Question

How does polarity influence the function of molecules and macromolecules within aqueous biological systems?

How do viruses differ from cells in structure and function?

What are the four levels of protein structure? How are they formed and destroyed?

Answer 1

How does polarity influence the function of molecules and macromolecules within aqueous biological systems?

Nearly all biological molecules have their organization influenced by interactions with the polar covalently bonded water molecule. The properties of water influence the bonding Abilities of Biomolecules. This bonding abilities/interaction allows the development of functional complexity by contributing integration of function.

Let's explain this with an example. Molecules (polar) in aqueous solution interact with water molecules through the formation of hydrogen and ionic interactions (dissolves).

However, some molecules (termed nonpolar molecules) cannot undergo any such interactions as they are not as favorable as are interactions between the water molecules themselves. Nonpolar molecules have a tendency to aggregate in water because the entropy of the water is increased through the release of water molecules. This phenomenon, termed the hydrophobic effect, helps promote many biochemical processes such as folding of proteins as nonpolar amino acids have a strong tendency to associate with one another inside the interior of the folded protein.

How do viruses differ from cells in structure and function?

The difference in structure:

Viruses are smaller than a single prokaryotic cell.

Virus structure is very simple compared to cells. The virus mainly consists of a nucleic acid core (DNA/RNA}, a protein coat or capsid, envelope, viral-specific enzymes whereas a cell consists of different organelle which carries out specific function (even prokaryotic cell has ribosome).

Difference in function

The virus needs a host to multiply whereas cell can multiply independently using its own machinery.

Four levels of Protein structure and their formation

The primary level of organization is simply the order of amino acids in the peptide chain formed by the peptide bond.

Secondary structures are 2-dimensional structures formed due to hydrogen bonding between the hydrogen of amine groups and oxygen of the carbonyl groups on the peptide backbone.

The two common secondary structures are the alpha -helix and the beta -sheet.

Tertiary structure involves the three-dimensional folding of a protein due to interactions of amino acid side chains.

Quaternary structure involves the association of two or more polypeptides into functional proteins.

Denaturation is disruption and possible destruction of both the secondary and tertiary structures. A variety of reagents and conditions can cause denaturation such as heat, Alcohol (Disrupts Hydrogen Bonding), Acids and Bases (Disrupt Salt Bridges), Metal Salts (Disrupt Disulfide Bonds)