An infectious agent purified from plant tissue is composed exclusively of a single type of nucleic acid encapsulated by a protective protein coat, completely devoid of cytoplasm, ribosomes, and metabolic machinery. Which of the following statements correctly explains why this entity cannot carry out protein synthesis independently?
- It lacks cellular ribosomes and metabolic organelles required to translate genomic information.Cevap
- BIts semi-permeable cell membrane restricts the uptake of amino acids from extracellular fluids.
- CIts peptidoglycan cell wall prevents intracellular enzymes from interacting with extracellular substrates.
- DIts membrane-bound organelles become temporarily dormant when released from host cytoplasm.
Cevap
The entity cannot synthesize proteins independently because it lacks cellular ribosomes and metabolic organelles required to translate genomic information.
Viruses are acellular entities composed of nucleic acid (DNA or RNA) enclosed in a protein capsid. Because they lack ribosomes, transfer RNA, ATP-generating organelles, and metabolic enzymes, they cannot synthesize proteins or replicate independently outside a living host cell.
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Acellular Nature and Structural Lack of Ribosomes in Viruses
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