BIO 39 Homework Assignment 1
Due date: upload must be completed by Friday September 25th at 11:59.00 pm PST.
Value: 6 points.
All homework answers must be submitted through Canvas for credit. All questions must
be answered in full; no partial credit will be given. Late homework assignments will NOT
be accepted. No Exceptions. If you have difficulty with the assignment, please email the
instructor or schedule a Zoom appointment.
Answer the following questions in their entirety. 1 point each unless noted otherwise.
1. Create a table to compare and contrast the characteristics of the four major
groups of microorganisms (bacteria, fungi, protozoa, and viruses) and helminths.
Be sure to include specific examples of each group.
2. Define normal flora. What areas of the human body are normal flora permitted?
Include specific anatomical sites that are tolerant to normal flora. List four
beneficial effects of mutualistic normal flora on the human body. Define
opportunistic pathogens. List the different ways that opportunistic pathogens
cause disease in humans. Define true pathogens.
3. Diagram (draw) the Gram positive cell wall. Be sure to label specific components
of the structure. What is the medical significance of LTAs?
4. Diagram (draw) the Gram negative cell wall. Be sure to label specific
components of the structure. What is the medical significance of LPS? What is
the medical significance of the O-linked side chain?
5. Diagram (draw) the Acid fast cell wall. Be sure to label specific components of
the structure. What are the clinically relevant features of the acid fast cell wall?
How does culture of Acid fast bacteria differ from Gram positive and negative
bacteria? How does the structure of the acid fast cell wall promote pathogenesis
in tuberculosis?
6. Diagram (draw) the Mycoplasma pneumoniae cell. What cell wall type, if any,
does Mycoplasma have? Explain why this species will not be seen on Gram stain
evaluations. Which groups of antibiotics will be ineffective against Mycoplasma?
Bacteria
Fungi
Protozoa
Virus
Helminth
Type of Cell
Prokaryote
Eukaryote
Eukaryote
Eukaryote
Eukaryote
Characteristics
Peptidoglycan in
CW
1) Ergosterol
1) Unicellular
2)
Heterotrophic
and could also
be a saprobe
or parasite
2) Motile
1) Acellular,
ametabolic
particles
1)
Multicellular,
lack cell wall
3) Complex
intracellular
structures
and life
cycles
2) Protein and
nucleic acid
3) some have
membrane
4) Asexual
reproduction
- mitosis
Lifestyles
1) Soil dwelling
1) Soil dwelling
2) Food
2) Food
3) Sewage and
industrial waste
treatment
3) Sewage and
industrial
waste
treatment
4) Biotechnology
5) mutualistic,
commensal, and
parasitic
6) major source of
disease
Major division
4)
Biotechnology
1) Soil and
aquatic
communities
(plankton)
2) disease
3)
commensal
and parasitic
1) obligate
intracellular
parasites
1) Free living
2) Disease parasitic
2)
Biotechnology
3) disease
4) parasitic
5) Commensal
and parasitic
6) disease
1) Yeastunicellular
1)
Trematodes
2) Moldsmulticellular
2)
Nematodes
3) Cestodes
Examples
1) Streptococcus
pyogenes – strep
throat, pathogen
2) Bifidus regularis probiotic
1) Candida
albicans –
yeast
infections
2) Aspergillus
fumigatus –
moldpulmonary
infections
1) Giardia
lamblia –
giardiasis
2)
Plasmodium
sp. - malaria
1) Influenza A
Virus upper/lower
respiratory
infection
2)
Coronavirus upper/lower
respiratory
infection
3) Norovirus intestinal tract
infection
1)
Schistosomes
2) Ascaris
lumbercoides
3) Taenia
solium
2. Normal flora is the bacteria and microbes that is associated with an animal, and the
prevalence and diversity of it can change with age, nutritional status, diet, and health
status. Normal flora is acquired from the environment such as from people or
environmental surfaces. Resident microbiota, lifelong members of the body’s normal
microbial community, is most of the normal flora. Normal flora is permitted in non-sterile
sites, such as the surface of the skin, mucous membranes, digestive tract, upper
respiratory system and the distal portion of the urogenital system. Normal flora is not
permitted in sterile areas like blood, internal organs, lower respiratory tract, and the
dermal tissues. A benefit of normal flora to a human is that its intestinal microbes can
carry out a variety of essential metabolic reactions like vitamins, enzymes, gas, organic
acids, and odor. It can also stimulate function and development of specific tissues, and
its metabolic products promote a healthy weight for host. Further, it prevents growth of
pathogens in host because it out-numbers and out-competes potential pathogens for
resources. Opportunistic pathogens are when normal flora of host becomes parasitic
when the host’s health becomes compromised or when the normal flora is in dysbiosis.
Opportunistic pathogen can cause disease when it is introduced to a sterile site by an
open wound or a foreign material. When there is a high prevalence of pathogens in the
environment, increase in antibiotic resistance of NF-OP, a compromised health, or
transmission of NF-OP from health care provider to patient, an opportunistic pathogen
can cause hospital acquired infections. True pathogens are non-NF species that can
cause harm to the host. It lives in water, food, soil, fomites, and vectors. An infected
individual can be symptomatic or a carrier.
3. The medical significance of lipoteichoic acids is that when it gets into non-sterile
areas, it elicits the body to have an immune response, specifically inflammation,
because the toxins released harms the individual. If not treated, it can cause sepsis.
4. The medical significance of lipopolysaccharide is that it is an endotoxin, which means
that it can cause fever, inflammation, hemorrhage, and diarrhea. The lipid A portion of
the LPS consists of the toxic portion of the LPS. The O-linked side chain is species
specific or strain specific and can be used for G- identification.
5. The acid fast cell wall has a thin layer of peptidoglycan and a very thick layer of lipid.
The lipid layer is about 60% of the cell wall mass and includes the mycolic acid. The
acid fast bacteria has a different culture growth rate compared to G+ and G- bacteria.
G+ and G- bacteria takes about 48 hours to grow while an acid fast bacteria takes about
2-8 weeks. It also has no gram stain reaction. The acid fast bacteria is a respiratory
transmission to lung. The mycolic acid can stimulate an immune response that
contributes to the pathology of tuberculosis. Since the bacteria cannot be coughed out
or covered in mucous, the macrophages from the immune system will form a tubercle to
combat the bacteria and prevent it from spreading altogether. Also, conventional
antibiotics are ineffective because of the cell wall structure. Therefore, it will take about
a minimum of 6 months for treatment using 3 antibiotics.
6. The mycoplasma pneumoniae cell has no cell wall, therefore there is no
peptidoglycan layer for the gram stain to act upon. Penicillin, cephalosporins, and
vancomycin will be ineffective against mycoplasma.
Double click on the Note (4) (1).pdf icon and it should bring you to a pdf that shows the
four labeled cell wall drawings