Vesicles Membranous sacs that move through the cytoplasm –Transport vesicles –Lysosomes –Peroxisomes

Lysosomes are sacs of digestive enzymes budded off the Golgi Lysosomes LYSOSOME Nucleus Figure 4.11A

Functions of lysosomal enzymes –digest food –destroy bacteria –recycle damaged organelles –function in embryonic development in animals

Figure 4.11B Rough ER Transport vesicle (containing inactive hydrolytic enzymes) Golgi apparatus Plasma membrane LYSOSOMES “Food” Engulfment of particle Food vacuole Digestion Lysosome engulfing damaged organelle

Controlled killing of cells - Apoptosis  occurs during embryonic development and day to day - classic example is digit formation. Lysosomes "kill" cells between digits Ducks - no lysosomal enzymes = webbed feet; chickens have activity = no web Syndactyly - Lack of web apoptosis in humans Lysosomes & Cell Death in Normal Development

Lysosomal storage diseases are hereditary –They interfere with other cellular functions –Examples: Pompe’s disease, Tay-Sachs disease –Both cause a build up of substances in the lysosome –Fatal diseases Lysosomes and Diseases

Non heritable lysosomal diseases –Silicosis & Asbestosis –Cancer (secreted lysosomal enzymes alter cell surface) –Rheumatoid Arthritis (secretion of high levels of lysosomal enzymes digest extracellular matrix) Lysosomes and Disease

Functions in the general maintenance of the cell Fluid-filled organelle with lysosomal and storage functions Stores amino acids, sugars, wastes % of cell volume Plant cells contain a large central vacuole Central vacuole Nucleus Figure 4.13A

Protists may have contractile vacuoles Figure 4.13B Nucleus Contractile vacuoles –These pump out excess water

The organelles of the endomembrane system are interconnected structurally and functionally A review of the endomembrane system Transport vesicle from ER Rough ER Transport vesicle from Golgi Plasma membrane Vacuole Lysosome Golgi apparatus Nuclear envelope Smooth ER Nucleus Figure 4.14

Mitochondrion Chloroplast ENERGY-CONVERTING ORGANELLES

Chloroplasts are found in plants and some protists Chloroplasts convert solar energy to the chemical energy in sugars: photosynthesis Why the world is green: chlorophyll Chloroplasts Chloroplast Stroma Inner and outer membranes Granum Intermembrane space Figure 4.15

Carry out cellular respiration –A process that uses chemical energy in food to make ATP for cellular work –Adenosine triphosphate- the energy source –These reactions require oxygen Double-membrane system Mitochondria

Mitochondrial Structure Outer membrane faces cytoplasm Inner membrane folds back on itself- cristae Membranes form two compartments –Intermembrane space –Mitochondrial matrix ATP-making machinery is embedded in the inner mitochondrial membrane

Figure 4.16 Outer membrane MITOCHONDRION Intermembrane space Inner membrane Cristae Matrix

Origins of Mitochondria and Chloroplasts Endosymbiotic theory May have evolved from ancient bacteria Mitochondria and chloroplasts resemble bacteria –Have own DNA, ribosomes –Divide on their own and same in size