Bio Lab 1

Why are bacterial smears heat-fixed prior to staining? ( Multiple answers)

To prevent contamination

To keep bacterial cell shape

To prevent bacteria from distortion

To kill bacteria

To attach bacteria to the slide

To revive bacteria

To kill bacteria

To attach bacteria to the slide

A Gram-positive organism stains what color

Yellow

Purple

Green

Pink

Red

Purple

The function of the mordant in the Gram stain is to combine crystal violet , forming a large complex that will more likely be retained in gram ___ bacterial cell walls than gram ____ bacterial cell walls during decolorization.

Positive

Negative

A Simple Stain that stains the bacteria is called direct stain. What is the name of the simple stain procedure that stains the background of the slide and leaves the organism unstained as shown in the image below?

Gram Stain

Flagella Stain

Background Stain

Negative Stain

Endospore Stain

Positive Stain

Negative Stain

Staining of the bacterial capsule cannot be accomplished by ordinary staining procedures because..

A. capsules are non-ionic and therefore won’t take up stain

B. capsules are shrunken or destroyed by high heat

C. capsules are made of numerous layers of peptidoglycin and are therefore resistant to take up stain.

A and B are true

A, B and C are true

A and B are true

The capsule staining procedure involves both ___ staining which stains the bacterial cell and ___ staining which stains the background. The ___ then appears as an unstained halo around the cell.

Positive staining

Negative staining

Capsule

Match the 4 steps to the chemicals or dyes used in the Gram stain procedure.

Primary Stain

Mordant

Decolorizer

Counterstain

Primary Stain - Crystal Violet

Mordant - Grams Iodine

Decolorizer - Ethyl Alcohol

Counterstain - Safranin

Primary dye for the Spore Staining is ____ and Counterstain is ____.

Malachite Green

Safranin

In the picture below round-shaped bacteria (cocci) are gram ___ and rod-shaped bacteria (bacilli) are gram ___.

Positive

Negative

( image color purple)

An acid fast bacterium stains a ___ color and a non-acid fast organism stains a ___ color.

Pink

Blue

( bright pink/red)

When performing a streak plate you should incinerate your loop between each section.

True

False

True

Endospores are extremely resistant to taking up stain, ___ is used in staining procedure to help drive stain into the endospore.

Water

Force

Vigorous smearing

Heat

Methanol fixation

Heat

___ involves the insertion of a gene into an organism’s genome in order to change the organism’s trait.

DNA mutation

Protein transformation

Genetic transformation

Species evolution

Genetic transformation

In pGLO transformation lab, a small circular piece of DNA that naturally occurs in bacteria was used as a vector to move genes from one organism to another. What is the name of this naturally occuring piece of extra chromosomal DNA?

Transformer

Transcript

Chromosome

Gene

Plasmid

Plasmid

Shown below is the setup of the transformation expirement. Indicate on each plate below what the results would be from a successful transformation.

WG

NG

WG

GG

Simple stains are commonly used to determine:

Cell size, arrangement, and gram reaction.

Cell size, arrangement, & presence of endospores.

Cells size, shape, and arrangement only.

Cell size, shape, arrangement, and presence of a capsule.

Cell size, shape, and arrangement only.

What is the function of the “streak plate” method? Why can’t bacteria be identified/tested directly from a broth?

The function is to get isolated colonies of bacteria; there are too many bacteria in the broth.

The function is to get isolated colonies of bacteria; one cannot tell if a broth contains a pure culture or if it is mixed/contaminated.

The function is to dilute out the bacterial until no growth is observed; there are too many bacteria in the broth.

The function is to dilute out the bacteria until no growth is observed; one cannot tell if a broth contains a pure culture or if it is mixed/contaminated.

The function is to get isolated colonies of bacteria; one cannot tell if a broth contains a pure or if it is mixed/contaminated.

The gene for GFP in the pGLO plasmid can be switch on in transformed cells by adding ___ to agar media.

Arabinose

Magic potion

UV light

Glucose

Antibiotics

Arabinose

Observe the image below, point “A” in the image showing a halo is pointing ___ and point “B” in the image (stained) is pointing to ___.

Capsule

Bacterial cell

The E. coli bacterium is naturally competent to uptake DNA.

True

False

False

In Endospore staining, after the decolonizing step, the endospores will be ___ in color while the bacterial cells will be ___ color.

Green

Colorless

Assume you stain bacillus by applying primary stain with heat which stains green and then counterstaining with dye which stains red. Through the microscope, the green structures in the image marked as “A” is (are) ___ and the red structures in the image marked as “B” is (are) ___.

Endospores

Vegetative cells

A student is looking at a bacterial specimen using the oil immersion lens but has forgotten to put immersion oil on the slide. The specimen will appear.

The same as it would if the immersion oil was used.

Smaller than it would if immersion oil was used.

Somewhat fuzzy and have poor resolution.

Larger than it would if immersion oil was used.

To have no color.

Somewhat fuzzy and have poor resolution.

Which of the following is not true regarding the acid-fast stain?

Non-acid fast microbes appear blue in a completed acid-fast stain.

Acid-fast cells appear red/pink in a completed acid-fast stain.

Acid-fast cells retain the primary dye after treatment with acid-alcohol.

Acid-fast cells will lose the primary dye after treatment with acid-alcohol.

Acid-fast cells will lose the primary dye after treatment with acid-alcohol.

Which of the following are the correct reasons for incubating the petri plates upside down? (Multiple answers)

To prevent bacteria from growing on the lid

To prevent condensation from directly falling on the bacterial colonies which could cause contamination from the lid.

Only fungal plates are incubated upside down.

To prevent colonies from mixing with each other due to moisture which interferes with colony counting or isolation.

To prevent condensation from directly falling on the bacterial colonies which could cause contamination from the lid.

To prevent colonies from mixing with each other due to moisture which interferes with colony counting or isolation.

Name the part of the microscope colored orange ocular lens. Name the part of the microscope that is colored blue object lens. Name the part of the microscope that is colored yellow course focus. Name the part of the microscope that is colored green iris diagram.

Ocular lens

Objective lens

Coarse focus

Iris diaphragm

Oil can be used on both the 40x and. -00x objectives.

True

False

False

Which in the micro lab, you are required to follow lab safety guidelines all the time. Which of the following lab safety rules are NOT to be followed.

You are always required to wear fives while working with bacteria.

Always clean your work with bleach and wash your hand when entering and leaving the lab.

Always knew your books and backpacks in the assigned cubicles and not on the bench tops.

When working with bacterial cultures for preparing slides you can have microscopes out and can use them at the same time, this will save you time.

You are always required to report all accidental cuts, burns, broken culture tubes, spilled culture et

Eating and drinking is allowed in the lab as along as open cultures are not in the bench top.

when working with bacterial cultures for preparing slides you can have microscopes out and can use them at the same time, this will save you time.

Eating and drinking is allowed in the lab as long as open cultures are not on the bench top.

If you happen to spill a bacterial culture on the floor during lab, which of the following in lab safety rules are NOT correct while following the steps for cleaning?

Immediately cover the spilled culture with disinfectant and paper towels.

You do not have to notify your instructor/lab IA

The paper towels and disinfectant over the spilled culture should be let to sit for at least 15 mins.

You dispose the paper towels over the spilled culture into a regular trash can.

Steps 1, 3 should not be followed

Only step 4 should not be followed

Only step 2 should not be followed

Steps 2, 4 should not be followed.

Steps 2, 4 should not be followed.

You are working with a culture of BSL-2 bacteria. What is NOT appropriate PPE for working with this biosafety level?

Gloves

Closed to shoes

Goggles

lab coat fully bottomed with sleeves rolled up to just past your elbows

All hair tied back securely with no sections of hair falling near the face.

Pants or if wearing shorts lab coat should go to the knees.

Lab coat fully bottomed with sleeves rolled up to just past your elbows.

When focusing with high dry and oil lenses it is okay to use the course focus knob.

True

False

False

Most modern microscopes are Parfocal, that is, an object in view under one objective will still be in view under the other objectives

True

False

True

Match

Ocular lenses

Objectives

Iris diaphragm and condenser

Condenser knob

Fine focus knob

Coarse focus knob

Mechanical stage adjustment knobs

Ocular lenses- magnify the image, usually 10x

Objectives - magnify the image usually 4x, 10x, 40x and 100x

Iris diaphragm and condenser - focus and regulate the amt of light reaching the specimen.

Condenser knob - raises and lowers the condenser to focus light on the specimen.

Fine focus knob - slowly brings the specimen into sharp focus.

Coarse focus knob - rapidly brings the specimen into gen focus.

Mechanical stage adjustment knobs - move the slide L/R and forward/backward in the stage.

This image of E. Coli was taken using the 100x lens which is also the __ lens. The microscope had a 10x ocular and a 15x ocular camera was used. What is the total magnification.

Oil immersion

1500x

Dinoflagellates and diatoms are commonly known as as ___.

Mushrooms

Fungi

Mold

Tapeworms

Plankton

Plankton

Match

Cyst

Endospore

Dimorhic

Hyphae

Yeast

Trophazite

Cyst - a resistant dormant stage.

Endospore - a highly resistant dormant structure.

Dimorphic - a fungus able to exist in two forms.

Hyphae - long, thin, microscopic filaments.

Yeast - unicellular fungi that reproduce by budding.

Trophazite - the active feeding stage.

To what genus does this organism belong?

Saccharomyces

Plasmodium

Rhizopus

Penicillium

Coprinus

Penicillium

The red arrow is pointing to the ___ and the blue arrow is pointing to the ___. The common name of this organism is ___.

Basidiospores

Basidium

Mushroom

These organisms are found in aquatic environments, have cell walls made of silica, and are known as.

Fungi

Diatoms

Dinoflagellates

Archaea

Diatoms

Name the genus of this organism. ___ A is a trophozoite. B is a ___.

Giardia

Cyst

The common name of this worm is ___ and the structure at the end of the arrow is ___.

Hookworm

Teeth (cutting plate)

A is a/an erythrocyte an B is a/an ___. The disease caused by the organism is ___.

Erythrocyte

Plasmodium parasite

Malaria

This organism belongs to the kingdom ___ and the genus ___. A is pointing at ___ and B is pointing at tentacle.

Fungi

Rhizopus

Sporangium

Sporangiophore

The female worm is ___. The male worm is A. The black arrow is pointing to the ___.

B

Vulva (Genital pore)

Name the genus of this organism___. These organisms are commonly known as ___.

Taenia

Tapeworm

The structure indicated by the brackets “A”is the ___. The structure indicated by arrow “B” is ___.

Scolex

Hooks

What is a colony and how does a colony relate to a bacterial cell?

Of the same species.

Have some genetic identity.

Originate from the flow bacterial cells.

Just one microorganisms.

A group of microorganisms.

Originate from one bacterial cell.

Have different genetic identity due to mutations.

Of the different species.

Of the same species

Have the same genetic identity

A group of microorganisms

Originate from one bacterial cell

How many types of microbe colonies are present on each of the plates?

1

2

Crystal violet is a basic dye, it has a ___ charge and congo red is an acidic dye, it has a ___ charge. Since cell membranes have a slightly negative charge, ___ would stain the bacterial cell and ___ would stain the background.

Positive

Negative

Crystal violet

Congo red

Why do you sterilize the loop between streaking each quarter of the plate?

The bacteria needs to be warmed to boost growth.

To kill all bacteria on the plate.

To prevent and epidemic.

Reduce the number of bacteria in each starter of the plate.

Reduce the number of bacteria in each quarter of the plate.

What is the name for the technologies that must be followed when working with microorganisms in order to prevent the accidental or in arverted spread of microorganisms beyond the intended working environment? ___ technique.

Septic

Sterile

Safe

Aseptic

Proper

Aseptic

It’s okay to set caps and lids down while performing an aseptic technique.

True

False

False

Colony morphology refers to the colors and shapes of the bacteria that are seen when observing the bacteria through a microscope.

True

False

False

Under de-colorization would result in all bacteria appearing gram-negative and over-decolonization would result in all bacteria appearing gram-positive.

True

False

False

What type of paper only should you use to clean your microscope lenses?

Kimwipes

Lens paper

Paper towel

Kimtech

Lens paper

What is the function of the revolving nosepiece?

Is used to regulates to amount of light on the spicemen.

Is used to support the microscope when carried.

Holds the slide.

Holds the objectives, can be rotated to change magnification.

You look through to see the specimen.

Supports the slide being viewed.

Holds the objectives, can be rotated to change magnification.

The area that can be seen through the experience of a microscope is the ___.

Working distance

Magnification

Image

Field of view

Specimen

Aperture

Field of view

You have a specimen in focus, with the 10x objective, you now switch over to the 40x objective but the image is a little blurry, what do you need to do to get the image clearly focused?

Lower the condenser

Turn the light down

Use the fine focus knob

Switch back to the 10x objective

Switch to the 100x objective

Use the coarse focus knob

Use the fine focus knob

How long is the minimum recommended time for washing hands?

1 minute

Couple hours

30 seconds

10 seconds

20 seconds

20 seconds

Proper hand washing technique is not necessary when you simply get soap all over your hands.

True

False

False

When scraping bacteria using an inoculation loop/needle from a plate or slant, it is important to get as much bacteria as possible on the loop/needle in order to get a successful subculture transfer

True

False

False

Provide the reasons why the use of the aseptic technique is essential when handling microbial cultures in the laboratory. Mark all that apply.

So that no contaminants are introduced into cultures.

So that inoculated culture remains sterile.

So that individual performing the lab work does not contaminate themselves.

So that mixed cultures are never grown.

So that work environment remains sterile.

So that the individual performing the lab work does not contaminate their environment.

So that no contaminants are introduced into cultures.

So that the individual performing the lab work does not contaminate themselves.

So that the individual performance the lab work does not contaminate their environment.

One should hold tubes at an angle whenever the cap is off.

True

False

True

Why must the inoculating loop be cool before touching it to a culture? ___. Should you set in down to let it cool?__.

So I does not kill the culture

No

If you omit the Gram’s iodine step while performing the gram stain, Gram positive cells will most likely be ___ in color.

Red/pink

Green

Purple

Clear

Red/pink

How does the smear preparation of cells from a liquid medium differs from the preparation of cells from a solid medium?

Bacteria is first smeared onto the slide then water is added.

The bacteria is emulsified in a drop of water when taken from a solid medium, but not from a liquid medium.

Stain is applied to the cells in the culture tube and then they are applied to the slide.

A needle is used instead of an inoculating loop.

The bacteria is emulsified in a drop of water when taken from a solid medium, but not from a liquid medium.

Which lab was the most difficult for you? Explain

The most difficult lab for me was the Gram staining lab. It required several steps that had to be done carefully and in the correct order. I found it challenging to apply the stains for the right amount of time and avoid washing them off too much or too little. Interpreting the results under the microscope was also difficult because some cells did not stain as clearly as expected. This lab taught me the importance of following procedures closely and paying attention to details. Even though it was challenging, it helped me improve my microscope skills and better understand the differences between Gram-positive and Gram-negative bacteria.