BRAINCAKEAntibiotics
An antibiotic is a chemical that kills bacteria or inhibits their growth, without harming the cells of the host. Many antibiotics were first found as substances made by fungi or bacteria to suppress competing microorganisms. The first, penicillin, was discovered by Alexander Fleming in 1928, when he noticed that the mould Penicillium had stopped bacteria growing on an agar plate. Many modern antibiotics are made synthetically or are chemically modified versions of natural ones.
Antibiotics work because of selective toxicity: they target structures or processes that bacteria have but human cells do not, or that are different in bacteria. The main targets are:
Sign in free to see the rest of this lesson, the R.E.C.I.P.E. recall steps and the quiz
BrainCake is free. Make an account in seconds and pick up where this page stops.
Key terms in this lesson
- peptidoglycan
- The polysaccharide, cross-linked by short peptide chains, that makes up the cell wall of bacteria and gives it strength.
- dna gyrase
- A bacterial enzyme (topoisomerase) that relieves supercoiling ahead of the replication fork by cutting, passing through and rejoining DNA strands.
More in Bacteria and Disease
- Exotoxins
- Staphylococcus spp.
- Host Tissue Invasion
- Mycobacterium tuberculosis
- Broad-spectrum, Narrow spectrum, Bacteriostatic and Bactericidal
- Antimetabolites
- Protein synthesis Inhibitors
- Cell Wall Agents
All 30 lessons in Bacteria and Disease · All Edexcel A-level Biology topics