Weak electrical attraction between the d+ve hydrogen and the d-ve oxygen on the next molecule.
Properties
Ice
Less Dense than water
Nota:
Because hydrogen bonds hold water in a rigid lattice.
High Specific Heat Capacity
Body temp
Nota:
A lot of energy needed to increase the temperature of water.
We are largely water so large changes of water in the external environment have relatively small effects on your body temp. (as with all living organisms)
High Boiling Point
Nota:
Due to hydrogen bonding
Sweat
Nota:
Humans use this property, when liquid sweat lies on the surface of the skin, sweat absorbs the heat energy from the body as it evaporates. The heat need is called latent heat of evaporation. It is our major cooling mechanism
Same as plant leaves in hot climate cool down by the evaporation of water on their surface.
Solvent
Dissolving
Metabolic reactions
Nota:
Many reactions will only take place in a solution as it is easy for the ions/molecules to react with other ions/molecules
water can flow so it can carry dissolved substances (eg glucose) from one place to another. This happens in our blood, xylem and phloem and urine.
Viscocity and Density
Nota:
most living organisms, containing a lot of water, have a density which is quite close to that of water. This makes it easy for them to swim as they can slightly change their density by filling or emptying air from parts of their body, to float or sink.
1.0 gdm-3
Cohesion and Surface
Tension
Nota:
Surface tension:
On the surface their is only cohesion from molecules below so they are pulled downwards. These pulling forces draw them closer together than other parts of the pond so it is a strong layer.
Proteins
Structure
Amino Acid
Peptide bond
Hydrolysis
Nota:
Where water is used to break down a substance. E.g. poypeptide + water --> amino acids
Condensation
Nota:
a condensation reaction where water is also produced.
Polypeptide
Nota:
Chain of amino acids with peptide bonds
Amine-NH2
Acid-COOH
R Groups
Primary structure
Nota:
The sequence of amino acids
20 different amino acids found naturally
Secondary structure
Tertiary
Quaternary
Carbohydrates
Nota:
General formula Cn(H2O)n
Monosaccharides
Benedicts solution
Add Benedicts soln.
Heat
Blue= no reducing
sugar
Green=some
Brown= more
Red=most
Reducing sugars Cu2+
reduced to Cu+ as
sugar gives electron.
Glucose
Alpha
Nota:
OH on carbon-1 is undA
glucose+glucose-->maltose-is only made of a glucose
glucose+galactose-->lactose
(animals)
glucose+fructose-->sucrose (plants)
Beta
Nota:
OH is aBove
Properties
Sweet
Form crystals
Soluble
in water
Polysaccharides
Starch
Amylose
Thousands of
a glucose
joined together
in a chain
Joined by a
glycosidic 1,4
bonds
Chains of
molecules coil into
a compact helix
Amylopectin
Thousands of a
glucose joined
together
Joined by a 1,4 and
1,6 a-glycosidic
bonds
1,6 bonds
creates branches
Structure
Compact- good for
storage
Iodine test
Nota:
Add Iodine soln, if starch is present, soln turns blue. (original colour orange/brown)
Glycogen
Thousands of
a glucose
joined together
in a chain
Both 1,4 and
1,6 (unlike
amylose)
Branched chains
(shorter than
amylopectin)
Structure
Arranged around
glycogenin (protein)
giving it a globular
arrangement
Food store in animals
Compact
Unreactive
Insoluble, forming
granules in liver and
muscle
Nota:
Important cos otherwise would affect conc. gradient as it would dissolve in water and affect osmosis.
Cellulose
Made of b glucose
1,4 glycosidic bonds
H bonds link adjacent chains
Nota:
60-70 chains form microfibrils,
the number of h bonds give microfibrils TENSILE STRENGTH.
Microfibrils held together by H-bonds form CELLULOSE FIBRES
Layers of fibres running in
dif. directions form CELL
WALLS