Chapter 24 The Chemistry of Life 24.1 A Basis for Life 24.2 Carbohydrates 24.3 Amino Acids and Their Polymers 24.4 Lipids 24.5 Nucleic Acids 24.6 Metabolism Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. .

Where do fish get their oxygen? CHEMISTRY & YOU Where do fish get their oxygen? Most fish obtain oxygen as water flows across their gills. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. .

The Structure of Cells The Structure of Cells What are the two major types of cells that occur in nature? Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. .

The Structure of Cells Until recently, life was defined as the ability of an organism to grow and to reproduce its own kind. Recent discoveries made at the fringes of life seem to blur this definition. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. .

The Structure of Cells As difficult as it is to define life, you can generally regard tiny structures called cells as the fundamental units of life. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. .

The Structure of Cells As difficult as it is to define life, you can generally regard tiny structures called cells as the fundamental units of life. Organisms are composed of as few as one cell or as many as billions of cells. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. .

The Structure of Cells Two major cell types occur in nature: prokaryotic cells and eukaryotic cells. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. .

The Structure of Cells Two major cell types occur in nature: prokaryotic cells and eukaryotic cells. The prokaryotic cell is the more ancient of the two. Microscopic examination of fossilized remains shows that prokaryotic cells were present on Earth at least 3 billion years ago. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. .

The Structure of Cells Two major cell types occur in nature: prokaryotic cells and eukaryotic cells. The prokaryotic cell is the more ancient of the two. Eukaryotic cells did not appear until about 1 billion years ago. Microscopic examination of fossilized remains shows that prokaryotic cells were present on Earth at least 3 billion years ago. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. .

The Structure of Cells Both eukaryotic and prokaryotic cells contain all the chemicals necessary for life, encased in a cell membrane. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. .

The Structure of Cells Both eukaryotic and prokaryotic cells contain all the chemicals necessary for life, encased in a cell membrane. The cell membrane is a sac that holds the contents of a cell and acts as a selective barrier for the passage of substances into and out of the cell. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. .

The Structure of Cells Eukaryotic cells are considerably larger and more complex than prokaryotic cells. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. .

The Structure of Cells Eukaryotic cells are considerably larger and more complex than prokaryotic cells. But the chemical processes carried out by both types of cells are very similar. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. .

The Structure of Cells One major feature that distinguishes eukaryotic cells from prokaryotic cells is that eukaryotic cells contain membrane-enclosed organelles. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. .

The Structure of Cells One major feature that distinguishes eukaryotic cells from prokaryotic cells is that eukaryotic cells contain membrane-enclosed organelles. Organelles, meaning little organs, are small structures suspended in the interior cellular fluid, or cytoplasm. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. .

The Structure of Cells The organelles are the sites of many specialized functions in eukaryotic cells. For example, the nucleus, a structure that is important in eukaryotic cell reproduction, is not present in prokaryotic cells. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. .

The Structure of Cells The organelles are the sites of many specialized functions in eukaryotic cells. Mitochondria (singular: mitochondrion) are the source of cellular energy in eukaryotic cells that use oxygen. Mitochondria are often referred to as the powerhouses of the cell. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. .

The Structure of Cells The organelles are the sites of many specialized functions in eukaryotic cells. Lysosomes are the sites for the digestion of substances taken into a cell. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. .

The Structure of Cells The organelles are the sites of many specialized functions in eukaryotic cells. Yet another membrane- enclosed structure is the highly folded, netlike endoplasmic reticulum (ER). The ER serves as an attachment site for ribosomes. The ribosomes are the sites where essential substances called proteins are made. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. .

What is a major difference between prokaryotic and eukaryotic cells? Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. .

What is a major difference between prokaryotic and eukaryotic cells? Eukaryotic cells are larger and more complex, containing membrane-enclosed organelles that perform specialized functions in the cells. Both eukaryotic and prokaryotic cells carry out similar chemical processes. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. .

The Energy and Carbon Cycle What compound is reduced during photosynthesis? What compounds are formed? Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. .

The Energy and Carbon Cycle Organisms must have energy to survive. The ultimate source of this energy is the sun. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. .

The Energy and Carbon Cycle Cells of green plants and certain algae contain organelles called chloroplasts that are able to capture solar energy and make food. Within a chloroplast is a light-capturing system of membranes that converts light energy into chemical energy by a process called photosynthesis. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. .

The Energy and Carbon Cycle Photosynthesis uses the energy from sunlight to reduce carbon dioxide to compounds that contain C—H bonds, mainly in the form of glucose (C6H12O6). 6CO2 + 6H2O + Energy → C6H12O6 + 6O2 Carbon dioxide (carbon in more oxidized state) Water from sunlight Glucose (carbon in more reduced state) Oxygen Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. .

The Energy and Carbon Cycle In the energy and carbon cycle, photosynthetic organisms produce necessary carbon compounds. Animals, which do not carry out photosynthesis, get these carbon compounds by eating plants or by eating animals that feed on plants. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. .

The Energy and Carbon Cycle Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. .

The Energy and Carbon Cycle Both plants and animals get energy by unleashing the energy stored in the chemical bonds of these carbon compounds. The nutrients are oxidized back to carbon dioxide and water in the process. C6H12O6 + 6O2 → 6CO2 + 6H2O + Energy Carbon dioxide (carbon in more oxidized state) Water Glucose (carbon in more reduced state) Oxygen Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. .

The Energy and Carbon Cycle Although plant life could survive without animals, animal life could never survive without plants. Without photosynthesis, the supply of carbon compounds that animals need to get energy would not exist. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. .

The Energy and Carbon Cycle Oxygen is another product of photosynthesis. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. .

The Energy and Carbon Cycle Oxygen is another product of photosynthesis. Photosynthetic land-dwelling and aquatic organisms produce the oxygen found in Earth’s atmosphere, oceans, and lakes. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. .

The Energy and Carbon Cycle Oxygen is another product of photosynthesis. Photosynthetic land-dwelling and aquatic organisms produce the oxygen found in Earth’s atmosphere, oceans, and lakes. Oxygen is needed for most organisms to live. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. .

The Energy and Carbon Cycle Oxygen is another product of photosynthesis. Photosynthetic land-dwelling and aquatic organisms produce the oxygen found in Earth’s atmosphere, oceans, and lakes. Oxygen is needed for most organisms to live. The importance of photosynthetic organisms is a major reason for the concern about the loss of such organisms through the destruction of forests. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. .

CHEMISTRY & YOU Fish, like all animals, need oxygen to survive. What process produces oxygen? Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. .

CHEMISTRY & YOU Fish, like all animals, need oxygen to survive. What process produces oxygen? During photosynthesis, plants use energy from sunlight, water, and carbon dioxide to produce oxygen. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. .

List the forms carbon takes in the carbon and energy cycle and explain what causes the transformations between forms. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. .

List the forms carbon takes in the carbon and energy cycle and explain what causes the transformations between forms. Carbon dioxide is taken from the air by plants, which reduce it to glucose. Decomposers return carbon compounds from dead organisms to the soil and air. Glucose and other carbon compounds are reduced by plants, animals, and other living things to carbon dioxide. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. .

Key Concepts The two major cell types that occur in nature are prokaryotic cells and eukaryotic cells. Photosynthesis uses sunlight to reduce CO2 to compounds that contain C—H bonds, mainly in the form of glucose. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. .

Glossary Terms photosynthesis: the process by which green plants and algae use radiant energy from the sun to synthesize glucose from carbon dioxide and water Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. .

END OF 24.1 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. .