The science of life
What does the word "biology" mean?
- Greek ”bios” = life
- Greek ”logos” = text, knowledge of
- Bio-logy = science of life
What is life?
Something that …
- … has a metabolism.
- … can grow and reproduce.
- … has the ability to move.
- … can evolve (develop) over time.
|A methane molecule consists of four hydrogen atoms (white) bound to a carbon atom (black). It is not living.
||An adenine molecule also has some nitrogen atoms (blue). It is not living.
Adenosine monophosphate also contains some oxygen atoms (red) and a phosphorous atom (yellow). It is not living.
|Several adenosine monophosphate molecules may be joined to form polyadenine. It is still not living.
||Several nucleotides (of which adenosine monophosphate is one) may be linked together like this. Although this is actually a DNA molecule, it is still not living.
Cells – the smallest living units:
- Cellular membrane to keep everything in place.
- DNA and RNA (genetic material).
- Enzymes (a kind of proteins) coordinate the metabolism.
A very simple bacterial cell with cellular membrane (blue), DNA (orange), and enzymes (green).