Prokaryotic Cells

Prokaryotic Cells

• No nucleus
• Mostly unicellular organisms
• They have no membrane bound organelles

General Structure of Prokaryotic Cells

• Ribosomes are organelles that are responsible for producing proteins.
• The prokaryotic DNA is not protected by a nuclear membrane and is found in the cytoplasm.
• The cytoskeleton are long polymer proteins that form thin fibers.
• The cytoskeleton is responsible for: cell shape, cell division, transportation of plasmids, organization of cell interior.
• Flagella are located on the surface of the cell and allow for bacteria to move.
• Cell walls surround the plasma membrane and function to protecting the organism, giving shape and rigidity.
• Capsule enables cell attachment.
• Pili allows for exchange of genetic information with other bacteria.
• Fimbriae (not shown) can also be found and are used to attach to surfaces such as a cell the bacteria might infect.

Bacteria and Archaea Cell Wall Composition

Bacteria

• They are ubiquitous (can be found everywhere) and are smaller than eukaryotic cells.
• They have a cell wall composed of a large polymer called peptidoglycan, which is made up of polysaccharides and amino acids.

• Bacterial membrane lipids have ester bonds.

Archaea

• They are often extremophiles (live in extreme environments such as extremely high temperatures, salt concentration, etc.).
• Their cells walls are composed of pseudo-peptidoglycan (different from bacterial peptidoglycan).
• Their membrane lipids have ether bonds.