(1) Biological Molecules Flashcards
A-Glucose & B-Glucose:
-Chemical Formula
-Structures
-Both types are ______ of each other.
C6 H12 06
A-Glucose: H O H
HO OH
B-Glucose: H O OH
HO H
Isomers
Test for Reducing Sugars:
- Add 2 cm3 of the ground up food sample into a test tube.
- Add Benedict’s reagent.
- Heat the mixture in a gently boiling water bath for five minutes.
Which Monosaccharides form these Disaccharides:
Maltose
Sucrose
Lactose
Name the Bond:
Name the reaction:
A-glucose + A-glucose = maltose
A-Glucose + Fructose = Sucrose
Galactose + B-Glucose = Lactose
Glyosidic
Condensation
Non-Reducing Sugars Test:
-Do Reducing Sugar Test
Solution should be negative (No positive colour change)
add 2cm3 of sample in test tube with 2cm3 dilute hydrochloric acid.
Boil in water bath for 5 minutes (Hydrolysis)
Add Alkali to neutralise(Sodium Carbonate).
Retest using Benedict’s Reagent which now turns brick red.
Test for Starch
Iodine Solution
Positive Indicator: Blue-Black Solution Colour
Describe how the structure of starch is related to its function as an energy storage molecule. (3 marks)
Starch
-Storage of A-glucose
Many A-glucoses joined by glyosidic bonds in condensation reactions.
Coiled: Compact so it can be stored in small spaces
Insoluble: So water potential not affected.
Large: So cannot move out of the cell
Describe how the structure of Glycogen is related to its function as an energy storage molecule. (3 marks)
Storage of A-glucose
many A-glucoses joined by glyosidic bonds in condensation reactions.
Coiled: Compact so it can be stored in small spaces
Insoluble: So water potential not affected.
Large: So cannot move out of the cell
Branched: A-glucose easily released for respiration.(High Surface area)
Describe how the structure of Cellulose is related to its function as an energy storage molecule. (3 marks)
Strengthening Cell Walls
Structure: many B-Glucoses joined by glycosidic bonds in condensation reactions
Long straight unbranched chains of B-Glucose
Chains are linked together by many hydrogen bonds to form microfibrils.
Many hydrogen bonds form collective strength.
Word Equation for formation of Triglycerides:
Glycerol + 3 fatty acids —> Triglyceride + 3 x H20
Phospholipid Structure related to their properties:
Phospholipids are polar molecules:
-Form a bilayer within all cell surface membranes. (Hydrophobic Barrier)
-Allows for the formation of glycolipids allowing for cell recognition.
Refer to what Saturated, Monounsaturated and Polyunsaturated mean
Saturated: No C=C
Mono-Unsaturated:
1 x C=C
Poly-Unsaturated: 1 or more C=C
Test for Lipids:
Emulsion Test:
-Add food sample and 5cm3 ethanol.
-Shake Test Tube thoroughly
-White Cloudy Emulsions indicate positive result.
General Structure of an amino acid:
Bond?
All proteins contain which elements?
R Group
Amine Group(NH2)
Carboxyl Group(COOH)
H
(C in the middle)
Joined by peptide bond
(HONC)
Hydrogen, Oxygen Nitrogen, Carbon
Describe the primary and secondary structures of a protein (3marks)
Primary Structure:
-Specific order of amino acids in a polypeptide.
JOINED BY PEPTIDE BONDS
-Determines its ultimate shape + function.
Secondary Structure:
-A-Helix(Long twisted polypeptide chain held in place by hydrogen bonds)
-Beta-Pleated Sheet
(Flatter, Sheet-like structure held in place by hydrogen bonds)
Describe the Tertiary and Quaternary Structure (3marks)
Tertiary Structure:
3D Shape of polypeptide chain.
Bonds:
Disulfide Bridges, fairly strong
Ionic Bonds: formed between carboxyl and amino groups. Weak easily broken by changes in pH
Hydrogen Bonds
Quaternary Structure:
Shows how individual sub-units are arranged to form a larger 3D Structure
( 1 Sub-unit = 4polypeptide chains)
Test for proteins:
Biuret Reagent
Lilac colouring indicates positive result
Explain the Induced Fit Model of enzymes
(before reaction) active site not
complementary to/does not fit
substrate;
2. Shape of active site changes as
substrate binds/as enzymesubstrate complex forms;
3. Stressing/distorting/bending bonds
(in substrate leading to reaction);
Effect of temperature and concentration of enzymes on rate of reaction:
Temperature:
Rise in temperature increases kinetic energy. Molecules move more rapidly, more frequent successful collisions. Greater rate of reaction.
Concentration:
Providing there is excess substrates. Increase in concentration causes increase in rate of reaction.
Competitive vs Non-Competitive Inhibitors:
Competitive:
-Has a molecular shape similar to substrate
-Disallows the substrate to bind with active site binding to the active site first.
Non-Competitive:
Attach themselves to allosteric site on the enzyme.
Changing the shape of the active site so enzyme is no longer complementary.
Explain Importance of inorganic ions to living organisms: Use named examples. 6 (Marks)
Iron used in haemoglobin to transport oxygenated blood.
Sodium and potassium involved in Co-Transport (Sodium-Potassium Pump)
Phosphate ions in DNA, RNA, ATP and phospholipid Bilayer.
Hydrogen Ions affect pH and enzyme activity.
Why would a T-Test be a relevant Statistical Test for a given scenario.
To compare the two means.
