Final answer:
The diphtheria toxin is deadly because it inhibits protein synthesis in host cells, leading to cell death. It is produced by Corynebacterium diphtheriae and can also spread throughout the body, damaging tissues like the heart and nerves.
Step-by-step explanation:
The diphtheria toxin is so deadly because it inhibits protein synthesis in host cells, ultimately leading to cell death. The toxin is produced by the bacterium Corynebacterium diphtheriae and acts as an A-B toxin, with the A subunit transferring adenosine diphosphate (ADP)-ribose to elongation-factor protein (EF-2) needed for protein synthesis.
This stops protein elongation and kills the cell. The toxin can also spread throughout the body, causing damage to tissues such as the heart and nerves.