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56 Cards in this Set

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  • Back
What parts of the body are usually sterile?
Blood, Brain, Lungs and heart
How many microorganisms are you born with?
0, first microorganisms received from vaginal tract
what kind of relationship do animals and microorganisms have?
Thought to be commensalist, then seems to be mutualistic ( both benefit)
How can microorganisms be beneficial to animals?
1. Provide protection from new microorganisms
2. Provide vitamins and metabolic pathways
3. Teach immune system
Define pathogen.
Microbial parasites that can cause infection
Define pathogenicity.
Ability of parasite to inflict damage to host
Define Virulence.
A measure of pathogenicity
Define opportunistic pathogen
Causes disease only in absence of normal host resistance. the normal microbiome contains opportunistic pathogens that are not dangerous.
Who is most susceptible to opportunistic pathogens?
those with immuno-deficiencies
Define infection
Situation where a microorganism gets established, causing damage
Define disease.
Damage or injury to host that impairs host function
What type of animal dietary habit evolved in different lineages?
What are the problems with herbivory?
Animals can't digest cellulose, lack cellulase enzyme.
-Also plants have very few amino acids and vitamins
What are the two digestive plans of herbivores? Give an example of an animal of each type
1. Foregut fermentation: Fermentation of cellulose performed in the chamber that precedes the acidic stomach
Ex. Ruminants

2. Hindgut fermentation: Uses cecum and/or large intestine after stomach
Ex. Horses
Why are cows good study subjects for dietary studies?
Because cows are big, you can cut a hole into the rumen and observe it
What is the rumen like in ruminants?
-Before the stomach
- Non-acidic
-39-40 Celsius
- Anaerobic
How is the pH maintained in the rumen?
by Saliva
Why is the temperature of a rumen higher than the rest of the ruminant?
Microbial activity
True or false: most rumen microorganisms produce cellulase.
False: only a small portion do. There is a great diversity of microbes in the rumen, all with different activity
What do the non cellulytic microbes of the rumen depend on for nutrients?
They depend on the cellulytic microbes to hydrolyze cellulose--> glucose, and then they use the glucose for growth
What is Glucose fermented into in the rumen?
Volatile Fatty Acids (Acetic, Propionic, Butyric), CH4, CO2
What are Volatile Fatty Acids, and who benefits from them?
VFA's are the production of glucose fermentation by microbes in ruminants, and they are absorbed by the host ( the animal)
What are common types of microbes in the rumen of cows?
Ciliated protozoa and prokaryotes
What is the role of ciliated protozoa in rumens?
They are predators, they eat bacteria
How was the microbial species composition determined in cow rumens?
By 16s RNA sequencing
how do we know that the microbes live in some sort of symbiosis; that they grow better with each other?
There are 10x more microbes growing in a rumen than can be grown individually on plates. 90% of rumen microbes can't be grown alone.
What is a ruminococcus?
A gram-positive bacteria that is key in cellulose degradation. surface contains cellulosomes that bind to cellulose fiber and degrade it
What is a cellulosome, and what is its construction?
A cellulosome is a cellular machinery located on the surface of ruminococcus. it is made up of scaffoldin attached to enzymes that attach to the fibers and have cellulose breakdown activity. The cellulosome itself is attached to the sell wall by a protein, catalyzed by sortase.
What are methanogens?
Strictly anaerobic bacteria that form methane from either Hydrogen and carbon dioxide, or acetate.
Why could methanogens be considered parasitic?
They use acetate, which then becomes unavailable to the host. 10% of energy value of feed can be lost as CH4
What is Monensin?
An antibiotic given to animals that inhibits methanogens, thus increasing the energy value of feed
What occurs to the food in a rumen after digestion has occured?
Small portions of contents are regurgitated, chewed up, and swallowed again. This is done to expose more parts of the plants to degraders
What part of the ruminant digestive system collects the small particles that are re-chewed up after original rumen digestion?
The Reticulum.
Where do food particles travel after the reticulum?
Passed to osmasum where excess water is collected, then passed onto stomach (abomasum)
What is the abomasum, and what happens there?
The abomasum is the stomach, and it is where small food particles are sent after the osmasum. It is very acidic, so all the microbes from the food particles are killed, and the amino acids and vitamins they contain digested.
Where does fermentation occur in non-ruminant herbivores?
Fermentation occurs in the Caecum, after the stomach
Where are organic acids absorbed in non-ruminant herbivores?
Large intestine or Cecum
Why are ruminant herbivored considered to grow their own food, while non-ruminant herbivores are not?
Ruminant herbivores have microbes growing in their rumen, that get transfered to their stomach and digested. Non-ruminant herbivores have fermentation after the stomach, so the microbes never get digested.
Why do non-ruminant herbivores have higher dietary needs, and what is their solution?
Higher needs because they don't digest the microbes growing in their body. Solution: Coprophagy, or the eating of own fecal matter. This allows them to digest the microbes and get vitamins and amino acids
What is special about the hawaiian bobtail squid?
It is in mutualistic symbiosis with marine bacterium Aliivibrio Fisheri that is bioluminescent. Bacteria lights up squid and camoflauges it ( like moonlight), gets nutrients in return
What are the two classes of endosymbionts?
Primary, or heritable, and Secondary
What do heritable symbionts lack?
a free-living replicative stage
What are primary symbionts required for?
host reproduction
What is a Bacteriome?
a specialized organ that contains endo or primary symbionts, in cells called bacteriocytes
What type of organism exhibits extreme gene reduction?
Primary symbionts. they lose all the genes for metabolism because nutrients provided by host. instead, their genes focus on increasing host fitness
Are all endosymbionts present in every cell?
No, Secondary symbionts can invade different cells and live extracellularly. They are not needed for reproduction also.
What do termite's guts contain?
endosymbionts. ruminococcus
Are most microorganisms benign, predatory, parasitic or neutral?
benign, or function unknown
What factors cause microbes to change in a human body?
Time and different conditions ( diet, environment, sex, occupation etc)
At what stage in life is microbial population richness highest? lowest? most stable? least stable
Highest: Adulthood
Lowest: Baby
Most Stable: Adulthood
Least Stable: Baby
What organ is first colonized by microorganisms?
skin, first contact
What is a humans natural protection from microorganisms? Why is it a good defense?
top layer of epidermis consisting of dead cells. Lacks nutrients, dry, and acidic
What are the two layers of epidermis?
Top layer of dead cells, bottom layer of constatnly replicating cells
What are the most likely parts of skin to host microbes? why?
Hair follicles and sweat glands because they are wet and warm, and have salts and nutrients.
What is Bacteriocin?
A secretion by normal skin microflora that kills incoming competitors., thus protecting from colonization
True or false: anaerobes cannot live on skin, because it is an aerobic environment
Somewhat false: aerotolerant anaerobes can inhabit hair canals. ex. propionobacterium acnes