7 Plasma Membrane Plasma membrane cytoplasmic plasma membrane

7) Plasma Membrane

Plasma membrane • cytoplasmic (plasma) membrane • also called cell membrane • ultra-thin layer of fat and protein

phospholipids Polar “Head” = Hydrophillic Non. Polar “Tails” = Hydrophobic

detail of “_________” of plasma membrane • a living, functioning part of the cell • ___________(selective permeability)

Cell Membrane

plasma membrane • a vulnerable part of the cell • easy to damage with heat or chemicals

Solution Solute Solvent (usually water)

Cell Membrane Tonic…

Things Can/Cannot go through: *Can Go Through: – Small, uncharged molecules (CO 2, O 2) – Small, polar molecules (H 2 O) – Large non polar molecules (Steroids)

Transport Passive – Does not require energy • Dialysis • Simple Diffusion • Osmosis • Facilitated Active – Requires Energy (Na+/K+ Pump)

Other things attached a Cell Membrane

8) ______ • The cytoplasm (cell fluid) • semi-liquid contents of the cell • complex mixture of chemicals – water – protein – many other chemicals • forms a colloidal system – two states, sol and gel

Cytoplasm: a colloidal system • ___: water continuous ____: protein continuous vulnerability: can permanently convert sol to gel with heat or chemicals

8 A Stuff in the cytoplasm: Ribosomes • ribosomes: bodies within the cytoplasm that function in protein synthesis – Composed of 2 subunits = 70 S (prokaryotic size) • S=Svedberg units of sedimentation with centrifugation – Consists of protein and ribosomal RNA (r. RNA)

8 B. ______ • inclusion bodies: store nutrients (starch, glycogen, fats) for later use during periods of starvation • Could store iron oxide or phosphate depending on cell.

8 C. Genetic Material • “Genes” are nucleic acids, discussed in unit 3 (used to make proteins!) • Single chromosome – DNA only; no histone proteins – an endless loop not surrounded by nuclear membrane – never condenses to become visible with light microscope; can see with electron microscope

8 D) _____ • plasmids: small loops of extrachromosomal DNA – may be 0, 1 or more – often carry genes for virulence or drug resistance – Replicate independently of chromosomal DNA

8 E) Endospore (Spore) • A survival form of bacteria produced within the cell in response to adverse environmental conditions spore • (Clostridium and Bacillus)

endospore • Central, terminal, subterminal spores ___________

spores: Left Bacillus; right Clostridium • Common spore-forming bacteria: – Bacillus spp. (aerobic, gram +, sporeforming bacilli) – Clostridium spp. (anaerobic, gram +, sporeforming bacilli)

• spore stained slide (green = spore)

endospore • Spores can survive: – boiling – freezing – drying – vacuum – many disinfectants – time (250 million years? )

endospore • to kill spores – steam autoclave – gas autoclave – some disinfectants – powerful radiation

spores: terms used • sporogenesis = spore formation • germination = reactivation • vegetative cells = not spores

Atypical Bacteria

Bacterial Taxonomy: How are these unicellular organisms classified? • complex system of classification – based on shape & size; oxygen, p. H, and temperature requirements; laboratory characteristics, biochemical analyses, serology tests, nucleic acid and protein analysis techniques. . … – Classification is now based on similarities in nucleotide sequences in r. RNA – The Bergey’s Manual is considered the official listing of all recognized bacteria • see appendix A in your text for the details (don’t memorize!)

Reminder • The majority of Bacteria and Archaea have not been cultured • Scientists estimate that only 1% of these microbes have been discovered! • And…of more than 2600 species of bacterial names, fewer than ____ are human pathogens.

Some atypical bacteria • not typical • will discuss – 1. – 2. – 3. – 4. – 5. fungus-like bacteria acid fast bacteria Mycoplasmas Chlamydias Rickettsias

Fungus-like (filamentous) bacteria • myc in word refers to fungus or something like a fungus (filamentous) • Streptomyces spp. : most important source of antibiotics – More than half of our _______ are produced by species of Streptomyces. – Antibiotics are substances produced by microbes that in small amounts inhibits another microbe.

Actinomyces • branching filaments and spore-case (sporangium) • Actinomyces spp. : cause actinomycosis (lumpy jaw) – large abscess in jaw – sulfur granules in pus – Figure 11. 22

Actinomycosis • Fungal-like bacterial disease • Infection follows trauma to body tissues • “lumpy jaw”

Actinomycosis

Actinomyces sulfur granules in pus

2. ______bacteria • gram positive bacilli with wax coat on cell wall • wax increases survival in environment • Nocardia spp. (weakly acid fast; require special acid-fast stain) – nocardiosis: infection of lungs, skin or other tissue • Mycobacterium spp. – M. tuberculosis (tuberculosis) – M. leprae (leprosy) – many other species

Mycobacterium tuberculosis fig. 24. 8

nocardia • Procaryotic, acid-fast, but grows much like a fungus

Nocardia: • nocardiosis, mycetoma • Follows penetration from the soil via a wound

• Nocardiosis growing back through ribs from lungs to skin • When inhaled, the disease strikes the lungs, where multiple abscesses form. • Symtoms can be similar to tuberculosis • Reports of death from nocardiosis have been linked to AIDS

Acid-fast stain: pp. 70 -71, fig. 3. 13 • Primary stain: ________ • Mordant: heat or detergent (cold method we will use in lab) accompanying primary stain, to force stain through wax coat on cells • Decolorization: acid alcohol – 3% HCl in 95% ethanol – acid-fast bacteria hold primary stain because wax resists acid alcohol – non acid-fast bacteria decolorize • Counterstain: ________ • red = acid-fast; blue = nonacid-fast

Mycobacterium leprae • Red = acid-fast

Mycobacterium ulcerans: Buruli ulcer • • Reservoir = swamps & slow-flowing rivers Increasing in world Global threat to public health (WHO) Page 594 in your text

3. ______ • smallest known cells (“submicroscopic”) • never have cell walls • don’t rupture because of small size and tough cell membrane • myco = filamentous; plasma = fluid • pleomorphic = variable shape • will grow on culture media “fried egg” colonies • Genera: Mycoplasma and Ureaplasma

Mycoplasmas cause: • pneumonia in humans and animals – walking pneumonia – 15 -20% of cases human pneumonia – Can be severe • mastitis in cows • urethritis in humans • stunting of plant growth

Mycoplasma pneumoniae • attached to surface of host cells

4. Chlamydias • Submicroscopic • Have cell walls: oval shape, gram negative • Obligate intracellular parasites= will grow only inside of living host cells – energy parasites • Genus Chlamydia • trachoma • genital chlamydia • http: //www. cdc. gov/std/Chlamydia/STDFact-Chlamydia. htm • Pneumonia • Chlamydophila psittaci • In pathogen group 4 figure 11. 24

2 forms of chlamydia cells • ________: – 0. 3 µm – rigid cell wall – can survive outside of host cell – Infectious • ________: – 0. 5 to 1. 0µm – fragile cell wall – Can’t survive outside of host cell – not infectious – adapted for growth

chlamydia reproduction red = elementary body; green = reticulate body • entering reproducing • See figure 11. 24 escaping

5. Rickettsias • tiny oval to rod-shaped bacteria; just visible with light microscope – See figure 11. 1 on page 304 • obligate intracellular parasites – But now widely separated from the chlamydia (see table 13. 1 on page 368) • most have arthropod vectors • Genera Rickettsia and Ehrlichia • Cause: – Rocky Mountain spotted fever (ticks are vectors) – Typhus fevers (various vectors) – Will study in pathogen group 9!

Rickettsia in host cell • Figure 11. 1