Hey guys,
I thought I'd post some Microbiology questions from previous exams up for us to answer together, that way we can all learn from each others knowledge =)
for the multiple choice you can select one or more answers
1. These are eukaryotes
a) bacteria
b) yeasts
c) prions
d) protozoa
e) viruses
2. Prokaryotes usually possess
a) a cell wall
b) golgi apparatus
c) a nucleus
d) ribosomes
e) mitochondria
3. All bacterial cell walls
a) contain peptidoglycan
b) contain cellulose
c) have a double membrane structure
d) are internal to the cytoplasmic membrane
e) provide protection against osmotic stress
4. Biofilms
a) provide protection to microbes from attack by antibiotics/chemicals
b) contain only one type of microbe
c) are found rarely in nature
d) may develop on plastic catheters/prostheses
e) are covered in a layer of polysaccharide/slime
5. Provide simple definitions for the following terms:
a) infection
b) pathogen
c) virulence
d) parasite
6. How may bacteria be beneficial to life on earth?
7. In health, large numbers of microbes inhabit our bodies. Are they important in maintaining health? If so, how? When might they be harmful?
8. To be successful pathogens bacteria have to be able to evade or nullify the human immune system. Give examples of mechanisms for this property.
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For my answers - god knows if their right LOL
1) b & d
2) a & d
3) a & e
4) a & d
Simple definitions for the terms:
a) Infection: Growth of a organism in a host
b) Pathogen: microbe capable of causing a disease
c) virulence: measure of pathogenicity (the disease-producing capacity of a pathogen)
d) parasite: an organism that lives on or in an organism of another species
8. They are recyclers & and produce valuable products (e.g. yeast)
9. Yes they ar important in maintaining health - through:
-protection (preventing colonization by moth pathogenic microbes)
- May antagonize pahogens by production of substances, which inhibit or kill non-indigenous species
- stimulate production of cross-reactive antibodies
- can provide excess nutrients tha can be absorbed by host (e.g. vitamin K or B12)
(still working on this question for harmful effects)
10.
a) penetration into host tissue may depend on secreted microbial products e.g collegenaise, hyaluronidase degrade connective tissue - allows spread of bacteria in skin
b) Coagulase - promotes fibrin clots - protects Staphylococcus aureus from phagocytosis
c) igA protease- degrades mucosal surface antibodies
d) Leukocidins - proteins that destroy phagocytic cells
e) cell surface components protect from immune system e.g. capsule, etc
Hope this makes sense :)
oh...and these are just the answers i gathered for from the practice exam....i think i missed your question about life on earth timmy...sorry
For the how are bacteria useful for life on earth bit... Doesn't this relate to like how they can be used to make useful things such as cheeses, wines, and oh yea antibiotics and stuff like that .???
oh wait! i think i did answer that LOL....the recycling part and makes useful products
Emma, I got the same answers for the multiple choice!
For the life on earth one it's basically what you've said:
a) decompose dead material and return nutrients to soil
b) part of nitrogen and carbon cycle
c) protect humans from pathogenic bacteria by colonising skin/producing toxins
d) help make cheeses/other foods
Thanx Timmy :D
Q7.) when may be harmful? would this be dependant on the host & parasite relationship such as ability to colonise which depends on adherance factors, physical conditions like temp, pH & chemical environment such as nutrient requirements, water etc. So also in relation to external influences such as diet habits; that can increase the step mutans & increase the sucrose? which increase chances to more microbes to colonize?? Is this right??
I was kinda thinking along the lines of:
harmful = things like biofilms (as in things like catheters it needs to be flushed out) on the notes it says that "biofilm protects from the effects of antibiotics and immune system" so it protects the bad bacteria? The temperature, PH, etc are important factors as this influnces their growth.
I got the information below from an article i read: (thought it sounded pretty relevant)
- Microbes metabolize sucrose to lactic acid and is a leading cause of tooth enamel decay. The acidic environment created in the mouth by this process is what causes the highly mineralized tooth enamel to decay. S. mutans is one of a few specialized organisms equipped with receptors for adhesion to the surface of teeth. Sucrose is utilized by S. mutans to produce a sticky, extracellular, dextran-based polysaccharide (glucan) that allows them to adhere to each other forming plaque. It is the combination of plaque and acid that leads to dental / tooth decay.
Hope this helps munners
Emma
Hey munners, with your question i put down things like what you said kind of such as when the environment changes then certain bacteria may be able to flourish and then cause disease, but i also said that bacteria may be harmful when they are relocated to a certain area and therefore become opportunistic bacteria such as when oral bacteria get stuck on heart valves= endocaditis etc.this is because they are not part of the natural flora of that area. Hope that helps.
P.S. oMG i did the multiple choise and only got one right. CRAPPPPPP want to cry.. :(
Hey guys i just have a quick thing. with the second multiple choice : prokaryots usually posses. we have said in these response that its a and d. which is a cell wall and ribosomes.My question is.. i was under the impression that prokarotes contained no organelles so how can they contian ribosomes ??
Just a bit confused.
thanks
Hey Nic,
Good question!
They don't contain all the usual organelles like the Eucaryotic cells but they have ribosomes for specific protein production - as instructed by the messenger RNA contained in the cel. It's in the first lecture notes on Microbiology (intro to microbiology) 4th Slide.
Hope this helps Nic :D
Ribosomes aren't really organelles. They're just small granular particles containing protein and RNA! Also, I think ribosomes are different in prokaryotes and eukaryotes!
now that you say that timmy i agree. i think i remember that from a past bio experience i have had :D sweet ok so taht is confirmed. prokaryotes contain ribosomes :D
Bacteria such as Cyanobacteria (blue green algae) and other Diazotrophs also partake in biological nitrogen fixation by converting nitrogen in the atmosphere to ammonia using the enzyme nitrogenase. Fixed nitrogen is required to biosynthesize the building blocks of life i.e amino acids in proteins and and nucleotides for DNA
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