Living things are composed of both atoms and molecules. Atoms are the basic building blocks of matter, and they combine to form molecules through chemical bonds. In the context of living organisms, atoms such as carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulfur are particularly important.
These atoms combine in various ways to form molecules, which are the chemical structures that make up the components of living organisms. For instance, molecules such as DNA, proteins, carbohydrates, and lipids play critical roles in the structure, function, and processes of living things.
In summary, living things are ultimately composed of atoms, which come together to form molecules, which in turn constitute the various components and systems within an organism.