Which of the following codons are referred to STOP codons? Select all that apply.

A. Yeast: Yeast are single-celled fungi with relatively low resistance to physical and chemical agents. They are susceptible to heat, disinfectants, and antiseptics because they lack specialized protective structures like endospores, making them easier to control compared to more resistant microbial forms.

B. Bacterial endospores: Bacterial endospores are highly resistant, dormant structures formed by certain bacteria such as Bacillus and Clostridium species. They have a tough protective coat, low water content, and metabolic inactivity, which make them impervious to heat, radiation, desiccation, and many chemical disinfectants. Endospores can survive extreme environmental conditions for extended periods, making them the most resistant microbial form.

C. Fungal spores: Fungal spores provide some resistance to environmental stress and disinfectants, but they are significantly less resistant than bacterial endospores. Most fungal spores can be inactivated by standard sterilization techniques such as autoclaving.

D. Protozoan cysts: Protozoan cysts are protective forms that allow protozoa to survive harsh environments, including changes in pH and desiccation. While they are moderately resistant, they are not as impervious to sterilization methods as bacterial endospores.

E. Naked viruses: Naked (non-enveloped) viruses are more resistant than enveloped viruses to detergents and some disinfectants due to the absence of a lipid envelope. However, they are still more susceptible to heat, radiation, and chemical agents than bacterial endospores.

A. semisynthetic drugs: Semisynthetic drugs are chemically modified natural antibiotics designed to improve their stability, spectrum, or pharmacokinetic properties. While some may target gram-positive bacteria, the term does not specifically indicate activity against a narrow group of organisms.

B. antibiotics: Antibiotics are naturally occurring or derived substances that inhibit or kill microorganisms. This term refers broadly to the type of drug rather than the range of bacteria it affects, so it does not specifically describe drugs limited to gram-positive bacteria.

C. broad-spectrum drugs: Broad-spectrum drugs are effective against a wide range of bacteria, including both gram-positive and gram-negative organisms. They are used when the specific pathogen is unknown but are not limited to gram-positive bacteria.

D. narrow-spectrum drugs: Narrow-spectrum drugs are effective against a limited group of microorganisms. In this context, a drug that targets only gram-positive bacteria is considered narrow-spectrum, as it does not act against gram-negative organisms and allows for more targeted therapy with reduced impact on normal flora.

E. synthetic drugs: Synthetic drugs are entirely chemically synthesized rather than derived from natural sources. While some synthetic drugs may target gram-positive bacteria, the term describes the origin of the drug, not its spectrum of activity.