Prokaryotes

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Prokaryotes Noun

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[pro-kar-ee-ohts]

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Prokaryotes

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A unicellular organism that lacks a nucleus, having its genetic material located directly in the cytoplasm.

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Example: This diagram shows the structure of a bacterium, a type of prokaryote. It highlights key features like the free-floating DNA in the nucleoid area.

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Bacteria Noun

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[bak-teer-ee-uh]

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Bacteria

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A domain of prokaryotes, typically having cell walls containing peptidoglycan and found in nearly every habitat on Earth.

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Example: Bacteria, which are prokaryotes, come in three main shapes: spherical (cocci), rod-shaped (bacilli), and spiral (spirilla).

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Archaea Noun

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[ar-kee-uh]

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Archaea

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A domain of prokaryotes with cell walls lacking peptidoglycan, often found living in extreme environmental conditions.

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Example: This image shows a labeled cross-section of an archaeon, a type of single-celled prokaryote, detailing its key structures like the nucleoid, ribosomes, and flagellum.

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Peptidoglycan Noun

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[pep-tid-oh-gly-kan]

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Peptidoglycan

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A polymer of sugars and amino acids forming a mesh-like layer outside the plasma membrane of most bacteria.

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Example: This diagram shows a bacterial cell and zooms in to reveal its tough outer layer, the cell wall, which is made of peptidoglycan.

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Flagella Noun

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[fluh-jel-uh]

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Flagella

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Long, whip-like appendages that protrude from the cell body of certain cells and are used for locomotion.

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Example: This diagram shows a bacterium, a type of prokaryote, with its long, tail-like flagellum, which it uses for movement.

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Pili Noun

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[pil-eye]

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Pili

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Short, hair-like appendages on the surface of many bacteria, used for attachment to surfaces and other cells.

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Example: This diagram shows a bacterial cell with pili, which are the short, hair-like structures used for attachment to surfaces or other cells.

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Bacilli Noun

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[buh-sil-eye]

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Bacilli

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A term used to describe any rod-shaped prokaryote or a specific taxonomic class of such bacteria.

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Example: This diagram shows the rod shape and key structures of a bacillus, a type of prokaryotic cell, including its cell wall and free-floating nuclear matter.

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Cocci Noun

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[kahk-sy]

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Cocci

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A term used to describe any bacterium or archaeon that has a spherical, ovoid, or generally round shape.

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Example: This diagram shows that cocci are spherical prokaryotes and illustrates their common arrangements, such as pairs (diplococci), chains (streptococci), and clusters (staphylococci).

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Spirilla Noun

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[spy-ril-uh]

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Spirilla

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A term used to describe any bacterium that has a rigid spiral or corkscrew shape and uses flagella for movement.

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Example: This image shows Spirilla, a type of prokaryote (bacterium), which is identified by its distinct spiral or corkscrew shape.

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Photoautotroph Noun

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[foh-toh-aw-toh-trohf]

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Photoautotroph

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An organism that produces its own food using light energy through the process of photosynthesis.

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Example: A photoautotroph, like this plant, uses light energy, water, and carbon dioxide to create its own food (carbohydrates) through photosynthesis.