Ex. 9 - Bacterial Endospores

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_____ are very resistant to environmental stresses that kill bacterial cells, resistant to extreme desiccation, high temperature, ionizing radiation, and penetration by chemicals

endospores

The absence of _____ does not necessarily mean that the unknown bacterium is not one of the endospore forming genera

endospores - can mean it is too young or there is not the correct nutrition for endospore formation

The great resistance of the mature prokaryotic endospore to the penetration of chemicals is a property that can be used ______

for detecting them

The mature endospore has a _____ than the surrounding sporangium or vegetative cells. This property makes the endospores look very ____

greater density (mass per unit vol.); bright (refractile)

The most significant endospore characteristic is its resistance to ______; this is believed to be related to the dry, crystalline-like state of the mature endospore

high temperatures

The vegetative cells of Bacillus and Clostridium are only moderately resistant to ____, but the spores are extremely resistant

ionizing radiation

Endospores and free spores sizes are ____ enough to be seen with _____ microscope

large; a light microscope

You can quick freeze an endospore preparation by immersing a glass vial containing spore suspension in _______

liquid nitrogen and then freeze-dry (lyphophilize) the frozen block

You can force a dye to penetrate into a spore by raising the dye temperature to 100 deg C, like a dye called _____. However, the dye easily penetrates bacterial cells

malachite green

Mature endospores that are in a dry, crystalline state totally lack _____ so they resist drying by the environment

metabolic activity

To overcome problem of difficulty seeing endospore sporangium is by using a _____ microscope, which accentuates the differences in density between sporangium and ______, increasing the contrast between them

phase-contrast; suspending fluid

Most genera of bacteria that form endospores are _____ and _____

rod-shaped and gram-positive

It is difficult to see the surrounding sporangium of the endospore with a brightfield microscope because the sporangium density is ____ to that of suspending fluid

similar

After you perform a gram stain, cells with endospores appear similar to those that have been stained with ____

simple basic dyes - because all dyes used for gram stain are basic dyes

The phase-contrast microscope is helpful because _____ isnt necessary. You only need to prepare a wet mount to observe the cells in their growth medium. This avoids _____

staining; shrinking and distorting the cells during staining

Bacteria produce spores only at the ____ of exponential or rapid growth and also need _____

the end; need the correct nutrients

The only advantage of a Gram stain vs simple stain is you can check for two things at once:

the presence of endospores and the gram characteristics of the sporangium/vegetative cell

Once a mature endospore is formed, the rest of the cell surrounding it is called

the sporangium

Some spore-forming bacteria produce _____ that are poisonous to humans. Other spore-forming bacteria infect wounds and cause diseases such as _____ and _____

toxins; tetanus and gangrene

A cell that lacks an endospore

vegetative cell

Mature endospores contain much less _____ than vegetative cells

water

Malachite green is a ______ dye with a _____ positive charge that will not bind strongly to the surface or interior of the cell.

weak basic; weak

Dyes used for simple stains do not penetrate __(1)__. After you perform a simple stain, the __(2)__ is colored and the __(1)__ appears because of the absence of dye

(1) endospore, (2) sporangium

The most commonly encountered endospore forming bacteria by a beginning microbiology student are _____

Bacillus and Clostridium

The 5 common endospore-forming bacteria

Bacillus, Sporolactobacillus, Clostridium, Desulfotomaculum (all rod-shaped), and Sporosarcina (sphere-shaped)

If only a brightfield microscope is available, most rely on _____ or _____ stain to help detect endospores

Gram stain or simple stain

______ staining procedure is rarely used. Procedures for observing spores that are less time-consuming and less messy are the use of _________ to detect endospores and free spores

Malachite green; a wet mount and phase-contrast microscope

Endospore-forming bacteria are common contaminants on _____ because spores survive most natural stresses and commonly found on airborne dust particles

Petri dishes

If the resulting spore retains no visible evidence of the sporangium, it is called

a free spore

Various types of endospore-forming bacteria, usually rod-shaped, form endospores ______

at particular locations in the rod - central and terminal

After forcibly dying the bacterial endospore and the bacterial cell, it is difficult to remove the dye from ____ but easily washed away with water in _____

bacterial endospores; bacterial cells

_____ endospores from these bacteria are mass produced and produce toxins that kill insects, harmless to humans

bioinsecticides - the spore germinates inside the insect and the resulting vegetative cell produces a toxin that kills the insect

To be able to see a stained endospore inside a sporangium with a brightfield, the sporangium must be ____ with safranin or basic fuchsin

counterstained

As an endospore matures inside the sporangium, it becomes ____ and dries out

desiccated (loses water)

After forming an endospore, the sporangium may ______ and eventually _____

die ; disintegrate (cell lysis)

Neither the simple stain or Gram stain are a _____ spore stain because neither stains the endospore

differential

No dye will penetrate a bacterial ______ under normal environmental temperatures

endospore

_____ is a structure that is formed inside certain types of bacteria

endospore (endo - inside)

Microbiologists refer to all spores formed inside bacteria as _____ regardless of whether they are observed as free spores or surrounded by a sporangium

endospores


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