--- title: "Prokaryotic and Eukaryotic Cells" description: "Compare typical bacterial, plant and animal cells by their DNA location and cell structures. Distinguish optional plasmids from the main chromosome, and compare measured cell sizes in micrometres." canonical: https://lightmysky.com/learn/science/prokaryotic-and-eukaryotic-cells-mt_vlL4GinuH6 source: https://lightmysky.com/learn/science/prokaryotic-and-eukaryotic-cells-mt_vlL4GinuH6.md retrieved: 2026-11-12 --- > **Agent view.** This is the Markdown twin of the page, for tools and assistants. > When to use this site, and the call that answers each job: https://lightmysky.com/agent-instructions.md > API description (OpenAPI 3.1): https://lightmysky.com/openapi.json · Authentication: https://lightmysky.com/auth.md > Pricing: https://lightmysky.com/pricing.md · Catalog: https://lightmysky.com/llms.txt · Full catalog: https://lightmysky.com/llms-full.txt > Every machine-readable file on this domain: https://lightmysky.com/.well-known/ai-catalog.json > Ask for Markdown with `Accept: text/markdown`, a `.md` address, or `?mode=agent`. # Prokaryotic and Eukaryotic Cells Compare typical bacterial, plant and animal cells by their DNA location and cell structures. Distinguish optional plasmids from the main chromosome, and compare measured cell sizes in micrometres. Subject: Science · Area: Organisms & Life Processes · Ages 14 to 15 Page: https://lightmysky.com/learn/science/prokaryotic-and-eukaryotic-cells-mt_vlL4GinuH6 ## Ready when they can - Names shared cell structures and explains how typical bacterial, photosynthetic plant and animal cells differ in nuclei, walls, chloroplasts and vacuoles. - Orders given bacterial, animal-cell and plant-cell measurements in micrometres and calculates a size ratio without assuming a fixed order for all cells. - Explains how a transferable plasmid can spread a trait such as antibiotic resistance without replacing the main chromosome. ## Lesson: Two kinds of cells Plant and animal cells are eukaryotic. Bacteria and archaea have a prokaryotic cell plan: no membrane-bound nucleus and no membrane-bound organelles such as mitochondria. Both cell plans include a cell membrane, cytoplasm, DNA and ribosomes. Ribosomes make proteins, so finding ribosomes does not distinguish the two plans. The main bacterial chromosome lies in the nucleoid, a DNA-containing region without a surrounding membrane. In most bacteria the chromosome is circular. Some bacteria also have plasmids, small DNA molecules separate from the main chromosome. Plasmids are usually circular, but not every bacterium has them. Most bacteria have a cell wall. Animals, plants, fungi and protists are eukaryotes. In a typical eukaryotic cell, most DNA is in a membrane-bound nucleus. Mitochondria help supply usable energy from food. A photosynthetic leaf cell has a wall, chloroplasts and usually a large central vacuole. Animal cells lack walls and chloroplasts but may have small vacuoles. Some plant cells, such as root cells, lack chloroplasts. *(drawing: Example lengths in micrometres: bacterium 3, animal cell 30, plant cell 60. These are sample measurements, not fixed sizes.)* **Example.** A micrometre is one millionth of a metre. Bacteria are usually smaller than plant and animal cells, but sizes vary. Order measurements, not displayed image sizes: micrographs may use different magnifications. Divide the larger length by the smaller for a size ratio. Here, 30 divided by 3 is 10. The animal cell is ten times as long as the bacterium. A plant cell is not always larger than an animal cell. Plasmids can carry genes that give a bacterium useful traits. Some carry antibiotic-resistance genes. When a transferable plasmid passes to another bacterium, those genes can spread too. Not every plasmid transfers between cells or carries resistance. Plasmids do not supply a nucleus or have to replace the main chromosome. **Recap.** Prokaryotes lack a membrane-bound nucleus. Typical eukaryotic cells have one. Plasmids are optional, and cell-size comparisons need measurements. *Lesson, questions, explanations and study cards written for this dataset. Cell-biology sources were consulted for facts and teaching design.* ## Practice 8 questions on this page, each with its working shown. ## Needs first - [Parts of Plant and Animal Cells](https://lightmysky.com/learn/science/parts-of-plant-and-animal-cells-mt_bABr-c2DfV) - [Cells Under the Microscope](https://lightmysky.com/learn/science/cells-under-the-microscope-mt_VfA4xo4kUv) ## Opens up - [Protists: the eukaryotes that are not plants, animals or fungi](https://lightmysky.com/learn/science/protists-the-eukaryotes-that-are-not-plants-animals-or-fungi-mt_CHb8H727nW) - [Bacterial Cell Envelopes and What the Gram Stain Reveals](https://lightmysky.com/learn/science/bacterial-cell-envelopes-and-what-the-gram-stain-reveals-mt_Q5zM0oO3Vu)