Review Flashcards: Viruses and Prokaryotic Cells

Flashcards reviewing the structure and characteristics of viruses and prokaryotic cells, comparing them to eukaryotic cells.

Why are viruses described as acellular?

Viruses are not made of cells, lacking a cell membrane, cytoplasm, and organelles.

Why are viruses described as non-living?

Viruses have no metabolism and cannot independently move, respire, replicate, or excrete.

What is the general structure of a virus particle?

Nucleic acids surrounded by a capsid (protein coat), attachment proteins for host cell binding, absence of cytoplasm/ribosomes/cell wall/cell-surface membrane, and sometimes a lipid envelope (e.g., HIV).

What are the distinguishing features of prokaryotic cells?

Cytoplasm lacking membrane-bound organelles, with genetic material not enclosed in a nucleus. Examples include bacteria and archaea, which are always unicellular.

Describe the general structure of prokaryotic cells.

Cell-surface membrane, cell wall (containing murein), cytoplasm, small ribosomes, circular DNA (free in cytoplasm and not associated with proteins), and sometimes a capsule, plasmids, and flagella.

How does a Eukaryotic cell differ from a Prokaryotic cell?

Eukaryotic cells have membrane-bound organelles (e.g., mitochondria, endoplasmic reticulum) and a nucleus containing long, linear DNA associated with histone proteins. They also have larger (80S) ribosomes and a cell wall only in plants, algae, and fungi; plasmids/capsule are never present.

How does a Prokaryotic cell differ from a Eukaryotic cell?

Prokaryotic cells lack membrane-bound organelles and a nucleus; DNA is short, circular, and not associated with proteins. Smaller (70S) ribosomes and a cell wall in all prokaryotic cells, flagella and a capsule sometimes present.