introduction concepts lectures 1-2

Question 1

microbiology

Answer 1

study of microorganisms
include: bacteria, viruses, fungi, parasites

Question 2

viruses

Answer 2

minuscule, accelular infectious agents
have either DNA or RNA
obligate intracellular parasites
no cytoplasmic membrane, cytosol, organelles
not alive (cannot carry out any metabolic pathway, neither grow or respond to environment, cannot reproduce independently)

Question 3

fungi

Answer 3

chemo-heterotrophic (cannot fi carbon - no photosynthesis)
cell wall composed of chitin
unicellular or multicellular
closely related to animals
functions = decompose dead organisms and recycle their nutrients, help plants absorb water and minerals, used for food and in manufacture of foods and beverages, produces antibiotics

Question 4

protozoa

Answer 4

eukaryotic, unicellular, lack a cell wall
motile by cilia, flagella, and or pseudopodia
distribution = requires moist environments, live in ponds, streams, lakes, critical in plankton

Question 5

prokaryotes

Answer 5

small in size but can be seen with light microscope, bigger than most viruses
DNA - single, circular DNA chromosomes, no membrane to enclose DNA, nucleoid region for DNA
plasmids encode specialized genetic information

Question 6

gram positive bacterial cell wall

Answer 6

thick layer of peptidoglycan
lipoteichoic acids - anchor peptidoglycan cell membrane and give cell negative charge
appear purple following gram staining procedures

Question 7

gram negative bacterial cell wall

Answer 7

thin layer of peptidoglycan
bilayer membrane outside peptidoglycan containing phospholipids, proteins and LPS
may be impediment to the treatment of disease
appears pink following gram staining procedures

Question 8

teichoic acid and lipoteichoic acid

Answer 8

only found in gram positive bacteria
can be used to determine serotypes

Question 9

lipopolysaccharide (LPS)

Answer 9

found only in gram negative bacteria
can be used to distinguish bacteria

Question 10

gram stain

Answer 10

fixation –> crystal violet –> iodine treatment –> decolorization –> counter stain safranin

Question 11

acid-fast stain

Answer 11

used to stain cells that have unusual cell walls
ex. impermeable to mycolic acid - waxy or resistant to water-based stains

Question 12

bacterial spores

Answer 12

endospore
unique structures produced by some bacteria that are defensive strategy against unfavorable conditions
formation cycle
1. vegetative cell
2. chromosome is duplicated and separated
3. cell is septated into a sporangium and forespore
4. sporangium engulfs forespore for further development
5. sporangium begins to actively synthesize spore layers around forespore
6. cortex and outer coat layers are deposited
7. mature endospore
8. free spore is released with the loss of the sporangium
9. germination spore swells and released vegetative cell

Question 13

criteria for bacterial classification

Answer 13

growth on media, microscopy, biochemical tests, immunologic tests

Question 14

non-selective media for growth

Answer 14

supports the growth of many different bacteria; intended to cultivate as many different species as possible
blood agar for bacteria or fungi - 2 components = nutrient medium and blood
buffered peptone water - bacteria and balanced pH with peptone
bolton’s broth - anaerobic bacteria, horse blood, nutrient medium

Question 15

selective media for growth

Answer 15

used to eliminate or reduce large numbers of irrelevant bacteria in specimens; incorporates inhibitory agents that prevents growth of irrelevant bacteria

Question 16

differential media for growth

Answer 16

makes use of bacteria’s ability to produce pigments or produce secreted enzymes
allows differentiation between two colonies of bacteria growing on the same plate

Question 17

bacterial microscopy criteria

Answer 17

used in conjunction with staining methods
lot of different microscopy methods *see lecture 1 slides 43-55

Question 18

biochemical tests criteria

Answer 18

lot of different tests
*see lecture 1 slides 56-65

Question 19

immunologic tests criteria

Answer 19

typically involves determining the serotype
sero = use of antibodies
add cells to media with antibodies to specific microorganisms
clumping = positive result

Question 20

eubacteria

Answer 20

classic bacteira
no true nucleus
gram positive, gram negative, and cell-wall lacking eubacteria

Question 21

archaebacteria

Answer 21

do not have classic peptidoglycan cell wall; may have characteristic similar to eukaryotic cells

Question 22

bacterial metabolic requirements

Answer 22

carbon, nitrogen, energy source, water, various ions
oxygen is not required by all bacteria

Question 23

obligate aerobes

Answer 23

must have O2

Question 24

obligate anaerobes

Answer 24

cannot live with O2

Question 25

facultative anaerobes

Answer 25

like O2, but okay without it

Question 26

aerotolerant anaerobes

Answer 26

do not need O2, but okay with it

Question 27

microaerophiles

Answer 27

need a little bit of O2

Question 28

DNA replication is tied to bacterial replication

Answer 28

coordinated process where two equivalent daughter cells are produced
binary fission
need sufficient metabolites to support synthesis of bacterial components - particularly nucleotides for DNA synthesis

Question 29

bacterial transcription location difference than eukaryotes

Answer 29

occurs in nucleoid of prokaryotes

Question 30

transfer of DNA: conjugation

Answer 30

transfer of genetic material - usually plasmid - between bacterial cells by direct cell-to-cell contact or by a bridge-like connection between two cells

Question 31

transfer of DNA: trandsuction

Answer 31

DNA is transferred from one bacterium to another by a virus

Question 32

transfer of DNA: transformation

Answer 32

occurs when a host organism takes in foreign DNA

Question 33

trp operon

Answer 33

repressible
always inactive/turned off
unless an inducer - lactose - is available form environment

Question 34

immunology slides

Answer 34

*see lecture 2 slides 39-end