1. A Tour of the Cell Figures 4.4 – 4.7
CHAPTER 4
A Tour of the Cell
Figures 4.4 – 4.7

2. The Two Major Categories of Cells
The countless cells on earth fall into two categories
Prokaryotic cells
Eukaryotic cells

3. Prokaryotic and eukaryotic cells differ in several respects
Prokaryotic cell
Nucleoid region
Eukaryotic cell
Nucleus
Organelles
Figure 4.4

4. Prokaryotic cells Are smaller than eukaryotic cells
Lack internal structures surrounded by membranes
Lack a nucleus

5. Prokaryotic flagella Nucleoid region (DNA) Plasma Ribosomes membrane
Cell wall
Capsule
Pili
Figure 4.5

6. A Panoramic View of Eukaryotic Cells
An idealized animal cell
Centriole
Ribosomes
Lysosome
Not in most
plant cells
Flagellum
Cytoskeleton
Plasma
membrane
Mitochondrion
Nucleus
Rough
endoplasmic
reticulum (ER)
Smooth
endoplasmic
reticulum (ER)
Golgi
apparatus
Figure 4.6A

7. An idealized plant cell
Not in animal cells
Cytoskeleton
Mitochondrion
Central
vacuole
Nucleus
Cell wall
Rough endoplamsic reticulum (ER)
Chloroplast
Ribosomes
Plasma
membrane
Smooth
endoplasmic
reticulum (ER)
Plasmodesmata
Golgi apparatus
Figure 4.6B

8. MEMBRANE STRUCTURE AND FUNCTION
The plasma membrane separates the living cell from its nonliving surroundings

9. A Fluid Mosaic of Lipids and Proteins
The membranes of cells are composed of
Lipids
Proteins

10. The lipids belong to a special category called phospholipids
Phospholipids form a two-layered membrane, the phospholipid bilayer
Outside cell
Hydrophilic
head
Hydrophobic
tail
Cytoplasm
(inside cell)
(a) Phospholipid bilayer of membrane
Figure 4.7A

11. Most membranes have specific proteins embedded in the phospholipid bilayer
Hydrophilic
region of
protein
Phospholipid
bilayer
Hydrophobic
region of protein
(b) Fluid mosaic model of membrane
Figure 4.7B