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 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 Tight junctions – continuous belts fused to prevent leakage ex: intestinal epithelium 2) Desmosomes – anchoring junctions ex: epithelial sheets 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