils + then fibres

Question 23

Function of cellulose

Answer 23

Plant cell walls -> adds rigidity by exerting inward pressure stopping water influx and making it turgid

Question 24

Roles of lipids

Answer 24

Cell membranes, energy, waterproofing, insulation, organ protection

Question 24

What elements do lipids contain?

Answer 24

C,H,O

Question 25

Test for lipids

Answer 25

1. Add ethanol + shake
2. Add water + shake
3. • result = cloudy

Question 26

What do triglycerides contain?

Answer 26

3 fatty acids + a glycerol
Ester bond attaches FAs to glycerol

Question 27

Difference between saturated and unsaturated Fatty acids

Answer 27

Saturated has no C=C
Unsaturated has 1 or > C=C

Question 28

How does structure of triglycerides relate to their function?

Answer 28

-High ration of C-H bonds to C atoms = energy store
-Low mass:energy = good store (> energy in small V)
Large, non-polar = insoluble = X affect water potential
-High H:O = releases water when oxidised (water source)

Question 29

Structure of phospholipids

Answer 29

2 fatty acids, glycerol + phosphate group

Question 30

What are the two parts of a phospholipid?

Answer 30

Hydrophilic head + hydrophobic tail

Question 31

How do the 2 parts of a phospholipid work together?

Answer 31

Form a bilayer within cell-surface membranes = acts as a hydrophobic barrier + contributes to flexibility + transfer of lipid-soluble substances

Question 32

Test for proteins

Answer 32

1. Add Biuret reagent to sample
2. Positive result = turns purple

Question 33

Structure of an amino acid

Answer 33

Central carbon attached to 4 chemical groups = amine, carboxyl, hydrogen atom + a variant R group

Question 34

Explain the formation of a peptide bond

Answer 34

-Condensation reaction - water made up of H of amine group + OH of carboxyl group forming a dipeptide
-Bond broken through hydrolysis reaction

Question 35

Primary structure of a protein

Answer 35

Specific sequence of amino acids (joined by polymerisation) -> determines shape + therefore function

Question 36

Secondary structure of a protein

Answer 36

Polypeptide folds + H bonds form within

Question 37

Tertiary structure of a protein

Answer 37

-Folding into a 3D structure
-Bonding between amino acids determined by primary structure
-Makes each protein distinctive
Bonds:
-Disulfide bridges
-Ionic bonds - between carboxyl + amine groups -> easily broken by pH changes
-H bonds - can be easily broken

Question 38

Quaternary structure of a protein

Answer 38

-Complex + has multiple polypeptide chains
E.g. haemoglobin
-Can have prosthetic (non-protein group) attached