Microbiology Chapter 4

Cytoplasm

A substance of the cell inside the plasma membrane Consists of: 80% water, protiens, carbohydrates,lipids,minerals

Dimensions of bacteria

Average<1.0-3.0 um in diameter Very small: nanobacteria 0.05-0.2um very big 300 um

Glycocalyx

Bacterial Surface coating - protects cells from drying out Enables bacteria to live in slime communities(biofilms)

Nuclear area

Bacterial chromosomes- a single circular molecule of DNA Not surrounded by nuclear membrane Plasmids-extrachromosomal geneticelements Small circular DNA molecules, carry genes for antiobiotic resistance

Streptococci

Chains

Basic shapes - morphology of bacteria

Coccus (sphere) Bacillus (rod), Spiral

pili

Long hollow tubules composed of pilin Bacteria typically only have one or two per cell Join two bacterial cells and mediate the transfer of DNA from one cell to another(conjugation) Also known conjugation pili or sex pili

Flagella Structure

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lophotrichous

Lophotrichous bacteria have multiple flagella located at the same spot on the bacteria's surfaces which act in concert to drive the bacteria in a single direction

Metachromatic granules(inclusion)

Metachromatic granules (volutin granules)---phosphate reserve that can be used in synthesizing ATP. These large granules stain red with methylene blue. They are characteristic of Corynebacterium diphtheriae. These granules are also found in algae, fungi, and protozoa.

inclusions

Metachromatic granules - Polysaccharide granules - lipid inclusions - sulfur granules - gas vacuoles - polyhidroxybutirate are nuclear or cytoplasmic aggregates of stainable substances, usually proteins

monotrichous

Monotrichous bacteria have a single flagellum

Gram negative cell wall

Multilayered structure composed of: thin layer of peptidoglycan Outer membrane: Bilayer - phospholipids Channel proteins(porins) lipopolysaccharide(LPS)

phospholipid bilayer

One layer consists of: hydrophylic heads(waterloving) hydrophobic tails(waterfearing)

Structures internal to the cell wall

Plasma membrane-Cytoplasm-nuclear area-ribosomes-inclusions-endospores

Endospores

Resting cells - dehydrated cells with a thick cell wall Formed in unfavorable conditions Layers of spore coats provide resistance to dehydrate, high temperatures, toxic chemicals radiation 25 Million years old spore germinated spores germinate into vegetative

Ribosomes

Small globular structures in cytoplasm Site of protein synthesis Consist of RNA and proteins Targeted bysome antibiotics

Fimbriae

Sticky, proteinaceous projections Used by bacteria to adhere to(each other, host, surfaces in the enviroment) Serve an important function in biofilms

Cell wall

Surrounds the whole cell protects cell from adverse effects of the outside enviroment withstands the pressure of the cell maintains the shape of bacterium Mains component peptidoglycan

Plasma Membrane

The structure surrounding the cell composed of phospholipid bilayer and protein

Gram positive cell wall

Thicker layer of peptidoglycan(precents the rinse out of a blue dye complex during the gram- staining- cell apear violet) Contains also teichoic acid lipoteichoic acids anchor peptidoglycan to cell membrane

Capsule

Tightly bound to the cell surface Has higher pathogencity - may prevent bacteria from being recognized and destroyed by host phagocytes Enables attachment to surfaces(plant roots,water pipes,surface of teeth etc)

Amphitrichous

] Amphitrichous bacteria have a single flagellum on each of two opposite ends (only one flagellum operates at a time, allowing the bacteria to reverse course rapidly by switching which flagellum is active).

Peritrichous

bacteria have flagella projecting in all directions (e.g., E. coli).

Sulfur granules

bacteria whose metabolism involves oxidizing sulfur may deposit these as an energy reserve. Thiobacillus is an example.

Flagella

canonical role of the flagellum is locomotion is a lash-like appendage that protrudes from the cell body of certain prokaryotic and eukaryotic cells

Polysaccharide granules(inclusion)

glycogen granules (which iodine stains reddish brown) and starch granules (which iodine stains blue).

Staphylococci

grapelike clusters

Proteins

integral proteins(channels) Peripheral proteins(enzymes) glycoproteins(receptors)

Vibrios

just somewhat curved

Slime layer

loosly attached to the cell surface(water soluble)

Lipid inclusions

most common is poly-b -hydroxybutyric acid (PHB). Found in Mycobacterium, Bacillus and others.

Bacilli

mostly single, but some form:

Diplococci

pairs

Spirilla

spirilla a cork-screw(rigid)

Spirochetes

spirochetes(flexible)

Gas vacuoles

these are adjusted so that the cell that contains them can float at the proper depth in water.

Streptobacilli

(chains)

Tetrads

(groups of 4)

Sarcinae

(groups of 8)

Diplobacilli

(pairs)

Palisades

(rods side by side)