Bacteria 1

Ribosome

CytoplasmNucleoid

GlycocalyxCell wall

Cytoplasmic membrane

Flagellum

Inclusions

Prokaryotic Cell Structure

Chapters 3 and 11

Eukaryotic cell structure-- you should review from Biol 131

Archeal cell structure – not much different than Bacteria

Bacterial Classification-- you are not responsible for the details presented in Chapter 11, but should read about different types of bacteria presented in class

We will be discussing classification again as part of bacterial metabolism

Bacteria 2

Why are bacteria so small?Size affects ‘surface to volume’ ratio

Advantages of large S/V:diffusion ratesmetabolic ratesreproductive rates

Limits to size reduction?‘defective’ bacteria

Really big bacteria?-- Epulopiscium fishelsoni

Epulopiscium web sitehttp://www.micro.cornell.edu/cals/micro/research/labs/angert-lab/epulopiscium.cfm

Bacteria 3

Classification of bacteria is ‘murky’

A “Muddle in the Middle”Few distinctive characteristicsGenetically promiscuous

-- “horizontal” gene transfer

Traditional classification:anatomical featuresstaining characteristicsmetabolic properties

Newer approach

Genetic analysis

Bergey’s manual is the ‘Bible’

Bacteria 4

Classification based upon anatomical features

3 common shapes

-- coupled with staining propertiese.g., “Gram-pos cocci”“Gram-neg bacilli”

Some unusual shapes also:

Bacteria 5

Classification based upon anatomical features -- more info about these is in Chap 11

Other unusual bacteria

Spirochetes

Cell wall-less (mycoplasmas)

Stalked

Filamentous

Myxobacteria fruiting bodies Streptomyces

Bacteria 6

External Anatomical Structures-- Bacterial Flagella

Prokaryotic vs eukaryotic

Arrangementsmonotrichous

lopho-

amphi-

peri-

How do we know movementis rotational?

Flagella movement Flagella Details

Bacteria 7

How do flagellatedbacteria move?

‘Run and Tumble’ pattern

Bacterial movement

Chromatium motility

Bacteria 8

Spirochetes -- very strange structure-- e.g., Borrelia, Treponema

Axial filaments

Outer sheath

Motility

Spirochetes

Borrelia Movement

Bacteria 9

Fimbriae and Pili

Fimbriae adhesion to surfaces

Pili (pilus)genetic recombination

other functions?

Bacteria 10

The glycocalyx

FunctionsBiofilms -- adherence -- virulencePrevent desiccation

Composition

Capsule layersvs

Slime layers“xantham gum”(Xanthomonas)

S. Pneumo evasion

Bacteria 11

Cell wall structure

Hans Christian Gram -- 1884-- Crystal violet

Gram positive structure-- thick layer of peptidoglycan

Gram negative structure-- inner vs outer membranes-- thin layer of peptidoglycan-- lipopolysaccharides and endotoxins

Acid fast staining-- Mycobacterium

Lipopolysaccharide(LPS) layer

Outer membrane

Peptidoglycan

Cell membraneEffect of penicillin

Bacteria 12

Cell Membrane Structure

Review basic membrane structure from Biol 131

-- Phospholipid bilayers

-- Membrane proteins

-- Membrane fluidity

Membranes ofthermophilic archaebacteria

Bacteria 13

Components of prokaryotic cytosol

No membrane-bound organelles

Cytoplasm

Ribosomes

DNA

Inclusions

food or waste storage

Bacteria 14

Endospores

Clostridium & Bacillus

Formation and regrowth

Special properties?-- desiccated-- DNA binding proteins-- Ca-dipicolinic acid

Magnetotactic bacteria-- possess magnetosomes

Endospore formation

Magnetotactic Bacteria