Microbiology: Module 2
Terms in this set (80)
A thin, loosely bound glycocalyx is referred to as a
All the following characteristics apply to bacteria except
- they include the ribosomes.
- they reproduce only by mitosis.
- they are composed of single cells.
- they lack a nucleus.
they reproduce only by mitosis.
All of the following are characteristics of the bacterial flagellum except
-It has a hook-like insertion to a basal body in the cell wall.
- It is used in conjugation.
- Counterclockwise rotation moves bacteria forward.
- It is composed of flagellin.
It is used in conjugation.
Many prokaryotic cells exhibit motility. This is generally by
Which one of the following is not a function of the Golgi apparatus?
-Synthesis of proteins
-Packaging of proteins.
-Processing of proteins
-Sorting of proteins
Synthesis of proteins
Prokaryotes go through the same kinds of energy reactions as eukaryotes, but without the double membrane organelles. Instead they use
the cytosol and cell membranes.
- have a thick cell wall, which retains crystal violet dye
-none of the above
-appear purple after Gram staining
- contain teichoic acids in their cell walls
none of the above
- dormant, enviromentally resistant structures
-are reproductive structures of some bacteria
-occur in some archaea
-can cause shock, fever, and inflammation
dormant, enviromentally resistant structures
Which of the following statements is FALSE?
-The cell walls of bacteria are composed of peptidoglycan.
- LPS is on the outer membrane of Gram-positive cells.
-Chitin is found mainly in the cell walls of fungi.
-Gram-positive bacteria have a cell wall with a thick layer of peptidoglycan.
LPS is on the outer membrane of Gram-positive cells.
Starting with Linnaeus, a hierarchical system was established for cataloging of living things. What did this mean at that time?
Grouping of species by shared and common characteristics.
What tests are used to help identify bacteria today?
-Physical characteristics including shape, size and arrangement of cells.
-Serological tests with antisera for the production of antibodies.
-Biochemical tests showing metabolic properties like fermentation tubes.
Which one of the following sequences exhibits increasing size?
-Viruses to protozoa to bacteria
-Viruses to bacteria to protozoa
-Fungi to protozoa to bacteria
-Bacteria to viruses to fungi
Viruses to bacteria to protozoa
Which one of the following groups is not resolved with the light microscope?
At the conclusion of the negative stain technique, one can observe
clear bacteria on a dark background.
The Gram stain technique is valuable in distinguishing
different types of bacteria.
Which of the following stains is used to identify Mycobacterium tuberculosis, with its thick waxy walls?
Acid fast stain
Dark-field microscopy is valuable for observing
An advantage of the SEM over the TEM is
thin sections are not needed with the SEM.
In the five-kingdom system of classification, which one of the following is not one of the kingdoms?
Bacteria lack __________ in the cell cytoplasm.
The bacterium __________ appears microscopically as grape-like clusters.
__________ are structures that some bacteria can use to exchange genetic information through conjugation.
Bacilli can grow as single rods or as __________ .
Gram developed a staining technique that separates bacteria into two distinct groups based on the characteristics of their __________ .
The __________ measurement is equivalent to one thousand nanometers.
Scientists often abbreviate the microbial names by writing the first letter of the __________ together with the full specific epithet.
The carbohydrate utilization test is an example of a __________ test to identify microbes.
The agglutination test uses __________ to test for a specific microbe.
Among the important characteristics of prokaryotes is the presence of a well-defined nucleus and nuclear membrane.
The flagellum is longer than the bacterial cell but is so thin that it cannot be visualized with normal bright field microscopy unless stained.
Heat fixing bonds the cells to the slide, kills organisms that may still be alive, and prepares them for staining.
Gram-positive bacteria are those that retain the crystal violet-iodine complex when a decolorizing agent is added, appearing blue-purple at the conclusion of the procedure.
An important application of fluorescence microscopy is when the fluorescein is attached to antibodies and mixed with a sample of the unknown organism. If the antibodies are specific for that organism, the organisms will fluoresce under UV light.
Gram (+) cell wall
Rigid outer boundary
Loose fibrous layer
Transports food into, and wastes out of the cell
contains a few genes, not essential for the cell
site of protein synthesis
fluid matrix for cell metabolism
stores essential genetic information
uses ultraviolet light as an energy source.
is used to observe dye-tagged antibodies.
Can be used to observe objects as small as 2.0 nm in diameter.
transmission electron microscopy
is synonymous with the compound microscope.
bright field microscopy
involves staining objects with heavy metals after sectioning.
transmission electron microscopy
uses visible light as an energy source.
Bright field microscopy
is used after Gram staining
produces the illuminated organism on a dark background.
Dark field microscopy
uses immersion oil to increase resolution with the 100X objective.
is used to observe a slice of bacterium.
transmission electron microscopy
The acid-fast stain is used to stain
bacteria with waxy cell walls.
Which of the following is an accurate description of viruses?
They are acellular obligatory parasites.
Bacteria of the genus Mycoplasma lack cell walls. What sort of environment do they require for survival?
Which of the following prokaryotic cells contain an outer membrane?
-Gram-negative bacteria only
-Gram-positive bacteria only
-both Gram-positive and Gram-negative bacteria
Gram-negative bacteria only
Which of the following may be a component of bacterial cell walls?
both lipoteichoic and mycolic acids
Species and strains of microbes can be distinguished from one another phenotypically using
Which of the following questions largely stimulated the research of microbes during what is known as the Golden Age of Microbiology?
What causes disease, and is spontaneous generation of microbes possible?
Which of the following is found only in eukaryotic cells?
Hydrogen bonds are found in all of the following EXCEPT
-between the R groups of amino acids in proteins.
- in the DNA double helix between nucleotides
-between phosphates in ATP.
- in the structure of complex polysaccharides.
- between water molecules.
between phosphates in ATP.
Which of the following would NOT normally be found as a component of a cell's nucleic acids?
One of the products of dehydration synthesis reactions is water.
Eukaryotic ribosomes are composed of 50S and 30S subunits.
A layer of polysaccharides external to the bacterial cell but firmly attached to it is called a slime layer.
Carbon atoms have four valence electrons and typically form polar covalent bonds.
Microbiologists study only single-celled organisms.
The smooth endoplasmic reticulum is the site of _______ synthesis.
The folding of a polypeptide into a three-dimensional shape is its _________ structure.
The production of wine from grape juice is the result of _______.
The amateur scientist _______ made his own microscopes and first reported the existence of microbes.
Antoni van Leeuwenhoek
The process of immobilizing organisms on a glass slide through the application of either heat or chemicals is ______________.
Use the basic steps of the scientific method to describe Pasteur's experiments to investigate spontaneous generation.
Pasteur was instrumental in investigating the argument of spontaneous generation and if live can develop from a nonliving matter. He set out to investigate this by using the basic steps of the scientific method which are 1) A group of observations that lead to a question 2) developing a hypothesis 3) developing an experiment to test this hypothesis and 4) based on the results, rejecting, accepting or re-developing a new hypothesis. He did this by observing the work of other scientists and coming up with his own hypothesis that said spontaneous generation is not possible. He tested this by using a swan-neck flask that was open-ended so it allowed air in, however, the s-like shape of the neck did not let microbes or larger molecules in. He performed the same initial steps as previous scientists to heat the solution to kill any existing microbes and then left his flask under the stairwell for a very long time. No microbes ever developed so he accepted his hypothesis that there is no way spontaneous generation can happen.
List and explain five types of techniques that can be used to identify unknown microorganisms.
There are five different types of techniques for identifying an unknown organisms including:
1) Using physical characteristics (cell morphology, colony morphology, unique identifiers such as flagella, endospores
2) Using biochemical tests to identify their ability to use or produce certain chemicals
3) Using serological tests to understand their reaction to certain antibodies
4) Using phage typing which is using viruses to see if they infect certain bacterial cells. If they kill the bacteria a plaque will form.
5) Doing an analysis of nucleic acids and comparing their neucleotide sequencing to find relationships
Compare a bacterial cell and a protozoa , name at least four similarities and four differences.
-all have a cytoplasmic membrane
-all have a cytosol
-some have a flagella
-all are absent of a hami
-Nucleus absent in bacteria; nucleus present in protozoa
-Cilia absent in bacteria; cilia present in protozoa
-Ribosomes small 70S in bacteria; ribosomes large 80S in protozoa
-Fimbriae or pili present in some bacteria; absent in all protozoa
Put the following substances in the order they are used in a Gram stain and then explain what each does: counterstain, decolorizing agent, mordant, primary stain.
Primary stain - flood the smear with the basic dye crystal violet for 1 minute and then rinse with water. The crystal violet colors all cells purple.
Mordant - The next step is to flood the smear with a mordant, or iodine, for 1 minute and then rinse with water. This binds to the dye making it less soluble. The cells are still purple at this point.
Decolorizing agent - You then would rinse the smear with ethanol and acetone for 10-30 seconds and then rinse with water. This acts as a decolorizing agent breaking down the thin cell walls of Gram-negative cells, allowing the stain and mordant to be washed away making the cells colorless while the thicker Gram-positive cells remain purple.
Counterstain - The final step is to flood the smear with safranin for 1 minute and then rinse with water. This is a counterstain which provides a contrast to the primary stain. The resulting pink color is masked by the darker purple in the Gram-positive cells while the Gram-negative cells appear pink.
Strep throat is caused by a Gram-positive bacteria called Streptococcus pyogenes that has a capsule. Describe how the capsule may contribute to the pathogens ability to cause disease.
The capsule that is surrounding the Streptococcus pyogenes bacteria is contributing to the pathogens ability to cause disease by helping to disguise the pathogen to look like other normal bacteria in the body which then prevents it from being recognized as a pathogen and allowing the body to respond by activating defensive cells from the host to rid of it.
What are two advantages of rapid identification tools, such as the rapid strep test used in Lamara's diagnosis, over growing a culture for identification and then prescribing treatments?
-increased speed of a diagnosis
-increased speed of providing treatment
What makes biofilms dangerous for patients with cystic fibrosis?
Biofilms typically render the organisms in them more resistant to antimicrobial drugs.
Some bacterial toxins cause the cells that line the digestive tract to secrete ions. This leaking of ions makes the contents of the digestive tract hypertonic. What effect does this have on the patient's water balance?
Due to the leaking of ions caused by some bacterial toxins, the contents of the digestive tract in the patient are hypertonic which means concentrations of solutes are higher inside the digestive tract than outside the digestive tract. Because the concentration of solute is higher which takes up space this obviously means that there is less room for water inside the digestive tract. As water moves down the concentration gradient through osmosis, cells placed in a hypertonic solution shrink because of the net movement of water out of the cell. This results in the patient having less water in the digestive tract causing dehydration.
With the exception of discovering new microbes, does it make sense to believe that the current taxonomic organization of microbes will remain the same in the future? Why or why not?
The reason is that our understanding of the interrelationships among organisms based on genetic sequences is undergoing rapid development and is still in the early stages. New techniques are developed regularly which will assist in studying and understanding these interrelationships among organisms.
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