Chapter Contents – page viii Chapter 7 A View of a CellA View of a Cell 7.1: The Discovery of CellsThe Discovery of Cells 7.1: Section CheckSection Check 7.2: The Plasma MembraneThe Plasma Membrane 7.2: Section CheckSection Check 7.3: Eukaryotic Cell StructureEukaryotic Cell Structure 7.3: Section CheckSection Check Chapter 7 SummarySummary Chapter 7 AssessmentAssessment

Chapter Intro-page 170 What You’ll Learn You will identify the parts of prokaryotic and eukaryotic cells. You will identify the structure and function of the plasma membrane. You will relate the structure of cell parts to their functions.

Chapter Intro-page 170 Cells are the foundation for the development of all life forms. Birth, growth, death, and all life functions begin as cellular functions. What You’ll Learn

Plasma Membrane Lysosomes Nucleus Mitochondrion Endoplasmic Reticulum Chapter Intro-page 174

7.1 Section Objectives – page 171 Relate advances in microscope technology to discoveries about cells and cell structure. Section Objectives: Compare the operation of a microscope with that of an electron microscope. Identify the main ideas of the cell theory.

Section 7.1 Summary – pages The History of the Cell Theory Before microscopes were invented, people believed that diseases were caused by curses and supernatural spirits. Microscopes enabled scientists to view and study cells, the basic units of living organisms. As scientists began using microscopes, they quickly realized they were entering a new world–one of microorganisms.

Section 7.1 Summary – pages The first person to record looking at water under a microscope was Anton van Leeuwenhoek. The microscope van Leeuwenhoek used is considered a simple light microscope because it contained one lens and used natural light to view objects. Development of Light Microscopes

Compound light microscopes use a series of lenses to magnify objects in steps. These microscopes can magnify objects up to times. Section 7.1 Summary – pages Development of Light Microscopes

Section 7.1 Summary – pages Microscope Lab Techniques Click image to view movie.

Section 7.1 Summary – pages Robert Hooke was an English scientist who lived at the same time as van Leeuwenhock. The Cell Theory Hooke used a compound light microscope to study cork, the dead cells of oak bark. Cells are the basic building blocks of all living things.

Section 7.1 Summary – pages The cell theory is made up of three main ideas: All cells come from preexisting cells. The cell is the basic unit of organization of organisms. All organisms are composed of one or more cells.

Section 7.1 Summary – pages The electron microscope was invented in the 1940s. This microscope uses a beam of electrons to magnify structures up to times their actual size. Development of Electron Microscopes

Section 7.1 Summary – pages There are two basic types of electron microscopes. The transmission electron microscope allows scientists to study the structures contained within a cell. The scanning electron microscope scans the surface of cells to learn their three dimensional shape. Development of Electron Microscopes

Section 7.1 Summary – pages Cells that do not contain internal membrane-bound structures are called prokaryotic cells. The cells of most unicellular organisms such as bacteria do not have membrane bound structures and are therefore called prokaryotes. Two Basic Cell Types Click here

Section 7.1 Summary – pages Most of the multi-cellular plants and animals we know are made up of cells containing membrane-bound structures and are therefore called eukaryotes. Cells containing membrane-bound structures are called eukaryotic cells. 7.1 Two Basic Cell Types Click here

Section 7.1 Summary – pages The membrane-bound structures within eukaryotic cells are called organelles. Each organelle has a specific function that contributes to cell survival. Two Basic Cell Types

Section 7.1 Summary – pages The nucleus is the central membrane- bound organelle that manages cellular functions. Separation of organelles into distinct compartments benefits the eukaryotic cells. Two Basic Cell Types

Section 1 Check Question 1 How did the invention of the microscope impact society's understanding of disease? B. Microscopes were invented after the development of the cell theory. A. Scientists were able to view microorganisms that were previously unknown.

Section 1 Check D. Scientists could view membrane-bound organelles of prokaryotes. C. It was once believed that viruses, not bacteria, caused diseases. How did the invention of the microscope impact society's understanding of disease? Question 1

Section 1 Check Which of the following uses a beam of light and a series of lenses to magnify objects in steps? Question 2 D. simple light microscope C. transmission electron microscope B. scanning electron microscope A. compound light microscope

Section 1 Check Plasma membrane Nucleus Nucleolus Chromosomes Organelles Question 3 What makes this cell eukaryotic? A. Because it has a cell wall. B. Because it contains DNA.

Section 1 Check Plasma membrane Nucleus Nucleolus Chromosomes Organelles Question 3 What makes this cell eukaryotic? C. Because it has membrane- bound organelles. D. Because it does not have DNA.

Section 2 Objectives – page 175 Section Objectives Relate the function of the plasma membrane to the fluid mosaic model. Explain how a cell’s plasma membrane functions.

Summary Section 2 – pages All living cells must maintain a balance regardless of internal and external conditions. Survival depends on the cell’s ability to maintain the proper conditions within itself.

Summary Section 2 – pages Why cells must control materials The plasma membrane is the boundary between the cell and its environment.

Summary Section 2 – pages It is the plasma membrane’s job to: allow waste and other products to leave the cell. remove excess amounts of these nutrients when levels get so high that they are harmful. allow a steady supply of glucose, amino acids, and lipids to come into the cell no matter what the external conditions are.

Summary Section 2 – pages This process of maintaining the cell’s environment is called homeostasis. Selective permeability is a process used to maintain homeostasis in which the plasma membrane allows some molecules into the cell while keeping others out.

Summary Section 2 – pages Water Plasma Membrane

Summary Section 2 – pages Structure of the Plasma Membrane The plasma membrane is composed of two layers of phospholipids back-to-back. Phospholipids are lipids with a phosphate attached to them.

Summary Section 2 – pages The lipids in a plasma membrane have a glycerol backbone, two fatty acid chains, and a phosphate group. Glycerol Backbone Two Fatty Acid Chains Phosphate Group

Summary Section 2 – pages Makeup of the phospholipid bilayer The phosphate group is critical for the formation and function of the plasma membrane. Phosphate Group

Summary Section 2 – pages Makeup of the phospholipid bilayer The fluid mosaic model describes the plasma membrane as a flexible boundary of a cell. The phospholipids move within the membrane.

Summary Section 2 – pages Other components of the plasma membrane: Cholesterol plays the important role of preventing the fatty acid chains of the phospholipids from sticking together. Cholesterol Molecule

Summary Section 2 – pages Other components of the plasma membrane: Transport proteins allow needed substances or waste materials to move through the plasma membrane. Click image to view movie.

Section 2 Check Which of the following best describes the plasma membrane's mechanism in maintaining homeostasis? Question 1 A. protein synthesis B. selective permeability C. fluid composition D. structural protein attachment

Section 2 Check Describe the structure of the plasma membrane. Question 2

Section 2 Check Why is the phosphate group of a phospholipid important to the plasma membrane? Question 3 Polar head (includes phosphate group) Nonpolar tails (fatty acids) Phospholipid molecule

Section 2 Check Explain why the model of the plasma membrane is called the fluid mosaic model. Question 4

Section 3 Objectives page 179 Section Objectives Compare and contrast the structures of plant and animal cells. Explain the advantages of highly folded membranes. Understand the structure and function of the parts of a typical eukaryotic cell.

Section 3 Summary – page The plasma membrane acts as a selectively permeable membrane. Cellular Boundaries

Section 3 Summary – page The cell wall The cell wall is a fairly rigid structure located outside the plasma membrane that provides additional support and protection.

Section 3 Summary – page Nucleus and cell control Chromatin Nucleolus Nuclear Envelope

Section 3 Summary – page Assembly, Transport, and Storage The endoplasmic reticulum (ER) is an organelle that is suspended in the cytoplasm and is the site of cellular chemical reactions.

Section 3 Summary – page Assembly, Transport, and Storage Endoplasmic Reticulum (ER) Ribosomes

Section 3 Summary – page Assembly, Transport, and Storage Golgi Apparatus

Section 3 Summary – page Vacuoles and storage Vacuoles are membrane-bound spaces used for temporary storage of materials. Notice the difference between vacuoles in plant and animal cells. Vacuole Animal Cell Plant Cell

Section 3 Summary – page Lysosomes and recycling Lysosomes are organelles that contain digestive enzymes. They digest excess or worn out organelles, food particles, and engulfed viruses or bacteria.

Section 3 Summary – page Energy Transformers: Chloroplasts are cell organelles that capture light energy and produce food to store for a later time. Chloroplasts and energy

Section 3 Summary – page The chloroplasts belongs to a group of plant organelles called plastids, which are used for storage. Chloroplasts contain green pigment called chlorophyll. Chlorophyll traps light energy and gives leaves and stems their green color. Chloroplasts and energy

Section 3 Summary – page Mitochondria are membrane-bound organelles in plant and animal cells that transform energy for the cell. Mitochondria and energy

Section 3 Summary – page A mitochondria, like the endoplasmic reticulum, has a highly folded inner membrane. Energy storing molecules are produced on inner folds. Mitochondria and energy

Section 3 Summary – page Cells have a support structure called the cytoskeleton within the cytoplasm. The cytoskeleton is composed of microtubules and microfilaments. Microtubules are thin, hollow cylinders made of protein and microfilaments are thin solid protein fibers. Structures for Support and Locomotion

Section 3 Summary – page Some cell surfaces have cilia and flagella, which are structures that aid in locomotion or feeding. Cilia and flagella can be distinguished by their structure and by the nature of their action. Cilia and flagella

Section 3 Summary – page Cilia are short, numerous, hair-like projections that move in a wavelike motion. Cilia and flagella Cilia

Section 3 Summary – page Flagella are long projections that move in a whip-like motion. Flagella and cilia are the major means of locomotion in unicellular organisms. Cilia and flagella Flagella

End of Chapter 7 Show