micro bio exam 1 LAB HW

After completing an experiment, all chemical and biological wastes should be

disposed of according to instructions provided in the lab experiment.

what type of flagella is shown? (has 4 tails)

lophotrichous

select all these that are features of prokaryotes in domain bacteria

may be pathogenic to humans inhabit extreme environments cells generally lack membrane bound organelles cell membranes of unbranched fatty acid chains cell walls contain peptidoglycan

Students enrolled in Microbiology are required to pick up a lab kit from the campus offering the course and also need to purchase a microscope and provide common household items to complete the lab experiments. (Down complete list of materials embedded in Lab 01)

true

Students should wash their hands with soap and water before and after every lab exercise.

true

age of a bacteria culture, temp the culture is grown at, and nutrient availability may influence the quality and amount of pigment thats produced by the bacterium

true

During the virtual microscope tutorial (https://depts.washington.edu/vurchin/index.php?view=mictutl) what new details are you able to see on the slide when the magnification is increased to 10x that you could not see at 4x? What about at 40x?

At 4x no individual cells can be identified, while at 10x you can make out individual cells and stained nuclei. At 40x you can make out more fine details of the cells and the shape of the stained nuclei. At higher magnifications you have a smaller field of view, so you're now seeing a more limited portion of the specimen. Also, remember that the specimen on your slide has a thickness, even though it looks very thin. As you adjust the focus, you're actually focusing on different layers of the specimen, an effect exaggerated at higher magnification. Think of the specimen as being as thick as your classroom. Then, you could be focusing variously on the ceiling, the desktops, or the floor. The "depth of field" is the portion currently in focus.

List two factors that may influence bacterial pigment production.

Bacterial pigment production may be influence by age of the culture, temperature at which it is incubated and nutrient availability.

Which of the following indicates the greatest risk?

Blue 3, Red 4, Yellow 3, White W

characteristics of eukaryotic cells

DNA in a nucleus that is bounded by a membranous nuclear envelope membrane-bound organelles cytoplasm in the region between the plasma membrane and nucleus

Match the following terms to the best description.

Ability to see two separate objects as discrete entities B. resolution B. resolution Distance between the slide and the tip of the objective lens E. working distance E. working distance Lens that stays in focus when magnification/focal length is changed A. parfocal A. parfocal Image that is observed when looking through the ocular lens C. virtual image

You washed your hands before beginning the experiment. While completing this experiment you wore all PPE (gloves, goggles and lab coat). You set up the experiment exactly as described in the protocol. You incubated your samples in your home incubator. Following analysis of bacterial growth on the petri plates you discarded them directly into the trash. You washed your hands when the experiment was complete.

All cultures must be disinfected with bleach prior to disposal.

List a minimum of four safety procedures that should always be adhered to when working with microorganisms.

Answers may include: •Wear personal protective equipment at all times during experiment (gloves, safety goggle, lab apron) • Wash hands with soap before and after each experiment • Do not eat. drink, chew gum, or smoke while performing an experiment • Do not put anything in your mouth while performing an experiment • Work on a non-porous surface • Avoid working over carpets and rugs • Disinfect your work are with isopropyl alcohol or 10% bleach after experiments • Extnguish flames before using isopropyl alcohol • Always use sterile equipment • Wear closed-toe shoes • Always read the experiment thoroughly before beginning • Tie back long hair • Do not wear dangling jewerly • Do not mouth pipette • Label all containers and cultures clearly • Immediately cover spills with a disinfecting agent • Never pick up broken glass with bare hands • Disinfect all microbes prior to disposal • Hold lab tools tip down while sterilizing

Describe the qualitative difference you notice with the different types of microscope views in the "Microscope Compare" and "Specimen Compare" exercises. (https://depts.washington.edu/vurchin/index.php?view=miccomp)

Answers may vary. The scanning electron microscope will make much more fine details on the samples visible. The confocal microscope will provide fluorescent images showing individual structures. The Nomarsky optics will give a good general appearance of the sample. The transmission electron microscope will give a much higher magnification. The phase contrast microscope will visualize features such as cell borders. The polarized light microscope will make ordinarily clear parts of the sample highly visible. The fluorescence/epifluorescence will illuminate certain proteins. Dark field provides an image with high contrast between the subject and the background.

List two safety precautions that should always be adhered to while using an open flame in the lab (Bunson burner or candle).

Open flame is obviously a safety hazard and must be given due respect. Make sure your work area is clear, organized, and free from flammable materials. Be sure to remove any dangling or loose clothing and tie back long hair before using the Bunsen burner. Never leave a flame unattended. Push the burner/candle towards center of bench or work area, away from all flammable materials (alcohol). When heating a substance in a test tube, point the mouth of the test tube away from yourself and other people. Always keep your head and clothing away from the flame. Never look directly into a container being heated. If using a Bunson burner: The gas should only be turned on just prior to lighting flame. Make sure you have your flint in hand before turning on the gas. Make sure the chemical exhaust hood is open before lighting the Bunsen burner. Make sure the gas is completely off when done working with the burner. When turned off, the lever is at a 90o angle to the gas nozzle.

Develop a hypothesis relating to the pH level of the culture media and the number of bacterial colonies observed in each culture.

Responses will vary. Possible Hypotheses: If the pH level of the growth media is too low, then most microorganisms will not be able to survive and grow.

What type of microscope would likely be used to examine the surface of human papilloma virus?

Scanning electron microscope

Match each microscope component to the correct description.

Supports the slide or material being viewed h. Stage Adjusts the level of light e. Iris diaphragm Used with scanning power objective to make large adjustments in focus i. Coarse adjustment knob You rotate the nosepiece putting these in place to increase the magnification g. Objective lens Supports the revolving nosepiece and ocular lens d. Head Illuminates the specimen b. Light

Which of the following best describes the colony morphology shown here?

Tan, large, circular, entire, umbonate, mucoid, opaque

A study is being done to test the effects of temperature on the number of microbial colonies. Four different incubators are set up, each at a different temperature with one culture plate in each. Each plate has the same nutrient content, pH, and are inoculated with microorganism samples from the same source. At the end of the experiment, the number of colonies on each plate is counted. What is the independent variable?

Temperature of the incubator

Before inocualtion with Pseudomonas aeruginosa this TSA slant had a light yellowish color. Now the agar is green. What accounts for the color change?

The bacterium secretes a green diffusible pigment (pyocyanin)

Which rule does NOT need to be followed during an experiment for results to be valid?

The experiment must be performed in a laboratory.

After removing the cap from the culture tube it is recommended that the neck of the tube is briefly passed through the flame of the Bunsen burner or held up to the incinerator for several second. What is the purpose of this step?

This creates an upward movement of airflow out of the tube that prevents airborne contaminants from traveling into the tube from the outside air

What is the purpose of a control?

To account for changes on the dependent variable that might occur from factors other than the independent variable.

a) Explain why the work environment (i.e. counter) should be decontaminated at the beginning and end of each lab experiment. b) Describe how to decontaminate the counter and work environment.

Wipe your lab bench with germicide before AND after each lab exercise/experiment. Always work on a spill absorbent pad. Let the germicide air dry as it does not kill instantaneously. Contact time is the length of time a germicide is in contact with a surface, and increasing contact time will improve disinfection. In the at-home lab, follow the directions on the label of your disinfectant. If you have a spill of a biohazard (live culture), drench it with germicide (10% bleach solution or other commercial disinfectant), cover with paper towels and let it sit for a minimum of twenty minutes before cleaning it up.

Select ALL of the TRUE statements regarding safety in the lab. (Mark all that apply)

Work in a well ventilated area and monitor laboratory exercises at all times. c. Do not eat, drink, chew gum or smoke while completing lab exercises. e. If there is a fire, evacuate and immediately call 911.

a. How was the letter e different when viewed through the ocular lenses than it was written on the glass slide? b. Which direction did the image move when the slide was moved right? What is the practical significance of this?

a. The letter e was upside down and reversed. The mirrors in the microscope flip and reverse the image before it reaches your eyes. This is called the lens effect. The image that you see is a virtual image. b. When you move the stage to the right, the image viewed through the ocular lens appears to move to the left, and vice versa. If looking at a motile organism and it appears to be moving left it is really moving right. This becomes significant when viewing a live specimen. If a motile organism appears to be moving towards you it is actually moving away from you. Thus, you will need to move the specimen opposite of what you are seeing to keep it in the field of view.

how would you classify this stain which is differential for mycobacteria species

acid fast (+)

select all of the true statements regarding proper aseptic culture technique

all tubes and plates should be labeled before any transfers are made when flaming a loop, begin at the base then slowly pull loop through flame until it is red hot after removing the cap of the culture tube, keep it in your hand facing down to minimize risk of contamination

what type of flagella is shown? (has 1 tail on each end)

amphitrichous

what type of flagellar arrangement is shown?

amphitrichous

Which document must employers and educational establishments make available upon request to advise people of potential hazards and necessary first aid procedures for a given substance?

an SDS sheet

an inoculating needle is typically used to subculture bacteria to which type of medium?

an inoculating needle is used for inoculating an agar deep. the agar deep medium is stabbed, not streaked. this technique is used in some biochemical tests to place the bacteria within the medium, rather than on the surface

If you do not understand a direction or part of a lab procedure, you should

ask instructor before proceeding

Approved eye protection devices (such as goggles) are worn ...

at all times while working in the lab

Clinical microbiology is an interdisciplinary science. Which of the following fields are represented in clinical microbiology? (Mark all that apply)

b. Molecular biology d. Microbiology e. Immunology f. Pharmacology

Select ALL of the TRUE statements regarding microscopy. (Mark all that apply)

b. Because most cells and microorganisms are somewhat transparent, dyes and stains may be used to help visualize them or differentiate cellular features. e. When cleaning a microscope lens you should use only lens paper in order to avoid scratching the lens. f. A monocular microscope has a single ocular eyepiece.

which of the following is a common reason to inoculate a culture onto a slant rather than into a broth

because you intend to store the culture as a stock culture in the refrigerator for several weeks

Which NFPA symbol color indicates the health risk?

blue

what term describes a single bacterium that is oval in shape?

coccus/ cocci

enriched media

contain chemical nutrients to support the growth of fastidious heterotrophs

selective media

contain chemical substances that inhibit growth of one group or species of bacteria while encouraging another group or species of bacteria to grow

differential medium

contains chemical indicators that allow the microbiologist to distinguish between two or more groups or species of bacteria

correct order of gram stain

crystal violet iodine decolorizer safranin

after an experiment, all chemical and biological waste should be

disposed of according to protocol in the experiment

find the effect of the following mistakes made when preforming a gram stain

failure to apply colorizer- will look gram positive (purple) failure to add iodine- will look gram negative (pink) reversal of crystal violet and sarafin- will look gram positive (purple) over decolorization- will look gram negative (pink)

Washing hands with soap and water sterilizes the skin.

false

handwashing removes all bacteria from the skin

false

nfpa diamond: red

fire hazard 0- no danger (will not burn) 4- extreme danger (below 73 degrees f)

Which of the following is inappropriate personal protective equipment to be worn while working in the lab?

flip flops

which of the following best describes the bacteria in this image

gram positve streptobaclili

nfpa diamond: blue

health hazard 0- no hazard (normal material) 4- extreme hazard (deadly)

pure culture

is an artificial situation in which only one species of bacteria has been isolated from all other species

what type of stain is shown here

negative stain

Was the culture used to inoculate the plate shown here a pure culture? (red and yellow streaks on augar plate)

no

characteristics of prokaryotic cells

no nucleus DNA in an unbound region called the nucleoid no membrane-bound organelles cytoplasm bound by the plasma membrane

when shifting from 4x lens to 40x lens only fine focus will be needed to resolve image. what is this an example of?

parfocal

what type of flagella is shown? (has flagella all over)

peritrichous

If a chemical or a biological sample splashes on your skin, wash at once with

plenty of water.

gram postive stain color

purple

nfpa diamond: yellow

reactivity 0- stable 4- might detonate

select all of these that are non-membrane bound organelles found in prokaryotic cells

ribosome

nfpa diamond: white

specific hazard (acid, alkali, corrosive, oxidizer, no water) 0- no danger 4- extreme danger

what structure of a compound light microscope does light pass through just before entering your eye?

the ocular lense

when viewing a specimen when the 10x objective lens on a compound microscope with a 50x magnification, what is the total magnification

500

If you are using a compound microscope with an ocular lens with a magnification of 10x and an objective lens of 25x, what is the total magnification of the sample?

250x

gram negative stain color

red