bb10a: cells, biomolecules & genetics 2003-04 semester 1 tuesday 30 sept. lecture 3 biomolecules...

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.


In contrast to “hydrophobic”substances, many biochemicallyimportant ions and molecules areso “hydrophilic” that Osmoticpressure results.


Another important property of H2O is it’s ability to dissociate into botha weak acid and a weak base.


The effect of water upon naturalselection is quite marked even atthe molecular level:

the case of the most abundantbiosynthesised molecule,

Glucose.



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:


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.


This effect is important in the stabilisation of biomembranes


Relative abundances of elements in the universe


Relative abundances of elements in Earth’s crust


Relative abundances of elements in humans


Universal Earth’s crustHuman bodyBiomolecules & 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.


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.


bb10a: cells, biomolecules & genetics 2003-04 semester 1 tuesday 30 sept. lecture 3 biomolecules...

Documents

water slide

water andrew pearson

o biomolecules

effect of water

universe biomolecules

humans biomolecules

biomolecules genetics

earths crust biomolecules