2.1 Macromolecules Study Guide

CHAPTER 2

Strand 2: Structure and Function of Life

Chapter Outline

2.1 Macromolecules (Bio.2.1)

2.2 Cell Structure and Function (Bio.2.2)

2.3 Photosynthesis and Respiration (Bio.2.3)

2.4 Cell Transport and Homeostasis (Bio.2.4)

2.5 Mitosis and Differentiation (Bio.2.5)

2.6 Organ Systems and Homeostasis (Bio.2.6)

2.7 Feedback Mechanisms (Bio.2.7)

Living cells are composed of chemical elements and molecules that form macromolecules. The macromolecules in a cell function to carry out important reactions that allow cycling of matter and flow of energy within and between organisms. All organisms are made of one or more cells. The structure and function of a cell determines the cell’s role in an organism. Multicellular organisms have systems of tissues and organs that work together to meet the needs of the whole organism. Cells grow, divide, and function in order to accomplish essential life processes. Feedback systems help organisms maintain homeostasis.

2.1 Macromolecules (Bio.2.1)

Explore this Phenomenon

The food you eat becomes part of your body and helps your cells function.

1. How does the matter you eat change to become part of your body and help your cells function? Create a diagram to show how the matter in your food becomes part of your cells.
2. How does the matter you eat affect the way your cells function? If you eat different foods, do your cells function differently?

Bio.2.1 Macromolecules

Construct an explanation based on evidence that all organisms are primarily composed of carbon, hydrogen, oxygen, and nitrogen, and that the matter taken into an organism is broken down and recombined to make macromolecules necessary for life functions. Emphasize that molecules are often transformed through enzymatic processes and the atoms involved are used to make carbohydrates, proteins, fats/lipids, and nucleic acids. (LS1.C)

Organisms take in matter, which ends up being incorporated into their cells. As you read this chapter, look for evidence that shows how the matter that an organism takes in is recombined into the macromolecules needed by cells. Also pay attention to the mechanisms that an organism uses to make macromolecules.

Molecules from Food

What makes up a healthy diet?

A healthy diet includes protein, fats, and carbohydrates. Why? Because these compounds are three of the main building blocks that make up your body. You obtain these building blocks from the food that you eat, and you use these building blocks to make the organic compounds necessary for life.

The main chemical components of living organisms are known as organic compounds. Organic compounds are molecules built around the element carbon (C). Living things are made up of very large molecules. These large molecules are called macromolecules because “macro” means large; they are made by smaller molecules bonding together. Our body gets these smaller molecules, the "building blocks” of organic molecules from the food we eat.

The four main types of macromolecules found in living organisms, shown in the table below, are:

1. Proteins
2. Carbohydrates
3.  Lipids
4. Nucleic Acids.

Review the elements found in each type of macromolecule. What pattern do you see?

Carbon, hydrogen, oxygen, and nitrogen are the building blocks for the macromolecules our cells need to function. Each macromolecule has a different function.

Carbohydrates

Carbohydrates are sugars. Cells use carbohydrates for energy. Some carbohydrate molecules, such as glucose, are relatively small, and are called simple sugars. Glucose has the chemical formula C₆H₁₂O₆. Other carbohydrates are made of many simple sugars connected together into a long chain. These long chains often consist of hundreds or thousands of simple sugars. Plants store sugar in large molecules called starch. Animals store sugar in large molecules called glycogen. You get the carbohydrates you need for energy from eating carbohydrate-rich foods, including fruits and vegetables, as well as grains, such as bread, rice, or corn.

Lipids

Have you ever tried to put oil in water? They don’t mix. Oil is a type of lipid. Lipids are molecules such as fats, oils, and waxes. The most common lipids in your diet are probably fats and oils. Animals use fats for long-term energy storage and to keep warm. Plants use oils for long-term energy storage. When preparing food, we often use animal fats, such as butter, or plant oils, such as olive oil or canola oil. There are many more types of lipids that are important to life. One of the most important are the phospholipids that make up the protective outer membrane of all cells. These lipid membranes are impermeable to most water soluble compounds.

Phospholipids in a membrane, shown as two layers (a bilayer) of phospholipids facing each other.

Nucleic acids

Deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) are the two main nucleic acids. DNA is a double-stranded nucleic acid. DNA is the molecule that stores our genetic information. DNA contains the instructions to build proteins, and is the molecule that stores genetic information and is passed from parent to offspring. The single-stranded RNA is involved in making proteins.

Proteins

Proteins are molecules that have many different functions in living things. It’s important for you and other animals to eat food with protein, because we cannot make certain amino acids on our own. You can get protein from plant sources, such as beans, and from animal sources, like milk or meat. When you eat food with protein, your body breaks the proteins down into individual amino acids and uses them to build new proteins. You really are what you eat!

All proteins are made of smaller molecules called amino acids that connect together like beads on a necklace.

Proteins do all of the work in cells. Some proteins help move molecules into and out of the cell. Other proteins break down molecules or build molecules. Every protein has a unique function. The order of the amino acids determines the function of the protein.

Enzymes are special proteins Enzymes are a special type of protein that speed up chemical reactions.

Enzymes are a special type of protein that speed up chemical reactions. For example, your stomach would not be able to break down food if it did not have special enzymes to speed up the rate of digestion. Enzymes also recombine the elements you eat into carbohydrates, lipids, and nucleic acids that your cells need.

Putting It Together

The food you eat becomes part of your body and helps your cells function.

1. Review the diagram you made before reading this chapter. Revise your diagram to show how the matter you eat is changed into molecules in your body that help your cells function.