Cells

by Lewin, Benjamin; Cassimeris, Lynne; Lingappa, Vishwanath R.; Plopper, George

• ISBN13: 9780763739058
• ISBN10: 0763739057
• Edition: 1st
• Format: Hardcover
• Copyright: 2006-10-27
• Publisher: Jones & Bartlett Learning

Summary

This important new textbook, designed for advanced undergraduate and early graduate courses in cell biology, covers the structures, organization, growth, regulation, movements, and interactions of cells, with emphasis on eukaryotic cells. Under the direction of Dr. Benjamin Lewin and three expert section editors, each chapter was prepared by top scientists who specialize in the given subject area, and all chapters have been carefully edited to maintain a consistent level throughout the text and to assure that all necessary topics are covered.

Table of Contents

Preface	iii
Acknowledgments	iv
About the cover	v
Contributors	xvii
Abbreviations	xix
Part 1 Introduction	1	(29)
What is a cell?	3	(27)
Benjamin Lewin
Introduction	4	(2)
Life began as a self-replicating structure	6	(1)
A prokaryotic cell consists of a single compartment	7	(2)
Prokaryotes are adapted for growth under many diverse conditions	9	(1)
A eukaryotic cell contains many membrane-delimited compartments	9	(1)
Membranes allow the cytoplasm to maintain compartments with distinct environments	10	(2)
The nucleus contains the genetic material and is surrounded by an envelope	12	(1)
The plasma membrane allows a cell to maintain homeostasis	13	(2)
Cells within cells: Organelles bounded by envelopes may have resulted from endosymbiosis	15	(2)
DNA is the cellular hereditary material, but there are other forms of hereditary information	17	(1)
Cells require mechanisms to repair damage to DNA	17	(1)
Mitochondria are energy factories	18	(1)
Chloroplasts power plant cells	19	(1)
Organelles require mechanisms for specific localization of proteins	20	(1)
Proteins are transported to and through membranes	21	(1)
Protein trafficking moves proteins through the ER and Golgi apparatus	22	(1)
Protein folding and unfolding is an essential feature of all cells	23	(1)
The shape of a eukaryotic cell is determined by its cytoskeleton	24	(1)
Localization of cell structures is important	25	(1)
Signal transduction pathways execute predefined responses	26	(1)
All organisms have cells that can grow and divide	27	(1)
Differentiation creates specialized cell types, including terminally differentiated cells	28	(2)
References	29	(1)
Part 2 Membranes and transport mechanisms	30	(174)
Transport of ions and small molecules across membranes	31	(66)
Stephan E. Lehnart
Andrew R. Marks
Introduction	32	(1)
Channels and carriers are the main types of membrane transport proteins	33	(2)
Hydration of ions influences their flux through transmembrane pores	35	(1)
Electrochemical gradients across the cell membrane generate the membrane potential	36	(2)
K+ channels catalyze selective and rapid ion permeation	38	(4)
Different K+ channels use a similar gate coupled to different activating or inactivating mechanisms	42	(2)
Voltage-dependent Na+ channels are activated by membrane depolarization and translate electrical signals	44	(3)
Epithelial Na+ channels regulate Na+ homeostasis	47	(3)
Plasma membrane Ca2+ channels activate intracellular functions	50	(2)
Cl- channels serve diverse biological functions	52	(4)
Selective water transport occurs through aquaporin channels	56	(2)
Action potentials are electrical signals that depend on several types of ion channels	58	(2)
Cardiac and skeletal muscles are activated by excitation-contraction coupling	60	(3)
Some glucose transporters are uniporters	63	(2)
Symporters and antiporters mediate coupled transport	65	(2)
The transmembrane Na+ gradient is essential for the function of many transporters	67	(3)
Some Na+ transporters regulate cytosolic or extracellular pH	70	(3)
The Ca2+-ATPase pumps Ca2+ into intracellular storage compartments	73	(2)
The Na+/K+-ATPase maintains the plasma membrane Na+ and K+ gradients	75	(3)
The F1F0-ATP synthase couples H+ movement to ATP synthesis or hydrolysis	78	(1)
H+-ATPases transport protons out of the cytosol	79	(3)
What's next?	82	(1)
Summary	82	(1)
Supplement: Derivation and application of the Nernst equation	83	(2)
Supplement: Most K+ channels undergo rectification	85	(1)
Supplement: Mutations in an anion channel cause cystic fibrosis	86	(11)
References	88	(9)
Membrane targeting of proteins	97	(56)
D. Thomas Rutkowski
Vishwanath R. Lingappa
Introduction	98	(2)
Proteins enter the secretory pathway by translocation across the ER membrane (an overview)	100	(2)
Proteins use signal sequences to target to the ER for translocation	102	(1)
Signal sequences are recognized by the signal recognition particle (SRP)	103	(1)
An interaction between SRP and its receptor allows proteins to dock at the ER membrane	104	(1)
The translocon is an aqueous channel that conducts proteins	105	(3)
Translation is coupled to translocation for most eukaryotic secretory and transmembrane proteins	108	(2)
Some proteins target and translocate posttranslationally	110	(1)
ATP hydrolysis drives translocation	111	(2)
Transmembrane proteins move out of the translocation channel and into the lipid bilayer	113	(2)
The orientation of transmembrane proteins is determined as they are integrated into the membrane	115	(3)
Signal sequences are removed by signal peptidase	118	(1)
The lipid GPI is added to some translocated proteins	118	(2)
Sugars are added to many translocating proteins	120	(1)
Chaperones assist folding of newly translocated proteins	121	(1)
Protein disulfide isomerase ensures the formation of the correct disulfide bonds as proteins fold	122	(1)
The calnexin/calreticulin chaperoning system recognizes carbohydrate modifications	123	(1)
The assembly of proteins into complexes is monitored	124	(1)
Terminally misfolded proteins in the ER are returned to the cytosol for degradation	125	(3)
Communication between the ER and nucleus prevents the accumulation of unfolded proteins in the lumen	128	(2)
The ER synthesizes the major cellular phospholipids	130	(2)
Lipids must be moved from the ER to the membranes of other organelles	132	(1)
The two leaflets of a membrane often differ in lipid composition	133	(1)
The ER is morphologically and functionally subdivided	133	(2)
The ER is a dynamic organelle	135	(3)
Signal sequences are also used to target proteins to other organelles	138	(1)
Import into mitochondria begins with signal sequence recognition at the outer membrane	138	(1)
Complexes in the inner and outer membranes cooperate in mitochondrial protein import	139	(2)
Proteins imported into chloroplasts must also cross two membranes	141	(1)
Proteins fold before they are imported into peroxisomes	142	(2)
What's next?	144	(1)
Summary	144	(9)
References	146	(7)
Protein trafficking between membranes	153	(51)
Graham Warren
Ira Mellman
Introduction	154	(2)
Overview of the exocytic pathway	156	(3)
Overview of the endocytic pathway	159	(3)
Concepts in vesicle-mediated protein transport	162	(2)
The concepts of signal-mediated and bulk flow protein transport	164	(2)
COPII-coated vesicles mediate transport from the ER to the Golgi apparatus	166	(2)
Resident proteins that escape from the ER are retrieved	168	(1)
COPI-coated vesicles mediate retrograde transport from the Golgi apparatus to the ER	169	(2)
There are two popular models for forward transport through the Golgi apparatus	171	(1)
Retention of proteins in the Golgi apparatus depends on the membrane-spanning domain	172	(2)
Rab GTPases and tethers are two types of proteins that regulate vesicle targeting	174	(2)
SNARE proteins likely mediate fusion of vesicles with target membranes	176	(3)
Endocytosis is often mediated by clathrin-coated vesicles	179	(3)
Adaptor complexes link clathrin and transmembrane cargo proteins	182	(3)
Some receptors recycle from early endosomes whereas others are degraded in lysosomes	185	(2)
Early endosomes become late endosomes and lysosomes by maturation	187	(2)
Sorting of lysosomal proteins occurs in the trans-Golgi network	189	(3)
Polarized epithelial cells transport proteins to apical and basolateral membranes	192	(2)
Some cells store proteins for later secretion	194	(1)
What's next?	195	(1)
Summary	196	(8)
References	196	(8)
Part 3 The nucleus	204	(112)
Nuclear structure and transport	205	(48)
Charles N. Cole
Pamela A. Silver
Introduction	206	(1)
Nuclei vary in appearance according to cell type and organism	207	(2)
Chromosomes occupy distinct territories	209	(1)
The nucleus contains subcompartments that are not membrane-bounded	210	(2)
Some processes occur at distinct nuclear sites and may reflect an underlying structure	212	(1)
The nucleus is bounded by the nuclear envelope	213	(1)
The nuclear lamina underlies the nuclear envelope	214	(2)
Large molecules are actively transported between the nucleus and cytoplasm	216	(1)
Nuclear pore complexes are symmetrical channels	217	(3)
Nuclear pore complexes are constructed from nucleoporins	220	(2)
Proteins are selectively transported into the nucleus through nuclear pores	222	(2)
Nuclear localization sequences target proteins to the nucleus	224	(1)
Cytoplasmic NLS receptors mediate nuclear protein import	224	(2)
Export of proteins from the nucleus is also receptor-mediated	226	(2)
The Ran GTPase controls the direction of nuclear transport	228	(2)
Multiple models have been proposed for the mechanism of nuclear transport	230	(2)
Nuclear transport can be regulated	232	(1)
Multiple classes of RNA are exported from the nucleus	233	(2)
Ribosomal subunits are assembled in the nucleolus and exported by exportin 1	235	(1)
tRNAs are exported by a dedicated exportin	236	(1)
Messenger RNAs are exported from the nucleus as RNA protein complexes	237	(2)
hnRNPs move from sites of processing to NPCs	239	(1)
mRNA export requires several novel factors	239	(2)
U snRNAs are exported, modified, assembled into complexes, and imported	241	(1)
Precursors to microRNAs are exported from the nucleus and processed in the cytoplasm	242	(1)
What's next?	242	(3)
Summary	245	(8)
References	246	(7)
Chromatin and chromosomes	253	(63)
Benjamin Lewin
Introduction	254	(1)
Chromatin is divided into euchromatin and heterochromatin	255	(1)
Chromosomes have banding patterns	256	(2)
Eukaryotic DNA has loops and domains attached to a scaffold	258	(1)
Specific sequences attach DNA to an interphase matrix	259	(1)
The centromere is essential for segregation	260	(2)
Centromeres have short DNA sequences in S. cerevisiae	262	(1)
The centromere binds a protein complex	263	(1)
Centromeres may contain repetitious DNA	263	(1)
Telomeres are replicated by a special mechanism	264	(1)
Telomeres seal the chromosome ends	265	(1)
Lampbrush chromosomes are extended	266	(1)
Polytene chromosomes form bands	267	(1)
Polytene chromosomes expand at sites of gene expression	268	(1)
The nucleosome is the subunit of all chromatin	269	(2)
DNA is coiled in arrays of nucleosomes	271	(1)
Nucleosomes have a common structure	272	(2)
DNA structure varies on the nucleosomal surface	274	(2)
Organization of the histone octamer	276	(2)
The path of nucleosomes in the chromatin fiber	278	(1)
Reproduction of chromatin requires assembly of nucleosomes	279	(3)
Do nucleosomes lie at specific positions?	282	(3)
Domains define regions that contain active genes	285	(2)
Are transcribed genes organized in nucleosomes?	287	(1)
Histone octamers are displaced by transcription	288	(2)
Nucleosome displacement and reassembly require special factors	290	(1)
DNAase hypersensitive sites change chromatin structure	290	(2)
Chromatin remodeling is an active process	292	(4)
Histone acetylation is associated with genetic activity	296	(3)
Heterochromatin propagates from a nucleation event	299	(1)
Heterochromatin depends on interactions with histones	300	(2)
X chromosomes undergo global changes	302	(2)
Chromosome condensation is caused by condensins	304	(2)
What's next?	306	(1)
Summary	307	(9)
References	309	(7)
Part 4 The cytoskeleton	316	(122)
Microtubules	317	(54)
Lynne Cassimeris
Introduction	318	(2)
General functions of microtubules	320	(3)
Microtubules are polar polymers of α- and β-tubulin	323	(2)
Purified tubulin subunits assemble into microtubules	325	(2)
Microtubule assembly and disassembly proceed by a unique process termed dynamic instability	327	(2)
A cap of GTP-tubulin subunits regulates the transitions o dynamic instability	329	(2)
Cells use microtubule-organizing centers to nucleate microtubule assembly	331	(2)
Microtubule dynamics in cells	333	(3)
Why do cells have dynamic microtubules?	336	(3)
Cells use several classes of proteins to regulate the stability of their microtubules	339	(3)
Introduction to microtubule-based motor proteins	342	(4)
How motor proteins work	346	(3)
How cargoes are loaded onto the right motor	349	(1)
Microtubule dynamics and motors combine to generate the asymmetric organization of cells	350	(4)
Interactions between microtubules and actin filaments	354	(2)
Cilia and flagella are motile structures	356	(5)
What's next?	361	(1)
Summary	362	(1)
Supplement: What if tubulin didn't hydrolyze GTP?	363	(1)
Supplement: Fluorescence recovery after photobleaching	364	(1)
Supplement: Tubulin synthesis and modification	365	(1)
Supplement: Motility assays for microtubule-based motor proteins	366	(5)
References	368	(3)
Actin	371	(40)
Enrique M. De La Cruz
E. Michael Ostap
Introduction	372	(1)
Actin is a ubiquitously expressed cytoskeletal protein	373	(1)
Actin monomers bind ATP and ADP	373	(1)
Actin filaments are structurally polarized polymers	374	(1)
Actin polymerization is a multistep and dynamic process	375	(3)
Actin subunits hydrolyze ATP after polymerization	378	(2)
Actin-binding proteins regulate actin polymerization and organization	380	(1)
Actin monomer-binding proteins influence polymerization	381	(1)
Nucleating proteins control cellular actin polymerization	382	(1)
Capping proteins regulate the length of actin filaments	383	(1)
Severing and depolymerizing proteins regulate actin filament dynamics	384	(1)
Crosslinking proteins organize actin filaments into bundles and orthogonal networks	385	(1)
Actin and actin-binding proteins work together to drive cell migration	386	(2)
Small G proteins regulate actin polymerization	388	(1)
Myosins are actin-based molecular motors with essential roles in many cellular processes	389	(3)
Myosins have three structural domains	392	(2)
ATP hydrolysis by myosin is a multistep reaction	394	(2)
Myosin motors have kinetic properties suited for their cellular roles	396	(1)
Myosins take nanometer steps and generate piconewton forces	396	(2)
Myosins are regulated by multiple mechanisms	398	(1)
Myosin-II functions in muscle contraction	399	(4)
What's next?	403	(1)
Summary	404	(1)
Supplement: Two models for how polymer assembly can generate force	404	(7)
References	405	(6)
Intermediate filaments	411	(27)
E. Birgitte Lane
Introduction	412	(1)
The six intermediate filament protein groups have similar structure but different expression	413	(2)
The two Largest intermediate filament groups are type I and type II keratins	415	(3)
Mutations in keratins cause epithelial cell fragility	418	(2)
Intermediate filaments of nerve, muscle, and connective tissue often show overlapping expression	420	(2)
Lamin intermediate filaments reinforce the nuclear envelope	422	(2)
Even the divergent lens filament proteins are conserved in evolution	424	(1)
Intermediate filament subunits assemble with high affinity into strain-resistant structures	425	(2)
Posttranslational modifications regulate the configuration of intermediate filament proteins	427	(2)
Proteins that associate with intermediate filaments are facultative rather than essential	429	(1)
Intermediate filament genes are present throughout metazoan evolution	430	(2)
What's next?	432	(1)
Summary	433	(5)
References	434	(4)
Part 5 Cell division, apoptosis, and cancer	438	(149)
Mitosis	439	(50)
Conly Rieder
Introduction	440	(3)
Mitosis is divided into stages	443	(2)
Mitosis requires the formation of a new apparatus called the spindle	445	(2)
Spindle formation and function depend on the dynamic behavior of microtubules and their associated motor proteins	447	(3)
Centrosomes are microtubule organizing centers	450	(1)
Centrosomes reproduce about the time the DNA is replicated	451	(2)
Spindles begin to form as separating asters interact	453	(3)
Spindles require chromosomes for stabilization but can ``self-organize'' without centrosomes	456	(2)
The centromere is a specialized region on the chromosome that contains the kinetochores	458	(1)
Kinetochores form at the onset of prometaphase and contain microtubule motor proteins	459	(1)
Kinetochores capture and stabilize their associated microtubules	460	(3)
Mistakes in kinetochore attachment are corrected	463	(2)
Kinetochore fibers must both shorten and elongate to allow chromosomes to move	465	(2)
The force to move a chromosome toward a pole is produced by two mechanisms	467	(1)
Congression involves pulling forces that act on the kinetochores	468	(1)
Congression is also regulated by the forces that act along the chromosome arms and the activity of sister kinetochores	469	(2)
Kinetochores control the metaphase/anaphase transition	471	(2)
Anaphase has two phases	473	(2)
Changes occur during telophase that lead the cell out of the mitotic state	475	(1)
During cytokinesis, the cytoplasm is partitioned to form two new daughter cells	476	(2)
Formation of the contractile ring requires the spindle and stem bodies	478	(3)
The contractile ring cleaves the cell in two	481	(2)
The segregation of nonnuclear organelles during cytokinesis is based on chance	483	(1)
What's next?	483	(1)
Summary	484	(5)
References	485	(4)
Cell cycle regulation	489	(44)
Srinivas Venkatram
Kathleen L. Gould
Susan L. Forsburg
Introduction	490	(1)
There are several experimental systems used in cell cycle analyses	491	(4)
The cell cycle requires coordination between events	495	(1)
The cell cycle as a cycle of CDK activities	496	(2)
CDK-cyclin complexes are regulated in several ways	498	(3)
Cells may exit from and reenter the cell cycle	501	(2)
Entry into cell cycle and S phase is tightly regulated	503	(1)
DNA replication requires the ordered assembly of protein complexes	504	(3)
Mitosis is orchestrated by several protein kinases	507	(3)
Many morphological changes occur during mitosis	510	(2)
Mitotic chromosome condensation and segregation depend on condensin and cohesin	512	(2)
Exit from mitosis requires more than cyclin proteolysis	514	(2)
Checkpoint controls coordinate different cell cycle events	516	(2)
DNA replication and DNA damage checkpoints monitor defects in DNA metabolism	518	(4)
The spindle assembly checkpoint monitors defects in chromosome-microtubule attachment	522	(2)
Cell cycle deregulation can lead to cancer	524	(1)
What's next?	525	(1)
Summary	526	(7)
References	527	(6)
Apoptosis	533	(28)
Douglas R. Green
Introduction	534	(2)
Caspases orchestrate apoptosis by cleaving specific substrates	536	(1)
Executioner caspases are activated by cleavage, whereas initiator caspases are activated by dimerization	537	(1)
Some inhibitor of apoptosis proteins (IAPs) block caspases	538	(1)
Some caspases have functions in inflammation	539	(1)
The death receptor pathway of apoptosis transmits external signals	539	(2)
Apoptosis signaling by TNFR1 is complex	541	(2)
The mitochondrial pathway of apoptosis	543	(1)
Bcl-2 family proteins mediate and regulate MOMP and apoptosis	544	(1)
The multidomain Bcl-2 proteins Bax and Bak are required for MOMP	545	(1)
The activation of Bax and Bak are controlled by other Bcl-2 family proteins	546	(1)
Cytochrome c, released upon MOMP, induces caspase activation	547	(1)
Some proteins released upon MOMP block IAPs	548	(1)
The death receptor pathway of apoptosis can engage MOMP through the cleavage of the BH3-only protein Bid	548	(2)
MOMP can cause ``caspase-independent'' cell death	550	(1)
The mitochondrial permeability transition can cause MOMP	550	(1)
Many discoveries about apoptosis were made in nematodes	551	(1)
Apoptosis in insects has features distinct from mammals and nematodes	552	(1)
The clearance of apoptotic cells requires cellular interaction	553	(1)
Apoptosis plays a role in diseases such as viral infection and cancer	554	(1)
Apoptotic cells are gone but not forgotten	555	(1)
What's next?	556	(1)
Summary	557	(4)
References	557	(4)
Cancer---Principles and overview	561	(26)
Robert A. Weinberg
Tumors are masses of cells derived from a single cell	562	(1)
Cancer cells have a number of phenotypic characteristics	563	(3)
Cancer cells arise after DNA damage	566	(1)
Cancer cells are created when certain genes are mutated	567	(2)
Cellular genomes harbor a number of proto-oncogenes	569	(1)
Elimination of tumor suppressor activity requires two mutations	570	(2)
The genesis of tumors is a complex process	572	(3)
Cell growth and proliferation are activated by growth factors	575	(2)
Cells are subject to growth inhibition and may exit from the cell cycle	577	(2)
Tumor suppressors block inappropriate entry into the cell cycle	579	(1)
Mutation of DNA repair and maintenance genes can increase the overall mutation rate	580	(1)
Cancer cells may achieve immortality	581	(1)
Access to vital supplies is provided by angiogenesis	582	(1)
Cancer cells may invade new locations in the body	583	(1)
What's next?	584	(1)
Summary	585	(2)
References	585	(2)
Part 6 Cell communication	587	(116)
Principles of cell signaling	589	(56)
Melanie H. Cobb
Elliott M. Ross
Introduction	590	(1)
Cellular signaling is primarily chemical	591	(1)
Receptors sense diverse stimuli but initiate a limited repertoire of cellular signals	592	(1)
Receptors are catalysts and amplifiers	593	(1)
Ligand binding changes receptor conformation	593	(2)
Signals are sorted and integrated in signaling pathways and networks	595	(2)
Cellular signaling pathways can be thought of as biochemical logic circuits	597	(1)
Scaffolds increase signaling efficiency and enhance spatial organization of signaling	598	(2)
Independent, modular domains specify protein-protein interactions	600	(2)
Cellular signaling is remarkably adaptive	602	(2)
Signaling proteins are frequently expressed as multiple species	604	(1)
Activating and deactivating reactions are separate and independently controlled	605	(1)
Cellular signaling uses both allostery and covalent modification	606	(1)
Second messengers provide readily diffusible pathways for information transfer	606	(2)
Ca2+ signaling serves diverse purposes in all eukaryotic cells	608	(1)
Lipids and lipid-derived compounds are signaling molecules	609	(3)
PI 3-kinase regulates both cell shape and the activation of essential growth and metabolic functions	612	(1)
Signaling through ion channel receptors is very fast	612	(2)
Nuclear receptors regulate transcription	614	(1)
G protein signaling modules are widely used and highly adaptable	615	(3)
Heterotrimeric G proteins regulate a wide variety of effectors	618	(1)
Heterotrimeric G proteins are controlled by a regulatory GIPase cycle	618	(2)
Small, monomeric GTP-binding proteins are multiuse switches	620	(1)
Protein phosphorylation/dephosphorylation is a major regulatory mechanism in the cell	621	(3)
Two-component protein phosphorylation systems are signaling relays	624	(1)
Pharmacological inhibitors of protein kinases may be used to understand and treat disease	625	(1)
Phosphoprotein phosphatases reverse the actions of kinases and are independently regulated	625	(1)
Covalent modification by ubiquitin and ubiquitin-like proteins is another way of regulating protein function	626	(2)
The Wnt pathway regulates cell fate during development and other processes in the adult	628	(1)
Diverse signaling mechanisms are regulated by protein tyrosine kinases	628	(2)
Src family protein kinases cooperate with receptor protein tyrosine kinases	630	(1)
MAPKs are central to many signaling pathways	631	(1)
Cyclin-dependent protein kinases control the cell cycle	632	(1)
Diverse receptors recruit protein tyrosine kinases to the plasma membrane	633	(4)
What's next?	637	(1)
Summary	637	(8)
References	637	(8)
The extracellular matrix and cell adhesion	645	(58)
George Plopper
Introduction	646	(2)
A brief history of research on the extracellular matrix	648	(1)
Collagen provides structural support to tissues	649	(3)
Fibronectins connect cells to collagenous matrices	652	(2)
Elastic fibers impart flexibility to tissues	654	(2)
Laminins provide an adhesive substrate for cells	656	(2)
Vitronectin facilitates targeted cell adhesion during blood clotting	658	(1)
Proteoglycans provide hydration to tissues	659	(3)
Hyaluronan is a glycosaminoglycan enriched in connective tissues	662	(2)
Heparan sulfate proteoglycans are cell surface coreceptors	664	(2)
The basal lamina is a specialized extracellular matrix	666	(1)
Proteases degrade extracellular matrix components	667	(3)
Most integrins are receptors for extracellular matrix proteins	670	(2)
Integrin receptors participate in cell signaling	672	(4)
Integrins and extracellular matrix molecules play key roles in development	676	(1)
Tight junctions form selectively permeable barriers between cells	677	(3)
Septate junctions in invertebrates are similar to tight junctions	680	(2)
Adherens junctions link adjacent cells	682	(2)
Desmosomes are intermediate filament-based cell adhesion complexes	684	(2)
Hemidesmosomes attach epithelial cells to the basal lamina	686	(2)
Gap junctions allow direct transfer of molecules between adjacent cells	688	(2)
Calcium-dependent cadherins mediate adhesion between cells	690	(2)
Calcium-independent NCAMs mediate adhesion between neural cells	692	(2)
Selectins control adhesion of circulating immune cells	694	(2)
What's next?	696	(1)
Summary	696	(7)
References	697	(6)
Part 7 Prokaryotic and plant cells	703	(104)
Prokaryotic cell biology	705	(58)
Jeff Errington
Matthew Chapman
Scott J. Hultgren
Michael Caparon
Introduction	706	(2)
Molecular phylogeny techniques are used to understand microbial evolution	708	(1)
Prokaryotic lifestyles are diverse	709	(2)
Archaea are prokaryotes with similarities to eukaryotic cells	711	(2)
Most prokaryotes produce a polysaccharide-rich layer called the capsule	713	(3)
The bacterial cell wall contains a crosslinked meshwork of peptidoglycan	716	(4)
The cell envelope of Gram-positive bacteria has unique features	720	(2)
Gram-negative bacteria have an outer membrane and a periplasmic space	722	(3)
The cytoplasmic membrane is a selective barrier for secretion	725	(1)
Prokaryotes have several secretion pathways	726	(2)
Pili and flagella are appendages on the cell surface of most prokaryotes	728	(3)
Prokaryotic genomes contain chromosomes and mobile DNA elements	731	(2)
The bacterial nucleoid and cytoplasm are highly ordered	733	(2)
Bacterial chromosomes are replicated in specialized replication factories	735	(2)
Prokaryotic chromosome segregation occurs in the absence of a mitotic spindle	737	(2)
Prokaryotic cell division involves formation of a complex cytokinetic ring	739	(3)
Prokaryotes respond to stress with complex developmental changes	742	(4)
Some prokaryotic life cycles include obligatory developmental changes	746	(1)
Some prokaryotes and eukaryotes have endosymbiotic relationships	747	(2)
Prokaryotes can colonize and cause disease in higher organisms	749	(2)
Biofilms are highly organized communities of microbes	751	(3)
What's next?	754	(1)
Summary	754	(9)
References	755	(8)
Plant cell biology	763	(44)
Clive Lloyd
Introduction	764	(1)
How plants grow	765	(1)
The meristem provides new growth modules in a repetitive manner	766	(2)
The plane in which a cell divides is important for tissue organization	768	(2)
Cytoplasmic structures predict the plane of cell division before mitosis begins	770	(2)
Plant mitosis occurs without centrosomes	772	(2)
The cytokinetic apparatus builds a new wall in the plane anticipated by the preprophase band	774	(2)
Secretion during cytokinesis forms the cell plate	776	(1)
Plasmodesmata are intercellular channels that connect plant cells	777	(2)
Cell expansion is driven by swelling of the vacuole	779	(1)
The large forces of turgor pressure are resisted by the strength of cellulose microfibrils in the cell wall	780	(2)
The cell wall must be loosened and reorganized to allow growth	782	(2)
Cellulose is synthesized at the plasma membrane, not preassembled and secreted like other wall components	784	(1)
Cortical microtubules are thought to organize components in the cell wall	785	(2)
Cortical microtubules are highly dynamic and can change their orientation	787	(3)
A dispersed Golgi system delivers vesicles to the cell surface for growth	790	(1)
Actin filaments form a network for delivering materials around the cell	791	(2)
Differentiation of xylem cells requires extensive specialization	793	(2)
Tip growth allows plant cells to extend processes	795	(2)
Plants contain unique organelles called plastids	797	(2)
Chloroplasts manufacture food from atmospheric CO2	799	(2)
What's next?	801	(1)
Summary	801	(6)
References	803	(4)
Glossary	807	(18)
Protein database index	825	(2)
Index	827