1 Flashcards
What is hydrolysis ?
Breaks a chemical bonds between 2 molecules
Using water
What is condensation reaction?
Create chemical bond
Removing a molecule of water
Glycogen-glycogen structure (3)
Polysaccharide of alpha glucose
Joined by glycosidic bonds
Branched structure
Glycogen compared to cellulose
Cellulose is made up of beta glucose monomers and glycogen is made up of alpha glucose monomers .
Cellulose molecule has straight chain and glycogen is branded .
Cellulose molecule has straight chain and glycogen is coiled .
Glycogen has 1-4 and 1-6 glycosidic bonds , cellulose has only 1-4 gylcosidic bonds
Glycogen structure related to its function (5)
Insoluble in water so doesn’t affect water potential.
coiled shape so molecules are more compact.
Polymer of alpha glucose so provide glucose for respiration .
Branched so have more ends for fast breakdown.
Large molecule so cant cross the cell membrane.
Relate 3 properties to starch function(6)
It its insoluble so doesn’t affect water potential.
Helical shape so it is compacted
Large molecule so cannot leave cell
What’s the test for reducing sugar
Heat with Benedict regnant .
Colour change from blue to orange
Test for non reducing sugar
Heat with Benedict regrant and no colour change .
Then boil with hydrochloric acid to hydrolysis
Then add sodium hydroxide to neutralise it .
Re-heat with Benedict reagent and colour change from blue to red.
Test for starch
Add starch in potassium iodide solution.
Colour change from brown to blue-black
How are triglycerides formed
One glycerol and 3 fatty acids.
Condensation reaction and remove 3 molecules of water.
Ester bonds are formed
Phospholipid compared with triglycerides
Both contain ester bond between glycerol and fatty acid.
Both contain glycerol.
Fatty acid on both may be saturated or unsaturated.
Both are insoluble in water.
Both contain C,H and O but phospholipid also contain P .
Triglyceride has 3 fatty acids and phospholipid has 2 fatty acids and phosphate group.
Triglycerides are hydrophobic and non polar, phospholipid have hydrophilic and hydrophobic region.
Phospholipid form mono layer on surface in water but triglycerides dont
Describe how an ester bond is formed in a phospholipid molecule
Condensation reaction between glycerol and fatty acid
Test for lipid
Shake the sample with ethanol then add water , it will have milky emulsion
Protein structure (7)
Polymer of amino acids.
Joined by peptide bond.
Formed by condensation.
Primary structure is order of amino acids.
Secondary structure is folding for polypeptide chain due to hydrogen bonding into alpha helix or beta pleated sheet.
Tertiary structure is 3D folding due to hydrogen bonding and disulphide bonds between R groups.
Quaternary structure is more than one polypeptide chain.
Test for protein
Add biuret reagent to the sample .
Colour change to violet
Induced fit model(3)
Before reaction active site is complementary but not perfectly fit to substrate.
Shape of active site changes as substrate binds and enzymes-substrate complex formed.
Bending bonds in substrate to increase rate of reaction
Increase temperature and reaction rate
Particles have more kinetic energy therefore they move more .
So more collision between substrate and active sites.
So more enzyme-substrate complex formed
If temperature is too high enzymes will denature and no longer complementary to substrate
Denaturation of enzyme
Heat above the optimum breaks hydrogen bonds.
Causes tertiary structure to unfold.
The active site changes shape.
Substrate no longer bind to the active site as its no longer complementary .
So fewer enzyme-substrate complex is form
Effects of change in pH
Ionic bonds holding tertiary structure break .
Active site distorts and substrate no longer binds to active site .
Fewer enzyme-substrate complex is formed
Concentration of substrate
Increase concentration of product slows as substrate is used up or high initial rate as plenty of substrate .
No increase at end ,levels off because no substrate left .
Describe and explain the temperature graph of enzyme rate
Initial rate of reaction fasater at 37c
Because more kinetics energy.
So more enzyme and substrate collision and more enzyme-substrate complex is formed
Graph level off at 37c.
Because all substrate used up
Comparison of competitive and non competitive inhibition
Competitive inhibit binds to active site of enzyme but non-competitive inhibitor binds at allosteric site.
Competitive inhibitor does not cause change shape of active site but non-competitive inhibitor does cause change in shape of active site.
With competitive inhibitor at high substrate concentations enzyme still available but with non-competitive inhibitor enzymes no longer available .
Describe DNA replication
DNA helicase unwind double helix.
Both strands acts as template.
Nucleotides line up in complementary pairs .
DNA polymerase joins nucleotides of new strand.
Forming phosphodiester bonds.
Each new DNA molecule consists of original template strand and one new strand
Describe structure of DNA
Polymer of nucleotides .
Each nucleotides formed from deoxyribose , a phosphate group and nitrogenous base.
Phosphodiester bonds between nucleotides .
Double helix held by hydrogen bonds.
Hydrogen bonds between adenine,thymine and cytosines,guanine.
