Topic 1 Biological Molecules

Question 1

3 main functions of lipid

Answer 1

1. Insulation
2. Energy store
3. Protection

Question 2

Triglycerides

Answer 2

1.Formed condensation of 3 fatty acids and one molecule of glycerol
1.Bonds formed are ester bonds
1.3 bonds formed 3 water molecules formed

Question 3

How triglycerides structure related to its properties

Answer 3

1. High ratio of carbon-hydrogen to c-c good as energy storage molecules
2. Fatty acid chain hydrophobic - insoluble doesn’t affect water potential
3. Low mass - lots of it can be present in an organism without affecting the ability to walk feed and run which is essential in survival
4. Metabolic water source - High ratio of hydrogen to oxygen atoms

Question 4

Phospholipids

Answer 4

1. One fatty acid is replaced by phosphate containing groups
2. Condensation reactions between glycerol 2 fatty acid and one phosphate group

Question 5

How phospholipids structure relates to its properties

Answer 5

1. Phosphate group is hydrophilic interacts with water due to the negative charge on oxygen hydrophilic head
2. Fatty acid is hydrophobic creates a polar molecule . Forms a phospholipid bilayer

Question 6

Unsaturated and saturated

Answer 6

Saturated - no double bonds in hydrocarbon chain
Unsaturated - double bonds in hydrocarbon chain

Question 7

Emulsion test for lipids

Answer 7

1. Dissolve sample in ethanol
2. Add water and shake
3. If lipid present form cloudy white emulsion if negative remains the same

Question 8

Amino acid

Answer 8

Is a monomer of a protein

Question 9

Di peptide

Answer 9

1.A condensation reaction between two amino acids forms a dipeptide
2.peptide bond
3. Water molecule removed

Question 10

Protein structure

Answer 10

1. Primary - sequence of amino acids
2. Secondary - folding of amino acids into alpha helices or beta - pleated sheats hydrogen bonds hold them together
3. Tertiary structure - alpha or beta fold further to form a specific , 3D structure
   Ionic and disulphide bridges hold the tertiary structures together hold stability to protein so it can carry out function
4. Quaternary - more than one polypeptide chain
   Polypeptide can bind to a non protein chain.

Question 11

Biuret test for proteins

Answer 11

1. Add biuret reagent
2. Shake
3. Protein present purple if not remain blue

Question 12

Enzymes

Answer 12

Proteins
Catalyse reactions by lowering activation energyv

Question 13

Induced fit model

Answer 13

1.Substare binds to active site
2.substrate induced a conformational change allows substrate bind to active site
3. Forming a substrate enzyme complex
4. Reduces activation energy

Question 14

How Different conditions affect enzyme activity

Answer 14

Temp-increase temp molecules gain kinetic energy more kinetic energy highly likely that enzyme substrate collide for enzyme substrate complex
Optimum temp - denatures enzyme denatured h bonds broken changing tertiary structure enzyme can no longer bind

Ph- when ph not optimum unbalance of h* and oh- can disrupt tertiary structure alter tertiary substrate not complementary to active site enzyme unactive denatures

Enzyme concentration -steady increase rate of reaction increases rapidly more active site available can bind to substarte
Levels off - not enough substrates some active site left empty rate of reaction no longer increases

Substrate concentartion- more substrate available for active site more enzyme substrate more likely to bind
Levels off - not enough active sites available rate of reaction no longer increases

Question 15

Enzyme inhibition

Answer 15

Competitive inhibition - competitive inhibitor also complementary to binding site bad as substrate can’t bind
No enzyme substrate can form decreases rate of reaction
Can fix this by increasing the substrate concentration

Non competitive inhibitors -
Tertiary structure of active site changes no longer substrate enzyme complex form
Incrreasw conc can’t fix this

Question 16

DNA and rna

Answer 16

• polymers of nucleotides
  -dna - deoxyribose sugar - pentoseeb