1. 4.15 Chloroplasts convert solar energy to chemical energy
ENERGY-CONVERTING ORGANELLES
4.15 Chloroplasts convert solar energy to chemical energy
Chloroplasts are found in plants and some protists
Chloroplasts convert solar energy to chemical energy in sugars
Chloroplast
Stroma
Inner and outer membranes
Granum
Intermembrane space
Figure 4.15

2. 4.16 Mitochondria harvest chemical energy from food
Mitochondria carry out cellular respiration
This process uses the chemical energy in food to make ATP for cellular work

3. MITOCHONDRION Outer membrane Intermembrane space Inner membrane
Cristae
Matrix
Figure 4.16

4. THE CYTOSKELETON AND RELATED STRUCTURES
4.17 The cell’s internal skeleton helps organize its structure and activities
A network of protein fibers makes up the cytoskeleton
Figure 4.17A

5. Microfilaments of actin enable cells to change shape and move
Intermediate filaments reinforce the cell and anchor certain organelles
Microtubules
give the cell rigidity
provide anchors for organelles
act as tracks for organelle movement

6. INTERMEDIATE FILAMENT
Tubulin subunit
Actin subunit
Fibrous subunits
25 nm
7 nm
10 nm
MICROFILAMENT
INTERMEDIATE FILAMENT
MICROTUBULE
Figure 4.17B

7. 4.18 Cilia and flagella move when microtubules bend
Eukaryotic cilia and flagella are locomotor appendages that protrude from certain cells
A cilia or flagellum is composed of a core of microtubules wrapped in an extension of the plasma membrane

8. Electron micrograph of sections:
FLAGELLUM
Electron micrograph of sections:
Outer microtubule doublet
Plasma membrane
Flagellum
Central microtubules
Outer microtubule doublet
Plasma membrane
Basal body
Basal body (structurally identical to centriole)
Figure 4.18A

9. Clusters of microtubules drive the whipping action of these organelles
Microtubule doublet
Sliding force
Dynein arm
Figure 4.18B

10. 4.19 Cell surfaces protect, support, and join cells
EUKARYOTIC CELL SURFACES AND JUNCTIONS
4.19 Cell surfaces protect, support, and join cells
Cells interact with their environments and each other via their surfaces
Plant cells are supported by rigid cell walls made largely of cellulose
They connect by plasmodesmata, channels that allow them to share water, food, and chemical messages

11. Walls of two adjacent plant cells
Vacuole
PLASMODESMATA
Layers of one plant cell wall
Cytoplasm
Plasma membrane
Figure 4.19A

12. Animal cells are embedded in an extracellular matrix
It is a sticky layer of glycoproteins
It binds cells together in tissues
It can also have protective and supportive functions

13. Tight junctions can bind cells together into leakproof sheets
Anchoring junctions link animal cells
Communicating junctions allow substances to flow from cell to cell
TIGHT JUNCTION
ANCHORING JUNCTION
COMMUNICATING
JUNCTION
Plasma membranes of adjacent cells
Extracellular matrix
Figure 4.19B

14. 4.20 Eukaryotic organelles comprise four functional categories

15. Table 4.20 (continued)