Structures of Prokaryotes

Information is derived from the chapter "4.1 Prokaryotic Cells" from the textbook "Biology" by Sylvia S. Mader and Michael Windelspecht.

Prokaryote

Cells that lack a membrane-bound nucleus; eubacteria and archaea. These microorganisms are characterized by their simple structure and lack of organelles.

Cell envelope

Prokaryotic grouping comprised of the cell wall, plasma membrane, and glycocalyx; provides support, structure, and defense to the cell.

Plasma Membrane

Phospholipid bilayer with embedded proteins which regulates the flow of materials into and out of the cytoplasm.

Mesosomes

Internal pouches which likely increase the surface area of the plasma membrane for enzyme attachment during metabolic processes.

Cell Wall

Maintains the shape of the cell, regardless of fluid uptake.

Glycocalyx

Layer of polysaccharides outside the cell in certain bacteria; provides support and defense against attack and prevents the cell from drying out.

Capsule

An efficient glycocalyx which is well-organized and not easily washed off.

Slime layer

An inefficient glycocalyx which is disorganized and easily washed away.

Cytoplasm

Semifluid solution comprised of organic and inorganic molecules which is encapsulated by the plasma membrane; contains enzymes for metabolic processes and houses the materials of the prokaryotic cell.

Nucleoid

Region of the cytoplasm which houses the prokaryotic chromosome.

Plasmid

Extrachromosomal circular pieces of DNA that can replicate independently of chromosomal DNA and may carry genes benefiting the organism, such as antibiotic resistance.

Deoxyribonucleic acid (DNA)

The genetic material of nearly all organisms which is comprised of the nitrogenous bases adenine, cytosine, guanine, and thymine

Ribonucleic acid (RNA)

Molecule which aids in a variety of imperative cellular functions; comprised of the nitrogenous bases adenine, cytosine, guanine, and uracil.

Ribosomes

Structures which act as the location of protein synthesis within prokaryotic and eukaryotic cells; smaller than eukaryotic ribosomes, but similar in function and efficacy.

Flagella

External whiplike structure made of protein and broken down into hooks, filaments, and basal bodies; facilitates movement through fluids within a 360 degree range of motion.

Basal body

Flagellum structure comprised of rings which is anchored within the cell wall and membrane

Fimbrae

Small, bristle-like fibers which sprout from the cell’s surface; facilitate the attachment of the prokaryotic cell to surfaces.

Conjugation Pili

Rigid and tubular structures which are used to pass DNA from one cell to another within multicellular prokaryotes; also allows the cell to absorb genetic material from its surroundings.