Another example of direct reversal is the removal of the methyl group from the methylated base O6 –methylguanine  In this case, a methyltransferase removes the methyl group from the guanine residue by transferring it to one of its own cysteine residues. This is costly to the cell because the methyltransferase is not catalytic; having once accepted a methyl group, it cannot be used again.

TLS Online TPP Program

#Id: 7739

#Unit 1. Molecules and their Interaction Relevant to Biology

Atoms are characterised by:

Radius

Ionization energy

Electron affinity

Electronegativity

Metallic character

Oxidation potential

TLS Online TPP Program

#Id: 7740

#Unit 1. Molecules and their Interaction Relevant to Biology

Atomic radii: The atomic radii of an atom depends on its position in the periodic table.

We can never determine the atomic radius of an atom because there is never a zero probability of finding an electron, and thus never a distinct boundary to the atom.

All that we can measure is the distance between two nuclei (internuclear distance).

TLS Online TPP Program

#Id: 7741

#Unit 1. Molecules and their Interaction Relevant to Biology

Atomic radii: The atomic radii of an atom depends on its position in the periodic table.

We can never determine the atomic radius of an atom because there is never a zero probability of finding an electron, and thus never a distinct boundary to the atom.

All that we can measure is the distance between two nuclei (internuclear distance).

TLS Online TPP Program

#Id: 7742

#Unit 1. Molecules and their Interaction Relevant to Biology

Atomic radii: The atomic radii of an atom depends on its position in the periodic table.

We can never determine the atomic radius of an atom because there is never a zero probability of finding an electron, and thus never a distinct boundary to the atom.

All that we can measure is the distance between two nuclei (internuclear distance).

TLS Online TPP Program

#Id: 7743

#Unit 1. Molecules and their Interaction Relevant to Biology

A covalent radius is one-half the distance between the nuclei of two identical atoms.

TLS Online TPP Program

#Id: 7744

#Unit 1. Molecules and their Interaction Relevant to Biology

An ionic radius is one-half the distance between the nuclei of two ions in an ionic bond.