1.1. What is Biology?

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What is biology?

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The science of life

What does the word "biology" mean?

  • Greek ”bios” = life
  • Greek ”logos” = text, knowledge of
  • Bio-logy = science of life

But ...

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.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.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.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 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.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).A very simple bacterial cell with cellular membrane (blue), DNA (orange), and enzymes (green).

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