Drugs Igcse
DRUGS
A drug is a chemical substance taken into the body that modifies or affects chemical reactions in the body.
Generally, drugs are developed for medical use.
Without drugs, people would live much shorter lives or suffer greater pain.
All drugs are dangerous when misused.
ANTIBIOTICS
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What are Antibiotics?
a chemical substance , produced by a microorganism (bacterium or fungus) which will inhibit the growth or replication of other microorganisms.
• Effective antibiotics show selective toxicity – killing or disabling pathogens without harming host cells.
• Wide range to treat fungal and bacterial infections.
• Antibiotics are not effective against viruses.
MECHANISMS OF ANTIBIOTIC ACTION
• interfere with making of bacterial cell walls:
eg., penicillin
Weaken bacterial cell walls. Walls made of
chains of peptidoglycan molecules. Penicillin
prevents linking of peptidoglycan molecules.
Cell wall becomes weak, bacterium bursts
(lysis).
• Do not act on viruses.
No form of cellular structure- no cell walls
or cell organelles.
[pic]
PRESCRIPTION OF AN antibiotic
• Usually a doctor faced with a patient who needs immediate treatment makes an educated guess at what is causing the infection and what antibiotic is needed so that treatment can start right away.
• Necessary to test which antibiotics the microorganism is sensitive to.
• Place discs soaked in different antibiotics onto agar jelly on which the bacterium is growing.
• If a clear area of a certain diameter appears around the disc the antibiotic is effective.
[pic]
[pic]
Antibiotic Resistant Bacteria Are:
Bacteria mutate and are able to resist the antibiotics that are meant to kill them.
This is a normal process speeded up by the overuse and misuse of antibiotics.
THE MORE WE USE ANTIBIOTICS THE MORE SELECTION PRESSURE WE PUT ON BACTERIA TO EVOLVE RESISTANCE.
HEROIN
A drug is a chemical substance taken into the body that modifies or affects chemical reactions in the body.
Generally, drugs are developed for medical use.
Without drugs, people would live much shorter lives or suffer greater pain.
All drugs are dangerous when misused.
ANTIBIOTICS
[pic]
What are Antibiotics?
a chemical substance , produced by a microorganism (bacterium or fungus) which will inhibit the growth or replication of other microorganisms.
• Effective antibiotics show selective toxicity – killing or disabling pathogens without harming host cells.
• Wide range to treat fungal and bacterial infections.
• Antibiotics are not effective against viruses.
MECHANISMS OF ANTIBIOTIC ACTION
• interfere with making of bacterial cell walls:
eg., penicillin
Weaken bacterial cell walls. Walls made of
chains of peptidoglycan molecules. Penicillin
prevents linking of peptidoglycan molecules.
Cell wall becomes weak, bacterium bursts
(lysis).
• Do not act on viruses.
No form of cellular structure- no cell walls
or cell organelles.
[pic]
PRESCRIPTION OF AN antibiotic
• Usually a doctor faced with a patient who needs immediate treatment makes an educated guess at what is causing the infection and what antibiotic is needed so that treatment can start right away.
• Necessary to test which antibiotics the microorganism is sensitive to.
• Place discs soaked in different antibiotics onto agar jelly on which the bacterium is growing.
• If a clear area of a certain diameter appears around the disc the antibiotic is effective.
[pic]
[pic]
Antibiotic Resistant Bacteria Are:
Bacteria mutate and are able to resist the antibiotics that are meant to kill them.
This is a normal process speeded up by the overuse and misuse of antibiotics.
THE MORE WE USE ANTIBIOTICS THE MORE SELECTION PRESSURE WE PUT ON BACTERIA TO EVOLVE RESISTANCE.
HEROIN