Dicotyledons: Examples of Plant Compounds

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Questions and Answers

What is the common name of the group of branching procaryotic microorganisms that are rich sources of antibiotics?

Cephalosporium

Cruciferae

Actinomycetes (correct)

Dicotyledons

What is the main function of antibiotics?

To boost the immune system

To stimulate the growth of microorganisms

To suppress the growth of other microorganisms and destroy them (correct)

To enhance the growth of fungi

What is the purpose of adding cycloheximide to the soil sample in the screening process for antibiotics?

To inhibit the growth of bacteria

To inhibit the growth of interfering fungi (correct)

To promote the growth of actinomycetes

To inhibit the growth of actinomycetes

What is the difference between bactericidal and bacteriostatic antibiotics?

Bactericidal kills bacteria, while bacteriostatic inhibits growth Signup and view all the answers

Who discovered penicillin in 1929?

Alexander Fleming Signup and view all the answers

What is the purpose of adding a 1:40 dilution of phenol to the soil sample in the screening process for antibiotics?

To inhibit the growth of interfering bacteria Signup and view all the answers

What is the temperature range for incubating the agar plates during the screening process for antibiotics?

25-30°C Signup and view all the answers

What is the genus of bacteria that is particularly noteworthy for producing antibiotics?

Streptomyces Signup and view all the answers

How long are the agar plates incubated during the screening process for antibiotics?

3-7 days Signup and view all the answers

What is the source of antibiotics such as streptomycin and chloramphenicol?

Streptomyces Signup and view all the answers

What is the origin of cephalosporins?

Fungi Signup and view all the answers

What is the purpose of transferring characteristic colonies of actinomycetes onto fresh medium containing pathogenic microorganisms?

To test the antibiotic activity of actinomycetes Signup and view all the answers

What is the purpose of using varying dilutions of the treated soil sample during the screening process for antibiotics?

To isolate individual colonies of actinomycetes Signup and view all the answers

What is the property of some cephalosporins that allows them to be administered orally?

Acid stability Signup and view all the answers

What is the purpose of using agar plates containing medium that supports the growth of actinomycetes during the screening process for antibiotics?

To support the growth of actinomycetes Signup and view all the answers

What is the antibacterial compound found in fresh garlic?

Alliine Signup and view all the answers

What is the purpose of bioautography assay in antibiotic discovery?

To determine whether a chemical substance is a new antibiotic or a known compound Signup and view all the answers

Which of the following is NOT a type of chromatography used in bioautography?

HPLC Signup and view all the answers

What is the role of the agar medium in bioautography?

To detect the presence of the antibiotic Signup and view all the answers

Why are antibiotics produced industrially through fermentation?

Because it allows for large-scale production Signup and view all the answers

What is the purpose of controlling the population size in fermentation?

To ensure maximum yield of antibiotics Signup and view all the answers

What is the characteristic of antibiotics that requires careful control of population size in fermentation?

They are secondary metabolites Signup and view all the answers

What is the purpose of using different solvent systems in bioautography?

To determine whether the antibiotic is a new or known compound Signup and view all the answers

What is the advantage of using advanced chromatographic tools in bioautography?

They improve the detection method Signup and view all the answers

Study Notes

Antibiotics

Substances produced by microorganisms (bacteria, fungi, actinomycetes) to suppress the growth of other microorganisms and destroy them.
Include synthetic antibacterial agents: sulfonamides and quinolones.

Types of Antibiotics

Bactericidal: kill bacteria.
Bacteriostatic: inhibit growth of susceptible bacteria, leading to eventual death.

History of Antimicrobial Therapy

1909: Paul Ehrlich developed salvarsan, used against syphilis.
1929: Penicillin discovered by Alexander Fleming.
1935: Sulfa drugs discovered.
1944: Streptomycin discovered by Waksman from Streptomyces griseus.

Sources of Antibiotics

Most clinically used antibiotics are of bacterial or fungal origin.
Streptomyces genus produces antibiotics such as streptomycin, chloramphenicol, chlortetracycline, tetracycline, erythromycin, and neomycin.
Penicillins, griseofulvin, and cephalosporins are of fungal origin.

Non-Microbial Sources of Antibacterials

Lichens: usnic acid and vulpinic acid contribute to bacteriostatic and antifungal properties.
Order Coniferae: Essential oils from Juniperus and Pinus spp. have antibacterial activity.
Monocotyledons: Fresh garlic's antibiotic action is due to alliine, a sulfur-containing amino acid; ginger has antibacterial properties and aloe vera gel.

Screening for Antibiotics

Method involves treating soil samples with chemicals that inhibit growth of interfering bacteria and fungi, but not actinomycetes.
Varying dilutions of treated soil samples are streaked on agar plates containing medium that supports actinomycete growth.
Incubation for 3-7 days at 25-30°C, then examination for characteristic colonies of actinomycetes.

Detection of Antibiotics

Bioautography assay: a rapid method for determining whether a chemical substance produced inhibition is a new antibiotic or a known compound.
Involves chromatographing the extract containing the newly discovered antibiotic along with reference in different solvent systems.
Detection of antibiotics on chromatogram uses biologic method by placing the developed chromatogram on agar medium seeded with an appropriate test organism.

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Description

This quiz covers examples of compounds found in dicotyledons, including sesquiterpene ketones, sulfur-containing compounds, and others from various plants like hops, myrrh, and compositous plants.