Microbiology Today

Question 1

who was CARL LINNAEUS?

Answer 1

developed TAXONOMY
3 kingdoms: animal, plant mineral (abandoned)

Question 2

what is the TAXONOMIC HIERARCHY CLASSIFICATION?

Answer 2

hierarchy of groups of RELATED organisms (TAXA)
based on DNA SEQUENCE similarities

Question 3

how are SPECIES DEFINED?

Answer 3

genomic RELATEDNESS determined by HOUSEKEEPING GENES
small subunit rRNA (16S in prokaryotes) - 95% identity = same GENUS
shares common TRAITS and ECOLOGICAL niches

Question 4

describe BACTERIA

Answer 4

found NEARLY everywhere
MOST are HARMLESS or BENEFICIAL
cell walls contain PEPTIDOGLYCAN
enormous METABOLIC DIVERSITY

Question 5

what are the SHAPES of BACTERIA?

Answer 5

coccus - spheres
bacillus - rods
vibrio - comma shaped rods, polar flagella
coccobacillus - very short rods/ovals
sprillum - waves
spirochetes - spirals

Question 6

describe ARCHAEA

Answer 6

found in EVERY habitat
EXTREMOPHILES
NON pathogenic (to humans)
cell walls have PSEUDOPEPTIDOGLYCAN

Question 7

describe EUKARYOTES

Answer 7

DEFINED NUCLEUS
protists, fungi, plants, animals
typically bigger than bacteria

Question 8

describe ALGAE

Answer 8

UNIcellular or MULTIcellular
vary widely in size, appearance, habitat
cell walls have CELLULOSE
PHOTOSYNTHETIC

Question 9

describe PROTOZOA

Answer 9

(paramecium)
very diverse
move with CILIA or FLAGELLA
some are PHOTOSYNTHETIC, PARASITIC, PATHOGENIC
ex. malaria

Question 10

describe FUNGI

Answer 10

UNIcellular or MULTIcellular
NON-PHOTOSYNTHETIC (heterotrophic)
cell walls contain CHITIN

Question 11

describe YEAST

Answer 11

UNICELLULAR
cause GONADAL INFECTIONS and ORAL THRUSH

Question 12

describe MOULS/FILAMENTOUS fungi

Answer 12

MULTICELLUALR
long filaments that form VISIBLE COLONIES
play a critical role in DECOMPOSITION and NUTRIENT CYCLING
PHARMACEUTICALS (penicillin, cyclosporine)

Question 13

what are VIRUSES?

Answer 13

ACELLULAR organisms
PROTEINS + GENETIC material (DNA?RNA)
HIJACK host’s cellular organisms to multiply and spread
can infect ALL cell types

Question 14

what are the TOOLS of mircobiolgy

Answer 14

petri dish
test tubes
bunsen burner
inoculation loop
microscopes
dyes and stains
growth media

Question 15

which microorganisms can be seen with a LIGHT MICROSCOPE?

Answer 15

bacteria, archaea, yeasts

Question 16

describe some properties of light

Answer 16

ENERGY propagated as WAVES
wavelength increases, energy decreases
light REFRACTS through a microscope (n of glass > n of air)

Question 17

what does resolution requrie?

Answer 17

CONTRAST - distinguish object from surroundings
WAVELENGTH - equal or smaller than object to be resolved
MAGNIFICATION - retina absorbs radiation of 380nm-750nm, can resolve points 150micrometer apart

Question 18

what is RESOLUTION?

Answer 18

ability to DISTINGUISH between two points
NOT just about making something bigger

Question 19

what is the NUMERICAL APERTURE

Answer 19

HIGHER NA = HIGHER RESOLVING power of objective

Question 20

describe a COMPOUND MICROSCOPE?

Answer 20

LIGHT microscopy
system of LENSES that focus, correct, comensate
OCCULAR LENSE = 10x magnification
OBJECTIVE LENSES = 10x,40x,100x magnification
NA written beside power on lense

Question 21

how do you find TOTAL MAGNIFICATION?

Answer 21

MULPICATIVE
OCCULAR LENSE x OBJECTIVE

Question 22

describe BRIGHT FIELD microscopy

Answer 22

submerging sample in WATER
sample must be MORE DENSE than water
object appears as a dark SILHOUETTE
limit of resolution of 1000x

Question 23

what is OIL IMMERSION?

Answer 23

putting a drop of oil between lens and objective MINIMIZES LOSS OF REFRACTIVE LIGHT at the angles, SHARPENING the image

Question 24

what is a WET MOUND?

Answer 24

way to OBSERVE MICROBES
place them in a DROP OF WATER on a GLASS SLIDE
see cells in NATURAL STATE
hard to see

Question 25

what is a SIMPLE STAIN?

Answer 25

dark colour specifically to CELLS (npt surrounding tissue)

Question 26

what is a DIFFERENTIAL STAIN?

Answer 26

stains ONE TYPE of CELL, but not another GRAM STAINING

Question 27

describe GRAM STAINS

Answer 27

differentiates between two types of bacteria GRAM POSITIVE = purple due to THICKER cell wall GRAM NEGATIVE = pink due to thinner cell wall (cannot retain the stain)

Question 28

what is ACID-FAST STAINING?

Answer 28

differentiates between two types of GRAM POSITIVE cells, those with WAXY MYCOLIC ACIDS in their CELL WALL and those without

Question 29

what is CAPSULE STAINING

Answer 29

NEGATIVE STAINING stains SURROUNDING medium, but not actual capsule ex. india ink

Question 30

what is ENDOSPORE STAINING?

Answer 30

endospore = structures produced within certain bacterial cells that allows them to survive harsh conditions; progeny RESISTANT to STRESSORS highly resistant to normal staining BACILLUS have highly resistant endospores

Question 31

describe dark field microscopy

Answer 31

extra OPAQUE DISK under CONDENSER LENS light from source CANNOT enter objective light SCATTERED FROM SAMPLE reaches objective lens specimen ILLUMINATED on dark background microbes are HALOS of bright light good for LIVE and UNSTAINED samples

Question 32

describe PHASE CONTRAST microscopy

Answer 32

uses DIFFERENCES in REFRACTIVE INDEXES between different ORGANELLES CONTRAST between cell and background increased view LIVE UNFIXED cells determine intracellular DENSITY

Question 33

describe FLUORESCENCE microscopy

Answer 33

specimen ABSORBS light of a defined wavelength and EMITS light of LOWER ENERGY

Question 34

what is AUTOFLUORESCENCE?

Answer 34

cell components NATURALLY fluoresce

Question 35

what are FLUROPHORES?

Answer 35

florescent COMPOUNDS or proteins, which are FUSED to cell substructures used to determine where cell structures are in relation to each other

Question 36

what is IMMUNOFLUORESENCE

Answer 36

identify PATHOGENIC microbes by observing which ANTIBODIES bind to them

Question 37

what is the ELECTRON MICROSCOPE?

Answer 37

use beams of electrons in the visible spectrum for visualization produce a sharp image of 100000x electron DENSE regions are DARKER cells are DEAD

Question 38

what is the SCANNING electron microscope?

Answer 38

creates an image by detecting REFLECTED electrons 3D

Question 39

what is the TRANSMISSION electron miscroscope?

Answer 39

uses electrons PASSING THROUGH thin sections of the sample to create an image must prepare cells so they become electron dense 2D