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1、Chater 2,rocaryotic Cell Structure,and Function, Bacteria,Section 1 Bacteria,I Shae and Arrangement cocci rods (bacilli) vibrios helices sirilla Sirochaeta,Sirochaeta,cocci,rods (bacilli),helices,Sirillus (siral-shaed) bacteria,Stahylococcus aureus (1000),Enterococcus faecalis (200),Bacillus megater
2、ium (600),Rhodosirillum rubrum (500),I Shae and Arrangement,I Shae and Arrangement,Vibrio cholerae (1000),Treonema allidum (500),Sirillum volutans (210),Sirillum volutans with biolar tuffs of flagella(400),I Shae and Arrangement,I Shae and Arrangement,Actinomyces, SEM (21,000),Mycolasma neumoniae, S
3、EM (62,000),Hyhomicrobium with hyhae and bud,I Shae and Arrangement,Sirolasma, SEM (13,000),Gallionella ferruginea with stalk,Walsbys square bacterium,Normal Shae:,II Size,II Size,Giant Bacteria,Euloiscium fishelsni (200) (Esther Angert, et al, 1993),Thiomargarita namibiensis (H N Schulz, et al, Sci
4、ence1999),Scanning electron micrograh of mineralized nanobacteria,Nanobacteria are tiny, slow-growing but extremely tough Gram-negative bacteria Sequencing of 16S rRNA suggests that they are roteobacteria similar in structure to the known athogenic secies Brucella and Bartonella However, at 80500 nm
5、 in size, they are one-twentieth to one-half the size of common bacteria, ossess a metabolic rate 10 000 times slower than that of Escherichia coli, and divide only every one to five days comared with the 20-minute cell-division rate of other bacteria (E O Kajander, et al An Alternative Mechanism fo
6、r athogenic Intra- and Extracellular Calcification and Stone Formation NAS 1998),The newly discovered Nanoarchaeum equitans (tiny cells) attached to its host Ignicoccus sec (big cells) Bar 1，5 m (Karl StetterNature20025),III Cell Structure and Function,Functions of rocaryotic Structures,General stru
7、cture,Secial structure,1 Cell wall,Gram Stain 1884, Danish hysician Christian Gram,The Gram-Staining rocedure,Examle of Gram Staining,(2) Functions,rotect the cell from mechanical disrution and osmosis Kee the shae of cell rovide the fulcrum for flagella movement Barrier action necessary for the cel
8、l division relate to athogenicity, antigenicity and sensibility to bacteriohage,(3) Thickness,G+: 2080nm G-: about 10 nm,The cell wall of G,The cell wall of G,Gram-ositive and Gram-Negative Cell Walls,(4) Comosition,i etidoglycan (or murein),Gram-ositive and Gram-Negative Cell Walls,etidoglycan subu
9、nit comosition,Diaminoacids resent in etidoglycan,etidoglycan Subunit Comosition,The etidoglycan with a direct cross-linkage between ositions 3 and 4 of the etide subunits, which is resent in most gram-negative and many gram-ositive bacteria,etidoglycan with lysin in osition 3 and an interetide brid
10、ge The bracket contains six tyical bridges: (1) Stahylococcus aureus, (2) S eidermidis, (3) Micrococcus roseus and Stretococcus thermohilus, (4) Lactobacillus viridescens, (5) Stretococcus salvarius, and (6) Leuconostoc cremoris The arrows indicate the olarity of etide bonds running in the C to N di
11、rection,An examle of the cross-bridge extending between ositions 2 and 4 from Corynebacterium oinsettiae The interbridge contains an L-diamino acid like ornithine, and L-homoserine (L-Hsr) is in osition 3 The abbreviations and structures of amino acids in the figure are found in aendix I,etidoglycan
12、 subunit comosition,etidoglycan Cross-Links,etidoglycan Structure,ii Teichoic acid,The Gram-ositive Enveloe,Teichoic Acid Structure,Function,Combine with Mg2+ to enhance the concentration and be helful to the enzyme activity on membrane Ensure the conglutination between G+ and the host Give G+ the s
13、ecific surface antigen rovide some secific adsortion recetor to hage Regulate the activity of autolysin Store u hoshorus,iii The Outer Membrane of G-(out wall layer),LS (lioolysaccharids),Concet,Cell enveloe: Microbiologists often call all structure from the lasma membrane outward the enveloe or cel
14、l enveloe This includes the wall and structures like casules when resent,Concet,erilasmic sace: Frequently a sace is seen between the lasma membrane and the out membrane in electron micrograhs of gram-negative bacteria, and some times a similar but smaller ga may be observed between the lasma membra
15、ne and wall in gram-ositive bacteria This sace is called the erilasmic sace,Concet,erilasm: The substance that occuies the erilasmic sace is the erilasm,The erilasmic sace of gram-negative bacteria contains many roteins that articiate in nutrient acquisitionfor examle, hydrolylic enzymes attacking nucleic acids and hoshorylated molecules, and binding roteins involved in transort of materials into the cell,Denitrifying and chemolithoautotrohic bacteria often have electron transort roteins in their erilasm The erilasmic sace also contains enzym
