polar molecule (allow for
up take up nutrients as
polar molecules)
ice forms an insulating
layer
many hydrogen
bonds between
molecules
high specific heat capacity
(not much change due to
temperature)
less dense when solid
(organisms don't freeze/
allow organisms to move)
amino acids
contain the amine group (H-N-H),
r group (variable, with different
charges), carboxylic acid group
(HO-C=O)
peptide bonds formed by
condensation reactions (removal of
water), broken by hydrolysis (addition of
water)
2 amino acids joined together
(dipeptide), many peptides
joined together (polypeptide)
structures
primary structure (the
specific sequence of amino
acids in a polypeptide chain)
secondary structure (the polypeptide
chain uses hydrogen bonds to form
alpha helix or beta folded sheets)
quarternary structure
(more than 1 polypeptide
chain, which could be
haemoglobin or insulin)
tertiary structure (the overall
3-D structure of final protein)
held together by hydrogen bonds, disulphide
bonds, ionic bonds (by different charged r
groups on amino acids)
globular or fibrous
globular- haemoglobin (soluble in water, made
from wide range of amino acids, contain haem
group, quarternary alpha hellix)
fibrous- collagen (non-soluble in
water, 35% of the same amino acid,
no group, tertiary left handed helix)
3 polypeptide chains in a helix with hydrogen bonds,
molecules held together by covalent bonds (fibril), many
fibrils to form fibre
in walls of arteries, tendons, cartilage
carbohydrates
glucose
beta glucose (has OH on top
of carbon 1)
alpha glucose (has OH on
bottom of carbon 1)
disaccharide
contain 2 units (maltose, 2
alpha glucose units)
polysaccharide
contain many repeating units
amylose- straight chain of
alpha glucose
amylopectin- branched
chain of alpha glucose (in starch)
insoluble (not effect water potential of
cells when stored in plant cells), 1,4
glycosidic bonds (easy to hydrolyse),
in a spiral (can store more in smaller
space)
glycogen- made from repeating
units of alpha glucose
insoluble (not effect water
potential of cells when stored in
animal cells), 1,4 glycosidic
bonds (easily to hydrolyse), 1,6
glycosidic bonds (makes branch
and easy for respiration)
cellulose- made from
repeating units of beta
glucose
insoluble (form structural part of cell
wall), beta glucose (very strong
bonding), hydrogen bongs between
chains (to give mechanical strength),
gaps between macrofibrils (allow some
water through)
lipids
oil (liquid at room temp),
fats (solid at room temp)
saturated (no double
bonds), unsaturated (1 or
many double bonds)
triglyceride-
glycersol and 3
fatty acid chains
contain lots of carbon, hydrogen
and oxygen,(so good for
respiration)
phospholipids-
glycersol, 2 fatty acid
chains, phosphate
group
has hydrophobic and
hydrophilic parts to form
bilayer in membrane
cholesterol- 4 fused
rings which contain
carbon, hydrogen and
oxygen
is narrow and
hydrophobic so can fit
between
phospholipids in
membrane to give
strengh and stability
food tests
lipids- emulsion test, boil with
ethanol, pour into water (positive,
white emulsion forms near top)
starch- add iodine (positive,
turns brown to blue/black)
protein- biuret test, add biuret
reagent (positive, blue to lilac)
non reducing sugar- boil with HCL
acid, cool, do reducing sugar test
(positive, blue to brick red)
reducing sugars- heat with benedicts
solution at 80 degress (positive, blue to
brick red)
using colourimeter- concentration of
reducing surgar
do benedicts test, filter out percipitate, pour
solution into curvett, set colourimeter using water,
test sample, plot transmission reading on calibration
curve (already values for known concentrations of
reducing sugars)