close

Вход

Забыли?

вход по аккаунту

?

4- Bacteria . ppt - Marietta College

код для вставкиСкачать
Bacteria
Chapter 5
Classification of bacteria is
�murky’
A “Muddle in the Middle”
Few distinctive characteristics
Genetically promiscuous
Traditional classification:
anatomical features
staining characteristics
metabolic properties
Newer approach
Genetic analysis
Bergey’s manual is the �Bible’
Bacteria
1
Classification based upon
anatomical features
3 common shapes
Some unusual shapes also:
Bacteria
2
Classification based upon
anatomical features
Other unusual bacteria
Spirochetes
Cell wall-less
Stalked
Filamentous
Streptomyces
Myxobacteria fruiting bodies
Bacteria
3
Classification based upon staining
Gram Positive vs
Gram Negative
Hans Christian Gram -- 1884
-- Crystal violet
Gram positive structure
-- thick layer of peptidoglycan
Effect of penicillin
Gram negative structure
-- inner vs outer membranes
-- lipopolysaccharides and endotoxins
Acid fast staining
-- Mycobacterium
Penicillin action
Bacteria
4
Classification based upon
metabolism
-- will explore further later
Heterotrophic
Autotrophic
Photosynthetic bacteria
-- cyanobacteria
-- purple sulfur bacteria
Chemoautotrophic
Rocky Mountain
wood tick
Rocky Mountain Spotted fever
R. rickettsii
�Metabolically defective’
Rickettsia
Chlamydia
Image from (and good source for more about Chlamydia)
http://www.chlamydiae.com/docs/biology/biol_devcycle.asp
Bacteria
5
Why are bacteria so small?
Size affects �surface to volume’ ratio
Advantages of large S/V:
diffusion rates
metabolic rates
reproductive rates
Limits to size reduction?
�defective’ bacteria
Really big bacteria?
-- Epulopiscium fishelsoni
Epulopiscium web site
http://www.micro.cornell.edu/cals/micro/research/labs/
angert-lab/epulopiscium.cfm
Bacteria
6
Why study Bacterial Cell Structure?
Mechanisms of virulence
Drug development
Identification
Some cell exterior structures
cell membrane (lipid bilayer)
cell wall (Gram-pos vs Gram-neg)
glycocalyx (capsule vs slime layer)
flagellum (prokaryotic vs eukaryotic)
pilus (adhesion vs sex)
Bacteria
7
Cell Membrane
Structure
Phospholipid bilayers
Membrane proteins
Membrane fluidity
Membranes of
thermophilic archaebacteria
Bacteria
8
Bacterial Flagella
Prokaryotic vs eukaryotic
Arrangements
monotrichous
lopho-
amphi-
peri-
How do we know movement
is rotational?
Bacterial Flagella
Bacteria
9
How do flagellated
bacteria move?
�Run and Tumble’ pattern
Chromatium motility
Bacteria
10
Spirochetes
-- very strange structure
-- e.g., Borrelia, Treponema
Axial filaments
Outer sheath
Motility
Borrelia Movement
Bacteria
11
Fimbriae and Pili
Fimbriae
adhesion to surfaces
Pili (pilus)
genetic recombination
other functions?
Bacteria
12
The glycocalyx
Functions
adherence
virulence
prevent desiccation
Composition
Capsule layers
vs
Slime layers
“xantham gum”(Xanthomonas)
Strep Pneumo
Bacteria
13
Endospores
Formation and regrowth
Special properties?
-- desiccated
-- DNA binding proteins
-- Ca-dipicolinic acid
Endospore formation
Magnetotactic bacteria
-- possess magnetosomes
Magnetotactic Bacteria
Bacteria
14
Документ
Категория
Презентации
Просмотров
29
Размер файла
5 741 Кб
Теги
1/--страниц
Пожаловаться на содержимое документа