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A car is a working machine – made from smaller systems working together.

A cell is an organic, living machine – made from organelles working together.

No part of a car, by itself, is functioning.

No part of a cell, by itself, is alive.

What we a “functioning car” is the way that parts work together.

What we call “life” is the way that organelles work together.

Let’s compare the parts of a car with the parts of a cell


Consider: The transmission, the axles and the engine.

Yet disconnect just one of these systems, and we effectively no longer have a car.

We’d just have an inert 2000 pound block of metal and plastic.

A car is not a car unless the parts are connected and working together.

The same is true for cells.

drive-train-transmission xpertechautorepair

Inside the engine, what would happen if we removed or froze the pistons?

We’d effectively no longer have an engine.

The same is true for organelles inside cells.


Similarly, consider the ways that organelles and organic molecules are interacting within our cells:

What would happen if we removed some of these parts?

We’d effectively no longer have a living cell.

Nucleus to ribosomes to ER GIF Protein synthesis NPR

Nucleus to ribosomes to ER GIF from NPR: Protein synthesis

You’ve seen parts inside cars. Now let’s look at the organelles (parts inside cells)

First, a note of caution about artwork: Many books simplify what a cell looks like, with a 2D black & white drawing, like this. This picture is “true” – but simplified.

In reality cells are 3D.

Organelles are suspended in cytoplasm throughout the cell.



Now let’s learn the job of each organelle using analogies:

CPO Life science organelle analogy




 lipid bilayer

 Controls which molecules go in/out of the cell

 Walls and doors


 Suspends and holds all the organelles

 the factory floor, where all the work is done.


 Chromosome (DNA) storage

 Control center


(made of DNA)

 Instructions for building and running the cell

 blueprints and instructions


 Converts energy from food molecules into a form usable by the cell



 biological protein synthesis (translation)

 Workers on the assembly line, building our product.


 gives the cell its shape and mechanical resistance to deformation

 Walls & studs, support and structure

golgi body

 Packages proteins into vesicles inside the cell, and send them to their destination.

 Receives product from ER. Like UPS, its packages and distributes the products.

endoplasmic reticulum


 Manufactures lipids and proteins

 Assembly line which makes our products


 Contain enzymes that can break down virtually all kinds of biomolecules.

 garbage disposal


 Multiple uses, often related to storing molecules.



Organelles unique to plants

Plant organelles chloroplast vacuole

Click here to read about the organelles in more depth.


Endomembrane system

More details here: The endomembrane system

Endomembrane system by Mariana Ruiz Villarreal LadyofHats

Endomembrane system by Mariana Ruiz Villarreal, LadyofHats

Learning Standards

2016 Massachusetts Science and Technology/Engineering Curriculum Framework

6.MS-LS1-2. Develop and use a model to describe how parts of cells contribute to the cellular functions of obtaining food, water, and other nutrients from its environment,
disposing of wastes, and providing energy for cellular processes.

2006 Massachusetts Science and Technology/Engineering Curriculum Framework

Biology High School Standards: Cells have specific structures and functions that make them distinctive. Processes in a cell can be classified broadly as growth, maintenance, and reproduction.

2.1 Relate cell parts/organelles (plasma membrane, nuclear envelope, nucleus, nucleolus, cytoplasm, mitochondrion, endoplasmic reticulum, Golgi apparatus, lysosome, ribosome, vacuole, cell wall, chloroplast, cytoskeleton, centriole, cilium, flagellum, pseudopod) to their functions. Explain the role of cell membranes as a highly selective barrier (diffusion, osmosis, facilitated diffusion, active transport).

Benchmarks for Science Literacy, AAAS

By the end of the 12th grade, students should know that

  • Every cell is covered by a membrane that controls what can enter and leave the cell. 5C/H1a
  • In all but quite primitive cells, a complex network of proteins provides organization and shape and, for animal cells, movement. 5C/H1b
  • Within the cells are specialized parts for the transport of materials, energy capture and release, protein building, waste disposal, passing information, and even movement. 5C/H2a

SAT Biology Subject Area Test

Cellular and molecular biology: Cell structure and organization, mitosis, photosynthesis, cellular respiration, enzymes, biosynthesis, biological chemistry

External links

Wayback archive of RegentsPrep.Org on Cells

Amoeba Sisters.com gifs

Khanacademy Eukaryotic-cells


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