Exam 4 - Lecture 19 Flashcards
true or false: “this whole lecture is an SOS”
… :D
a single _______ causes a particular disease.
microbe
true or false: a disease can be caused by many different microbes.
true; examples are conjunctivitis and meningitis
what is symbiosis?
an association of two or more different species of organisms (good or bad).
in symbiosis, at least one member or the pair benefits from the relationship. the other may be:
- injured
- relatively unharmed
- may also benefit
in symbiosis, the microbe is the _________ and the larger organism is the ______.
- symbiont
- host
what is an ectosymbiont?
an organism located on the surface of another organism (like bacteria on skin)
what is an endosymbiont?
organism located within another organism (like bacteria in our gut)
what is a consortium?
a host with more than one associated symbiont (like us)
what are the seven types of microbial interactions?
- mutualism
- cooperation
- commensalism
- predation
- parasitism
- ammensalism
- competition
symbiotic relationships can be what three things? (time wise)
- intermittent
- cyclic
- permanent
what is mutualism?
- both partners benefit
- some degree of obligation involved
- partners cannot live separately; codependency
what kind of interaction do aphids and Buchnera aphidicola have? who is the symbiont?
- (endo)symbiont: B. aphidicola
- mutualistic interaction
- aphids consume sap deficient in essential amino acids and vitamins
- insect provides vitamins and amino acids (Arg) and gets secure habitat and nutrients in return
the inability of the aphid/B. aphidicola to grow without the other is an example of:
coevolution
what is the relationship between termites and a protozoan? who is the symbiont?
- mutualistic interaction
- symbiont: the protozoan with no name
- termites eat wood that contain cellulose and are unable to break up the long chains of glucose
- protozoans digests the cellulose and provides nutrients for the protozoan in return for food from the termite
what mutualistic relationships does the protozoan from the termite-protozoan relationship have?
- N2 fixing bacteria to make NH3
- bacteria TG1 makes glutamine (Gln) from NH3
- spirochetes provide motility for protozoan
what are ruminants?
animals that have stomachs divided into four compartments and are able to acquire nutrients from plants by fermenting them in a specialized compartment (rumen) prior to digestion
what is the rumen?
- upper part of the ruminant stomach
- contains large, diverse population of microbes
rumen ecosystem order of events:
- plant material (grass) is coated w saliva and swallowed
- in the rumen, grass is coated with microbes and broken down into pulpy, partially digested mass
- regurgitated, chewed, re-swallowed
- liquified grass passes into omasum/abomasum
- further digested
the microbial community within the ruminant have their own ____________ relationships.
- mutualistic
what is cooperation?
a relationship that benefits both organisms but is not obligatory for the survival of either organism
cooperation typically involves ___________ relationships.
syntrophic
what are syntrophic relationships?
when one species lives off the byproducts of another species
- often involves carbon and nitrogen/sulfur cycles
what is commensalism?
one organism benefits while the other is unaffected
the organism that benefits from commensalism is called the:
commensal
true or false: commensalism relationships are often syntrophic.
true
true or false: commensals can live once separated from the host.
true
what is an example of commensalism in nitrification?
- two different bacteria carry out nitrification together
- NH3 to NO2 by Nitrosomonas
- NO2 to NO3 by Nitrobacter
the microbial succession during the spoilage of milk and biofilm formation are examples of what type of relationship?
- commensalism that occurs when the environment is made more favorable by one species for another
what is predation?
- one organism gains (predator) and the other is harmed (prey)
- this “harm” is usually killing
true or false: predators can only attack from outside the cell.
false; they can attack from the outside or inside of the prey cell
what are four examples of bacteria that use predation?
- Bdellovibrio: penetrates cell wall, grows outside plasma membrane in periplasm
- Vampirococcus: epibiotic mode of attacking prey (lives on the surface)
- Daptobacter: pepntrates prey then directly consumes the cytoplasmic contents totally intracellularly
- Myxococcus (wolf pack): uses gliding motion to creep, overtake prey, and release degradative enzymes
what is parasitism?
- one organism gains and the other is harmed
- the host is typically not killed (at least until the parasite can reproduce)
there is always some degree of ______________ between a host and a successful parasite.
co-existence
what is the hallmark(s) of parasitic relationships?
- not beneficial for the host
- host grows better without the parasite
what is ammensalism?
an association between two organisms where one is harmed/inhibited and the other in unaffected
what specific type of ammensalism is based on the release of a specific compound?
antibiosis
what is an example of an ammensalism relationship?
antibiotic production by fungi and bacteria
what bacteria do South American Attine acts use to control fungal parasites? what kind of relationship is this for the bacteria and the fungi?
- antibiotic-producing Actinobacteria
- ammensalism
what is competition?
occurs when two organisms try to acquire the same resource
what are the two possible outcomes of competition?
- one organism dominates
- sharing of the resource (both survive at lower pop levels)
what is a microbiome/microbiota?
all of the microbes living in and on the human body
the ratio of bacteria to human cells has been changed from _____ to _____.
from 10:1 to 1:1
how many microbial genes are there? how about human genes?
- over 1,000,000 microbial
- 23,000 human
all of the genes of the host and the microbiota are called the:
metagenome
what are superorganisms?
- gene-encoded metabolic processes of the host become integrated with those of the symbiont
- a blend of host and microbial traits where host and microbial cells co-metabolize various substances, resulting in unique products
normal microbiota varies depending on:
- age
- sex
- diet
- anatomical site
when does the relationship between microbiota and the host occur?
at birth
true or false: antibiotic treatment can disrupt the microbiome balance.
true, but it can return to “normal” after the antibiotics are removed
is the normal microbiota interaction with the human commensalism, mutualism ,or cooperation?
mutualism
normal microbiota often prevent _____________ by pathogens.
colonization
what is pathogenicity?
ability to produce pathological change of disease
