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CELL SHAPE Coccus - sphere - coccus Single Diplococcus – two Clusters of cocci Streptococcus Bacillus- cylinder, rod Spiral shape- Rigid spirilla curved rods Flexible: spirochetes TYPICAL BACTERIAL CELL, BINARY FISSION

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slide1

CELL SHAPE

  • Coccus - sphere - coccus Single
  • Diplococcus – two
  • Clusters of cocci
  • Streptococcus
  • Bacillus- cylinder, rod
  • Spiral shape-
  • Rigid
  • spirilla
  • curved rods
  • Flexible: spirochetes
  • TYPICAL BACTERIAL CELL, BINARY FISSION
  • CELL COMPONENTS
  • Cytoplasmic membrane phospholipid bilayerfluid mosaic modelsemi - permeable barrierosmosis
          • solvent (HOH), solute
  • isotonic, hypertonic, hypotonic
  • Cytoplasmic membrane protein functions
  • Food accumulation- group translocation
  • active transport
  • Catalysis of metabolic pathways - e.g., electron transport chain
  • Cell wall component synthesis
  • Signal transduction - e.g. chemotaxis
  • CELL WALL
  • Gram positive organisms: Peptidoglycan, Teichoic acid
  • Gram negative organisms: Peptidoglycan
  • Periplasmic gel
  • Lipoprotein
  • Outer membrane – Phospholipid monolayer
  • Lipopolysaccharide
  • Pores
  • Peptidoglycan - polysaccharide with amino acid components. N - acetyl glucoseamine, N - acetyl muramic acid, Amino acid side chains, Cross-linking (interbridge)
  • FLAGELLA - Flagellin, hook, outer rings, inner ring
  • Rotation: counter clockwise, clockwise, chemotaxis
  • NUCLEOID – chromosome, haploid, double-stranded, supercoil
  • CYTOPLASM – water, ribosomes, soluble proteins, enzymes, low molecular weight precursors, RNA, ATP
  • PILI (SEX); FIMBRIAE (ATTACHMENT)
  • CAPSULE/GLYCOCALYX
  • COMPARISON: EUCARYOTES AND PROCARYOTES
  • SPORULATION – Endospores, durable, inert, survival mechanism, germination
slide2

BACTERIAL CELL SHAPE

  • COCCUS - SPHERE - COCCI
  • Single - Micrococcus luteus
  • Diplococcus - Neisseria gonorrhoeae
  • Neisseria meningitidis
  • Clusters - Staphylococcus aureus
  • Streptococcus - Streptococcus pyogenes
  • BACILLUS - ROD, CYLINDER - BACILLI
  • Bacillus anthracisANTHRAX
  • CorynebacteriumdiphtheriaeDIPHTHERIA
  • [pleomorphic]
  • SPIRAL
    • RIGID - SPIRILLA Rhodospirillumrubrum[photosynthetic]
    • CURVEDVibrio choleraeCHOLERA
    • FLEXIBLE - SPIROCHETES
  • TreponemapallidumSYPHILIS
  • BorreliaburgdorferiLYME DISEASE
slide3

MICROORGANISMS

Reproduce themselves faithfully and the species continues to occupy its niche in the environment

Have the capacity to change genetically

Mutation

Genetic exchanges

permits survival in changing environments

slide5

“TYPICAL” BACTERIAL CELL - BINARY FISSION

~1 x 3 µm

0 min

20 min

40 min

60 min

PLASMIDS – SMALL EXTRA-CHROMO-SOMAL DNA MOLECULES

NOT NORMALLY REQUIRED FOR GROWTH

OFTEN CODE FOR TOXINS, DRUG RESISTANCE

slide6

ACCUMULATE FOOD

Oxidize food Energy

Convert food Low molecular weight compounds

Amino acids

Fatty acids

Monosaccharides

Nucleotides

SYNTHESIZE MACROMOLECULES:

Proteins, Lipids, Polysaccharides, RNA, DNA

DIVIDE

slide7

CYTOPLASMIC MEMBRANE -

PHOSPHOLIPID BILAYER

outside

Hydrophobic fatty acids

~8 nm

inside

Hydrophilic phosphates

FLUID MOSAIC STRUCTURE - VISCOUS

~ 8 nm thick

selectively permeable - H2O

osmosis - isotonic solutions

slide8

NET H2O

change

OUT

IN

[H2O] X

[solute] Y

[H2O] LOW

[solute] HIGH

[H2O] HIGH

[solute] LOW

[H2O] X

[solute] Y

[H2O] HIGH

[solute] LOW

[H2O] LOW

[solute] HIGH

none

ISOTONIC

HYPERTONIC

out

HYPOTONIC

in

slide9

CYTOPLASMIC MEMBRANES - FUNCTIONS

1. FOOD ACCUMULATION

A. Group translocation (substance modified)

(outside) glucose glucose-6-PO4 (inside)

B. Active transport

Potassium K+ ions

METABOLIC PATHWAYS

Electron transport chain

Chemiosmosis; ATP synthesis

3. CELL WALL COMPONENT SYNTHESIS

4. SIGNAL TRANSDUCTION; e.g., chemotaxis

sense change in environment

respond to change

5. SECRETION

e.g., toxins

slide10

CELL WALLS AND CYTOPLASMIC MEMBRANES

Gram Positive

Gram Negative

Teichoic acid

Pore

Lipopolysaccharide

Phospholipid monolayer

Lipoprotein

Periplasm

Phospholipid Bilayer

Proteins

Cytoplasm

slide11

PEPTIDOGLYCAN: REPEATING DISACCHARIDES WITH AMINO ACID SIDE CHAINS

N-Acetyl Glucosamine

N-Acetyl Muramic Acid

Amino acid side chain

slide12

L-ALANINE

D-GLUTAMIC ACID

DIAMINO PIMELIC ACID

D-ALANINE

slide13

L-ALA

D-GLU

DAP

D-ALA

D-ALA

DAP

D-GLU

L-ALA

G–M–G–M–G–M–G–M

G–M–G–M–G–M–G

Polysaccharide

INTERBRIDGE between side chains

Amino acid side chain

INTERBRIDGE:

Gram negative - covalent bond amino acids 3-4

Gram positive - penta glycene between amino acids 3-4

slide15

MOTILITY

1. SWIMMING

Extracellular flagella rotate

Escherichia coli 20 - 90 micrometers/sec

2. FLEXING

Flagellum located in periplasm rotates, cell flexes as

flagellum rotates

Treponemapallidum

3. GLIDING

Move over solid surfaces without flagella

Two forms of gliding:

A. Adventurous (twitching) - done by individual cells

B. Social - done by many cells in unison

slide16

FLAGELLUM (-A) FLAGELLIN

rings

hook

14 nm x 10 µm

Cytoplasmic membrane

Outer

membrane

Peptidoglycan

200 revolutions/sec

Counter clockwise - forward swim

Clockwise - random tumble

Chemotaxis - net movement toward attractant,

away from repellent

Cells swimming toward attraction tumble less often.

Net result movement toward attraction

slide17

JUNCTION

FLAGELLIN

MONOMER

FILAMENT

HOOK

CAP

CENTRAL EXPORT CHANNEL

BEARINGS

L-RING

P-RING

ROD

OUTER MEMBRANE

CELL WALL- PEPTIDOGLYCAN

H+

PERIPLASMIC SPACE

CYTOPLASMIC MEMBRANE

H+

MS-RING

STATOR/MOTOR (CROSS-SECTION)

C-RING

(CROSS

SECTION)

EXPORT APPARATUS

SECRETION

ATP

ADP

ROTOR: C, MS, ROD, HOOK, FILAMENT

slide18

FILAMENT

HOOK

L-RING

P-RING

OUTER MEMBRANE

PEPTIDOGLYCAN LAYER

MS-RING

ROD

PERIPLASMIC SPACE

CYTOPLASMIC MEMBRANE

STATOR

CROSS-SECTION

C-RING

CROSS-SECTION

slide20

Several mechanisms, one of which is pilus extension (attachment to the solid surface) and pilus retraction. (Type IV pili.)

Examples of twitching:

Neisseria gonorhoeae- spread over body cell surfaces (?)

Pseudomonas aeruginosa- spread over body cell surfaces (?) 0.2 µM/sec

Gram negative

Opportunistic pathogen

Burn victims - bacteremia

Cystic fibrosis - chronic lung infection

Ulcerative keratitis - contact lens

Example of social gliding:

Myxococcusxanthus- cells form fruiting bodies = clumps containing spores

(Note: M. xanthuscan also twitch)

4. SWARMING:

Depends on flagella

Cells move in unison over solid surface

Escherichia coli, Salmonella enterica

slide21

ADHESIVE ORGANELLES

Contain adhesin (protein which binds something)

Function: attachment

Kinds: 1. pili/fimbriae

2. non-pilus adhesin (surface protein)

PILI 7nm x 1µm

1 x 3 µm

examples: Escherichia coli

sex pili - attach to female

slide22

P PILUS - Escherichia Coli

CYSTITIS (BLADDER)

Sticks to glycolipid on uroepithelial cells and RBC

(11 genes)

Adhesin

Linkers

Central

hole

Pilus

Usher

(pore)

Outer membrane

Periplasm

Cytoplasmic membrane

slide23

Hemophilus

influenzae

HIB Pilus

Respiratory

epithelium

E. coli

P Pilus

Uroepithelial cells

J. Bacteriol. 184.17. cover 2002

slide24

Aggregate

- nutrients

Growth

Starvation

+ nutrients

Fruiting body

Spores

MYXOCOCCUS XANTHUS FORMS SINGLE-SPECIES BIOFILMS AND EXHIBITS SOCIAL BEHAVIOR

slide26

CAPSULE / GLYCOCALYX

Streptococcus pneumoniae

Polysaccharide

Pathogenicity factor

slide27

NUCLEOID - E. coli

  • 1 chromosome - haploid

~ 1100 µm circumference

Supercoil - double strand

  • 4.6 x 106nucleotides / strand

~ 5,300 genes

~ 3 x 109molecular weight

660 molecular weight / nucleotide pair

CYTOPLASM

HOH, soluble materials - low molecular weight precursors

Enzymes, ribosomes, RNA [transfer; messenger], ATP

slide28

PROKARYOTE GENOMES

Genome = all genetic information of an organism

Number Nucleotide Pairs

Number Genes

E. coli 4.6 x 106 ~ 5,300

Haemophilus 1.8 x 106 ~ 1,800

influenzae

Methanococcus 1.7 x 106 ~ 1,800

jannaschii

(archea)

bacterial e coli cell composition
BACTERIAL (E. COLI) CELL COMPOSITION

NUMBER MOLECULES MOL WT % OF DIFFERENT PER CELL CELL

KINDS OF

MOLECULES

DNA 1 1-2 3 X 109 1

PROTEIN 5,000 2 X 106 3 – 4 X 104 15

RNA (TOTAL) 6

RIBOSOMAL 3 20,000 EACH

TRANSFER 60 200,000 2,000

MESSENGER 600 1500

PHOSPHOLIPID ~MANY 22,000,000 700 3

RIBOSOMES 1 20,000

PEPTIDOGLYCAN 1 1 ~10 X 109 1

OTHER CELL WALL COMPONENTS, LOW MOLECULAR WEIGHT PRECURSORS, VITAMINS

WATER 70

slide31

EUKARYOTES

PROKARYOTES

1. True nucleus

chromosomes in

nuclear membrane

Introns common

2. Divide by mitosis

3. Sexual reproduction; meiosis (eggs, sperm)

4. Mitochondria

5. Chloroplasts

6. Cell walls

animals - none

plants - cellulose

fungi - chitin

7. Ribosomes - 80S

8. Size - 8 to 100 micron diameter

1. Nucleoid

Introns rare

2. Divide by binary fission

3. Primitive sex

4. None

5. None - chromatophores

6. Present, with peptidoglycan

7. Ribosomes - 70S

8. Size - 1 x 3 microns

Macroscopic microbe - Epulopisciumfishelsoni > 50 micron diameter > 500 micron length

slide32

ENDOSPORES

Dormant, inert, durable

Resist chemicals (e.g., bleach),

heat, drying, radiation

Formed by growing cells

Nucleoid

Cell membrane

spore coat

GERMINATION-spores resume metabolism and form growing cells

slide33

DISEASES CAUSED BY EXOTOXINS PRODUCED BY

  • SPORE- FORMING ORGANISMS
    • ANTHRAX - Bacillus anthracis
    • BOTULISM - Clostridium botulinum
                • ANAEROBE - GROWS WITHOUT
                • MOLECULAR OXYGEN
    • TETANUS - Clostridium tetani
                • ANAEROBE
slide34

ANTHRAX-

(disease of cattle, sometimes spread to humans)

Cutaneous anthrax:

Bacillus anthracisspores in soil or contaminated animal products.

Enter body through wounds, germinate and grow.

Set up local infection (sometimes it spreads)

Pulmonary anthrax:

Spores are breathed, germinate in the lungs, infect lungs, massive swelling, rapid death

Toxins: Pore Forming Protein Assembles in Cytoplasmic

Membrane; Edema Factor, Lethal Factor Bind Pore;

Endocytosis into cells; EF and LF exit through pore into cytoplasm; Massive swelling; Inhibition of host immune system ability to respond to infection

slide35

TETANUS- Clostridium tetanispores - ubiquitous in soil

  • Enter body through wounds; germinate; grow at the site of infection; secrete neurotoxin.
  • Neurotoxin processed (cleaved) to heavy & light chains; heavy chain binds receptor on nerve cell at site of injury and creates pore.
  • Light chain is protease, enters pore; spreads up nerves to spinal cord; fixed at “presynaptic inhibitory motor neuron”
  • Disrupts movement of nerve cell vesicles containing neurotransmitters needed to dampen nerve impulses. Causes involuntary contractions; muscles
  • continue to work. (convulsions - spastic paralysis = tetany); asphyxiation; death;
  • toxin is tetanospasmin
  • Neonatal tetanus: 500,00 people die/year in the world
  • Tetanus vaccinations in U.S. (DT or DPT or DaPT)
slide36

BOTULISM- Clostridium botulinumspores on vegetables, smoked fish, similar items contaminated

  • Spores survive home canning/preservation process,
  • Germinate in the anaerobic environment of the canned food, cells grow and secrete neurotoxin
  • People ingest the toxin, absorb it from their intestine.
  • Neurotoxin – similar to tetanus toxin; One protein processed to heavy chain (binds peripheral nerve cell; creates pore); Light chain is protease; acts at end of peripheral nerve, disrupts nerve impulse transmission to muscle.
  • Result is flaccid paralysis; respiratory failure; DEATH
  • Treatment - anti botulism antitoxin
slide37

TAKE AWAY:

STRUCTURES OF BACTERIAL CELLS; THEIR FUNCTIONS AND MACROMOLECULAR COMPOSITIONS

MOTILITY MECHANISMS

SPORULATON PROCESS &

DISEASES RESULTING FROM ORGANISMS WHICH FORM

SPORES

UNDERSTAND:

WHY STRUCTURES ARE USEFUL

HOW EACH ACCOMPLISHES ITS FUNCTION

HOW FLAGELLUM ROTATION IS ACCOMPLISHED

HOW A BIOMOLECULAR MACHINE WORKS

ROLE OF GENETIC INFORMATION

SPORULATON IS DEVELOPMENTAL PROCESS – TWO CELL

TYPES