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Chapter 4: The Organization of Cells CHAPTER 4 The Organization of Cells
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Chapter 4: The Organization of Cells
CHAPTER 4The Organization of Cells
Chapter 4: The Organization of Cells
Chapter 4: The Organization of CellsThe Cell: The Basic Unit of LifeThe Cell: The Basic Unit of Life
Prokaryotic CellsProkaryotic Cells
Eukaryotic CellsEukaryotic Cells
Organelles that Process InformationOrganelles that Process Information
The The EndomembraneEndomembrane System System
Chapter 4: The Organization of Cells
Chapter 4: The Organization of CellsOrganelles that Process EnergyOrganelles that Process Energy
Other Organelles Enclosed by MembranesOther Organelles Enclosed by Membranes
The CytoskeletonThe Cytoskeleton
ExtracellularExtracellular Structures Structures
Chapter 4: The Organization of Cells
The Cell: The Basic Unit of Life• All cells come from preexisting cells All cells come from preexisting cells
and have certain processes, and have certain processes, molecules, and structures in common.molecules, and structures in common.
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Chapter 4: The Organization of Cells
The Cell: The Basic Unit of Life• To maintain adequate exchanges with
its environment, a cell’s surface area must be large compared with its volume.
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Chapter 4: The Organization of Cells
The Cell: The Basic Unit of Life• Microscopes are needed to visualize
cells.
• Electron microscopes allow observation of greater detail than light microscopes do.
Chapter 4: The Organization of Cells
The Cell: The Basic Unit of Life• Prokaryotic cell organization is Prokaryotic cell organization is
characteristic of the kingdoms characteristic of the kingdoms Eubacteria and Archaebacteria. Eubacteria and Archaebacteria.
• Prokaryotic cells lack internal Prokaryotic cells lack internal compartments.compartments.
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Chapter 4: The Organization of Cells
The Cell: The Basic Unit of Life• Eukaryotic cell organization is
characteristic of the other four kingdoms.
• Eukaryotic cells have many membrane-enclosed compartments, including a nucleus containing DNA.
Review Figure 4.888
Chapter 4: The Organization of Cells
4.8
Figure 4.8Figure 4.8
figure 04-08.jpg
Chapter 4: The Organization of Cells
Prokaryotic Cells
• All prokaryotic cells have a plasma All prokaryotic cells have a plasma membrane, a nucleoid region with membrane, a nucleoid region with DNA, and a cytoplasm containing DNA, and a cytoplasm containing ribosomes, dissolved enzymes, water, ribosomes, dissolved enzymes, water, and small molecules. and small molecules.
• Some prokaryotes have a cell wall, Some prokaryotes have a cell wall, outer membrane, and capsule, some outer membrane, and capsule, some contain photosynthetic membranes, contain photosynthetic membranes, and some have mesosomes. and some have mesosomes.
Fig.4.4Fig.4.41010
Chapter 4: The Organization of Cells
4.4
Figure 4.4Figure 4.4
figure 04-04.jpg
Chapter 4: The Organization of Cells
Prokaryotic Cells
• Some porkaryotes have rotating flagella for movement.
• Pili are projections by which prokaryotic cells attach to one another or to environmental surfaces.
Review Figure 4.61212
Chapter 4: The Organization of Cells
4.6
Figure 4.6Figure 4.6
figure 04-06.jpg
Chapter 4: The Organization of Cells
Eukaryotic Cells
• Like prokaryotic cells, eukaryotic cells Like prokaryotic cells, eukaryotic cells have a plasma membrane, cytoplasm, have a plasma membrane, cytoplasm, and ribosomes. and ribosomes.
• However, eukaryotic cells are larger However, eukaryotic cells are larger and contain many membrane-enclosed and contain many membrane-enclosed organelles. organelles.
Review Figure 4.7Review Figure 4.71414
Chapter 4: The Organization of Cells
4.7 – Part 1
Figure 4.7 – Part 1Figure 4.7 – Part 1
figure 04-07a.jpg
Chapter 4: The Organization of Cells
4.7 – Part 2
Figure 4.7 – Part 2Figure 4.7 – Part 2
figure 04-07b.jpg
Chapter 4: The Organization of Cells
Eukaryotic Cells
• Membranes that envelop organelles in eukaryotic cells are partial barriers ensuring that the chemical composition of the organelle’s interior differs from that of the surrounding cytoplasm.
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Chapter 4: The Organization of Cells
Organelles that Process Information
• The nucleus is usually the largest The nucleus is usually the largest organelle in a cell. organelle in a cell.
• It is surrounded by the nuclear It is surrounded by the nuclear envelope. envelope.
• Within the nucleus, the nucleolus is Within the nucleus, the nucleolus is the source of the ribosomes found in the source of the ribosomes found in the cytoplasm.the cytoplasm.
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Chapter 4: The Organization of Cells
Organelles that Process Information
• Nuclear pores have complex structures governing what enters and leaves the nucleus.
Review Figure 4.10
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Chapter 4: The Organization of Cells
4.10
Figure 4.10Figure 4.10
figure 04-10.jpg
Chapter 4: The Organization of Cells
Organelles that Process Information
• The nucleus contains most of the cell’s DNA, which associates with protein to form chromatin.
• Chromatin is diffuse throughout the nucleus. Just before cell division, it condenses to form chromosomes.
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Chapter 4: The Organization of Cells
The Endomembrane System
• The endomembrane system is made The endomembrane system is made up of a series of interrelated up of a series of interrelated membranes and compartments.membranes and compartments.
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Chapter 4: The Organization of Cells
The Endomembrane System
• The rough endoplasmic reticulum has ribosomes that synthesize proteins.
• The smooth endoplasmic reticulum lacks ribosomes and is associated with synthesis of lipids.
Review Figure 4.112323
Chapter 4: The Organization of Cells
The Endomembrane System
• The Golgi apparatus adds signal molecules to proteins, directing them to destinations.
• It receives materials from the rough ER via vesicles that fuse with the cis region of the Golgi.
Review Figures 4.122525
Chapter 4: The Organization of Cells
4.12
Figure 4.12Figure 4.12
figure 04-12.jpg
Chapter 4: The Organization of Cells
The Endomembrane System
• Vesicles originating from the Vesicles originating from the transtrans region of the Golgi contain proteins for region of the Golgi contain proteins for different cellular locations. different cellular locations.
• Some fuse with the plasma membrane Some fuse with the plasma membrane and release their contents outside the and release their contents outside the cell. cell.
Review Figure 4.12Review Figure 4.122828
Chapter 4: The Organization of Cells
The Endomembrane System
• Lysosomes are vesicles containing digestive enzymes.
• Lysosomes fuse with the food vacuoles to form secondary lysosomes, in which digestion occurs.
• Undigested materials are secreted from the cell when the secondary lysosome fuses with the plasma membrane.
Review Figure 4.132929
Chapter 4: The Organization of Cells
4.13
Figure 4.13Figure 4.13
figure 04-13.jpg
Chapter 4: The Organization of Cells
Organelles that Process Energy• Mitochondria are enclosed by an outer Mitochondria are enclosed by an outer
membrane and an inner membrane membrane and an inner membrane that folds inward to form cristae. that folds inward to form cristae.
• Mitochondria contain proteins needed Mitochondria contain proteins needed for cellular respiration and generation for cellular respiration and generation of ATP. of ATP.
Review Figure Review Figure 4.14.1443030
Chapter 4: The Organization of Cells
4.14
Figure 4.14Figure 4.14
figure 04-14.jpg
Chapter 4: The Organization of Cells
Organelles that Process Energy• Eukaryotic cells contain mitochondria
space.
• Green plant cells also contain chloroplasts enclosed by double membranes and containing an internal system of thylakoids organized as grana.
Review Figure 4.153232
Chapter 4: The Organization of Cells
Figure 4.15
Figure 4.15Figure 4.15
figure 04-15.jpg
Chapter 4: The Organization of Cells
Organelles that Process Energy• Thylakoids within chloroplasts contain Thylakoids within chloroplasts contain
the chlorophyll and proteins that the chlorophyll and proteins that harvest light energy for harvest light energy for photosynthesis.photosynthesis.
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Chapter 4: The Organization of Cells
Organelles that Process Energy• Mitochondria and chloroplasts contain
their own DNA and ribosomes and can make some of their own proteins.
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Chapter 4: The Organization of Cells
Organelles that Process Energy• The endosymbiosis theory of the
evolutionary origin of mitochondria and chloroplasts states that they originated when large prokaryotes engulfed, but did not digest, smaller ones.
• Mutual benefits permitted this symbiotic relationship to evolve into eukaryotic organelles of today.
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Chapter 4: The Organization of Cells
Other Organelles Enclosed by Membranes
• Peroxisomes and glyoxysomes contain Peroxisomes and glyoxysomes contain special enzymes and carry out special enzymes and carry out specialized chemical reactions inside specialized chemical reactions inside the cell.the cell.
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Chapter 4: The Organization of Cells
Other Organelles Enclosed by Membranes
• Vacuoles consist of a membrane-enclosed compartment of water and dissolved substances.
• They take in water and enlarge, providing pressure to stretch the cell wall and structural support for a plant.
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Chapter 4: The Organization of Cells
The Cytoskeleton
• The cytoskeleton within the cytoplasm The cytoskeleton within the cytoplasm of eukaryotic cells provides shape, of eukaryotic cells provides shape, strength, and movement. strength, and movement.
• It consists of three interacting types of It consists of three interacting types of protein fibers.protein fibers.
Review Fig.21Review Fig.213939
Chapter 4: The Organization of Cells
The Cytoskeleton
• Microfilaments consist of two chains of actin units forming a double helix.
• Microfilaments strengthen cellular structures and provide movement in animal cell division, cytoplasmic streaming, and pseudopod extension.
• They occur as individual, bundled, or networked fibers.
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Chapter 4: The Organization of Cells
The Cytoskeleton
• Intermediate filaments are formed of Intermediate filaments are formed of keratins and add strength to cell keratins and add strength to cell attachments in multicellular attachments in multicellular organisms.organisms.
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Chapter 4: The Organization of Cells
The Cytoskeleton
• Microtubules are composed of dimers of the protein tubulin, and can lengthen and shorten.
• Cilia and flagella both have a characteristic 9 + 2 pattern of microtubules.
Review Figure 4.244242
Chapter 4: The Organization of Cells
4.24
Figure 4.24Figure 4.24
figure 04-24.jpg
Chapter 4: The Organization of Cells
The Cytoskeleton
• Movements of cilia and flagella are due to binding of the motor protein dynein to microtubules.
• Microtubules also bind motor proteins that move organelles through the cell.
Fig.4.254444
Chapter 4: The Organization of Cells
4.25
Figure 4.25Figure 4.25
figure 04-25.jpg
Chapter 4: The Organization of Cells
The Cytoskeleton
• Centrioles, made up of triplets of microtubules, are involved in the distribution of chromosomes during nuclear division.
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Chapter 4: The Organization of Cells
Extracellular Structures
• Materials external to the plasma Materials external to the plasma membrane provide protection, membrane provide protection, support, and attachment for cells in support, and attachment for cells in multicellular systems.multicellular systems.
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Chapter 4: The Organization of Cells
Extracellular Structures
• Cell walls of plants consist principally of cellulose.
• They are pierced by plasmodesmata that join the cytoplasm of adjacent cells.
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Chapter 4: The Organization of Cells
Extracellular Structures
• In animals, the extracellular matrix consists of different proteins, including proteoglycan.
• In bone and cartilage, the collagen predominates.
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