Antibiotic such as penicillin blocks _______.
cell wall formation in bacteria
Understanding How Penicillin Works: Blocking Bacterial Cell Walls
Antibiotics are powerful medicines used to fight infections caused by bacteria. They work in different ways to either kill bacteria or stop them from growing. The question asks what a specific antibiotic, penicillin, blocks in bacteria.
Penicillin is a well-known antibiotic that was discovered by Sir Alexander Fleming. Its main target is the bacterial cell wall.
Penicillin and Bacterial Cell Wall Formation
Bacteria have a strong outer layer called a cell wall, which is essential for their survival. The cell wall provides structural support, protects the bacterium from osmotic pressure (preventing it from bursting in watery environments), and maintains its shape.
Penicillin works by interfering with the synthesis of peptidoglycan, which is a key component of the bacterial cell wall. Specifically, it inhibits the enzymes (transpeptidases, also known as penicillin-binding proteins or PBPs) that help cross-link the peptidoglycan layers. When these links cannot be formed properly, the cell wall becomes weak and unstable.
Because of the weakened cell wall, the internal pressure of the bacterium causes it to swell and eventually burst, leading to the death of the bacterial cell. This is why penicillin is effective at killing actively growing bacteria that are busy building their cell walls.
Importantly, human cells do not have a cell wall; they have a cell membrane instead. This difference is why penicillin is toxic to bacteria but generally safe for humans, as it targets a structure unique to the bacterial cell.
Analyzing Other Options
- RNA synthesis in bacteria: Some antibiotics, like Rifampicin, block RNA synthesis by inhibiting RNA polymerase. Penicillin does not work this way.
- DNA synthesis in bacteria: Some antibiotics, like Fluoroquinolones (e.g., Ciprofloxacin), block DNA synthesis by inhibiting enzymes like DNA gyrase. Penicillin does not work this way.
- Division in bacteria: Blocking cell wall formation ultimately prevents bacteria from dividing successfully and kills them, but penicillin's primary, direct action is on the cell wall synthesis process itself, which then leads to inhibited division and cell lysis. Other antibiotics, like Sulfa drugs, interfere with metabolic pathways necessary for bacterial growth and division in a different manner.
Therefore, the most accurate description of what penicillin blocks is the formation of the cell wall in bacteria.
| Antibiotic Type | Primary Target in Bacteria |
|---|---|
| Penicillin (and related drugs like Cephalosporins) | Cell Wall Synthesis |
| Rifampicin | RNA Synthesis |
| Fluoroquinolones | DNA Synthesis |
| Tetracyclines, Macrolides | Protein Synthesis (Ribosomes) |
Revision Table: Penicillin Action
Review the key points about how penicillin works:
- Target: Bacterial cell wall.
- Mechanism: Blocks peptidoglycan synthesis by inhibiting transpeptidases (PBPs).
- Outcome: Weakened cell wall, cell lysis (bursting), bacterial death.
- Selectivity: Affects bacteria only because human cells lack a cell wall.
Additional Information: Antibiotic Mechanisms
Antibiotics can target various essential processes in bacteria:
- Cell Wall Synthesis Inhibition: Penicillins, Cephalosporins, Vancomycin. These weaken the cell wall.
- Protein Synthesis Inhibition: Tetracyclines, Macrolides (Erythromycin), Aminoglycosides (Gentamicin), Chloramphenicol. These interfere with bacterial ribosomes.
- DNA/RNA Synthesis Inhibition: Fluoroquinolones (DNA gyrase), Rifampicin (RNA polymerase).
- Metabolic Pathway Inhibition: Sulfonamides, Trimethoprim. These block the synthesis of essential metabolites like folic acid.
- Cell Membrane Disruption: Polymyxins. These damage the bacterial cell membrane.
Understanding these different mechanisms helps explain why different antibiotics are used for different types of bacterial infections.
Similar Questions
Which one of the following is the correct sequence of organs that occur in the path of urine flow in human body?
Which one of the following is the Structure of a cardiac muscle cell ?
Which one of the following cell organelles mainly functions as storehouse of digestive enzymes?
Which one of the following statements is correct?
Apart from hyper acid secretion, peptic ulcers are also developed due to bacterial infection. The causative agent is __________.
Which one of the following body parts/organs of the human body does not have smooth muscles?
Which one of the following functions is not carried out by smooth endoplasmic reticulum?
Which one of the following statements regarding haemoglobin is correct?
Which one of the following viruses is responsible for the recent death of lions in Gir National Park?
Which of the following roles is/are played by epididymis, vas deferens, seminal vesicles and prostate in male reproductive system of human?
Important Questions from Human body
A resting person, usually has a pulse rate between ______ and ______ beats per minute
In humans, neck and head are joined by which joint ?
The human skeleton is composed of around ______ bones at birth.
During respiration, the gaseous exchange takes place in:
At which period of life, body undergoes changes leading to reproductive maturity?
