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Chapter 7
A Tour of the Cell
cells –
basic units of structure/function
microscopy –
light microscope (LM)
electron microscope (TEM, SEM)
-resolving power
-Leeuwenhoek (1600’s)
-Robert Hooke (1665)
-cell fractionation - centrifuge
Figure 7.1 The size range of cells
Prokaryotic vs. Eukaryotic cells
(largest distinction)
• Cytoplasm/cytosol
• Cell size limitations
plasma membrane – thin, transparent,
phospholipid bilayer, flexible, selectively
permeable, porous
Structures found in all cells
•
•
•
•
Cytosol
Plasma membrane
Ribosomes
DNA (chromatin/chromosomes)
Organization – Ultrastructure:
Nucleus
~ 5mm diameter
nuclear envelope: pore complex
chromosomes/chromatin
nucleolus: nucleolar organizers
Figure 7.4 A prokaryotic cell
Figure 7.5 Geometric relationships explain why most cells are microscopic
Figure 7.6 The plasma membrane
Figure 7.9 The nucleus and its envelope
Ribosomes
free
bound
Endomembrane system
endoplasmic reticulum (ER)
cisternae
rough
smooth
Figure 7.11 Endoplasmic reticulum (ER)
Figure 7.10 Ribosomes
Golgi apparatus
dictyosome
Lysosome
Microbodies
peroxisomes – produce H2O2
glyoxysomes – initiate conversion of fat to
sugar
Vacuole
Mitochondrion
Figure 7.12 The Golgi apparatus
Figure 7.16 Review: relationships among organelles of the endomembrane system
Figure 7.14 The formation and functions of lysosomes (Layer 3)
Figure 7.13 Lysosomes
Figure 7.19 Peroxisomes
Figure 7.15 The plant cell vacuole
Figure 7.17 The mitochondrion, site of cellular respiration
Plastids
chloroplasts
amyloplasts
chromoplasts:
xanthophyll – yellow
carotene – orange
phycoerythrin – red
Figure 7.18 The chloroplast, site of photosynthesis
Cytoskeleton
microtubules
microfilaments
intermediate filaments
Centrioles
Cilia
Flagella (eukaryotic 9+2)
Pseudopodia
Table 7.2 The structure and function of the cytoskeleton
Figure 7.20 The cytoskeleton
Figure 7.22 Centrosome containing a pair of centrioles
Figure 7.23 A comparison of the beating of flagella and cilia
Cell wall
primary
middle lamella
secondary
plasmodesma (plants)
ECM (extracellular matrix)
Figure 7.28 Plant cell walls
Figure 7.29 Extracellular matrix (ECM) of an animal cell
Intercellular junctions
1) Tight junctions –
continuous belts
fused to prevent leakage
ex: intestinal epithelium
2) Desmosomes –
anchoring junctions
ex: epithelial sheets
3) Gap junctions –
communicating junctions
ex: in heart muscle cells
Figure 7.30 Intercellular junctions in animal tissues
Figure 7.8 Overview of a plant cell
Figure 7.7 Overview of an animal cell