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.
Figure 21 Illustrates hydrogen bonding between two water molecules as observed in water. The hydrogen bonds are short, linear and strong. These are two-center hydrogen bonds. Although each water molecule in liquid water and in ice forms four hydrogen bonds, only one hydrogen bond is shown here.