Chapter 2 of 10All chapters
Chapter 2 of 10
Cells
The smallest unit that is alive.
Two kinds
Prokaryotic cells, such as bacteria, have no nucleus. Eukaryotic cells, in plants, animals and fungi, keep their DNA in a nucleus and contain specialised compartments.
- Mitochondria release energy; chloroplasts in plants capture light.
- Both have their own DNA and were probably once free-living bacteria.
The membrane
A cell membrane controls what enters and leaves, which is what keeps the inside different from the outside. Almost every drug and toxin has to solve the problem of crossing it.