Nokea
Enzymes that remove functional groups from a substrate without adding water, or that add functional groups to a double bond, are called
- A. oxidoreductases.
- B. transferases.
- C. hydrolases.
- D. lyases.
Correct Answer: D
Rationale: The correct answer is D: lyases. Lyases are enzymes that catalyze the breaking of chemical bonds without the addition of water. They can remove functional groups from substrates or add functional groups to double bonds without the use of water.
A: Oxidoreductases involve the transfer of electrons.
B: Transferases transfer functional groups from one molecule to another.
C: Hydrolases catalyze the breaking of bonds by adding water.
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Botulism agent causes severe food toxicoinfection. Point out the most characteristic morphologic feature of botulism agent.
- A. Gram-positive spore-forming bacilli with subterminal spore
- B. Thick gram-positive non-sporeforming bacilli
- C. Gram-positive spore-forming bacilli with terminal spore
- D. Thin mobile spore-forming bacilli with central spore
Correct Answer: B
Rationale: The correct answer is B: Thick gram-positive non-sporeforming bacilli. In botulism, the causative agent, Clostridium botulinum, is a thick gram-positive bacilli that does not form spores. This is a key characteristic morphologic feature.
A: Gram-positive spore-forming bacilli with subterminal spore - This is incorrect as Clostridium botulinum does not have subterminal spores.
C: Gram-positive spore-forming bacilli with terminal spore - Incorrect because Clostridium botulinum does not form spores.
D: Thin mobile spore-forming bacilli with central spore - Incorrect because Clostridium botulinum is not thin, mobile, or spore-forming.
In summary, the most characteristic morphologic feature of the botulism agent is being thick, gram-positive, and non-sporeforming, making choice B the correct answer.
In which of the following especially dangerous infections, the respiratory tract is not damaged:
- A. Tularemia
- B. Plague
- C. Anthrax
- D. Cholera
Correct Answer: D
Rationale: The correct answer is D, Cholera. Cholera is caused by the bacterium Vibrio cholerae and primarily affects the intestines, leading to severe watery diarrhea and dehydration. It does not damage the respiratory tract.
Choice A, Tularemia, affects the respiratory tract and other organs. Choice B, Plague, can cause respiratory symptoms like cough and difficulty breathing. Choice C, Anthrax, can affect the respiratory tract if inhaled in its spore form.
The specific binding of HIV to the CD4 surface molecules of the target cells is brought about by:
- A. Gp120
- B. Gp41
- C. Gp32
- D. Gp55
Correct Answer: A
Rationale: The correct answer is A: Gp120. Gp120 is a glycoprotein on the surface of the HIV virus that specifically binds to the CD4 receptor on target cells. This binding is essential for the virus to enter the host cell and initiate the infection process. Gp41 is another glycoprotein on the virus that helps with membrane fusion, not binding to CD4. Gp32 and Gp55 are not involved in the specific binding of HIV to CD4 molecules. So, A is correct as it directly plays a key role in the initial attachment of HIV to target cells.
Gram-negative, capsulated bacteria with capsule, lactose-positive colonies. Isolated for the first time in pneumonia, but have more important role in urinary infections, otitis, meningitides, sepsis, nosocomial infections:
- A. Staphylococcus aureus
- B. Klebsiella pneumonia
- C. Streptococcus pneumoniae
- D. Mycobacterium tuberculosis
Correct Answer: B
Rationale: The correct answer is B: Klebsiella pneumoniae. This bacterium is gram-negative, capsulated, and forms lactose-positive colonies. It was first isolated in pneumonia but is more commonly associated with urinary infections, otitis, meningitides, sepsis, and nosocomial infections. Klebsiella pneumoniae fits all the characteristics mentioned in the question, making it the correct choice.
Incorrect choices:
A: Staphylococcus aureus is gram-positive and does not have a capsule.
C: Streptococcus pneumoniae is also gram-positive and does not fit the description given.
D: Mycobacterium tuberculosis is an acid-fast bacterium associated with tuberculosis, but it is neither gram-negative nor lactose-positive.
This drug has a destructive effect on erythrocytic forms of malarial plasmodia and dysenteric amoebae. It is used for treatment and prevention of such diseases as malaria, amebiasis and interstitial disease. What drug is it?
- A. Chingamin
- B. Emetine hydrochloride
- C. Quinine
- D. Erythromycin
Correct Answer: C
Rationale: The correct answer is C: Quinine. Quinine is known for its destructive effect on erythrocytic forms of malarial plasmodia and dysenteric amoebae. It is commonly used for the treatment and prevention of diseases such as malaria, amebiasis, and interstitial disease. Quinine works by interfering with the parasite's ability to break down hemoglobin in red blood cells, ultimately leading to their destruction.
Incorrect choices:
A: Chingamin - Chingamin is not typically used to treat malaria, amebiasis, or interstitial disease.
B: Emetine hydrochloride - Emetine hydrochloride is primarily used for treating amoebic dysentery and is not commonly used for malaria treatment.
D: Erythromycin - Erythromycin is an antibiotic used to treat bacterial infections, not parasitic infections like malaria or amebiasis.