Cover Author: Mark Wheelis
Title: Priciples of Modern Microbiology
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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 cellís 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
Link: Jones and Bartlett Publishers