Biological Molecules Flashcards
Glucose + glucose
Maltose + H2O
Glucose + galactose
Lactose + H2O
Glucose + fructose
Sucrose + H2O
Properties of starch
Large - cannot cross cell surface membrane
Insoluble - osmotically inactive
Helical - forms a compact store
Branched - glucose is easily released
Properties of glycogen
Insoluble - osmotically inactive
Branched - for easy release of glucose
Test for reducing sugars
Benedict’s test
Benedict’s test method
Add sample to same volume of Benedict’s solution
Heat to 95° in a water bath
Test for starch
Iodine test
Positive result of starch test
Colour change
Orange —> blue/ black
Positive result of Benedict’s test
Colour change
Blue —> brick red
Test for protein
Biurets test
Positive result for biurets test
Colour change
Blue —> lilac
Test for lipids
Emulsion test
Emulsion test method
Place sample in test tube with ethanol
Shake mixture so fat dissolves
Add water and mix
Positive result for emulsion test
White emulsion forms
Method for testing non reducing sugar
Carry out Benedict’s test on sample - negative result
Heat sample in water bath to 95° with HCl
Let cool
Neutralise with alkali
Add Benedict’s solution and heat in water bath to 95°
Positive result shows none reducing sugar present
Alpha glucose
Condensation reaction with peptides
What bond joins amino acids
Peptide bonds as a result of a condensation reaction
What bonds join phospholipids
Esther bonds as a result of a condensation reaction
What bonds join monosaccharides
Glycosidic bonds as a result of condensation reactions
Primary structure of proteins
Sequence of amino acids in a polypeptide chain
Secondary structure of proteins
Coiling/ folding of the polypeptide chain due to hydrogen bonding
Form either alpha helix or beta pleated sheets
Tertiary structure of a protein
Further coiling / folding of polypeptide chain due
Ionic bonds form
Disulphide bridges form
Quaternary structure of proteins
Proteins with more than one polypeptide chain due Ionic
Properties of water (4)
Metabolic reactions
- metabolite
Solvent
-transport nutrients
-remove waste products
Temperature regulation
-high heat capacity
Absorbs lots of heat energy before temperature increases
-large latent heat of vaporisation
Cooling effect
Support
- internal cohesive forces between molecules
Supports water tubes eg. Xylem
-external cohesive forces provide surface tension
-not easily compressed
Induced fit enzyme
Active site of enzyme is flexible
Presence of specific substrate induces a change in active site shape
Active site becomes complementary
Enzyme remains unchanged at end of reaction
Effect of pH on enzymes
Small optimum pH window
Too high or too low pH can denature enzymes
Active site changes shape due to change in tertiary structure
Effect of temperature on enzymes
Higher temp more kinetic energy
Increases frequency of collisions between active site and substrate (more enzyme-substrate complexes)
Too high temp can denature enzymes by changing active site shape by altering tertiary structure
Competitive inhibition
Inhibitor has a similar structure to substrate and competes to attach to active site
Substrate cannot bind
RoR decreases
Addition of more substrate can increase RoR
Non-competitive inhibition
Inhibitor doesn’t have similar structure to substrate
Combines elsewhere on the enzyme - not the active site
Enzyme inhibitor complex forms
Alters tertiary structure of enzyme
Substrate cannot bind as it’s no longer complementary
ATP
ATP is hydrolysed to release energy and then resynthesized
ATP (+atp hydrolyse) —> ADP +Pi
ATP
ATP is hydrolysed to release energy and then resynthesized
ATP (+atp hydrolyse) —> ADP +Pi
