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.
A molecule of water has two hydrogen atoms. Both of these atoms can form a hydrogen bond with oxygen atoms of different water molecules. Every water molecule can be hydrogen bonded with up to three other water molecules (See Fig. 3-7). However, because hydrogen bonds are weaker than covalent bonds, in liquid water they form, break, and reform easily.