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What Is in a Prokaryotic Cell?

Prokaryotes, bacteria and archea lack a cell nucleus, contrasting them from most other organisms--the eukaryotes. Single-celled organisms prove vital to all life on Earth, despite some of the diseases they cause in human, animal and plant life. Some bacteria residing in the body produce vitamins essential to human health. Bacteria also give some foods flavor and help with the process of digestion.

  1. Outer Layers

    • The most outer layer, or capsule, protects prokaryotic cells from drying out. It also makes it hard for phagocytes to engulf prokaryotes. Bacterium lacking a capsule do not cause disease. The cell envelope lies under the capsule as another layer. The cytoplasmic membrane, cell wall, and in some cases, the outer capsule, make up the envelope. The cell wall gives the prokaryotes their diverse shapes: cocci, bacilli, spirochaete and vibrio.

    Cytoplasm

    • The cytoplasm resides within the bacterial cell. Water, enzymes, wastes, nutrients and gases make up the gel-like material of the cytoplasm, also known as the protoplasm. The cytoplasm holds the ribosomes, a chromosome and plasmids. The cell wall sheaths both the cytoplasm and its contents. The chromosome is a single strand of DNA, carrying out reproduction of the bacteria in a region of the cell called the nucleoid. Plasmids are made of DNA and circular in shape. Plasmids help the bacteria to become resistant to certain antibiotics and metals.

    Cytoplasmic Membrane

    • Phospholipids and proteins make up the cytoplasmic membrane, which encloses the cytoplasm. The membrane performs an organized monitoring of all materials flowing in and out of the cell. It allows the bacteria to intake needed proteins and metabolic energy through a process called active transport. The membrane also produces energy, gives the cell motility, rids the cell of waste and forms endospores.

    Flagella

    • Hairlike structures on the outside of the prokaryote allow the cell to move around. They move fast like a propeller, thrusting the cell towards nutrients in its host, away from toxic chemicals and towards light. The energy causing the flagella to propel the bacteria comes from protons moving through proteins within the cytoplasmic membrane.

    Nucleoid

    • Prokaryotic cells do not have a nucleus. However, the region where chromosomal DNA resides is called the nucleoid. The chromosome can contain as many as 3,500 genes. The DNA within the nucleoid decides what chemical reactions happen in the prokaryote; these chemical reactions, or synthesis, involve various proteins and enzymes.

    Ribosomes

    • Ribosomes transform nucleic acid into amino acids. Amino acids make up proteins which are vital to all life, since they perform all functions. Proteins are the molecules that perform all the functions of cells and living organisms. The prokaryotic cell distributes ribosomes throughout cytoplasm. Antibotics will target ribosomes in order to stop protein functions, killing the bacterial prokayotic cell. Eukaryote ribosomes are not affected. Humans and animals can ingest the antibiotic without fear of their eukaryotic cell proteins being inhibited.

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