Chapter 1- Biological Molecules Flashcards
Monomer
Smaller units used to make larger molecules
Polymer
Molecules made from monomers joined together (complex + large)
Condensation reaction
Joins 2 monosaccharides by forming a glycosidic bond and removing water
Hydrolysis reaction
Water added to disaccharide to break the bond and release the monosaccharides.
What are the 3 monosaccharides?
Glucose, galactose, fructose
What are the two isomers of glucose?
Alpha and beta
How are disaccharides formed?
In a condensation reaction
Glucose + glucose ->
Maltose
Glucose + fructose ->
Sucrose
Glucose + galactose ->
Lactose
Test for reducing sugars
- Add equal volume of sample + Benedict’s to test tube
- Heat in water bath
- Turns red/orange
Test for non-reducing sugars
1 . Negative Benedict’s test
2. + dilute HCl + gently boil =in water bath
3. Add sodium hydrogen carbonate to neutralise
4. Repeat Benedict’s
5. Colour change if positive
Test for starch
- Add 2 drops iodine solution + shake
- Colour change to blue-black if present
Monomer in starch
Alpha glucose
Function of starch
Energy storage
How does the structure of starch relate to its function?
-Insoluble = X affect water potential
-Large = X diffuse out
-Compact = a lot in small space
-Hydrolysed into alpha glucose = easily transported for respiration
-Branched = has many ends = enzymes act simultaneously = rapid energy release
Monomer in glycogen
Alpha glucose
Function of glycogen and in what organisms?
Carbohydrate store in animals + bacteria
How does the structure of glycogen relate to its function?
-Insoluble = X affect osmosis
-Compact = lot in small space
-Highly branched = > ends to act on = rapid glucose release for respiration
Monomer in cellulose
Beta glucose (every other one is inverted)
Structure of cellulose
Straight, unbranched, parallel chains = H bonds for cross linkages for strength
How are the cellulose chains grouped?
In microfibrils + then fibres
Function of cellulose
Plant cell walls -> adds rigidity by exerting inward pressure stopping water influx and making it turgid
Roles of lipids
Cell membranes, energy, waterproofing, insulation, organ protection
What elements do lipids contain?
C,H,O
Test for lipids
- Add ethanol + shake
- Add water + shake
- result = cloudy
What do triglycerides contain?
3 fatty acids + a glycerol
Ester bond attaches FAs to glycerol
Difference between saturated and unsaturated Fatty acids
Saturated has no C=C
Unsaturated has 1 or > C=C
How does structure of triglycerides relate to their function?
-High ration of C-H bonds to C atoms = energy store
-Low mass:energy = good store (> energy in small V)
Large, non-polar = insoluble = X affect water potential
-High H:O = releases water when oxidised (water source)
Structure of phospholipids
2 fatty acids, glycerol + phosphate group
What are the two parts of a phospholipid?
Hydrophilic head + hydrophobic tail
How do the 2 parts of a phospholipid work together?
Form a bilayer within cell-surface membranes = acts as a hydrophobic barrier + contributes to flexibility + transfer of lipid-soluble substances
Test for proteins
- Add Biuret reagent to sample
- Positive result = turns purple
Structure of an amino acid
Central carbon attached to 4 chemical groups = amine, carboxyl, hydrogen atom + a variant R group
Explain the formation of a peptide bond
-Condensation reaction - water made up of H of amine group + OH of carboxyl group forming a dipeptide
-Bond broken through hydrolysis reaction
Primary structure of a protein
Specific sequence of amino acids (joined by polymerisation) -> determines shape + therefore function
Secondary structure of a protein
Polypeptide folds + H bonds form within
Tertiary structure of a protein
-Folding into a 3D structure
-Bonding between amino acids determined by primary structure
-Makes each protein distinctive
Bonds:
-Disulfide bridges
-Ionic bonds - between carboxyl + amine groups -> easily broken by pH changes
-H bonds - can be easily broken
Quaternary structure of a protein
-Complex + has multiple polypeptide chains
E.g. haemoglobin
-Can have prosthetic (non-protein group) attached
