Nokea
The main function of bacterial ribosomes is:
- A. DNA replication
- B. protein synthesis
- C. cell wall synthesis
- D. RNA splicing
Correct Answer: B
Rationale: The correct answer is B: protein synthesis. Bacterial ribosomes are responsible for translating messenger RNA into proteins through a process called translation. Ribosomes are composed of both protein and RNA molecules and facilitate the binding of transfer RNA to the messenger RNA to assemble the amino acids in the correct order to form a protein. DNA replication (A) is carried out by enzymes such as DNA polymerase, not ribosomes. Cell wall synthesis (C) is a process involving enzymes that build the structure of the cell wall in bacteria. RNA splicing (D) is a eukaryotic process that involves removing introns from pre-mRNA molecules, which is not a function of bacterial ribosomes.
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The key function of bacterial capsules is:
- A. facilitating motility
- B. resisting phagocytosis
- C. synthesizing DNA
- D. producing energy
Correct Answer: B
Rationale: The correct answer is B: resisting phagocytosis. Bacterial capsules are composed of polysaccharides that help bacteria evade phagocytosis by immune cells. This physical barrier prevents immune cells from engulfing and destroying the bacteria. Facilitating motility (A), synthesizing DNA (C), and producing energy (D) are not primary functions of bacterial capsules. Motility is usually facilitated by flagella, DNA synthesis occurs in the bacterial chromosome, and energy production is typically carried out by metabolic processes within the bacterial cell.
A patient with a deep tissue infection had a wound culture revealing Gram-positive cocci in clusters. The bacteria were catalase-positive and coagulase-negative. What is the most likely causative agent?
- A. Staphylococcus epidermidis
- B. Staphylococcus aureus
- C. Streptococcus pyogenes
- D. Enterococcus faecalis
Correct Answer: A
Rationale: The correct answer is A: Staphylococcus epidermidis. The presence of Gram-positive cocci in clusters that are catalase-positive and coagulase-negative points towards coagulase-negative staphylococci like Staphylococcus epidermidis. Staphylococcus aureus is catalase-positive and coagulase-positive. Streptococcus pyogenes is catalase-negative. Enterococcus faecalis is catalase-negative and not typically seen in clusters. Therefore, the most likely causative agent in this scenario is Staphylococcus epidermidis.
Flagellin is:
- A. A protein
- B. A carbohydrate
- C. A staining method
- D. An organelle
Correct Answer: A
Rationale: Flagellin is a protein component of bacterial flagella. It is not a carbohydrate, staining method, or an organelle. The correct answer is A because flagellin is a structural protein that forms the flagellar filament. It helps in bacterial motility and pathogenicity. Therefore, the correct choice is A.
Factors for transmission of nosocomial infections are:
- A. Medical dressings
- B. Breast milk
- C. Toys
- D. All are correct
Correct Answer: D
Rationale: The correct answer is D because all the factors listed can contribute to the transmission of nosocomial infections. Medical dressings can harbor pathogens, breast milk can be a source of infection if not handled properly, and toys can serve as fomites for spreading germs. Choosing any other option would be incorrect as they all play a role in facilitating the transmission of nosocomial infections. It is important to consider all potential sources of infection in healthcare settings to effectively prevent the spread of nosocomial infections.
Slime, blood and protozoa 30-200 microns of length have been revealed in a man's feces. The body is covered with cilias and has correct oval form with a little bit narrowed forward and wide round shaped back end. On the forward end a mouth is visible. In cytoplasm there are two nucleuses and two short vacuoles. For whom are the described attributes typical?
- A. Balantidium
- B. Lamblia
- C. Dysenteric amoeba
- D. Trichomonas
Correct Answer: A
Rationale: Rationale: The described attributes match those of Balantidium. The presence of cilia, oval shape with a narrowed front and wide back end, visible mouth, two nucleuses, and short vacuoles are all characteristic features of Balantidium. Balantidium is a ciliated protozoan parasite commonly found in the human intestine. The other choices can be eliminated based on specific characteristics: Lamblia lacks cilia and has a different shape, Dysenteric amoeba typically has a single nucleus, and Trichomonas does not have cilia or multiple nuclei. Therefore, based on the specific attributes described, the correct answer is Balantidium (Choice A).