1. Overview: The Fundamental Units of Life
All organisms are made of cells
Cell structure is correlated to cellular function
For the Discovery Video Cells, go to Animation and Video Files.
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2. Microscopy
Scientists use microscopes to visualize cells too small to see with the naked eye
In a light microscope (LM), visible light passes through a specimen and then through glass lenses, which magnify the image
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3. TEMs are used mainly to study the internal structure of cells
Two basic types of electron microscopes (EMs) are used to study subcellular structures
Scanning electron microscopes (SEMs) focus a beam of electrons onto the surface of a specimen, providing images that look 3-D
Transmission electron microscopes (TEMs) focus a beam of electrons through a specimen
TEMs are used mainly to study the internal structure of cells
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4. (b) Transmission electron microscopy (TEM) Longitudinal section of
Fig. 6-4
TECHNIQUE
RESULTS
1 µm
(a) Scanning electron
microscopy (SEM)
Cilia
(b) Transmission electron
microscopy (TEM)
Longitudinal
section of
cilium
Cross section
of cilium
1 µm
Figure 6.4 Electron microscopy

5. Cell fractionation takes cells apart and separates the major organelles from one another
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6. Protists, fungi, animals, and plants all consist of eukaryotic cells
Concept 6.2: Eukaryotic cells have internal membranes that compartmentalize their functions
The basic structural and functional unit of every organism is one of two types of cells: prokaryotic or eukaryotic
Only organisms of the domains Bacteria and Archaea consist of prokaryotic cells
Protists, fungi, animals, and plants all consist of eukaryotic cells
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7. Comparing Prokaryotic and Eukaryotic Cells
Basic features of all cells:
Plasma membrane
Semifluid substance called cytosol
Chromosomes (carry genes)
Ribosomes (make proteins)
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8. Prokaryotic cells are characterized by having
No nucleus
DNA in an unbound region called the nucleoid
No membrane-bound organelles
Cytoplasm bound by the plasma membrane
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9. A typical rod-shaped bacterium (b)
Fig. 6-6
Fimbriae
Nucleoid
Ribosomes
Plasma membrane
Bacterial
chromosome
Cell wall
Capsule
0.5 µm
Flagella
(a)
A typical rod-shaped bacterium
(b)
A thin section through the bacterium Bacillus coagulans (TEM)
Figure 6.6 A prokaryotic cell

10. Eukaryotic cells are characterized by having
DNA in a nucleus that is bounded by a membranous nuclear envelope
Membrane-bound organelles
Cytoplasm in the region between the plasma membrane and nucleus
Eukaryotic cells are generally much larger than prokaryotic cells
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11. The plasma membrane is a selective barrier that allows sufficient passage of oxygen, nutrients, and waste to service the volume of every cell
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12. Carbohydrate side chain
Fig. 6-7
(a)
TEM of a plasma
membrane
Outside of cell
Inside of
cell
0.1 µm
Carbohydrate side chain
Hydrophilic
region
Figure 6.7 The plasma membrane
Hydrophobic
region
Hydrophilic
region
Phospholipid
Proteins
(b) Structure of the plasma membrane

13. The surface area to volume ratio of a cell is critical
The logistics of carrying out cellular metabolism sets limits on the size of cells
The surface area to volume ratio of a cell is critical
Small cells have a greater surface area relative to volume
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14. A Panoramic View of the Eukaryotic Cell
Plant and animal cells have most of the same organelles
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15. ENDOPLASMIC RETICULUM (ER) Nucleolus NUCLEUS Rough ER Smooth ER
Fig. 6-9a
Nuclear
envelope
ENDOPLASMIC RETICULUM (ER)
Nucleolus
NUCLEUS
Rough ER
Smooth ER
Flagellum
Chromatin
Centrosome
Plasma membrane
CYTOSKELETON:
Microfilaments
Intermediate
filaments
Microtubules
Ribosomes
Figure 6.9 Animal and plant cells—animal cell
Microvilli
Golgi
apparatus
Peroxisome
Mitochondrion
Lysosome

16. Rough endoplasmic reticulum
Fig. 6-9b
Nuclear envelope
Rough endoplasmic reticulum
NUCLEUS
Nucleolus
Chromatin
Smooth endoplasmic reticulum
Ribosomes
Central vacuole
Golgi
apparatus
Microfilaments
Intermediate filaments
CYTO-
SKELETON
Microtubules
Figure 6.9 Animal and plant cells—plant cell
Mitochondrion
Peroxisome
Chloroplast
Plasma membrane
Cell wall
Plasmodesmata
Wall of adjacent cell

17. The nucleus contains most of the DNA in a eukaryotic cell
Concept 6.3: The eukaryotic cell’s genetic instructions are housed in the nucleus and carried out by the ribosomes
The nucleus contains most of the DNA in a eukaryotic cell
Ribosomes use the information from the DNA to make proteins
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18. The Nucleus: Information Central
The nucleus contains most of the cell’s genes and is usually the most conspicuous organelle
The nuclear envelope encloses the nucleus, separating it from the cytoplasm
The nuclear membrane is a double membrane; each membrane consists of a lipid bilayer
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19. Close-up of nuclear envelope
Fig. 6-10
Nucleus
1 µm
Nucleolus
Chromatin
Nuclear envelope:
Inner membrane
Outer membrane
Nuclear pore
Pore complex
Rough ER
Surface of
nuclear envelope
Ribosome
1 µm
Figure 6.10 The nucleus and its envelope
0.25 µm
Close-up of nuclear envelope
Pore complexes (TEM)
Nuclear lamina (TEM)

20. The shape of the nucleus is maintained by the nuclear lamina, which is composed of protein
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21. In the nucleus, DNA and proteins that assist in the folding of DNA form genetic material called chromatin
Chromatin condenses to form discrete chromosomes
The nucleolus is located within the nucleus and is the site of ribosomal RNA (rRNA) synthesis
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22. Ribosomes: Protein Factories
Ribosomes are particles made of ribosomal RNA and protein
Ribosomes carry out protein synthesis in two locations:
In the cytosol (free ribosomes)
On the outside of the endoplasmic reticulum or the nuclear envelope (bound ribosomes)
For the Cell Biology Video Staining of Endoplasmic Reticulum, go to Animation and Video Files.
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

23. Endoplasmic reticulum (ER)
Fig. 6-11
Cytosol
Endoplasmic reticulum (ER)
Free ribosomes
Bound ribosomes
Large subunit
Figure 6.11 Ribosomes
Small subunit
0.5 µm
TEM showing ER and ribosomes
Diagram of a ribosome

24. Endomembrane System
Endo = inside

25. Components of the endomembrane system:
Concept 6.4: The endomembrane system regulates protein traffic and performs metabolic functions in the cell
Components of the endomembrane system:
Nuclear envelope
Endoplasmic reticulum
Golgi apparatus
Lysosomes
Vacuoles
Plasma membrane
These components are either continuous or connected via transfer by vesicles
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26. The Endoplasmic Reticulum: Biosynthetic Factory
The endoplasmic reticulum (ER) accounts for more than half of the total membrane in many eukaryotic cells
The ER membrane is continuous with the nuclear envelope
There are two distinct regions of ER:
Smooth ER, which lacks ribosomes
Rough ER, with ribosomes studding its surface
For the Cell Biology Video ER and Mitochondria in Leaf Cells, go to Animation and Video Files.

27. Smooth ER Nuclear envelope Rough ER ER lumen Cisternae Transitional ER
Fig. 6-12
Smooth ER
Nuclear envelope
Rough ER
ER lumen
Cisternae
Transitional ER
Ribosomes
Transport vesicle
200 nm
Smooth ER
Rough ER
Figure 6.12 Endoplasmic reticulum (ER)

28. Functions of Rough ER The rough ER Has bound ribosomes
Distributes transport vesicles, proteins surrounded by membranes
Is a membrane factory for the cell

29. Functions of Smooth ER The smooth ER Synthesizes lipids
Metabolizes carbohydrates
Stores calcium

30. The Golgi Apparatus: Shipping and Receiving Center
The Golgi apparatus consists of flattened membranous sacs called cisternae
Functions of the Golgi apparatus:
Modifies products of the ER
Manufactures certain macromolecules
Sorts and packages materials into transport vesicles
For the Cell Biology Video ER to Golgi Traffic, go to Animation and Video Files.
For the Cell Biology Video Golgi Complex in 3D, go to Animation and Video Files.
For the Cell Biology Video Secretion From the Golgi, go to Animation and Video Files.

31. (“receiving” side of Golgi apparatus) 0.1 µm
Fig. 6-13
cis face
(“receiving” side of Golgi apparatus)
0.1 µm
Cisternae
Figure 6.13 The Golgi apparatus
trans face
(“shipping” side of Golgi apparatus)
TEM of Golgi apparatus

32. Lysosomes: Digestive Compartments
A lysosome is a membranous sac of hydrolytic enzymes that can digest macromolecules
Lysosomal enzymes can hydrolyze proteins, fats, polysaccharides, and nucleic acids
Lysosomes also use enzymes to recycle the cell’s own organelles and macromolecules, a process called autophagy

33. Fig. 6-14
Nucleus
1 µm
Vesicle containing
two damaged organelles
1 µm
Mitochondrion
fragment
Peroxisome
fragment
Lysosome
Digestive
enzymes
Lysosome
Lysosome
Plasma
membrane
Peroxisome
Figure 6.14a Lysosomes
Digestion
Food vacuole
Mitochondrion
Digestion
Vesicle
(a) Phagocytosis
(b) Autophagy

34. Nucleus Rough ER Smooth ER Plasma membrane Fig. 6-16-1
Figure 6.16 Review: relationships among organelles of the endomembrane system
Plasma membrane

35. Nucleus Rough ER Smooth ER cis Golgi Plasma membrane trans Golgi
Fig
Nucleus
Rough ER
Smooth ER
cis Golgi
Figure 6.16 Review: relationships among organelles of the endomembrane system
Plasma membrane
trans Golgi

36. Nucleus Rough ER Smooth ER cis Golgi Plasma membrane trans Golgi
Fig
Nucleus
Rough ER
Smooth ER
cis Golgi
Figure 6.16 Review: relationships among organelles of the endomembrane system
Plasma membrane
trans Golgi

37. Mitochondria and Chloroplast and Peroxisomes
(energy/metabolism)

38. Peroxisomes are oxidative organelles
Concept 6.5: Mitochondria and chloroplasts change energy from one form to another
Mitochondria are the sites of cellular respiration, a metabolic process that generates ATP
Chloroplasts, found in plants and algae, are the sites of photosynthesis
Peroxisomes are oxidative organelles
For the Cell Biology Video ER and Mitochondria in Leaf Cells, go to Animation and Video Files.
For the Cell Biology Video Mitochondria in 3D, go to Animation and Video Files.
For the Cell Biology Video Chloroplast Movement, go to Animation and Video Files.
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

39. Mitochondria and chloroplasts
Are not part of the endomembrane system
Have a double membrane
Have proteins made by free ribosomes
Contain their own DNA (endosymbiotic theory- mitochondria as precursor to bacteria?)
Mitochondria and chloroplasts have their own DNA, which replicates and propagates itself entirely independently of the main DNA in the chromosomes of the nucleus. All the mitochondria in you are descended from the small population of mitochondria that travelled from your mother in her egg.

40. Mitochondria: Chemical Energy Conversion
They have a smooth outer membrane and an inner membrane folded into cristae
The inner membrane creates two compartments: intermembrane space and mitochondrial matrix
Cristae present a large surface area for enzymes that synthesize ATP
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41. in the mitochondrial matrix
Fig. 6-17
Intermembrane space
Outer membrane
Free ribosomes
in the mitochondrial matrix
Inner membrane
Cristae
Figure 6.17 The mitochondrion, site of cellular respiration
Matrix
0.1 µm

42. Chloroplasts: Capture of Light Energy
The chloroplast is a member of a family of organelles called plastids
Chloroplasts contain the green pigment chlorophyll, as well as enzymes and other molecules that function in photosynthesis
Chloroplasts are found in leaves and other green organs of plants and in algae
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43. Inner and outer membranes
Fig. 6-18
Ribosomes
Stroma
Inner and outer membranes
Granum
1 µm
Thylakoid
Figure 6.18 The chloroplast, site of photosynthesis

44. Peroxisomes: Oxidation
Peroxisomes are specialized metabolic compartments bounded by a single membrane
Peroxisomes help break down fatty acids and produce hydrogen peroxide in the process which is then converted into water
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45. Cytoskeleton

46. The cytoskeleton helps to support the cell and maintain its shape
Concept 6.6: The cytoskeleton is a network of fibers that organizes structures and activities in the cell
The cytoskeleton is a network of fibers extending throughout the cytoplasm
It organizes the cell’s structures and activities, anchoring many organelles
The cytoskeleton helps to support the cell and maintain its shape
For the Cell Biology Video The Cytoskeleton in a Neuron Growth Cone, go to Animation and Video Files
For the Cell Biology Video Cytoskeletal Protein Dynamics, go to Animation and Video Files.

47. Components of the Cytoskeleton
Three main types of fibers make up the cytoskeleton:
Microtubules are the thickest of the three components of the cytoskeleton
Microfilaments, also called actin filaments, are the thinnest components
Intermediate filaments are fibers with diameters in a middle range
For the Cell Biology Video Actin Network in Crawling Cells, go to Animation and Video Files.
For the Cell Biology Video Actin Visualization in Dendrites, go to Animation and Video Files.
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48. Centrosomes and Centrioles
In many cells, microtubules grow out from a centrosome near the nucleus
The centrosome is a “microtubule-organizing center”
In animal cells, the centrosome has a pair of centrioles, each with nine triplets of microtubules arranged in a ring
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

49. Extracellular Components

50. These extracellular structures include:
Concept 6.7: Extracellular components and connections between cells help coordinate cellular activities
Most cells synthesize and secrete materials that are external to the plasma membrane
These extracellular structures include:
Cell walls of plants
The extracellular matrix (ECM) of animal cells
Intercellular junctions
For the Cell Biology Video Ciliary Motion, go to Animation and Video Files.
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51. Cell Walls of Plants
The cell wall is an extracellular structure that distinguishes plant cells from animal cells
The cell wall protects the plant cell, maintains its shape, and prevents excessive uptake of water
Plant cell walls are made of cellulose fibers embedded in other polysaccharides and protein
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

52. The Extracellular Matrix (ECM) of Animal Cells
Animal cells lack cell walls but are covered by an elaborate extracellular matrix (ECM)
ECM proteins bind to receptor proteins in the plasma membrane called integrins
For the Cell Biology Video Cartoon Model of a Collagen Triple Helix, go to Animation and Video Files.
For the Cell Biology Video Staining of the Extracellular Matrix, go to Animation and Video Files.
For the Cell Biology Video Fibronectin Fibrils, go to Animation and Video Files.
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

53. Proteoglycan complex Collagen EXTRACELLULAR FLUID Fibronectin
Fig. 6-30a
Collagen
Proteoglycan complex
EXTRACELLULAR FLUID
Fibronectin
Integrins
Plasma membrane
Figure 6.30 Extracellular matrix (ECM) of an animal cell, part 1
Micro-filaments
CYTOPLASM

54. Functions of the ECM: Support Adhesion Movement Regulation
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55. Intercellular Junctions
Neighboring cells in tissues, organs, or organ systems often adhere, interact, and communicate through direct physical contact
Intercellular junctions facilitate this contact
There are several types of intercellular junctions
Plasmodesmata
Tight junctions
Desmosomes
Gap junctions
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