Organisms and the Environment

Chapter Four: Physical ScienceConnections

• 4.1 Elements and Compounds

• 4.2 The Compounds of Life

• 4.3 Physical Variables

4.2 Carbon compounds and cells

• Life as we know it is carbon based.

• A carbon atom can form chemical bonds with other carbon atoms in long chains or rings.

4.2 Carbon compounds and cells

• Carbon compounds in living things include: carbohydrates, proteins, lipids and nucleic acids.

4.2 Carbohydrates, fats and proteins

• Carbohydrates are energy-rich compounds made from carbon, hydrogen, and oxygen.

• Cells use carbohydrates to get and store energy.

• Carbohydrates are also called sugars or starches.

4.2 Carbohydrates• Plant cells store energy as starch.• Rice, potatoes, and wheat are plant starches.

4.2 Lipids

• Lipids are made by cells to store energy for long periods of time.

• Lipids include fats, oils, and waxes.

Can you think of examples of lipids in plants or animals?

4.2 Proteins

• Proteins are very large molecules made of carbon, hydrogen, oxygen, nitrogen, and sometimes sulfur.

• Protein molecules are made of smaller molecules called amino acids.

4.2 Nucleic acids• Nucleic acids are compounds made of long,

repeating chains called nucleotides. • DNA is a nucleic acid that contains the

information cells need to make all of their proteins.

4.2 DNA

• Some scientists refer to DNA as the “blueprints” for life.

What is a blueprint and why might scientists use this “analogy”?

Investigation 4A

• How is carbon dioxide important to living things?

Carbon Dioxide and Living Things