1. Section 3: Chemical Compounds in Cells
What are elements and compounds?
How is water important to the function of cells?
What are the functions of carbohydrates, lipids, proteins, and nucleic acids?

2. Elements and Compounds
Elements = any substance that cannot be broken down into simpler substances
Compounds = the chemical combination of 2 or more elements

3. Elements and Compounds
Carbon dioxide, which is found in gas bubbles, is a chemical compound. So is water.

4. Compounds in Bacteria and Mammals
All cells contain carbohydrates, lipids, proteins, and nucleic acids, as well as water and other inorganic compounds. But do all cells contain the same percentages of these compounds? The graph compares the percentage of some compounds found in a bacterial cell and a cell from a mammal.

5. Compounds in Bacteria and Mammals
Reading Graphs:
What do the red bars represent? What do the blue bars represent?
Red bars represent percentages of compounds in bacterial cells; blue bars represent percentages of compounds in mammalian cells.

6. Compounds in Bacteria and Mammals
Interpreting Data:
What percentage of a mammalian cell is made up of water? How does this compare to the percentage of water in a bacterial cell?
About 70%; the percentages are the same.

7. Compounds in Bacteria and Mammals
Interpreting Data:
Which kind of compound–proteins or nucleic acids–makes up the larger percentage of a mammalian cell?
Proteins

8. Compounds in Bacteria and Mammals
Drawing Conclusions:
In general, how do a bacterial cell and mammalian cell compare in their chemical composition?
They are similar, though mammalian cells have a lower percentage of nucleic acids, and bacterial cells have a lower percentage of lipids and fewer proteins.

9. Water
Most chemical reactions required for life within cells could not take place without water.
Water dissolves chemicals that cells need
Plants need water to make sugar
Water helps cells keep their size and shape
Water helps insulate cells

10. Organic and Inorganic Compounds
Contain Carbon, among other elements
Made by living things
Inorganic Compounds
Do not contain Carbon

11. Carbohydrates Provide Energy Important components of cell parts
Sugars, Starches, Cellulose, etc.

12. Lipids Highly concentrated energy source Store energy
Make up cell membranes
Fats, Oils and Waxes

13. Proteins Make up many structures and organelles
Made of chains of Amino Acids
Make up Enzymes
Perform important functions in the chemical reactions that must take place in cells

14. Click the SciLinks button for links on proteins.

15. Nucleic Acids
Contain the instructions that cells need to carry out all of the functions of life
DNA and RNA