BRAINCAKEAntibiotics
Gram negative bacteria e.g. E. coli have a thin layer of peptidoglycan (murein) between two layers of inner and outer phospholipid membrane. Gram positive bacteria have a thick layer of peptidoglycan containing chemicals such as teichoic acid. e.g. MRSA.
Beta-lactams such as penicillin inhibit the formation of peptidoglycan so are effective against gram positive bacteria. Penicillin inhibits the enzyme required for the synthesis and assembly of the peptide cross-linkages in bacterial cell walls. The cell walls are weakened. As water enters naturally by osmosis the cell wall is unable to withstand the pressure. The cell bursts and the bacterium dies.
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
- phospholipid
- A lipid in which one fatty acid is replaced by a phosphate group, giving a hydrophilic head and hydrophobic tails.
- osmosis
- The net movement of water molecules from a region of higher water potential to a region of lower water potential through a selectively permeable membrane.
More in Cell Recognition and the Immune System
- Herd Immunity
- Vaccination Programme Failure
- Ethics
- MMR Vaccine Case Study
- Structure of HIV Virus
- Replication of HIV Virus
- AIDS
- The ELISA Test
All 30 lessons in Cell Recognition and the Immune System · All AQA AS-level Biology topics