Biology

Antibiotics and Immunity

974 Questions

Prepare for your science sections with these questions on antibiotics and immunity. The hub covers various classes of antibiotics, their sources, and mechanisms of microbial resistance. It also addresses the human antiviral response.

Antibiotic classes and sourcesMicrobial resistance mechanismsAntiviral proteinsDisease treatments

Antibiotics and Immunity Questions

Multiple choice

The spreading factor responsible for Streptococci infection is:

  1. streptokinase

  2. muramic acid

  3. deoxyribonuclease C

  4. peptidoglycan

  5. none of the above
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Deoxyribosenuclease 3 is an extracellular enzyme produced by Streptococci [Gr.p A]. It is spreading factor, an important enzyme in skin and soft tissue infection.

Multiple choice

Which of the following fungi is used in production of antibiotics Penicillin?

  1. S. cerevisae

  2. Neurospora crasa

  3. Penicillium

  4. Giberella fugikurni

  5. Penicillium camemberti
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Penicillium fungi are used in production of antibiotics Penicillin (PCN or pen). Penicillin antibiotics are very historically important as it was the first drug depicted for many severe diseases like syphilis.

Multiple choice

The actinobacteria of the genus Streptomyces are of immense importance to both ecological and human welfare. Which of the following antibiotics are derived from the members of genus Streptomyces?

  1. Penicillin, Streptomycin, Griseofulvin

  2. Chloramphenicol, Griseofulvin, Oxytetracycline

  3. Streptomycin, Chloramphenicol, Oxytetracycline

  4. Streptomycin, Oxytetracycline, Bacitracin

  5. Griseofulvin, Chloramphenicol, Penicillin
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Streptomycin: Streptomyces griseus Chloramphenicol: Streptomyces venezuelae Oxytetracycline: Streptomyces rimosus All are derived from members of genus Streptomyces.

Multiple choice

Which of the following is/are responsible for the prevention of ribosomal association at the end of initiation step?

Different antibiotics affect translation in various ways. Some of them prevent ribosomal association with mRNA or block amino acid binding sites on the ribosome to cause damage in the process of translation.

  1. Erythromycin

  2. Chloramphenicol and tetracycline

  3. Streptomycin

  4. Tobramycin and kanamycin

  5. Neomycin
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Tobramycin and kanamycin prevent ribosomal association at the end of initiation step and cause misreading of the genetic code.

Multiple choice

How does chloramphenicol affect bacterial translation?

Different antibiotics affect translation in various ways. Some of them prevent ribosomal association with mRNA or block amino acid binding sites on the ribosome to cause damage in the process of translation.

  1. Chloramphenicol causes misreading of the genetic code.

  2. Chloramphenicol inhibits translocation of mRNA along ribosome.

  3. Chloramphenicol blocks peptidyl transferase and formation of peptide bond on the 50S ribosomal subunit.

  4. Chloramphenicol blocks A-site of 50S subunit.

  5. Chloramphenicol inhibits interaction with tRNA and mRNA.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

It is an antibiotic, which causes inhibition of bacterial translation process by blocking synthesis of peptide bond.

Multiple choice

“Inhibition of the prokaryotic transcription is caused by rifampin, an antibiotic.” Which of the following options is correct for rifampin action?

  1. Binds with the β-subunit of prokaryotic RNA polymerase.

  2. Binds with RNA polymerase II.

  3. Binds with DNA template and blocks movement of RNA polymerase.

  4. Binds with promoter region.

  5. None of the above

Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Rifampin is an antibiotic that is widely used for the treatment of tuberculosis and leprosy. It binds with the β-subunit of prokaryotic RNA polymerase and inhibits the movement of the enzyme and its activity.

Multiple choice

All of the following components are present in a gram positive bacterial cell wall except

  1. teichoic acid

  2. M-protein

  3. lipid A and O polysaccharide

  4. polysaccharides

  5. glycerol or ribitol
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Lipid A is specifically present in gram negative bacteria in the outer lipopolysaccharide membrane. It is the lipid portion of the outer membrane. When the bacteria die, they release lipid A. It is an endotoxin. It is responsible for fever, shock and dilation of blood vessels. From the core polysaccharide, O polysaccharide extends out, which is composed of sugar units. It acts as an antigen and helps distinguish different species of gram negative bacteria like E. coli. These are the only structures that are specifically confined to gram negative bacteria and are absent in gram positive bacteria.

Multiple choice

A gram negative bacterium is less sensitive to antibiotics because its

  1. peptidoglycan is thick

  2. peptidoglycan lacks teichoic acid

  3. peptidoglycan is thin

  4. peptidoglycan lacks lipid A

  5. petidoglycan contains alcohol
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The peptidoglycan of a gram negative bacterium consists of fewer number of layers and it is thin. In addition to this, the outer lipopolysaccharide layer is not permeable to antibiotics like penicillin. Therefore, a typical gram negative bacterium is less sensitive to antibiotics.

Multiple choice

Bacterial capsule is medically important because the capsule is a

  1. simple cell structure

  2. prokaryotic cell structure

  3. virulent cell structure

  4. avirulent cell structure

  5. complex cell structure
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A bacterial capsule is, in fact, a virulent structure as it imparts virulence to a bacterial cell by helping the cell in attachment, adherence and by avoiding phagocytosis.