Many molecules used to build and repair cells can be synthesized from basic organic building blocks but some cannot. Adult humans can synthesize 12 amino acids. The remaining 8 amino acids must be obtained from the diet. Some unsaturated fatty acids cannot be synthesized by humans. One example is linoleic acid.
Vitamins are organic molecules required in very small quantities.
Many of these are cofactors for various enzymes. Let's fill out the table as we consider how cells adapted to form various tissues. Toxicity from overdose. Orange and deep green vegetables and fruits Vitamin C, Ascorbic acid . Collagen synthesis, antioxidant, detoxification, iron absorbance.