Description
Biology 152: Paramedical Microbiology
Study Guide: UNIT 2
Reading: Tortora Chapters 3, 4, pp. 367-374
Items in Red and Bold:
may not be covered in class, so you will need to look up this information in
the text (Tortora)
Define the following terms:
bacteriophage
taxis
axial filament
chemotaxis
fimbriae
phototaxis
pili
plasmid
Answer the following questions:
1. Compare and contrast the following different types of microscopy, and give an example of
how each would be used:
a. compound light (brightfield) microscope
b. phase contrast microscopy
c. fluorescence microscopy
d. transmission electron microscopy
e. scanning electron microscopy.
2. If you are looking at an organism that is 40
μm
in length, what is its length in millimeters?
3. Organize the following in order by size (largest to smallest), and estimate a metric size range
for each of them. Describe what type of microscope would be used to view each of them.
a. protein molecule
b. mosquito
c. bluebird
d. white blood cell
e.
Staphylococcus epidermidis
(bacterial cell)
4. Identify the three basic shapes of bacteria. What specific arrangements of cocci and bacilli
are found? (streptococci, etc)
5. Describe the basic structure and components of a prokaryotic cell including the cell wall,
membrane, nucleoid, ribosomes, inclusions, and endospores.
6. How do the cell walls of
Mycoplasma
, the Archaea and
Mycobacterium
differ from the cell
walls of most other bacteria?
7. Describe the structure and function of the plasma membrane in prokaryotic cells.
8. Review the structure and function of the components of a typical eukaryotic cell. Be
able to differentiate between plant and animal cells (this was covered in Bio 130 and
should be a review).
9. Describe the function and structure of each of the following components of viruses: nucleic
acid, capsid, capsomeres, envelope, spikes.
10. Describe the four basic types of virus morphology.
11. Describe the structure of peptidoglycan.
What is the major advantage conferred by a bacterial cell wall made of peptidoglycan? What
is the mechanism of action of penicillin?
12. Compare and contrast the composition and characteristics of the cell wall of gram negative
and gram positive cells.
13. What type of toxin is LPS, and how does it contribute to the pathogenicity of
Gram negative bacteria?
14. Compare and contrast Gram positive and Gram negative bacterial cell walls in
terms of their sensitivity to desiccation (drying out), physical
disruption, lysozyme, and penicillin.
15. Describe the steps of the gram stain, and know why gram + and gram - cells stain
differently.
16. Compare and contrast prokaryotic cells, eukaryotic cells, and viruses with regards
to size, complexity, general structure, where genetic material is located, and
whether or not they are acellular, unicellular, or multicellular.
17. Explain why bacteria cannot be identified based on morphology alone.
18. Compare and contrast the two forms of glycocalyx. Where is the glycocalyx found
in the cell? What type of molecule is the glycocalyx made of? What are the
Explanation & Answer
Attached.
RUNNING HEAD: PARAMEDICAL MICROBIOLOGY
Assignment 1
Name
School
1
PARAMEDICAL MICROBIOLOGY
Bacteriophage is a group of viruses that infect and multiplies in bacteria. It is also known as a
bacteria virus or a phage
Taxis - a behavioral response to an external stimulus by an organism or a cell.
Axial filament - it is a central filament of cilia or flagellum.
Chemotaxis – it is when of an organism move due to a chemical stimulus.
Fimbriae – it is a filamentous structure that extends from a cell’s surface used by bacteria to
attach to one another.
Phototaxis is when an organism move due to light stimulus. It could be away from the light or
towards the light.
Pili- they are hair like structures on bacterial cells surface used in reproduction to exchange
genetic material.
Plasmid- it is an extra DNA molecule that can replicate on its own. The genes present give the
cell added advantages.
1a.
Compound light (bright field microscope) - it has several lens. It has its own source of
light. It uses a compound lens system. It has a higher magnification.
b. Phase contrast microscopy- it shows contrast in a sample without staining it by using
a phase condenser/ phase slider and a special phase contrast lens. It is a compound
microscope.
c. Fluorescence microscopy – they fluorescence a sample by using different light
wavelength to study the specimen.
2
PARAMEDICAL MICROBIOLOGY
d. Transmission electron microscopy – it uses accelerated beam of electrons to observe
a specimen (very small).
e. Scanning electron microscopy – it uses a focused beam of electrons to scan a
sample’s surface to produce images.
2. 1000um =1 mm; 40um* 1000=40,000 mm
3. Bluebird, mosquito, white blood cell, protein molecule and Staphylococcus epidermidis
(bacterial cell).
A bluebird can be viewed using a scanning electron microscope.
A mosquito can be viewed using an electron microscope.
White blood cells can be viewed using a compound microscope.
A protein molecule can be viewed using an electron microscope.
A bacterial cell can be viewed using a compound microscope.
4. The basic shapes of a bacteria; coccus/spherical, spiral/twisted and bacillus/rod shaped.
Coccus can occur in various arrangement; streptococcus, diplococcus, tetracoccus, sacina
and straphylcoccus. The bacillus can occur as single bacillus, streptobacillus or
coccobacillus.
5. Prokaryotic cells have various structures. The cell membrane/plasma membrane that
separates the cell from the environment, the nucleoid that has the genetic material, the
cytoplasm inside the cell where other cellular components are found, the ribosomes
where proteins are synthesized. The cell wall prevents dehydration, helps the cell
maintain its shape and provides an extra layer of protection. The capsule enhances the
cell to attach to its environment. Inclusions are external structures in the cytoplasm where
the cells store excess ...