| 5.1 Most eucaryotes are microbes |
| 5.2 Eucaryotic cells are characterized by an endomembrane system and a cytoskeletal system |
| 5.3 Special signal sequences on proteins target them to particular places in the eucaryotic cell |
| 5.4 There are two types of targeting mechanism |
| 5.5 Proteins that cross two membranes have two signal sequences |
| The Endomembrane System |
| 5.6 The endomembrane system exchanges materials by the budding and fusion of membrane vesicles |
| 5.7 The nuclear envelope encloses the chromosomes |
| 5.8 Pore complexes in the nuclear envelope regulate the passage of materials between the cytoplasm and the nucleoplasm |
| 5.9 mRNA molecules are capped and tailed to mark them for export |
| 5.10 The endoplasmic reticulum is responsible for membrane synthesis |
| 5.11 The ER is also the site of synthesis of secretory proteins, digestive enzymes, and cell walls |
| 5.12 The Golgi sorts the mixed contents of ER membranes and lumen into different vesicles |
| 5.13 Secretory vesicles fuse with the cell membrane |
| 5.14 Lysosomal vesicles fuse with the endosome, which then targets proteins to the lysosome |
| 5.15 Endocytosis is the first step in intracellular digestion, and in recycling surface |
| 5.16 The endosome recycles membrane proteins |
| 5.17 Vesicles containing material to be digested fuse with lysosomes |
| 5.18 Exocytosis eliminates indigestible residue |
| 5.19 Many protists are armed with extrusomes |
| Mitochondria and Chloroplasts |
| 5.20 Mitochondria and chloroplasts are not part of the endomembrane system |
| 5.21 Mitochondria and chloroplasts have their own chromosomes and their own protein-synthesizing system |
| 5.22 Many mitochondrial and chloroplast proteins, and some lipids, are imported from the cytoplasm |
| 5.23 Mitochondria and chloroplasts exchange small molecules with the cytoplasm via permeases in their inner membrane |
| 5.24 Mitochondria and chloroplasts have an evolutionary origin different that that of the nucleus |
| 5.25 Hydrogenosomes are another relict symbiosis |
| 5.26 Some chloroplasts appear to be more recent endosymbioses |
| The Cytoskeletal System |
| 5.27 Microtubules are hollow tubes composed of thousands of molecules of tubulin |
| 5.28 Centrosomes organize the cell’s microtubule network |
| 5.29 Microtubules serve as tracks for endomembrane vesicles to slide on |
| 5.30 Microfilaments are chains of actin monomers |
| 5.31 Microfilaments maintain cell shape and stabilizes the membrane |
| 5.32 Microfilaments also provide tracks for membrane vesicles to slide along |
| Motility |
| 5.33 Amoeboid movement is mediated by microfilaments and myosin |
| 5.34 Flagella and cilia contain a bundle of microtubules that slide against each other |
| 5.35 Dynein binding to flagellar microtubules controls the state of the flagellum/cilium |
| 5.36 Flagella and cilia originate in a centriole-like basal body |
| 5.37 Flagella and cilia differ in their beat pattern and in their length |
| The Cell Wall and Pellicle |
| 5.38 The eucaryotic cell wall is usually composed of polysaccharide |
| 5.39 Some protists make walls that are heavily impregnated with inorganic salts |
| 5.40 The pellicle is a complex structure that includes the cell membrane and an underlying layer of protein or polysaccharide |
| 5.41 Some amoebas make shells for protection against predation |
| The Contractile Vacuole |
| 5.42 The contractile vacuole collects water from the cytoplasm and expels it to the outside by exocytosis |
| 5.43 The contractile vacuole collects water through a system of tubules or vesicles |
| Reproduction In Protists |
| 5.44 Open mitosis is common in protists |
| 5.45 Sex is occasional in protists; reproduction is normally asexual |
