Biological Molecules 1 Flashcards
Glucose + glucose =
Maltose + water
Glucose +fructose =
Sucrose + water
Glucose + galactose =
Lactose + water
Benedict’s test for reducing sugars
- Add small amount of sample with same volume of bendicts
- Heat in water bath
- Red/orange? Positive
- Remains blue? No reducing sugar present
All mono and disaccharides are reducing sugars apart from sucrose
Testing for non-reducing sugars (sucrose)
- Carry about Benedicts test on small sample to confirm negative result
- Hydrolyse another sample of sucrose by heating with dilute acid HCl
- Neutralise acid NaOH
- Add same volume of Benedicts and heat in water bath
- Red colour indicates a non-reducing sugar (sucrose) was originally present
Starch
- storage compound in plants
- long branched chains of A glucose linked by glycosidic bonds due to condensation reactions
- starch in starch grains in cytoplasm
- insoluble&osmotically inactive, helical shape (compact store)
- detected using iodine test
Glycogen
- storage carbohydrate found in cytoplasm of animal cells
- formed by condensation of A glucose
- stored in large amounts in liver and muscle tissues
- insoluble&osmotically inactive, more branches so can be hydrolysed rapidly to release glucose for respiration
Cellulose
- found in cell wall of plants, providing rigidity and shape
- polymer of B glucose joined by glycosidic bonds as a result of a condensation reaction
- long straight chains produced as every other monomer is inverted
- OH groups project from the chain and form hydrogen bonds producing a microfibril
- microfibrils joined to make macrofibrils
- macrofibrils in layers are orientated in different directions
- embed in a matrix providing rigidity
- fully permeable
Triglycerides
- 3 fatty acids combined to 1 glycerol during a condensation reaction with the loss of 3 water molecules, forming an ester bond
- saturated fatty acid means no double bonds between carbon atoms
- unsaturated fatty acid means double bonds between carbon atoms
- release twice as much energy due to high proportion of carbon-hydrogen bonds
- release water when respired due to high ratio of hydrogen to oxygen atoms
- insoluble&osmotically inactive
- present in waxy cuticle of insects and plant leaves
Phospholipids
- lipids containing a phosphate group
- consists of 1 glycerol, 2 fatty acids & a phosphate group joined by a condensation reaction producing ester bonds
- polar hydrophilic head (attracts water) and non-polar hydrophobic tails (repels water)
- form a phospholipid bilayer enabling lipid soluble molecules to pass through quickly
- detected using emulsion test (add ethanol)
Role of water in metabolic reactions
Solvent
Metabolite (condensation and hydrolysis)
Used for photosynthesis
Product of respiration
Role of water as a solvent
Transport nutrients
Remove excretory products
In metabolic reactions
Role of water in temp regulation
High heat capacity - absorbs lots of heat before rising in temp, prevents fluctuations, minimises increase in temp
Large latent heat of vaporisation - cooling effect with little loss of water through evaporation - helps maintain constant body temp as high amount of heat energy is removed from body to evaporate sweat
Role of water in support
Strong cohesion between water molecules due to hydrogen bonds producing surface tension where water meets air
High surface tension due to strong cohesive forces
Strong cohesive forces essential in maintaining water column in xylem
Not easily compressed so provides support
Provides buoyancy for aquatic organisms
Glycerol
C3 H8 O3
