biological molecules Flashcards
properties of water
- cohesion and surface tension
- high specific heat capacity
- high latent heat of vaporisation
- solvent
carbohydrates general
contain oxygen, carbon and hydrogen 3 forms 1. glucose = energy source 2. starch and glycogen = energy store 3. cellulose = support/ structure
glucose
- alpha and beta
- energy source
- component of starch and carbs
- hexose sugar
- highly soluble/ easily transportable
disaccharides
2 alpha glucose = maltose (R)
2 beta glucose = cellulose
alpha glucose + fructose = sucrose (NR)
alpha glucose + b galactose = lactose (R)
starch
energy store in plants
amylose
- straight chain
- helical
- 1-4 glycosidic
- NO branches
amylopectin
- spiral chape
- 1-4, 1-6 glycosidic
- SOME branches
both plant energy stores, compact so more can be stored and insoluble
glycogen
animal and fungi energy store
- 1-4, 1-6 glycosidic bonds
- branched structure
- alpha unit = basic unit
starch vs glycogen
starch less compact and less branched, plants have lower metabolic activity and respiration rate compared to animals so require less energy
cellulose
plant cell wall component provides structure and support
- straight-chain
- beta = basic unit
- 1-4 glycosidic, H bonds
- NO branches
- insoluble
- flexible
forms fibres - high tensile strength + crisscrossing
lipids general
contain carbon, hydrogen and oxygen atoms
soluble in alcohol
triglycerides
function = energy source, energy store, insulation
1 glycerol molecule + 3 fatty acids
made by condensation reactions
- ester bond between fatty acid and glycerol
NON-polar - can’t dissolve in water
phospholipid
function = make up cell membranes, water-proofing
phosphate head + 2 fatty acid tails
2 ester bonds form
1 between phosphate and body of the molecule
1 between fatty acid tails and body
polar molecules - hydrophobic and hydrophilic parts
cholesterol
4 carbon-based rings
proteins general
polynucleotides made up of amino acids
peptide bonds form in condensation reactions
protein structure levels
PRIMARY
- sequence of amino acids joined by peptide bonds
SECONDARY
- alpha helix coil held together by H bonds
- beta pleated sheets held together by H bonds between parallel chains
TERTIARY
- 3D and globular proteins
- coils, pleats and straight chains
- H, ionic, disulfide bonds and hydrophobic/philic interactions
QUATERNARY
- 2 or more globular chains
- different subunits
- H, ionic, disulfide bonds and hydrophobic/philic interactions
globular vs conjugated
globular
- spherical
- soluble in H2O
- compact
- tertiary structure
conjugated
- type of globular
- contain prosthetic group
fibrous
long thin structures
insoluble in water
metabolically inactive
STRUCTURAL role
CATIONS
calcium 2+
sodium 1+
potassium 1+
hydrogen 1+
ammonium 1+
nerve impulse transmission, muscle contraction
kidney function, carb absorption
protein synthesis, stomata opening
pH, blood regulation, catalysis of reactions
pH, production of nitrate ions, amino acid + nucleic acid
ANIONS
nitrate 1-
chloride 1-
hydrogen carbonate 1-
hydroxide 1-
phosphate 3-
nitrogen supply in plants, protein production
balance + charge of K+ and Na+ ions
pH, carbon dioxide transport
pH, catalysis of reactions
cell membranes, nucleic acid, ATP, bone formation
non-reducing sugar test
boil in HCl
add sodium hydrogen carbonate
add excess benedict’s
heat 80 degrees 5 mins
reducing sugar test
excess benedict’s
heat 80 degreed 5 mins
sugar concentration colours
most concentrated - brick red
- orange
- yellow
- green
starch test
add iodine
red - blue/black
protein test
add biurets
violet - blue
lipid test
ethanol
water
clear - emulsion/cloudy
chromatography TLC
thin-layer chromatography
qualitative method
separates individual components of the mixture
2 phases
1 - stationary (paper/silica gel)
2 - mobile (organic solvent)
used to separate amino acids rate depends on - solubility in the solvent - interaction with silica (OH groups very polar allows the formation of H bonds) - polarity (very polar = fast) - molecule size
for colourless molecules
- UV
- ninhydrin
- iodine
Rf value
= distance travelled by substance/ distance travelled by solvent
