What are some nonpolar covalent bond examples in living things?

Covalent bonds are common in the molecules of living organisms. This bonds are created is by sharing electrons. The more electrons they share the stronger the bond will be.
Non-polar covalent bonds appear between two atoms of the same element or between different elements that equally share electrons.

• `O_2` and `CO_2`
  `O_2` is non-polar because the electrons are equally shared between the two oxygen atoms. The same case is with `CO_2`.
  
  Breathe in and out! When you inhale, `O_2` comes in your lungs, and when you exhale, `CO_2` goes out. This process happens because `CO_2` and `O_2` are nonpolar molecules.
  

• `CH_3`
  Our intestinal gas/ flatus is produced as a byproduct of bacterial fermentation in our colon.
  
  Click here for: Why is `CH_4` a non-polar molecule?
  

• DNA
  Each strand of the DNA is polar, but each strand with its polarity neutralizes the molecule of the DNA in total.
  

• NON-POLAR amino acids `->` their R-groups, white on the picture below, hydrocarbon alkyl groups (alkane branches) or aromatic rings, exception: benzene ring in the amino acid Tyrosine which is polar. Aminoacids are monomers that form proteins.
  Alanine, Cysteine, Glycine, Isoleucine, Leucine, Methionine, Phenylalanine, Proline, Tryptophan, Valine