MICRO 3050 cumulative final – Clemson
Questions & Answers
what is a microorganism - ANSWERSan organism too small to be seen by the naked
eye
define cellular - ANSWERSfit on the tree of life
are seen as "living"
define acellular - ANSWERSViruses, Viroids, Virusoids, Prions
not on tree of life
define prokaryotic - ANSWERSno nucleus
no membrane bound organelles
single chromosome
define eukaryotic - ANSWERScomplex nucleus
membrane bound organelles
capable of mitosis/meiosis
what are the 3 domains of life - ANSWERSbacteria
archea
eukarya
difference between bacteria and arches - ANSWERSbacteria - made of peptidoglycan
archea - no peptidoglycan, distinct ssu RNA sequences, abundant in extreme
environments
how do microbial populations change and evolve? - ANSWERSvertically - mutation of
genetic material, new genotypes, natural selection (all from their parents)
horizontally - increase in diversity within the same generation
define the prokaryote "species" - ANSWERSgroup of microbes that are more related to
other microbes
species is a controversial term
,what is a microbial species - ANSWERStwo organisms that can made and have
successful offspring by excual reproduction
whats a type strain - ANSWERSthe first strain isolated
might not be representative of the rest of the species
what are Koch's postulates - ANSWERS1. The suspected pathogen must be present in
all cases of the disease and absent from healthy animals. (find in all sick, never healthy)
2. The suspected pathogen must be grown in pure culture. (isolate and grow in pure
culture)
3. Cells from a pure culture of the suspected pathogen must cause diseases in a
healthy animal. (infect new host with culture and get the same disease)
4. The suspected pathogen must be reisolated and shown to be the same as the
original. (reisolate organism)
what are the problems with Koch's postulate? - ANSWERS1. 90% of disease causing
pathogens can't be cultured in a lab
2. there's no good animal model
3. a # of pathogens live in healthy people without causing disease - opportunistic
compound light microscope - ANSWERSuses light to illuminate specimens (bright field,
dark field, phase contrast, fluorescence)
refractive index - ANSWERSa measure of how greatly a substance slows the velocity of
light
direction and magnitude - ANSWERSdetermined be the refractive indices of the two
media forming the interface.
focal point - ANSWERSfocuses light rays
focal length - ANSWERSdistance between center of lens and focal point
shorter length = greater magnification
parfocal lens - ANSWERSstays in focus when magnification and focal length change
paracentric lens - ANSWERSwhen a specimen is in the center of the microscopic field,
it will remain centered when different objective lenses are moved into the light path.
total magnification - ANSWERSmag. Of ocular lense x mag. Of objective lense.
ocular lens - ANSWERSmultiplies magnification of the objective lens by 10
objective lens - ANSWERSeach lens magnifies the specimen
each has a different magnifying power
, resolution - ANSWERSability of a lens to separate or distinguish small objects that are
close together.
-formula: D=0.5 λ /(n(sintheta)
-smaller numerator = better resolution
-bigger n value, the better the resolution
-shorter wavelength = better resolution
numerical aperture - ANSWERSmeasure of light gathering ability (nsintheta)
theta - angle of light collected which is determined by the working distance
more light = higher NA = better resolution
what is working distance - ANSWERSdistance from the bottom of the objective lens to
the top of the organism being observed
stage - ANSWERSslide being viewed rests upon it, light passes through the hole
condenser - ANSWERSfocuses light on specimen
course adjustment knob - ANSWERSUsed for focus on scanning. Usually the low power
lens is used enabling the movement of the tube.
fine adjustment knob - ANSWERSUsed for focus on oil. Moves the body tube for
focussing the high power lens.
arm - ANSWERSIt supports the tube of the microscope and connects to the base of the
microscope.
stage clip - ANSWERSStage clips hold the slides in proper place
heat fixation - ANSWERSdestroys the proteins and internal structures of the cell but
keeps the external cell structures in tact allowing you to see the morphology and shape
of cell
chemical fixation - ANSWERSpreserves internal structure
done with formaldehyde or HCL
shorter wavelength = better _____ - ANSWERSresolution
bright field microscope - ANSWERSdark image against a brighter background; has
several lenses (parfocal, parcentric)
dark field microscope - ANSWERSimage is formed by light reflected or refracted by
specimen; produces a bright image of the object against a dark background; used to
observe living, unstained preparations (to identify bacteria, observe internal structures in
eukaryotes)
Questions & Answers
what is a microorganism - ANSWERSan organism too small to be seen by the naked
eye
define cellular - ANSWERSfit on the tree of life
are seen as "living"
define acellular - ANSWERSViruses, Viroids, Virusoids, Prions
not on tree of life
define prokaryotic - ANSWERSno nucleus
no membrane bound organelles
single chromosome
define eukaryotic - ANSWERScomplex nucleus
membrane bound organelles
capable of mitosis/meiosis
what are the 3 domains of life - ANSWERSbacteria
archea
eukarya
difference between bacteria and arches - ANSWERSbacteria - made of peptidoglycan
archea - no peptidoglycan, distinct ssu RNA sequences, abundant in extreme
environments
how do microbial populations change and evolve? - ANSWERSvertically - mutation of
genetic material, new genotypes, natural selection (all from their parents)
horizontally - increase in diversity within the same generation
define the prokaryote "species" - ANSWERSgroup of microbes that are more related to
other microbes
species is a controversial term
,what is a microbial species - ANSWERStwo organisms that can made and have
successful offspring by excual reproduction
whats a type strain - ANSWERSthe first strain isolated
might not be representative of the rest of the species
what are Koch's postulates - ANSWERS1. The suspected pathogen must be present in
all cases of the disease and absent from healthy animals. (find in all sick, never healthy)
2. The suspected pathogen must be grown in pure culture. (isolate and grow in pure
culture)
3. Cells from a pure culture of the suspected pathogen must cause diseases in a
healthy animal. (infect new host with culture and get the same disease)
4. The suspected pathogen must be reisolated and shown to be the same as the
original. (reisolate organism)
what are the problems with Koch's postulate? - ANSWERS1. 90% of disease causing
pathogens can't be cultured in a lab
2. there's no good animal model
3. a # of pathogens live in healthy people without causing disease - opportunistic
compound light microscope - ANSWERSuses light to illuminate specimens (bright field,
dark field, phase contrast, fluorescence)
refractive index - ANSWERSa measure of how greatly a substance slows the velocity of
light
direction and magnitude - ANSWERSdetermined be the refractive indices of the two
media forming the interface.
focal point - ANSWERSfocuses light rays
focal length - ANSWERSdistance between center of lens and focal point
shorter length = greater magnification
parfocal lens - ANSWERSstays in focus when magnification and focal length change
paracentric lens - ANSWERSwhen a specimen is in the center of the microscopic field,
it will remain centered when different objective lenses are moved into the light path.
total magnification - ANSWERSmag. Of ocular lense x mag. Of objective lense.
ocular lens - ANSWERSmultiplies magnification of the objective lens by 10
objective lens - ANSWERSeach lens magnifies the specimen
each has a different magnifying power
, resolution - ANSWERSability of a lens to separate or distinguish small objects that are
close together.
-formula: D=0.5 λ /(n(sintheta)
-smaller numerator = better resolution
-bigger n value, the better the resolution
-shorter wavelength = better resolution
numerical aperture - ANSWERSmeasure of light gathering ability (nsintheta)
theta - angle of light collected which is determined by the working distance
more light = higher NA = better resolution
what is working distance - ANSWERSdistance from the bottom of the objective lens to
the top of the organism being observed
stage - ANSWERSslide being viewed rests upon it, light passes through the hole
condenser - ANSWERSfocuses light on specimen
course adjustment knob - ANSWERSUsed for focus on scanning. Usually the low power
lens is used enabling the movement of the tube.
fine adjustment knob - ANSWERSUsed for focus on oil. Moves the body tube for
focussing the high power lens.
arm - ANSWERSIt supports the tube of the microscope and connects to the base of the
microscope.
stage clip - ANSWERSStage clips hold the slides in proper place
heat fixation - ANSWERSdestroys the proteins and internal structures of the cell but
keeps the external cell structures in tact allowing you to see the morphology and shape
of cell
chemical fixation - ANSWERSpreserves internal structure
done with formaldehyde or HCL
shorter wavelength = better _____ - ANSWERSresolution
bright field microscope - ANSWERSdark image against a brighter background; has
several lenses (parfocal, parcentric)
dark field microscope - ANSWERSimage is formed by light reflected or refracted by
specimen; produces a bright image of the object against a dark background; used to
observe living, unstained preparations (to identify bacteria, observe internal structures in
eukaryotes)
