BB10A: Cells, Biomolecules & Genetics2003-04 Semester 1
• Tuesday 30 Sept.• Lecture 3
• Biomolecules & their interactions with Water
• Andrew Pearson
Life on our planet has evolved to cope with a predominantly aqueous environment:
roughly 70% of theEarth’s surface & animalbodies are H2O
Biomolecules & their interactions with Water
The properties of H2O have thereforehad a powerful effect upon the forces ofnatural selection at the level of the
Biomolecule.
Let us look at some properties of H2O.
Biomolecules & their interactions with Water
Biomolecules & their interactions with Water
Biomolecules & their interactions with Water
In contrast to “hydrophobic”substances, many biochemicallyimportant ions and molecules areso “hydrophilic” that Osmoticpressure results.
Biomolecules & their interactions with Water
Biomolecules & their interactions with Water
Another important property of H2O is it’s ability to dissociate into botha weak acid and a weak base.
Biomolecules & their interactions with Water
Biomolecules & their interactions with Water
Biomolecules & their interactions with Water
The effect of water upon naturalselection is quite marked even atthe molecular level:
the case of the most abundantbiosynthesised molecule,
Glucose.
Biomolecules & their interactions with Water
Biomolecules & their interactions with Water
Biomolecules & their interactions with Water
Biomolecules & their interactions with Water
Biomolecules & their interactions with Water
Biomolecules & their interactions with Water
Proteoglycan aggregate
Chondroitin sulphateKeratan sulphate
HyaluronicAcid core
The less it is allowed to interact withaqueous media, the stronger a H-bondcan be.
This is important in the stability ofmacromolecules such as DNA:
Biomolecules & their interactions with Water
Biomolecules & their interactions with Water
All things naturally prefer (are more stable in) the lowestpossible energy state.
For H2O in the biosphere(i.e. between 0oC and 100oC)this means random motion, not anordered structure.
Biomolecules & their interactions with Water
Biomolecules & their interactions with Water
Biomolecules & their interactions with Water
Biomolecules & their interactions with Water
This effect is important in the stabilisation of biomembranes
Biomolecules & their interactions with Water
Biomolecules & their interactions with Water
Biomolecules & their interactions with Water
Biomolecules & their interactions with Water
Relative abundances of elements in the universe
Biomolecules & their interactions with Water
Relative abundances of elements in Earth’s crust
Biomolecules & their interactions with Water
Relative abundances of elements in humans
Biomolecules & their interactions with Water
Universal Earth’s crustHuman bodyBiomolecules & their interactions with Water
Biomolecules & their interactions with Water
Apart from photosynthesising organisms,which take energy from e/m radiation, allthe biochemical needs of the biosphere forlife come from:chemical elements, salts and moleculesfound in the lower regions of the atmosphere,the hydrosphere and the upper parts of thelithosphere.
Biomolecules & their interactions with Water
Ecology studies are often enhanced by under-standing how and why elements cycle through different systems in the biosphere, & recent perturbations of ecological balances by human activities have brought these matters into sharp focus.
Biomolecules & their interactions with Water
Biomolecules & their interactions with Water
Biomolecules & their interactions with Water
Biomolecules & their interactions with Water
Biomolecules & their interactions with Water
Biomolecules & their interactions with Water
Biomolecules & their interactions with Water
Biomolecules & their interactions with Water
Biomolecules & their interactions with Water
Biomolecules & their interactions with Water
Biomolecules & their interactions with Water
Biomolecules & their interactions with Water
Biomolecules & their interactions with Water
Biomolecules & their interactions with Water
Biomolecules & their interactions with Water