Explain what happened to the field of vision with an increased magnifications?
With an increase of magnifications the field of vision decreased. ( see smaller)
Explain the procedure for focusing a slide under 100x. Begin with 4X and include, how emissions oil is placed on a slide?
- Plug microscope
- Turn it on
- Clean the ocular lens
- Place the glass slide on stage clips
- Begin with the 4x by using the coarse objective lens
- Then 10x
- 40x by sing the fine adjustment knob
- Then switch for 100x add oil
- Then use the fine adjustment knob to help bringing the slide so it could touch with the 100x objectives lens
- Then observe using the ocular lens
Why is immersion oil use with the 100x objectives?
To refract the light and to see clearer and shaper
State function of the iris diagram?
To control the amount of light that that pass through the specimen.
Explain the difference between magnifications and resolution?
Magnifications is control the size while resolution control the clarity of how clear and sharpe you could see.
Defined the term of working distance?
The distance between the objectives lens ans the specimen
State what happen to working distance when magnification increases?
When magnification increase the working distance decrease. ( probably see a small portion ot the image )
Explain why you think the light microscope is important for Understanding the biology you are studying in this course, especially studying bacteria, algae, fungi and protozoa?
Because bacteria are to small to see with the naked eyes so we used light microscope for clarity.
There are various types of microscopes. Why are there are so many different type of microscopes and what specific observations can be made using the microscopes mentioned?
Because of the different bacteria structure for example some microscopes are use to see shape while others for movement
What information of other field of biology can be gained by studying bacteria?
We can utilities them for bio remediation and also we would be able to identify the pathogenic and non pathogenic bacteria and and what to used for treatment
Give an example of basic and acidic dye?
- Basic crystal violet
- Acidic India ink
Explain why basic dye are often used in microbiology?
Because bacteria are to small to see with the naked eyes so we use stains for contrasts and visibility
Defined bacteria cell morphology?
It the shapes, the size, the structure of a bacteria
Name three common bacteria shape?
- Bacillus
- Vibrio
- Spirochet
Explain the steps involved in preparing a smear front a broth culture. How would this procedure differ if a bacteria culture an agar slant was used?
The step for s broth culture
- Label
- Smear using sterile needle loop
- Air dry
- Heat fix
- Add crystal violet depending of the sty of Smear for 1 minutes
- Wash
- Add alcohol
- Wash
- Add safranin 30 second
- Wash
- Put inside bibulous paper
- Observe under 100x objectives
The difference between broth and crystal is that for agar would need to added water before Smearing while for the broth is already liquid it doesn't require to added water.
Why are Smear heat fixed prior to staining?
To kill and prepare the bacteria or for adherence into the glass slide .
Described the morphology of Staphylococcus aureus?
It will appear purple for gram staining with rod like shape cluster together
State one advantage or disadvantage of heat fixing bacterial smears?
- Advantage: they can adhere to the slide
- Disadvantage: distord or damage the cell
Described other ways. That microorganisms could be examined and identify beyond the techniques you perform in lab?
By using the DNA pylomorase methods
How do you think some of the earlier scientists discovered there were benefits or advantage to using certain dyes in order to stain cell they were observing under the microscope?
Through trial and errors
give an example of a gram positive rod ?
- Escherichia coli
- Staphylococcus aureus
Described the gram reaction and morphology of Staphylococcus aureus?
They are gram positive bacteria with cocci shape
Explain why iodine is used in the Gram staining procedure?
To help intensity the bacteria and also help it bind to the stain to form the crystal violet
Explain why it is necessary to use 2 stains crystal violet and safranin in gram staining?
Because of the different structure of cell wall for example gram-positive have a thick cell wall which make it hard to bind to the layer while gram negative have a thin cell wall
Explain gram stain is considered a differential staining procedure?
Because we used more than one fye and also it help differentiates into group base on their chemical reaction
State one factor that effect gram staining result?
Not properly Smear which result in the cell being damaged
How would a person who's colorblind go about interpreting gram staining results?
By suing a contrast magnification or by using a colleague.
If you want to observe colonies of S.marcescens, what form of culture medium would you used ? Explain why
I would used a solid agar because it help to observer the individual colonies
Why are the necks of test tube flamed during the aseptice transfer procedure?
To help sterilize and prevent contamination
Are there any situations where it would be important to study microbiology without using pure cultures? Provide an explanation for your answer
Yes because of their natural environment
Studies of Mycobacterium tuberculosis, the causative agent of tuberculosis, have recently been conducted by isolating the DNA of M. tuberculosis from patients. Explain the possible advantage and disadvantages of conducting studies in this manner?
- Rapid identification, improved diagnosis test
- Inability to study live bacteria
Explains in a series of step how to transfer a bacteria culture from an agar slamt to a test tube of nutrients broth?
- Prepared work place
- Sterile loop
- Open the agar
- Use Sterile loop with bacteria
- Transfer to nutrients broth
- Recap
- Sterile loop
- Clean up
Why it is important to become skills and efficient in aseptic transfer techniques?
Because it help ensure accurate results and maintenance safety and contamination
Name three source of bacteria contaminated
- Hands
- Unproper sterile
- Breath
E.coli is aseptically transferred into thbe of nutrients btoh and if incubation for 34 hourse at 37C . Describe the appearance of the tube indicating E.coli grew?
It would appear milky and cloudy
Defined the term colony?
A growth of visible cluster of bacteria living together
State one reason why acid fast organisms are hard to stain?
Because of their waxy lipid layer known as mycolic acid in the cell wall
Explain why acid-fast staining is considered a differential staining procedure. Your answer should be specific for acid-fast staining?
It difference between them is the cell wall
In the acid- fasting staining procedure performed in this exercise, how were mycolic acids solubilize so that the cells would absorb the dye?
In one of the experiment for the Staphylococcus aureus the bacteria was positive and it appeared of the color blue
Are mycolic acid soluble in acid alcohol or carbolfuchin ? Explain your answer
Mycolic acid soluble in carbolfuchin because of they cell wall that contain a hight amount of mycolic acid which make them hydrophobic
Explain why an acid- fasting procedure would be performed on a sputum sample?
More accurate result of detecting the bacteria
Name a bacteria that would stain red upon performing the acid' fast staining?
Mycobacterium tuberculosis
Name a hacterua that would stain green upon performing the acid- fast staining?
Mycobacterium smegmatis
Name a bacteria that is acid fast
Mycobacterium sgmegmatis
Explain the similarities and differences between acid-fast staining and gram staining?
- Both are important in microbiology
- The difference is they target difference structure feature of bacteria cell wall.
Sudan IV is a dye used to detect and stain lipids. Explain the differences in appearance between an acid-fast and a non acid-fast staining with Sudan IV?
The differences is the lipid content in the cell wall of acid fast which allow them to penetrate better in Sudan IV
State one reason why capsules are hard to stain?
Because they are water soluble and therefore do not retain stains
Name basic dye used in capsules staining?
India ink
Explain why capsule staining is considered a a combination of both simple and negative staining procedure?
Because we utilize a basic dye stain for the simple of the cell and acid dye for background of the cell
Name one bacterium that capable of producing a capsule ?
Klebsiella pneumoniae
State one way that capsule increase virulence of an organism?
Because it allow the bacteria to adhere to the surface and inhibits phagocytosis by the white blood cell
State difference between capsules and endospores?
- Capsule polysaccharides
- Endospores tough complex structure
Explain why a capsule inhibits phagocytosis
It make it harder for immune system to recognize it
Explain why a negative stain is prepared prior to heat fixing when performing a capsule?
To preserve the natural form
Capsule-producing bacteria tend to grow well and produce large capsule on skim milk agar. Why do you think this is so?
Because the nutrient promote bacetria growth and capsule production
State one reason why endospores are hard to stain?
Because of their chemical resistance
Name two genera of bacteria that can produce endospores?
Bacillus and Clostridium
Name the dye used to stain endospores?
Safranin
Why is stains endospores?
To lower the surface tension so that the dye can penetrate the endospore
If dipicolonic acid was removed from endospores what would happen?
It will not be able to resisted the heat
What would happens when too much steam is used during endospores staining?
It would result to inaccurate staining result
Why are endospores a concern for people that prepare home canned, non- acidic vegetable such as beans ?
Because it would result in contamination of the food which could caused illness
Endospores are sometimes describe as dormant cell. Explain why?
Because of of their protective structure and metabolic inactivaty
There are times when our drinking water become contaminated with bacteria when from raw sewage. When this happens, citizens are instructed to boil the water for a certain number of minutes to kill the bacteria do you think all the bacteria in the water killed?Explain your answer
Some of the bacteria are being killed, not all of them, because some have a layer of protective that made them able to live in harsh conditions
An autoclave is a piece of laboratory equipment used to sterilize laboratory and stream It surgical inc. Equipment and culture media, how it is possible for an orto clave to destroy tenderspoEquipment and culture media, how it is possible for an autoclave to destroy endospore?
By using high pressure steam, which able to penetrate that protective layer.
Explain the difference between optimal and maximum temperature?
- Optimal is the temperature an organism grow best in case environment temperature drop to minimum
- Maximum is the highest temperature organisms grow best.
Explain how temperature affect microbial Growth?
By slowing down microbial molecules functions, denature, solidify.
Classify the following organism as Psychrophiles, Mesophiles, Thermophiles?
- Normal flora of human small intestine
- A my microbe isolated from a glacier
- A microbe isolated from volcano
- Mesophiles
- Psychrophiles
- Thermophiles
Explain what will happen to a microbe if it grown 10° above its maximum temperature?
It could slow down the function of the microbe which could result in death .
Name a bacterium that is a Thermophiles?
Themus aquaticus
Give an example of a microbe that can grow in each if the following?
- Acidic environment
- Neutral environment
- Alkaline environment
- Sulfolobus
- Escherichia coli
- Cyanobacteria
Explain how PH affects microbial Growth?
Altered membrane transport, altered enzyme functioning, Changing protein gradient
An investigator finds that a particular microbe optimally grow at a ph of 4.5. Describe what would happens if the microbe is place in a ph broth of 2.5?
The growth rate would likely decrease
Explain why humans inhibit the growth of certain microbes?
Because the human skin ph is acidic, which create a favorite environment that benefits the microbe.
What class of microbes acidophiled, naturophile or Thermophiles will you most likely expect to grow in vagina of human females? Explain your answer
Acidophiles because those microbe thrive in those conditions.
Are there instruments that will be used to prevent alterations in ph that will inhibit microbial growth over time? Explain your answer
Yes for example ph meter which monitors and maintain stable ph and promote growth
A person regularly consume over the counter antacid ? Explain the effects this might have ob the normal flora of the digestive system
Altered the normal floral would likely to increase the stomach ph which can result over the growth of bacteria
Explain how solute concentration affect microbial Growth?
By affecting osmotic pressure and membrane lipid integrity
Explain the recent so can be used as a food preservative?
By reducing moisture and water activity
Explain the difference between a halophile and halotolerant organism?
- Halophiles is those organism that can't live hight salt concentrations
- Halotolerant is those organism that can't lived without it however grow better in it
Why do jams and jellies rarely become contaminated with bacteria or mold?
Because of the hight concentration of sugar which create a hypertonic environments for the bacteria to lived in it
A microbiologist inoculated, an extreme halophiles in nutrients both containing 1% NaCl and the tube is incubated and then examined. Predict what the microbiologist will see and provide an explanation for your answer?
Would likely to be observed limited or no growth microbe.
Explain the difference between an osmophile and halophiles?
- Osmophile high concentrations of sugar
- Halophiles is hight concentrations of salt
Name a bacteria genus that is halotolerant ?
Halothiobacillus neapolitanus
Name an extreme halophiles and a location on earth where extreme halophiles live ?
The ocean, lake
What adaptations od bacteria have in order to increase the water concentration inside their class when they are in an environment of hight solute concentration, such as existence in slat marsh?
They would likely exchange k+ to proton to keep osmosis balance
Is there any potential disadvantage to using high solute concentration as a sound food preservative?explain your answer
One would be health concern or alteration, calcium loss
What us the function of reassuring in thioglycollate broth?
To determine how various organisms tolerate oxygen
Described the concentration of oxygen throughout a tube of thioglycollate broth
The most will be at the top, some might in the middle, and no oxygen in the bottom
What does the anaerobes use the oxygen it requires for ?
For growth and their metabolic function
Why can a facultative anaerobes grow in the presence of oxygen but an anaerobes cannot?
Because of the capability and metabolic adaptation of the facultative anaerobes whole for anaerobes they can't because of their lack of protective mechanisms against oxygen
Defined the term microaerophile?
Those organism that need oxygen for growth and metabolic function while they are living and environment with lower oxygen
Name a microbe that is anearobes
Clostridium perfringens
Based on their oxygen requirement what type of organism would you expect to find in?
- A swamps
- The human gut
- Microaerophile
- Anaerobic
An instrument known as a Gas-pak is used to grow anaerobs. Explain how it work
It work generate hydrogen and carbon dioxide gas which remove oxygen from a seal container
For each of the type of organism listed, explain if it would grow in a Gas-peak?
- Facultaive
- Microaerophile
- Yes
- No
One of the treatment for gas gangrene is oxygen therapy. Explain why this treatment would be the effective to treat this disease?
By killing the growth of the bacteria which lead to death of the cell.