How Cells Function

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All cells are madeof the same elements.

• All living and nonliving things are made up of atoms.

• All cells are made up of the same elements.• The Periodic Table shows the different

elements.– What are some examples?

What is a chemical reaction?

• Most activities that take place within cells involve atoms and molecules interacting.

• Chemical reaction– Bonds between atoms are broken and new

bonds form to make different molecules– Energy is needed to form bonds, and energy is

released when bonds break.– Cells use chemical energy for life activities.

Large molecules supportcell function.

• In living things, there are 4 main types of large molecules.

• They share one important characteristic—they all contain carbon atoms.

1. Carbohydrates

• Provide the cell with ENERGY!• Sugars made from atoms of carbon,

oxygen, and hydrogen.• What happens when you eat a candy

bar?

2. Lipids

• Fats, oils, and waxes found in living things.

• Lipids that make up the cell membrane have 2 parts:– A water-loving head (polar)– Two water-hating tails (nonpolar)

• Let’s look at the structure of lipids on page C43.

3. Proteins

• Made up of amino acids.• Carry out most of the chemical activity in cells.• Enzymes are proteins that control chemical

reactions inside the cells.• Proteins are an important part of your cell

membrane. (Transporting materials through facilitated diffusion.)

4. Nucleic Acids• Molecules that hold the instructions for the

maintenance, growth, and reproduction of a cell.• 2 types

– DNA– RNA

• The subunits of nucleic acids are called nucleotides.

• The order of nucleotides in DNA makes up the genetic code.

About 2/3 of every cell is water.

• All of the chemical reactions inside the cell take place in water.

• What elements are in water?• Some substances are attracted to

water, while others repel it. Why?

Structure of Water

• Water is POLAR.• Check out these terms:

– Hydrophobic– Hydrophillic

• Now think about lipids, why is it important that a cell membrane contains lipids?

Review Questions• Explain how just a few elements can make

up all living things.• What functions do proteins,

carbohydrates, lipids, and nucleic acids perform?

• What does it mean to describe water molecules as being polar?