A Tour of the Cell

Page
6

Detoxifies poison

Stores calcium

Slide 42

Functions of Rough ER

The rough ER

Has bound ribosomes, which secrete glycoproteins (proteins covalently bonded to carbohydrates)

Distributes transport vesicles, proteins surrounded by membranes

Is a membrane factory for the cell

Slide 43

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

The Golgi Apparatus: Shipping and Receiving Center

Slide 44

Fig. 6-13

cis face

(“receiving” side of Golgi apparatus)

Cisternae

trans face

(“shipping” side of Golgi apparatus)

TEM of Golgi apparatus

0.1 µm

Slide 45

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

Animation: Lysosome Formation

Slide 46

Some types of cell can engulf another cell by phagocytosis; this forms a food vacuole

A lysosome fuses with the food vacuole and digests the molecules

Lysosomes also use enzymes to recycle the cell’s own organelles and macromolecules, a process called autophagy

Slide 47

Fig. 6-14

Nucleus

1 µm

Lysosome

Digestive

enzymes

Lysosome

Plasma

membrane

Food vacuole

(a) Phagocytosis

Digestion

(b) Autophagy

Peroxisome

Vesicle

Lysosome

Mitochondrion

Peroxisome

fragment

Mitochondrion

fragment

Vesicle containing

two damaged organelles

1 µm

Digestion

Slide 48

Fig. 6-14a

Nucleus

1 µm

Lysosome

Lysosome

Digestive enzymes

Plasma membrane

Food vacuole

Digestion

(a) Phagocytosis

Slide 49

Fig. 6-14b

Vesicle containing

two damaged organelles

Mitochondrion fragment

Peroxisome fragment

Peroxisome

Lysosome

Digestion

Mitochondrion

Vesicle

(b) Autophagy

1 µm

Slide 50

Vacuoles: Diverse Maintenance Compartments