microbio chs. 4 and 5 + lab info

What structures do ALL bacteria have?

• cytoplasmic membrane

• ribosomes

• chromosome(s)

• cytoplasm

When are bacteria independent or group-acting?

• independent in most conditions and with most of their functions

• act in a group within biofilms or the help of nanowires to transfer e- to one another

What is the average size of a bacteria?

1 micron

What are the most common shapes of bacteria ranked?

1. coccus

2. bacillus

3. curved

What are the 3 shapes of curved bacteria?

• spirillum: small waves

• vibrio: comma-shaped

• spirochete: spirals w/ multiple heads

What is pleomorphism?

when cells of the same species vary in shape and size - due to cell wall variations

What are the arrangements of cocci bacteria (6)?

• single*

• diplo*

• tetrads (4s)

• clusters (staphylo-)

• chains (strepto-)*

• sarcina: cuboidal packets of 8, 16

*also found in rods

What are biofilms?

microbial habitats with access to nutrients, water, and atmosphere. they are usually stratified (multiple layers) with aerobic microbes near the surfaces

How are biofilms formed and where?

• typically on warm surfaces with a layer of polysaccharides or glycoproteins

• occur when the first colonizers secrete substances to attract more species

• “zorbs” form without a surface

What are bacterial flagella and their function?

• small propellers

• provide motility and self-propulsion

What are the 3 parts of bacterial flagella?

1. filament: protein-based external helix

2. hook: curved, tubular anchor

3. basal body: stack of rings attached to cell membrane

What are the patterns of flagella?

1. polar: attached at one or both cell ends

   1. monotrichous: single flagellum

   2. lophotrichous: multiple tufts at 1 end

   3. amphitrichous: flagella at both ends

2. peritrichous: randomly scattered on cell

How do flagella execute chemotaxis?

they move either away or towards a chemical stimulus, based on if it is positive or negative. this initiates from receptors in the cell membrane binding to environmental molecules

What are runs and tumbles for flagella?

• runs: smooth linear movement

• tumble: reversals

runs will be extended in favor of an attractant OR away from a toxin

What are axial filaments?

coiled threads on spirochetes that cause “wiggles”: internal flagella between cell wall and cytoplasmic membrane

What are fimbriae and their function?

• small, bristle-like protein fibers on the surface

• cause mutual clinging of cells in a biofilm

• some pathogens use this to infect

What is a pilus and its function?

• long, tubelike structure made of a protein called pilin

• connects 2 different cells for conjugation - DNA transfer btw Gram neg cells

What are nanowires and their functions?

• very thin, long tails of the cell membrane used as channels

• transfer AA for nutrients or create energy from e- on some surface in the ANAEROBIC environment

  • rock breathing by sharing electrons with iron ions on rock surface

What are the 2 surface coatings groups and their functions?

• S layer

• glycocalyx

function as protection from the environment

What is the structure and function of the bacterial S layer?

• made of thousands of single proteins linked in a fence-like armor

• form in hostile conditions

  • may help with attachment

What is the structure and function of a glycocalyx?

• coat of repeating polysaccharide units, may have protein

• protection and maybe adhesion

What is a slime layer?

a type of glycocalyx; LOOSE shield against water and nutrient loss

What is a bacterial capsule

a type of glycocalyx; denser, thicker, and tighter to cell. can be examined using a special stain

How do capsules impact pathogens?

protects from WBCs and pathogens, which can be critical to human health - they escape their killers basically

What are components of a bacterial cell envelope?

ALWAYS cell wall and cytoplasmic membrane. OPTIONAL outer membrane

What is the structure and function of the bacterial cell wall?

• made of peptidoglycan = long sugar chains linked by proteins - ONLY found in bacteria

• determines shape of cell and prevents bursting

• excess water from osmosis cannot enter

What are differences in the Gram pos/neg cell walls?

• positive: thick wall with multiple layers; contains acidic polysaccharides called teichoic acid and lipoteichoic acid

• negative: single, thin sheet of peptidoglycan

What is the origin of acid fast staining?

some genera (such as Mycobacterium and Nocardia) have unique lipids in their cell wall - specifically mycolic acid that is pathogenic. they are highly heat and dye resistant, so they have their own method!

What is important about Mycoplasma genus?

they LACK a cell wall. instead sterols protect them from osmotic lysis

What is the structure and functions of the bacterial cell membrane?

• flexible sheet of phospholipid bilayer with embedded proteins

• site of energy reactions, nutrient processing, synthesis

• regulate transport with selective permeability

• embedded proteins allow for cell respiration and ATP synthesis

How is the Gram neg outer membrane organized?

• outer layer of lipopolysaccharide (LPS)

  • endotoxin from lipid

  • cell markers/receptors from polysaccharide

• inner layer of phospholipids

  • porin protein channels provide access and adjust size for defense

What are the steps of a Gram stain?

1. crystal violet

2. mordant - Gram’s iodine

3. alcohol wash

4. counterstain

What is the function and structure of bacterial cytoplasm?

• jelly solution where everything floats in

  • 70-80% water

• another site of metabolic and energy activities

What is the structure and function of bacterial chromosomes?

• 1 or more circular strands of DNA within the nucleoid

  • the double helix coils around proteins

  • divided into sections called genes

• stores genetic information

What are plasmids?

extra sources of genetic information - can be about things like protection. occur from conjugation to nearby bacteria

What is the structure and function of bacterial ribosomes?

• composed of RNA and protein, typically as polysomes attached to cell membrane

• characterized by S units to describe size = 70S for bacteria

  • composed of small (30S) and large (50S) subunits

• used to synthesize proteins

What are inclusion bodies?

pockets of nutrients encased in membranes to access when the environment is poor - can include glycogen or PHB

What are 3 examples of unique inclusion bodies?

• gas vesicles: provide buoyancy in aquatic bacteria

• granules: crystals of inorganic compounds (sulfur, phosphate)

• magnetosomes: crystals of iron oxide that act magnetically in cell

What is the structure and function of the bacterial cytoskeleton?

• helical ribbons under the cytoplasmic membrane of rods and spirals

• contribute to shape and cell division

What are bacterial endospores and their composition/traits?

very resistant structures in genera such as Bacillus, Clostridium, that germinate when vegetative cell dies

• used for SURVIVAL purposes, as a result of environmental conditions depleting

• strong from calcium and dipicolinic acid

• metabolically inactive, basically immortal

How are bacterial endospores formed?

• triggered by carbon and/or nitrogen depletion

• vegetative cell becomes a sporangium

• sporangium engulfs forespore to allow it to form layers

• forespore is released as an endospore when the sporangium dies

• endospore germinates and releases an exact copy of the same vegetative cell it began with

What is the medical significance of bacterial endospores?

they intrude sterility and are difficult to kill; need invasive methods like pressurized steam

How are Archaea extremophiles?

they inhabit harsh, unlivable conditions: extremely hot, salty, anaerobic, gaseous environments

What are the differences of the 2 Bergey’s Manuals?

• Determinative Bacteriology: based on phenotype

• Systemic Bacteriology: based on relatedness of small subunit RNA as well as phenotype

How did organelles originate?

came from bacteria parasitizing a descendant of the LCA (least common ancestor), and later became permanent as the mitochondria

What are the cellular complexities of microbes?

• unicellular: protozoa

• multicellular: helminths

• either: algae and fungi

What is important about the eukaryotic flagella?

• thicker and covered by cell membrane extension

• contain microtubules - 9 pairs form a single flagella (9 + 2 arrangement)

• locomotion

What is important about eukaryotic cilia?

• shorter and more numerous than flagella

• present in protozoa and animal cells

• function for LOCOMOTION, possibly feeding and filtering

What are traits of the eukaryotic glycocalyx?

• outermost boundary in contact with the environment

• polysaccharide-based

• for protection and adhesion

What is notable about the eukaryotic cell wall?

• present in fungi (chitin), algae, and plants (cellulose)

• support the shape and structure

What is important about the eukaryotic cell membrane?

• typical phospholipid bilayer with embedded proteins

• also has rigid sterols for protection and stability

• for transport of molecules

What are traits of the nucleus?

• housed inside nuclear envelope

• contains chromatin to make chromosomes

• for instructions and info in the form of DNA

• “control center”

What is the basic function of a ER?

microscopic tunnel for transportation and storage

What is important about the RER?

• emerges from outer membrane of the nuclear envelope

• transports materials from the nucleus to exterior

• houses ribosomes

• site of protein synthesis

What is the SER’s role?

• stores lipids

• processes nutrients

What does the Golgi body do?

• site of protein modification and sends to final destination

• pinches off condensing vesicles conveyed to other organelles

What are the assembly steps inside the eukaryotic cell?

1. a segment of genetic code (DNA) with protein instructions is copied into RNA

2. RNA passes through nuclear pores to RER

3. RER ribosomes synthesize proteins

4. Golgi modifies and sends them off

5. vesicles are used by cell

What is significant about lysosomes?

• Golgi-made vesicles with many enzymes

• food digestion and protection from infectious microorganisms

What is significant about vacuoles?

• membrane-bound sacs with fluids and solids

• stores materials to be digested, secreted, absorbed

What is the significance of mitochondria?

• generate a constant energy supply for the cell

• cristae in the inner membrane hold enzymes and electron carriers

• contains independent DNA and 70S ribosomes in the matrix

What is important about chloroplasts?

• for converting sunlight into chemical energy

• primary producers of nutrients

• manufacture O2

• has independent DNA and 70S ribosomes

What is significant about eukaryotic ribosomes?

• contain 40S small subunit and 60S large subunit = 80S

• for creating proteins

What is significant about the eukaryotic cytoskeleton?

• flexible framework with actin filaments, intermediate filaments, microtubules

• for anchorage, movement, shape changes

What are the 2 morphological forms of microscopic fungi?

• yeast: has round/oval cells that grow as spherical buds

  • may form pseudohypha with rows of buds

• hyphae: long, threadlike cells (molds, filamentous fungi)

DIMORPHIC fungi can be both forms

How are fungi classified in terms of nutrition?

all are HETEROTROPHS that get nutrients from substrates by secreting enzymes to make the molecules digestible. they are mainly SAPROBES that get energy from dead remnants

What are mycoses?

animal/human diseases caused by fungi

How do microscopic fungi appear organized?

• yeast are similar to bacteria - soft, uniform texture

• filamentous fungi have hairy textures with hyphae that intertwine as a MYCELIUM

What is the role of septa?

cross wall divisions/separations between hyphae - vary in utility (no communication to sharing nutrients)

What are vegetative hyphae?

what show as visible dark mass on the substrate the fungus is “eating”; branch to create fertile hyphae

How do fungi primarily reproduce?

they can grow outwards or from mycelium but PRIMARILY through spore formation (benefits of survival, multiplication, genetic variation)

What are the 2 types of asexual spores and their traits?

1) sporangiospores: originate from cleaving inside “head” of stalk called sporangium

2) conidiospores: free spores without enclosures - originate from pinching the tip or segmenting parts of the vegetative hypha

What is important about sexual fungal reproduction?

• majority of fungi form sexual spores

• used in fusion or union

• advantageous with adaptation and gene diversity

What temperatures do fungi prefer and what is the application to disease?

prefer colder temps, so they mainly infect the surface of humans

With prokaryotes, fungi are…?

major decomposers of organic material

What are mycorrhizae?

symbiotic associations between roots of plants to help uptake of water and nutrients

What are protists?

composed of algae and protozoa - unicellular prokaryotes (algae can be multi though)

What are important traits of algae?

• major photosynthesizers in fresh and sea water

• contain all eukaryotic organelles, including chloroplasts

• problematic with red tides and releasing toxins

What are key forms and functions of protozoa?

• contains all organelles besides chloroplasts, analogous to mouth, legs, repro system

• contains endoplasm with nucleus, mitochondria, vacuoles; ectoplasm for motility and feeding

What are the nutrients and habitats of protozoa?

• chemoheterotrophic: need feed in a complex form, typically dead remnants or grazing on bacteria

• live in water, soil, or as parasites in animals, plants

What are the 3 methods of movement of protozoa?

• pseudopods (“false feet”) - amoeboid movement and feeding

• flagella - peritrichous and make up undulating membrane

• cilia - forms walking legs, also line oral groove

What are sporozoa?

protozoa that have no structures for motility

What is the life cycle of a protozoa? (complex)

• exist as trophozoites when in a motile feeding stage with access to food and moisture

• enter a resting stage as cysts when environment conditions are poor

  • formed by rounding into sphere during encystment and forming a tough cuticle from the ectoplasm

  • can be dispersed and cause disease

• cyst will release trophozoite when there are adequate nutrients

How do protozoa reproduce?

mainly through mitosis but can be sexual - ciliates perform conjugation and fuse temporarily

What are the helminths?

roundworms, flukes, tapeworms

How are helminths classified based on body?

• flatworms (Platyhelminths): thin, segmented bodies

  • cestodes are long and ribbonlike = tapeworms

  • trematodes are flat and oval-like = flukes

• roundworms (Aschelminths): long, cylindrical, and unsegmented

What is the complexity of helminths?

• all multicellular

• some organ systems are present - mainly repro in parasites

• chemoheterotrophs

What are the life cycles of helminths?

fertilized egg (embryo), larva, adult; can be hermaphrodites

How do helminths continue their life cycle as parasites?

• transmits eggs to host

• adulthood and mating (full life process) occur in the definitive host

How do helminths infect humans?

through ingestion, which typically starts from contamination of food or water sources. they have adapted to lay MANY eggs so that they survive and make it to a host

What are steps of the pinworm (roundworm) cycle?

• a person swallows eggs or comes into contact with them physically

• hatch in intestine and release larvae, causing enterobiasis

• M and F mate

• F leaves through anus to deposit eggs

• itchy butt

• contaminate fingers

• continue spread

What is important about the anatomy of helminths?

• have a scolex (head) with suckers or hooks to grasp onto intestines = tapeworms only

• different segments have gametes, which allow for the hermaphroditic self-fertilization in some species

How is a smear prepared from a solid medium?

1. mark areas with a wax pencil

2. add 1 drop of distilled water to the circle

3. flame the loophole

4. transfer a small amount of the culture using the sterile tool and mix with the water

5. allow smears to dry with slide heater

6. pass it through the flame 2 or 3 times

How to prepare a smear from a liquid medium?

1. mark areas on slide using wax paper

2. flame the loop

3. place 2-5 loops of the liquid culture using the sterile tool on the slide

4. spread the bacteria in a circle

5. allow smears to dry on slide heater

6. flame 2-3 times

How to execute a negative stain?

1. place a drop of nigrosin or India ink on one end of the slide

2. mix loopful of culture (add water if from solid)

3. draw second slide against the surface until it contacts

4. push slide to the left to spread the ink

5. allow it to air-dry

How to perform a Gram stain?

1. cover the fixed smear with crystal violet for 30 secs

2. wash with water

3. cover smear with Gram’s iodine for 10 secs

4. wash with water

5. decolorize with ethanol

6. wash with water

7. cover smear with safranin counterstain for 30 secs

8. wash with water

9. blot dry in bibulous paper

How to perform an acid-fast stain?

1. cover fixed smear with carbolfuchsin for 5 minutes - has high affinity for mycolic acid in cell wall of AF

2. wash with water

3. cover smear with acid-alcohol for 1 minute - easily decolorizes MOST organisms

4. wash with water

5. cover with methylene blue for 1 minute - MOST microbes will retain this after alcohol wash

6. wash with water

7. blot with bibulous paper

What are traits of Escherichia coli?

• bacillus, single

• Gram-negative

• NAF

What are traits of Staphylococcus epidermis?

• staphylococcus: clusters of spheres

• Gram-positive