Site of metabolic reactions
Barrier for entry and exit of substances
Protection from desiccation
Cell wall: Acts as a protective physical barrier against substances, mechanical damage, and osmotic lysis.
Capsule: Provides protection from other cells and promotes the cohesion of bacterial groups for additional defense.
Cell-surface membrane: Functions as a partially permeable barrier, controlling the passage of substances in and out of the cell.
Circular DNA: Contains genetic information essential for bacterial cell replication.
Plasmids: Carry genes that can enhance bacterial survival under adverse conditions.
Prokaryotic cells are simpler, smaller, lack a true nucleus, and have no membrane-bound organelles.
Eukaryotic cells are larger, more complex, and contain a true nucleus and membrane-bound organelles.
Prokaryotes divide by binary fission, have a single circular chromosome, and smaller ribosomes.
Eukaryotes divide through mitosis or meiosis, possess multiple linear chromosomes, and larger ribosomes.
- Viruses consist of genetic material (DNA or RNA) enclosed in a protective protein coat called a capsid.
- Some viruses may have an outer lipid envelope and spike proteins for attaching to host cells.
- They lack cellular structures and are reliant on host cells for replication.