Notesale: Turn your study into money

Document Preview

Extracts from the notes are below, to see the PDF you'll receive please use the links above

---

Biological Molecules
Monomers and Polymers:








Covalent Bonding – share electrons, form molecules, strong bond
...

Hydrogen Bonding – uneven distribution of electrons leads to a polar molecule, negative and positive region
attract creating a weak bond
...
g
...
022× 1023 (Avogadro
Constant), it is the molecular mass of a substance expressed in grams
...


Carbohydrates:




Carbon atoms – readily form bonds, backbone for other atoms, organic molecules
...
g
...
g
...
g
...

Reducing sugar test (Benedict’s test) – Benedict’s reagent is an alkaline solution of copper (II) sulphate, 2cm3
of sample and of Benedict’s reagent, heat in water bath, reducing sugar = insoluble red precipitate of copper
(I) oxide: blue = none green = very low yellow = low brown = medium brick-red = high
...
g
...

Polysaccharides – used as energy store (E
...
starch) or used for structure (E
...
cellulose)
...


Glycogen

Main storage
polysaccharide in
animals and fungi
...




Structure:

Relationship between
function and structure:
Made of 2 units – amylose and amylopectin
...

polymer of
Helix - compact
...

bonds
...

Large – cannot diffuse out
Amylopectin – polymer of alpha-glucose
of cells
...

Forms branched
structure
...

metabolic requirements
in animals than plants)
...

Strong, adjacent, long, unbranched chains
Hydrogen bonds – strong,
of beta-glucose joined by hydrogen bonds
important for structure
...


Functions of carbohydrates:
o Used in respiration - glucose
o Energy stores – starch, glycogen
o Structure – cellulose
o Transport – sucrose

Lipids:







Insoluble in water, soluble in organic solvents e
...
ethanol
E
...
polar dissolving polar = NaCl + H2O
LIKE DISSOLVES LIKE
E
...
non-polar dissolving non-polar = lipid + ethanol
Roles of lipids: energy, waterproofing, insulation, protection, storage, buoyancy
...

Most common lipid = triglycerides
...

o Fatty acids vary in length, effecting properties (e
...

melting point)
...

o Saturated (no double bonds, straight)/ unsaturated (2+ double bonds, kinked)
...

o Hydrophobic tail – repelled by water
...

o Inside cell membranes:



Test for lipids: emulsion test, 5cm3 ethanol, 2cm3 sample, shake, 5cm3 water, shake, cloudy-white =
lipid

Proteins:




Are made of amino acids which are polymerised
...

Have the general structure:
E
...




2 amino acids join in a condensation reaction to form a dipeptide linked by a peptide bond:



Protein functions: structural = soft tissue E
...
muscle, skin, hair, catalytic = enzymes, signalling =
hormones/receptors, immunological = antibodies
...

o Secondary structure – the way a chain of amino acids of a polypeptide is folded, can be alphahelix or beta-pleated sheet
...




o





Quaternary structure – number of polypeptide chains linked together sometimes with a
prosthetic group, e
...
haemoglobin = 2 alpha, 2 beta, 4 haem groups
...
05% copper (II) sulphate solution and mix, purple = peptide bonds present
...
g
...
g
...

Fibrous – long chains running parallel, cross-bridged e
...
collagen – unbranched polypeptide chain 
very tightly wound  twisted into 2nd helix  x3 = rope, found in tendons, ends of molecules spread
throughout fibre to prevent breakage
...

Lower activation energy of the reaction it catalyses
...

Soluble in water because of their hydrophilic side groups
...

Lock-and-key theory = precise and complimentary structures
...

Co-factors:
o Something an enzyme requires to work
...
g
...

o Coenzymes – organic molecules that temporarily bond to
enzyme e
...
vitamin C, ATP
...

o Substrate concentration – as long as there’s enough enzymes
reaction rates will increase
...

o Temperature – rise increases kinetic energy  collide more frequently, too high = bonds break 
active site changes shape  denatured, too low = not denatured just slowed
...

o Competitive inhibitors – have molecular shape similar to substrate allowing them to occupy the
active site, competing with substrate for available active sites
...
E
...
respiriatory enzyme (malonate) that acts on succinate
...




---