Activity 2.2: �Molecules Cells Are Made Of

Environmental Literacy Project�Michigan State University

Unit Map

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Facts and questions about organisms

Some things we know:

• All organisms are made of cells
• All the functions of organisms are done by cells working together
• All cells are made of molecules
• All molecules are made of atoms

Some unanswered questions

• What kinds of molecules are cells made of?
• How do those molecules move and change when cells do their functions, such as:
• Growing
• Moving
• Changing matter and energy?

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What kinds of molecules are cells made of?

We can find out what materials cells are made of by reading nutrition labels for plants, animals, and decomposers that we eat.

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We will use labels with a serving size of 100 g.

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This means that

1 g = 1% of the materials in the food

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Molecules in Food

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What are cells made of?�CARBOHYDRATES

glucose

starch

fiber

What atoms are carbohydrates made of?

Carbohydrates in Carrots (Plant Root)

Total carbohydrate = starch + sugar + fiber (such as cellulose)

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How much starch is in 100 grams of carrots?

Molecules in Food

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What are cells made of? �FATS

Fat molecule

1 glycerol

3 fatty acids

What atoms are fats made of?

Fat in Peanuts (Plant Seeds)

How much fat is in 100 grams of peanuts?

Molecules in Food

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What are cells made of?�PROTEIN

What atoms are proteins made of?

Two of the Amino Acids

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Protein in Carrots (Plant Roots)

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How much protein is in 100 grams of carrots?

Molecules in Food

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Organic Molecules in All Cells

FATS

GLUCOSE

STARCH

PROTEINS

CARBOHYDRATES:

What atoms are organic molecules in plants made of?

Other Molecules in Cells

Vitamins, minerals, and cholesterol make up less than 1% of cell mass (less than 1 gram out of 100 grams).

Minerals in Cells

Cells also contain minerals that are used �for cell functions. These minerals have different kinds of atoms, including:

• Nitrogen
• Phosphorous
• Calcium
• Sodium

Minerals

• NO₃ (Nitrate)
• PO₄ (Phosphate)
• K (Potassium)
• Ca (Calcium)

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Add into your table at least 2 minerals and fill in the other rows.

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Molecules in Food

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Water in Cells

Besides organic materials or biomass (fats, proteins, and carbohydrates) cells are made up mostly of water.

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About how much water is in 100 grams of carrots?

Water

• H₂O!

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Add into your table one water and fill in the other rows.

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Adding up materials in carrots �(plant root cells)

Organic materials in carrots

Protein: 1% (1 g out of 100 g)

Carbohydrates: 10%

Fat: 0%

Cholesterol and vitamins: less than 1%

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Inorganic materials in carrots

Minerals (sodium, iron): less than 1%

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What’s left?

WATER: about 89%

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Adding up materials in beef �(animal muscle cells)

Organic materials in beef:

Fat: 21% (21 g out of 100 g)

Carbohydrates: 0%

Protein: 18%

Cholesterol and vitamins: less than 1%

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Inorganic materials in beef:

Minerals (calcium, sodium, iron): less than 1%

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What’s left?

WATER: about 60%

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Chemical energy in cells

Calories are a measurement of chemical energy in cells and food: the energy available from high-energy bonds in organic molecules

High-energy C-C and C-H bonds are yellow. This color represents the usable energy stored in these bonds.

Which molecules have chemical energy?

PROTEINS

FATS

GLUCOSE

STARCH

CARBOHYDRATES:

WATER

MINERALS

Exit Ticket

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Conclusions

What molecules make up animal cells? What molecules make up the food that animals eat?

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Predictions

Why do you think that animals need organic molecules in their food?

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Try it yourself!

• Use the food label cards to fill in the table showing the materials in different kinds of cells on the 2.2 Food Labels worksheet.
• What patterns do you notice when you compare a food made of animal cells (beef) with foods made of plant cells (carrots, celery, spinach)? Explain the patterns you found on the worksheet.

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Cells are really complicated!

• Large organic molecules are really larger than our pictures:
• Fats: 50-100 carbon atoms (+ H and O)
• Proteins: hundreds of carbon atoms (+ H, N, and O)
• Starch: thousands of carbon atoms (+ H and O)
• Cellulose (fiber): thousands of carbon atoms (+ H and O)

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• There are also other large organic molecules, such as deoxyribonucleic acid (DNA)

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Cells are really complicated!

There are many more small organic molecules than the ones in this lesson. Look at the Metabolic Pathways poster to see some of them.

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