Knowing the Difference Between Prokaryotic and Eukaryotic Cells for Middle School Science

One of the first steps in understanding cells is differentiating between prokaryotic and eukaryotic cells. The presentation below shows a sorting activity with information on the cells. If you continue to read below the presentation, you will get more information on prokaryotic and eukaryotic cells.

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Prokaryotic and Eukaryotic Cells Sorting Activity

Prokaryotes vs. Eukaryotes: Understanding the Differences

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. The main difference between them is that eukaryotic cells have a nucleus, while prokaryotic cells do not.

Prokaryotic Cells

Prokaryotic cells are simple, small cells that lack a nucleus and most other cell structures. Without a nucleus, their genetic material (DNA) floats freely in the cell.

Examples of Prokaryotes:

• Bacteria – Found everywhere, from soil to your skin!

  
  

  • Cyanobacteria - A type of prokaryotic bacteria that perform photosynthesis, much like plants. They are often called blue-green algae, although they are not true algae. Cyanobacteria live in freshwater, oceans, and even extreme environments like hot springs. They played a crucial role in Earth's history by producing oxygen through photosynthesis, helping to create the oxygen-rich atmosphere we have today.

    
    

  • Lactobacillus acidophilus – Found in yogurt and the human gut, helps with digestion and supports gut health.

    
    

  • Rhizobium – Lives in the roots of legume plants and helps fix nitrogen, improving soil fertility.

    
    

  • Escherichia coli (E. coli) – Some strains are harmless and live in the intestines, but others can cause food poisoning.

    
    

  • Salmonella – Causes foodborne illnesses, commonly found in contaminated food like raw eggs or undercooked meat.

    
    

  • Mycobacterium tuberculosis – The bacterium responsible for tuberculosis, a serious lung infection.

    
    

• Archaea – These microscopic organisms are similar to bacteria but live in extreme environments like hot springs, deep-sea vents, and salty lakes.

  
  

  • Methanogens – These archaea produce methane as a byproduct of their metabolism and are found in environments like swamps, deep-sea vents, and the intestines of some animals

    
    

  • Halophiles – These archaea thrive in extremely salty environments, such as the Great Salt Lake and the Dead Sea

    
    

  • Thermophiles – These heat-loving archaea live in hot environments like hydrothermal vents and hot springs

    
    

  • Acidophiles – These archaea thrive in highly acidic environments, such as sulfuric hot springs

    
    

  • Psychrophiles – These archaea prefer extremely cold environments, such as deep ocean waters and polar ice

    
    

Key Characteristics of Prokaryotic Cells:

• No nucleus (DNA is in the cytoplasm)

  
  

• No membrane-bound organelles (such as mitochondria or chloroplasts)

  
  

• Small in size (usually 0.1 to 5 micrometers)

  
  

• Can reproduce quickly through a process called binary fission (one cell splits into two identical cells)

Eukaryotic Cells

Eukaryotic cells are larger, more complex cells that have a nucleus and many specialized structures called organelles. These cells can be found in both unicellular and multicellular organisms, meaning they can exist as a single cell or be part of a larger organism made of many cells.

Examples of Eukaryotes:

• Animals – Humans, dogs, insects, and fish are all made of eukaryotic cells.

  
  

• Plants – Trees, flowers, and grass are eukaryotes and have special organelles like chloroplasts, which help them make food through photosynthesis.

  
  

• Fungi – Mushrooms, mold, and yeast are examples of fungi, which can be unicellular or multicellular.

  
  

• Protists – These are microscopic, mostly unicellular organisms, like amoebas and paramecia, that live in water.

Key Characteristics of Eukaryotic Cells:

• Have a nucleus (which contains DNA)

  
  

• Have membrane-bound organelles, such as mitochondria (which produce energy) and the endoplasmic reticulum (which helps build proteins and other molecules)

  
  

• Larger in size (usually 10 to 100 micrometers)

  
  

• Can reproduce in different ways, including mitosis (cell division) and meiosis (for reproduction in multicellular organisms)

  
  

Comparison Chart: Prokaryotes vs. Eukaryotes

Understanding the difference between prokaryotic and eukaryotic cells helps us see how life on Earth is structured. Bacteria and archaea (prokaryotes) play important roles in ecosystems, from breaking down waste to helping us digest food. Eukaryotic cells make up more complex organisms, including plants and animals, which provide food, oxygen, and other resources necessary for life.

The study of cells helps scientists develop medicines, improve agriculture, and even understand how life evolved. Whether we’re looking at tiny bacteria or giant trees, it all comes down to cells!

The Biosphere

Middle School Science