Biological Molecules Flashcards
Describe how to carry out benedict reagent and how it works.
Add Benedicts reagent and heat.
Cu2+ ions are reduced to become Cu+
Copper oxide precipitate forms that is brick red
Semi quantitative test
How to test for non-reducing sugars
Boil in HCl
Neutralise with sodium hydrogen carbonate
Test with benedicts (heat)
Acid hydrolysed to reveal reducing centre
Describe test for protein.
Add equal amounts of biuret reagent (NaOH + CuSO4) and sample.
Blue to purple in presence of peptide bonds
Draw basic amino acid
H. H. O
|. |. ||
N. —- C. —- C
|. |. |
H. R. OH
Tetrahedral shape
Amine group and carboxyl group
How do biological molecules provide evidence for evolution?
Animals share common chemistry (bio molecules)
Share common ancestor
Describe Primary Secondary Tertiary Quaternary structure
1) sequence of amino acids
2) alpha helix and beta pleated sheets, hydrogen bonds
3) chain folds again, ionic hydrogen and disulphides bonds
4) interactions between multiple polypeptide chains. Prosthetic groups (non-protein)
How does change to one amino acid affect function of protein?
Determines position of H Ionic and S bonds.
Affects shape of protein
Affects function
Why do saturated fatty acids have a higher MP than unsaturated fatty acids?
Unsat: double bonds between carbon atoms, kink means not compact. Weaker intermolecular forces mean a lower MP, less energy needed to break bonds
Link celluloses structure to function
Beta glucose = alternating = straight chains = compact + micro/macrofibrils = strong
Hydrogen bonds = strong
Inward pressure prevent too much osmosis
Test for starch
+iodine
Yellow/orange to blue-black
Functions of carbohydrates
Structure and energy storage
Glucose + glucose = A
Glucose + fructose = B
Glucose + galactose = C
A= maltose B= Sucrose C= Lactose
Link phospholipid properties to function
Polar (hydrophilic head, hydrophobic tail)= sits upright out of water = plasma membrane
+carbohydrate = glycolipid (cell recognition
Hydrophilic head holds cell surface membrane.
Link triglyceride properties to function
Non polar + insoluble + large= doesn’t affect water potential of cell
Lots of carbon hydrogen bonds = 2x as many calories as carbs and protein
Low mass: energy= light storage molecule
Condensation reaction= metabolic water source
Why are phospholipids polar molecules?
Two regions that behave in different ways
Hydrophobic tails
Hydrophilic head
Why are lipids not polymers?
No identical repeating units.
How and why are the monomers in cellulose arranges?
Beta glucose molecules alternate
So OH groups adjacent for condensation reaction.
Name macromolecules and monomers and polymers
Lipid-glycerol + fatty acid chains
Carbohydrates - monosaccharides = polysaccharides
Proteins - amino acids= polypeptides
Nucleic acids- nucleotides = polynucleotides
Name bonds formed by condensation of
Lipids
Proteins
Monosaccharides
Nucleotides
Ester
Peptide
Glycosidic
Phosphodiester
What’s an isomer
Same chemical formula different structure
Link starches structure to its function
Helical= compact storage of energy
Branched = more glycosidic bonds hydrolysed at once= fast release of glucose
Large, insoluble and uncharged= won’t affect water potential of cell
Alpha glucose= easily transported and readily used in respiration
What are the roles of lipids
Waterproofing (hydrophobic)= sebum or waxy cuticle
Energy source = C-H bonds
Plasma membranes (phospholipids) = flexibility
Thermal + electrical insulation= poor conductor of heat and electricity
Protection of internal organs
Why do lipids store more energy than carbs and protein?
Higher amount of hydrogen carbon bonds
Higher
O:H and O:C
What are lipids soluble in?
Organic solvents (contain carbon)
