Which of the following statements is incorrect?
- A. BLASTX searches protein databases
- B. BLASTX use translated nucleotide as the query sequence
- C. Both TBLASTX and TBLASTN translate query into 6 reading frames
- D. BLASTN searches protein databases
Correct Answer: D
Rationale: The correct answer is D because BLASTN searches nucleotide databases, not protein databases. BLASTN uses a nucleotide sequence as the query to find similar sequences in nucleotide databases. This is different from BLASTX, which searches protein databases using translated nucleotide sequences (answer A is correct). TBLASTX and TBLASTN translate the query sequence into six reading frames to search for similarities in both nucleotide and protein databases (answer C is correct). BLASTN is specifically designed for nucleotide sequence searches, making statement D incorrect.
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AIRE is expressed in
- A. Bone marrow
- B. Thymic cortical region
- C. Thymic medullary region
- D. LN cortex
Correct Answer: C
Rationale: The correct answer is C: Thymic medullary region. AIRE (Autoimmune Regulator) is expressed in the thymic medullary region. This region is crucial for central tolerance by deleting self-reactive T cells to prevent autoimmune reactions. AIRE regulates the expression of tissue-specific antigens in medullary thymic epithelial cells, leading to negative selection of autoreactive T cells. Choices A, B, and D are incorrect as AIRE is not primarily expressed in bone marrow, thymic cortical region, or LN cortex.
Which group(s) of microorganisms is (are) thought to be the oldest living organisms?
- A. eukaryotes
- B. heterotrophic prokaryotes
- C. Archaea
- D. viruses
Correct Answer: C
Rationale: The correct answer is C: Archaea. Archaea are thought to be the oldest living organisms due to their unique characteristics and genetic similarities to the earliest forms of life. They are known for thriving in extreme environments, resembling conditions on early Earth. Other choices are incorrect because eukaryotes are more complex and evolved later, heterotrophic prokaryotes came after autotrophic prokaryotes, and viruses are not considered living organisms.
If HLA-DR4 is considered a 'risk' allele for disease 'X', this means:
- A. All individuals with the HLA-DR4 allele will get disease X
- B. All individuals with disease X have the HLA-DR4 allele
- C. An individual with the HLA-DR4 allele has an increased chance of developing disease X compared to other individuals
- D. All of the above are true
Correct Answer: C
Rationale: The correct answer is C because having the HLA-DR4 allele increases the likelihood of developing disease X but does not guarantee it. Choice A is incorrect because not all individuals with HLA-DR4 will get disease X. Choice B is incorrect because not all individuals with disease X have the HLA-DR4 allele. Choice D is incorrect because it falsely states that all statements are true, which is not the case.
What role do the B-complex vitamins play in wound healing?
- A. Decrease metabolism
- B. Protect protein from being used for energy
- C. Provide metabolic energy for the inflammatory process
- D. Coenzymes for fat, protein, and carbohydrate metabolism
Correct Answer: C
Rationale: B-complex vitamins support energy production, which fuels the inflammatory and reparative processes during wound healing.
The HIV protein that allows fusion of the viral envelope with the cell plasma membrane is
- A. gp120
- B. gp41
- C. gp160
- D. CXCR4
Correct Answer: B
Rationale: The correct answer is B: gp41. Gp41 is responsible for the fusion of the viral envelope with the cell plasma membrane by undergoing conformational changes that allow the viral and cellular membranes to merge. Gp120 attaches to the host cell receptor (CD4), facilitating the binding of the virus to the host cell. Gp160 is the precursor protein that is cleaved into gp120 and gp41 during viral maturation. CXCR4 is a cellular co-receptor used by some strains of HIV to enter host cells but is not directly involved in the fusion process.