Enhancer sequences are regulatory DNA sequences that, when bound by specific proteins called transcription factors, enhance the transcription of an associated gene. Regulation of transcription is the most common form of gene control, and the activity of transcription factors allows genes to be specifically regulated during development and in different types of cells. Transcription factors can bind to enhancer sequences located upstream or downstream from an associated gene, resulting in stimulation or enhancement of transcription of the related gene. Enhancer sequences act upon genes on the same DNA molecule; however, enhancer sequences can be located thousands of base pairs away from the transcription start site of the gene being regulated. Because DNA is folded and coiled in the nucleus, the enhancer may actually be located near the transcription start site in the folded state.

Correct Option: B

Enhancer sequences are regulatory DNA sequences that, when bound by specific proteins called transcription factors, enhance the transcription of an associated gene. Regulation of transcription is the most common form of gene control, and the activity of transcription factors allows genes to be specifically regulated during development and in different types of cells. Transcription factors can bind to enhancer sequences located upstream or downstream from an associated gene, resulting in stimulation or enhancement of transcription of the related gene. Enhancer sequences act upon genes on the same DNA molecule; however, enhancer sequences can be located thousands of base pairs away from the transcription start site of the gene being regulated. Because DNA is folded and coiled in the nucleus, the enhancer may actually be located near the transcription start site in the folded state.

N-methyl-N’-nitro-N-nitrosoguanidine is a highly reactive chemical that
introduces alkyl radicals into biologically active molecules and thereby prevents their proper functioning. It could be used as an antineoplastic agent, but it might be very toxic, with carcinogenic, mutagenic, teratogenic, and immunosuppressant actions. It could also be used as a component of poison gases. This substance is reasonably anticipated to be a human carcinogen. The mutations induced by this mutagen are mostly purine-pyrimidine transitions of GC → AT.

Correct Option: A

N-methyl-N’-nitro-N-nitrosoguanidine is a highly reactive chemical that
introduces alkyl radicals into biologically active molecules and thereby prevents their proper functioning. It could be used as an antineoplastic agent, but it might be very toxic, with carcinogenic, mutagenic, teratogenic, and immunosuppressant actions. It could also be used as a component of poison gases. This substance is reasonably anticipated to be a human carcinogen. The mutations induced by this mutagen are mostly purine-pyrimidine transitions of GC → AT.

Diphtheria toxin consists of a single polypeptide. Proteolysis yields two fragments (A and B) which are held together by a disulfide bond. The toxin binds to EGF-like domain of Heparin-binding EGF-like growth factor (HB-EGF) through fragment B and is internalized with HB-EGF by receptor-mediated endocytosis. Diphtheria toxin catalyzes the ADP-ribosylation of, and inactivates, the elongation factor eEF-2. In this way, it acts to inhibit translation during eukaryotic protein synthesis. Tetracyclines are antibiotics which inhibit the bacterial growth by stopping protein synthesis. Three different specific mechanisms of tetracycline resistance have been identified so far: tetracycline efflux, ribosome protection and tetracycline modification. Streptomycin is a water-soluble aminoglycoside derived from Streptomyces griseus. Streptomycin is an aminoglycoside antibiotic that is currently used largely in the therapy of active tuberculosis. Like other aminoglycosides, streptomycin is thought to act by binding to bacterial ribosomes and inhibiting protein synthesis. Nevertheless, streptomycin is considered bacteriocidal as well as bacteriostatic.

Correct Option: D

Diphtheria toxin consists of a single polypeptide. Proteolysis yields two fragments (A and B) which are held together by a disulfide bond. The toxin binds to EGF-like domain of Heparin-binding EGF-like growth factor (HB-EGF) through fragment B and is internalized with HB-EGF by receptor-mediated endocytosis. Diphtheria toxin catalyzes the ADP-ribosylation of, and inactivates, the elongation factor eEF-2. In this way, it acts to inhibit translation during eukaryotic protein synthesis. Tetracyclines are antibiotics which inhibit the bacterial growth by stopping protein synthesis. Three different specific mechanisms of tetracycline resistance have been identified so far: tetracycline efflux, ribosome protection and tetracycline modification. Streptomycin is a water-soluble aminoglycoside derived from Streptomyces griseus. Streptomycin is an aminoglycoside antibiotic that is currently used largely in the therapy of active tuberculosis. Like other aminoglycosides, streptomycin is thought to act by binding to bacterial ribosomes and inhibiting protein synthesis. Nevertheless, streptomycin is considered bacteriocidal as well as bacteriostatic.

The folding of many newly synthesized proteins in the cell depends on a set of conserved proteins known as molecular chaperones. These prevent the formation of misfolded protein structures, both under normal conditions and when cells are exposed to stresses such as high temperature. Significant progress has been made in the understanding of the ATP-dependent mechanisms used by the Hsp70 and chaperonin families of molecular chaperones, which can cooperate to assist in folding new polypeptide chains.

Correct Option: A

The folding of many newly synthesized proteins in the cell depends on a set of conserved proteins known as molecular chaperones. These prevent the formation of misfolded protein structures, both under normal conditions and when cells are exposed to stresses such as high temperature. Significant progress has been made in the understanding of the ATP-dependent mechanisms used by the Hsp70 and chaperonin families of molecular chaperones, which can cooperate to assist in folding new polypeptide chains.