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Prokaryotic vs. Eukaryotic Cells — Reading Comprehension

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MS-LS1-1
MS-LS1-2

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This NGSS-aligned reading passage helps middle school students compare prokaryotic and eukaryotic cells. Supporting standard MS-LS1-1, the passage explains how prokaryotic cells are simple and lack a nucleus, while eukaryotic cells are complex and contain organelles like the nucleus and mitochondria. It highlights examples such as bacteria and plants and emphasizes how both types perform life functions. This resource builds life science literacy with key terms like cytoplasm, flagella, and DNA, and supports comprehension of structure and function in living organisms according to the Next Generation Science Standards.

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"Celltypes" by Science Primer (National Center for Biotechnology Information). Vectorized by Mortadelo2005. / Wikimedia Commons.

All living things are made of cells, but not all cells are the same. Scientists classify cells into two main types: prokaryotic cells and eukaryotic cells. These two cell types differ in structure, complexity, and where they are found in nature.

Prokaryotic cells are simple cells found in single-celled organisms like bacteria and archaea. They do not have a nucleus. Instead, their DNA floats freely in the cytoplasm, the jelly-like material inside the cell. Prokaryotic cells also lack other membrane-bound organelles. Most have a cell wall and may have flagella or pili to help them move or stick to surfaces. Despite their simplicity, they carry out all the basic functions of life.

In contrast, eukaryotic cells are more complex. They do have a nucleus, which holds the cell’s DNA. Eukaryotic cells contain many organelles, such as mitochondria (which produce energy), endoplasmic reticulum (which builds proteins), and chloroplasts (in plant cells for photosynthesis). These cells are found in animals, plants, fungi, and protists. Many eukaryotic organisms are multicellular, and their cells can be specialized to perform specific jobs.

The biggest differences between prokaryotic and eukaryotic cells are the presence of a nucleus and organelles. Eukaryotic cells are also usually larger and can be part of complex organisms. Prokaryotic cells are smaller, but they are ancient and have adapted to live in many environments, including extreme ones.

Understanding the differences between these two cell types helps scientists learn how life evolved and how organisms function.

Fun Fact: The cells in your body are eukaryotic—but the bacteria living in your gut are prokaryotic!

What is one major difference between prokaryotic and eukaryotic cells?

Only prokaryotic cells have DNAEukaryotic cells have a nucleus, prokaryotic cells do notProkaryotic cells are found in animalsEukaryotic cells are always smaller

Where is DNA found in a prokaryotic cell?

Inside the mitochondriaIn the nucleusFloating in the cytoplasmInside a vacuole

What types of organisms are made of eukaryotic cells?

BacteriaArchaeaAnimals, plants, fungi, and protistsViruses

What are organelles?

Cell walls made of proteinSmall cell parts that do specific jobsBacteria that help digestionStructures only in prokaryotic cells

Which cell type usually has a cell wall and flagella?

EukaryoticFungalMuscleProkaryotic

What is a shared feature of all cells?

A nucleusOrganellesDNA and a cell membraneChloroplasts

What is the main idea of the passage?

Both cell types grow only in soilProkaryotic and eukaryotic cells are the sameCells are all shaped like circlesProkaryotic and eukaryotic cells have important differences

If a cell has a nucleus and mitochondria, what type is it?

ProkaryoticPlant cell onlyBacterialEukaryotic