Micro Lab

88 cards·by nataliejai

Explain the difference between magnification and resolving power

Magnification is the enlargement of the visual picture of a specimen. Resolving power deals w/ the resolution where objects are still distin

What is the limiting factor of a light microscope

Resolving power

Explain the relationship between working distance and magnification

As the magnification increases, working distance increases

Why must oil be applied to achieve max resolution?

At max res. Optimal light intensity is required. Oil concentrates the light and prevents it from being refracted out of the ocular lens

Total magnification =

Ocular lens x fixed magnification

Which lens requires the maximum amount of light and why

The 100x, because the greater the magnification, the more light intensity is needed to achieve resolution

Total magnification of a compound microscope using oil immersion is?

1000x

Who was the first person to observe living organisms under a microscope

Antwon Van Leuhook

It is unnecessary to use coarse adjustment knob after changing from one objective to another because our microscopes are….

Parfocal

Circle all that applies it is possible to obtain greater resolution by…

(increasing wavelength, decreasing wavelength, increasing numerical aperture, decreasing numerical aperture)

What is a pure culture?

contains only organisms from a single genus and species

Why all media and equipment should be sterilized.

Equipment must be sterilized in order to kill natural-occurring microorganisms that may contaminate the experiment

Define aseptic or sterile technique

Aseptic sterile technique – must be sterilized in order to kill natural-occurring microorganisms that may contaminate the experiment

question

A Gram stain is of greater value to the microbiologist than a simple stain because it not only enables microbiologists to see bacteria but d

Why is Iodine used in the Gram stain

Iodine is used in Gram stain as a mordant and has no staining properties. It creates a complex with the crystal violet and is used to determ

Which two organisms Acid-fast staining is clinically important?

Mycobacterium tuberculosis, Mycobacterium leprae

Why young cell is more desirables than old cells in the Gram stain?

older Gm+ cells are subject to autolysis, which is the breakdown of cell structures due to enzymes released by age. This can give a false Gm

Name the three most common methods for isolation of pure culture.

Spread plating Streak plating Pouring over the plate

Culture media and glassware are sterilized in an autoclave at

121 C/ 15 lbs of pressure

The proper nutrients for bacterial growth should include

carbohydrates, proteins, lipids, vitamins

Why do bacterial cells sporulate?

Bacterial cells sporulate because this increases the chances of survival of the bacterial cell. Sporulation increases the number of “childre

Why are endospores difficult to stain?

Endospores have dipicolinic acid and calcium ions present in the cortex. This forms calcium dipicolinate which makes it difficult to stain t

What is the main physiological difference between the Bacillus and Clostridium genera?

Bacillus are aerobes Clostridium are anaerobes

Why do negative stains color the background rather than the bacteria?

Capsules are hard to stain because of their resistance and low permeability. They color the background because it will show the presence of

Give two reasons for capsule formation by bacteria

Potential energy/food reserve when it is not available Phagocytosis protection Helps w/ bacterial virulence

What is the chemical composition of capsule?

The chemical composition of the capsule is glycocalyx. It is usually a polymer made of polysaccharides or polypeptides.

Why motility might be of value to a microbe?

Motility can help microbes run from a threat such as another microbe or chemical. It can also help with finding energy, food source, water,

How will you distinguish between motility and Brownian motion?

Motility is movement in a consistent path. Brownian motion is a movement that is irregular and jerky. Brownian movement is not really moveme

To which structure(s) of the cell are the flagella attached?

Flagella are attached to the cell membrane and cell wall. The rings in the basal body are attached to the cell membrane, while the hook and

List the various arrangements of flagella

Monotrichous - single flagellum Lophotrichous - multiple flagella from one pole Peritrichous - multiple flagella all around the cell Amphi

What is the chemical equation for aerobic respiration?

C6H12O6 + 6O2 → 6CO2 + 6H2O + energy

During Fermentation, organic molecules are the electron acceptors, which results in incomplete oxidation of carbohydrates and various other

Acids, aldehydes, and alcohols….. Methane, carbon dioxide and hydrogen

In lactose-fermenting organisms, what is lactose broken down into? What are the two enzymes that these organisms often possess and their fun

B- galactosidase: breaks down lactose Lactose permease: transports lactose into the cell Products are galactose and sucrose

What test would you perform to check for acid production and for gas production during carbohydrate fermentation? What will you see if your

Using phenol Red carbohydrate test (red if alkaline, yellow if acid) and a durham tube for gas production

What test would you perform to determine how carbohydrates are broken down? List the predicted results for each type of metabolism for each

Oxidative fermentative test

What are two ways that selective media are used to isolate or identify particular organisms?

answer

How do differential media differ from selective media?

answer

Differential selective medium used to differentiate between lactose-fermenting organisms?

answer

Selective medium used for the isolation of Staphylococcus and Streptococcus organisms in samples where gram - organisms are commonly found.

Columbia CNA agar

Differentially selective medium used for the identification of Salmonella and Shigella organisms

answer

Differential medium used for the identification of Gram- enteric pathogens

Triple Sugar Iron Agar

Differential selective medium used for isolation and enumeration of coagulase positive staphylococci from food

Baird Parker Agar

Differentially selective medium used for the detection and isolation of gram negative intestinal pathogens

Eosin Methylene Blue

Selective medium used for the isolation of staphylococcus and streptococcus organisms in samples containing coliform organisms such as E. co

Phenylethanol Agar w/ blood

Selective medium used for the isolation of Staphylococcus organisms since it contains 7.5% sodium chloride which favors their growth but dis

answer

Differentially selective medium used for the detection and isolation of dysentery, typhoid, and paratyphoid organisms

MacConkey’s Agar

Differentially selective medium used for isolation of pathogenic staphylococci

answer

Differentially selective medium used for the isolation and ID of oral streptococci

Mitis- Salivarius Agar

IMViC stands for International molecular victim in concern

answer

Which organisms are identified using the IMViC tests and where are these usually found innature?

Escherichia coli and Enterobacter aerogenes are both identified with IMViC test. E. Coli is found in the intestinal tracts of humans and ani

Some organisms are capable of degrading the amino acid ________ to indole. Which reagent do you use to test for this and what is the result

= Lysine, methyl red Tryptophan The reagent used for this is Kovak’s reagent. If there is indole present then there will be a small layer of

In the methyl red test, what are the two types of results that you can obtain by growing organisms from Question #2 in a glucose broth? What

The two types of results are either a red color or a yellow color. E. Coli will degrade glucose into dextrose. E. aerogenes will turn glucos

Some organisms are able to use citrate as a carbon source, which is useful to differentiate between the organisms from Question #2. Which of

E. coli is unable to use citrate because it does not have the proper electron carrier molecules to transport the citrate into the cell

The catalase test is used to determine whether an organism can utilize oxygen. What do most organisms produce in the presence of oxygen and

= most organisms produce CO2 and/or H2O the catalase breaks down to a nontoxic form:H2O and oxygen

What is meant by decarboxylation, what are the enzymes that decarboxylate lysine and ornithine, and what are the resulting compounds for eac

answer

The oxidase is used to identify organisms that possess one particular enzyme of the electron transport chain, ________. Briefly describe the

Cytochrome oxidase The Kovak oxidase test is used. This is dimethyl-p-phenylenediamine with alpha-naphthol. It is spread across the sample a

Which two genera are differentiated from other Gm- organisms by using the phenylalanine test?

Proteus Providencia

Draw the chemical reaction that describes the function of urease?

NH2CONH2 → 2NH3 + CO2↑ Ammonia is produced and results in a pink color of pH is 8.1 is higher

What is the first test that you would want to perform to identify an unknown microorganism? Explain the test.

Perform a gram stain, showing either a pink (negative) or a violet/purple (positive) stain

What is an enzyme

A molecule composed of proteins that, when activated, speeds up a chemical reaction

What is the main purpose of extracellular enzymes and what would happen if they failed in their purpose? What are the 3 types?

Main purpose of extracellular: break down large macromolecules such as proteins, starches, and lipids, to their broken down components so th

What are the two main purposes of intracellular enzymes?

To either dissimilate (breaking down nutrients as energy), or assimilate (building up components/materials) out of smaller molecules

What are the differences between fastidious and nonfastidious organisms in terms of diet, enzyme system, and waste products?

Fastidious: many complex enzymes, very narrow/select diet, few waste products Nonfastidious: a few enzymes (simple), wide diet, many waste p

Rank the following in order of increasing energy production (3 is highest) :anaerobic respiration, aerobic respiration, and fermentation.

3-aerobic respiration 2-anaerobic 1-fermentation

According to the manual, what is the central compound in the conversion of carbohydrates into energy, and how is it useful in the ID of an o

Pyruvic acid, depending on whether it is an aerobe or an anaerobe, it will ferment or be used in the Krebs Cycle

What is the conversion of a six-carbon sugar, such as glucose into a three-carbon molecule

Glycolysis

What are the final hydrogen/electron acceptors in aerobes, anaerobes, and fermenters?

The final hydrogen/electron acceptors in aerobes, anaerobes, and fermenters are either oxygen nitrate, sulfate or phosphate Aerobes:oxygen,

List the three compounds that anaerobes can reduce nitrate (NO3) to

NO2 & N (g)

What is osmosis?

= Osmosis is the movement of water across semipermeable membranes. It moves in and out of cells depending on whether or not it is hypotonic

What will happen to a bacterial cell w/ a semipermeable membrane if it is placed in a flask of distilled water (hypotonic solution)? What is

= Water will flow into the cell and cause the cytoplasms to expand. This is called plasmoptysis and is prevented by a cell wall in bacterial

If the above situation is reversed, where the organisms in a flask w/ high-solute concentration (hypertonic), what would happen and what is

Water will flow out of the cell and the cytoplasm would shrink. This is called plasmolysis

Most microorganisms are inhibited when the salt concentration is between ______ and the sugar concentration is between ______.

10-15% and 50-60%

What do we call that need high-salt concentrations to grow and microorganisms that need high-sugar concentrations to grow?

= halophilic (salt) saccharophilic (sugar)

What do we call microorganisms that need a neutral pH 6-8 to grow, high pH to grow, low pH to grow, and that can survive but not grow in low

= neutralophilic (neutral) alkalophilic (high pH) acidophilic (low pH) acidoduric (survice but not grow in low pH)

How is microbial antibiotic sensitivity measure? Please explain the interpretation of results from this measurement.

Sensitivity is measured by performing a Standardized Disk Sensitivity Test. Bacteria is smeared or mixed in nutrient agar and an antibiotic

What is an antibiotic?

= a biological based antagonist used against microorganisms

Compare and contrast antibiotics vs disinfectants and antiseptics.

= Antibiotic is a microbe antagonist that is usually inserted into the body to target specific microorganisms. Disinfectants and antiseptics

What are the hazards of indiscriminate, prolonged use of an antibiotic?

The hazards are bacteria can be potentially start to become resistant to the antibiotic, which makes the antibiotic useless. Also, antibioti

Is there a relationship between the Gram reaction of organisms and their inhibition by UV light?

UV light has the ability to inhibit both Gram+ and Gram- bacteria. The UV light, anywhere from 13.6 nm to 400 nm, still has the ability to p

How does UV light radiation damage bacteria?

UV radiation causes dimerization in pyrimidines within the DNA. This means that it will cause a thymine dimer which hinders the ability of t

List two reasons that UV light is not always effective

Photoreactivation helps repair damage from UV light Enzymes that help withstand exposure from UV light UV light does not penetrate certain p

What other types of radiation damage bacteria?

IR rays, gamma rays, x-rays, cosmic rays

Some enzymes can repair damages due to radiation exposure. If they work in the dark, they are called _______. Enzymes that work when a cell

Dark photoreactivation Photoreactivation

What are the aforementioned repairing and why is it vital?

Photoreactivation repairing is vital because if the cell was only being damaged and had nothing to prevent the damage, then it would have a

Compare and contrast antiseptics and disinfectants.

Antiseptics are antimicrobial agents that kill microbes on living tissue. Disinfectants are antimicrobial agents that kill microbes on livin

In the filter paper test, how is antiseptic/disinfectant sensitivity determined? Say, if you test several microbes for the same antimicrobia

You can tell by seeing which of the microbes stops reproducing or growing. The microbes are in a nutrient broth and then they are put on a n

Describe another method that can be used to test the effect of organic material on antiseptics or disinfectants.

answer

List three natural organic substrates that might interfere with an antiseptic or disinfectant.

Serum Mucus Feces