The modern working definition of a gene is a portion (or sequence) of DNA that codes for a known cellular function or process (e.g. the function make melanin molecules). A single 'gene' is most similar to a single 'word' in the English language.
Polar covalent bonds hold the actual hydrogen and oxygen atoms within the molecule of water but if you meant what holds water together as a liquid then that is called hydrogenâ¦ bonding between molecules, a type of dipole interaction.
The weak bonds between water molecules are called 'hydrogen' bonds. Hydrogen bonding is due to the fact that most of the time the electrons in a water molecule are around the oxygen atom - thus conferring a negative charge on the oxygen part of the molecule and as a consequence a positive charge on the hydrogens.