Download Chapter 2 Cell Structure and Function

CHAPTER 3
CELL STRUCTURE AND FUNCTION
BEHAVIORAL OBJECTIVES
1. Explain how surface area-to-volume ratio limits the size of cells. [3.1, p.42]
2. Recognize that different features of the cell are best observed with different types of microscopes. [3.1, pp.4243, Fig. 3.2]
3. Describe the chemical structure of the plasma membrane. [3.2, pp.44-46, Fig. 3.4]
4. Explain the diverse ways cells use to control passage of materials through the plasma membrane. [3.2, pp. 4648, Fig. 3.6, Table 3.2]
5. Predict the results of placing a cell in solutions of various tonicity. [3.2, p.47, Fig. 3.5]
6. Describe the structure of the nucleus and its importance to the cell. [3.2, p.49, Fig. 3.7]
7. Discuss the features and importance of ribosomes. [3.2, p.50, Fig. 3.8]
8. Explain the relationship among the endoplasmic reticulum, the Golgi apparatus, and lysosomes. [3.2, pp. 5052, Figs. 3.8 & 3.9]
9. Describe the structure and function of the mitochondria within the cell. [3.2, p. 52, Fig. 3.10]
10. Describe the structure and function of the cytoskeleton within the cytoplasm. [3.2, p.53]
11. Describe the relationship between centrioles and cilia or flagella. [3.2, pp. 53-54, Figs. 3.11 & 3.12]
12. Understand the functioning of a metabolic pathway and the importance of enzymes within it. [3.3, p. 55]
13. Describe a generalized equation for an enzymatic reaction. [3.3, p.54, Fig. 3.13]
14. Explain the function of coenzymes. [3.3, p. 55]
15. Associate the summary chemical reaction of aerobic cellular respiration with glycolysis, the Krebs cycle, and
the electron transport system. [3.3, p. 55, Fig. 3.14, Table 3.4]
16. Outline the chemical reactions that take place during aerobic cellular respiration, and relate the results to the
three metabolic pathways involved. [3.3, p. 56, Fig. 3.14]
17. Explain the relationship between the mitochondria and the Krebs cycle and electron transport system. [3.3, pp.
52-53, 55-56]
18. Compare the conditions required for aerobic cellular respiration with those that result in fermentation. [3.3,
p. 57]
19. Understand and use the bold-faced and italicized terms included in this chapter. [Understanding Key Terms,
p.59]
EXTENDED LECTURE OUTLINE
3.1 Cell Size
All living things are composed of cells, and new cells arise only from preexisting ones. Cells are small to maintain
an optimal surface area to volume ratio.
Microscopy and Cell Structure
The compound light microscope passes light rays through specimens and uses glass lenses to view objects.
The transmission electron microscope passes electrons through a specimen, focuses with magnetic lenses, and
projects images onto a fluorescent screen or photographic film.
The scanning electron microscope passes a beam of electrons over the surface of a metal-coated specimen,
collecting them to produce a television-type picture on a screen.
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Image 0056l.jpg (Fig. 3.1)
Image 0057l.jpg (Fig. TA3.1)
Image 0058al.jpg (Fig. 3.2a)
Image 0058bl.jpg (Fig. 3.2b)
Image 0058cl.jpg (Fig. 3.2c)
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Human Body/Anatomy/Cell Shape
Human Body/Anatomy/Cell Size
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Cells/Cell Structures/Surface to Volume
Transparencies
35 (Fig. TA3.1)
36 (Fig. 3.2a)
37 (Fig. 3.2b)
38 (Fig. 3.2c)
3.2 Cellular Organization
A human cell is bounded by a plasma membrane which encloses a central nucleus surrounded by cytoplasm. The
cytoplasm contains organelles, small membranous structures, and the cytoskeleton.
The Plasma Membrane
Plasma membrane is a bilayer of phospholipids with embedded or attached proteins. Glycoproteins and glycolipids
serve as identification markers. Embedded proteins may serve as hormone receptors, transport channels, and
enzymes in metabolic reactions.
Plasma Membrane Functions
Keeps a cell intact and being selectively permeable, it regulates the entrance and exit of molecules.
Diffusion
Diffusion is the random movement of molecules from an area of higher concentration to one of lower
concentration.
Osmosis
Osmosis is the diffusion of water across a plasma membrane.
Transport by Carriers
Transport by carriers occurs in two manners. In facilitated transport a protein carrier helps a molecule
across the membrane, using no energy. In active transport, a protein carrier transports a molecule but
requires energy .
Endocytosis and Exocytosis
Endocytosis occurs as the plasma membrane forms a vesicle around a particle. Exocytosis is the
reverse process.
The Nucleus
The nucleus DNA directs protein synthesis in the cytoplasm. It contains one or more nucleoli, where ribosomal
RNA (rRNA) is manufactured. The nuclear envelope is a double membrane with nuclear pores.
Ribosomes
Ribosomes are a mix of rRNA and proteins. They are the sites of protein synthesis in the cytoplasm.
Membranous Canals and Vesicles
The endomembrane system consists of the nuclear envelope, endoplasmic reticulum, the Golgi apparatus, and
several vesicles.
The Endoplasmic Reticulum
The endoplasmic reticulum (ER) is a series of membranes that form tubular channels within the
cytoplasm. Rough ER (with ribosomes) specializes in protein synthesis. Smooth ER produces different
compounds in different cells.
The Golgi Apparatus
The Golgi apparatus, a stack of flattened vacuoles with vesicles near the edges, packages, stores, and
distributes the proteins the ER produces.
Lysosomes
The Golgi apparatus produces lysosomes, which contain hydrolytic enzymes that digest unwanted
materials inside the cell, including worn-out cell parts.
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Mitochondria
Mitochondria are organelles bounded by a double membrane. The inner membrane is folded into cristae. The gellike material between the cristae is matrix. Mitochondria convert the energy stored in glucose into ATP molecules
in a process called aerobic cellular respiration.
The Cytoskeleton
Filamentous protein structures, microtubules, and actin filaments form a cytoskeleton that serves as a framework
for the cell's interior.
Centrioles
Centrioles are short cyclinders with a 9 + 0 arrangement of microtubules that occur in pairs within the
centrome, the major microtubule organizing center of the cell. Centrioles also give rise to basal bodies
that direct the formation of cilia and flagella.
Cilia and Flagella
Cilia and flagella are hairlike projections of cells responsible for locomotion. Each cilium and flagellum
has a basal body at its base.
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Image 0059a.jpg (Fig. 3.3)
Image 0059bl.jpg (Fig 3.3)
Image 0059cl.jpg (Fig. 3.3)
Image 0060l.jpg (Fig. 3.3b)
Image 0061al.jpg (Fig. 3.4)
Image 0061bl.jpg (Fig. 3.4)
Image 0062l.jpg (Fig. 3.5)
Image 0063l.jpg (Fig. 3.6)
Image 0064al.jpg (Fig. 3.7)
Image 0064bl.jpg (Fig. 3.7)
Image 0064cl.jpg (Fig. 3.7)
Image 0065l.jpg (Fig. 3.8)
Image 0066l.jpg (Fig. 3.9)
Image 0067l.jpg (Fig. 3.9)
Image 0068l.jpg (Fig. 3.10)
Image 0069l.jpg (Fig. TA3.2)
Image 0070l.jpg (Fig. 3.11)
Image 0071l.jpg (Fig. 3.12)
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Human Body/Anatomy/Cell Components
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Cell/Membrane Structure and Function/How Molecules Cross
the Plasma Membrane
Cell/Membrane Structure and Function/Diffusion
Cell/Membrane Structure and Function/Diffusion_1
Cell/Membrane Structure and Function/Diffusion_2
Cell/Membrane Structure and Function/Osmosis_1
Cell/Membrane Structure and Function/Osmosis_2
Cell/Membrane Structure and Function/Osmosis_3
Cell/Membrane Structure and Function/Facilitated Diffusion
Cell/Membrane Structure and Function/Transport Moves
Substances
Cell/Membrane Structure and Function/Active transport
Cell/Membrane Structure and Function/Sodium-Potassium
Pump_1
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Cell/Membrane Structure and Function/Sodium-Potassium
Pump_2
Cell/Membrane Structure and Function/Cotransport
Cell/Membrane Structure and Function/Endocytosis and
Exocytosis
Cell/Cell Structure and Function/Animal Cell Anatomy
Cell/Cell Structure and Function/Rough Endoplasmic Reticulum
(ER)
Cell/Cell Structure and Function/Golgi apparatus
Cell/Cell Structure and Function/Secretion
Cell/Cell Respiration/Organization of Cristae
Cells/Cell Structures/Eukaryotes
Cells/Cell Membrane/Membrane Structure
Cells/Cell Membrane/Diffusion
Cells/Cell Membrane/Osmosis
Cells/Cell Membrane/Facilitated Diffusion
Cells/Cell Membrane/Active Transport
Cells/Cell Membrane/Exo-Endocytosis
Cells/Cell Membrane/Cell Interactions
Cells/Cell Structures/Endomembrane
Cells/Cell Structures/Energy Organelles
Cells/Cell Structures/Cytoskeleton
39 (Fig. 3.3a)
40 (Fig. 3.4)
41 (Fig. 3.5)
42 (Fig. 3.6)
43 (Fig. 3.7)
44 (Fig. 3.8)
45 (Fig. 3.9)
46 (Fig. 3.10)
47 (Fig. 3.11)
3.3 Cellular Metabolism
Chemical reactions in cell are organized into metabolic pathways where every reaction has its own enzyme.
Enzymes and Coenzymes
Enzymes are named for their substrates and have an active site specific for the substrate. Many enzymes have
nonprotein molecules, called coenzymes, to assist them. Some coenzymes, like NAD, remove hydrogen from
substrates.
Cellular Respiration
Glucose breaks down into carbon dioxide and water requires three subpathways: Glycolysis, the Krebs cycle, and
the electron transport system. Glycolysis needs no oxygen and takes place in the cytoplasm of the cell. During
glycolysis, glucose breaks down into two molecules of pyruvate, with a net gain of 2 ATP. A transition reaction
converts pyruvate to active acetate that can enter the mitochondrion and the Krebs cycle. The Krebs cycle takes
place in the matrix and requires oxygen. Two ATP and 4 CO2 molecules form as the cycle turns twice, once for
each pyruvate molecule. NADH2 carries hydrogen atoms from glycolysis and the Krebs cycle to electron carriers
(electron transport system) embedded in the cristae. As electrons pass down the system of carriers, energy is
released to generate 32 ATP. Altogether aerobic cellular respiration generates 36 ATP.
Fermentation
When no oxygen is present for pyruvate to enter the Krebs cycle, pyruvate is converted to lactic acid through
fermentation, producing few ATP. Lactic acid is toxic to many cells and leads to muscle fatigue.
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Image 0072l.jpg (Fig. 3.13)
Image 0073l.jpg (Fig. 3.14)
Image 0074l.jpg (Fig. TA3.3)
Image 0075l.jpg (Fig. 3A)
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Image 0076l.jpg (Fig. TA3.4)
Cell/Energy and Enzymes/Enzymes are Specific
Cell/Energy and Enzymes/How Enzymes Work
Cell/Energy and Enzymes/The ATP Cycle
Cell/Cell Respiration/Electron Transport
Cell/Cell Respiration/Overview of Glycolysis
Cell/Cell Respiration/Glycolysis_1
Cell/Cell Respiration/Glycolysis_2
Cell/Cell Respiration/Acetyl-CoA Formation
Cell/Cell Respiration/Overview of the Krebs Cycle
Cell/Cell Respiration/Krebs Cycle
Cell/Cell Respiration/Products of Krebs Cycle
Cell/Cell Respiration/Electron Transport Chain in Mitochondria
Cell/Cell Respiration/Electron Transport System
Cell/Cell Respiration/Transferring Hydrogen Atoms
Cell/Cell Respiration/Chemiosmosis
Cells/Metabolism/Thermodynamics
Cells/Metabolism/Coupled Reactions
Cells/Metabolism/Enzymes
Cells/Metabolism/Pathways
Cells/Respiration/Introduction
Cells/Respiration/Glycolysis
Cells/Respiration/Transition
Cells/Respiration/Krebs Cycle
Cells/Respiration/Electron Transport
Cells/Respiration/Fermentation
Cells/Respiration/Summary
Cells/Respiration/Other Nutrients
Embryonic Stem cells: The Future of Organ Transplants
The Case of Rachel Martin and Lactic Acid
48 (Fig. 3.13)
49 (Fig. 3.14)
50 (Table 3.4)
51 (Fig. TA3.2)
SEVENTH EDITION CHANGES
New/Revised Text:
This was chapter 2 in the previous edition.
3.3 Cellular Metabolism. The discussion of cellular respiration has been simplified. The phrase aerobic
cellular respiration has been changed to cellular respiration for clarity.
New Bioethical Focus: Stem Cells
New/Revised Figures:
3.3 Animal cell; 3.5 Tonicity; 3.7 The nucleus and the nuclear envelope; 3.9 The Golgi apparatus; 3.12
Sperm cells; 3.14 Cellular respiration
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STUDENT ACTIVITIES
Stem Cells and Bioethics
1. Read the Bioethical Focus “Stem Cells”. Explain to students the tragic effects of progressive neurological
diseases such as Parkinson disease and how stem cell research using embryos might provide a remedy. Next,
discuss the current political administration that rejects the use of embryos in stem cell research. Survey the
class for opinions.
Why so tiny?
2. Illustrate limits to cell size by giving a group of students 27 wooden blocks (children’s toy blocks). Stack
them in a single cube (of 3x3x3 blocks). Use “wb” as units of measurement. So each face of a block has a
surface area of 1 wb2, and each block has a volume of 1 wb3. Draw a table on the chalkboard like this, and
help the students calculate the surface area-to-volume ratio of three configurations of these 27 blocks.
arrangement
surface area
volume
SA/V
All in one cube
54 wb2
27 wb3
2 wb2/wb3
3 sheets of 9 blocks
90 wb2
27 wb3
3.33 wb2/wb3
27 individual blocks
162wb2
27 wb3
6 wb2/wb3
This allows students to visualize how smaller cells have a greater surface area-to-volume ratio.
Do Onions Make You Cry?
3. Enzymes trigger metabolic reactions in cells. It is also true that cells compartmentalize different compounds,
an asset of eukaryotic cells that prokaryotes do not possess. To illustrate both the action of enzymes and of
cell compartmentalization, consider the following:
Plants, such as onions and garlic, produce compounds aimed at deterring predators. These same compounds
are what make onions and garlic so appealing to us as flavorings and food. In onions and garlic, one enzyme is
stored between cells, and another compound is stored within cells. When the bulb of either plant is cut, either
with a knife or from a grazing predator, the enzyme and the compound mix, producing a chemical reaction
that releases a lachrymator--a potent compound that stings human eyes. Tears result when the lachrymator
contacts moist eye tissues, producing sulfuric acid. A demonstration of this reaction in the classroom is
illustrative.
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