Precursor cell, is widely used to denote any ancestral cell type (either stem cell or progenitor cell) of a particular lineage; it is often used when such distinctions do not matter or are not known.

TLS Online TPP Program

#Id: 8252

#Unit 1. Molecules and their Interaction Relevant to Biology

There are four major DIPOLES that decide VWI

1. spontaneous (or instantaneous) dipoles

2. Dipole-Dipole Interaction

3. Induced Dipoles

4. Spontaneous Dipole-Induced Dipole Interaction

TLS Online TPP Program

#Id: 8253

#Unit 1. Molecules and their Interaction Relevant to Biology

Spontaneous (or instantaneous) dipoles

When groups of electrons move to one end of the atom, it creates a dipole. 

TLS Online TPP Program

#Id: 8254

#Unit 1. Molecules and their Interaction Relevant to Biology

Dipole-Dipole Interaction

Dipole-Dipole interactions occur between molecules that have permanent dipoles; these molecules are also referred to as polar molecules.

TLS Online TPP Program

#Id: 8255

#Unit 1. Molecules and their Interaction Relevant to Biology

Potential energy of Dipole-Dipole Interaction

V is the potential energy

μ is the dipole moment

ϵo is the vacuum permittivity.

R is the length between the two nuclei

TLS Online TPP Program

#Id: 8256

#Unit 1. Molecules and their Interaction Relevant to Biology

The negative sign indicates that energy is released out of the system, because energy is released when bonds are formed, even weak bonds.

TLS Online TPP Program

#Id: 8257

#Unit 1. Molecules and their Interaction Relevant to Biology

The negative sign also suggests that the interaction is driven by an attractive force.