chapter 1: bacterial taxonomy

Question 1

steps of the gram stain

Answer 1

(a) Pour crystal violet stain (blue dye) and wait 60 seconds
(b) Wash off with water and flood with iodine solution
(c) Wash off with water and then decolorize with 95% alcohol
(d) Finally, counter-stain with safranin (red dye). Wait 30 seconds then wash off with water

Question 2

results of gram stain = blue then

Answer 2

gram positive

Question 3

results of gram stain = red then

Answer 3

gram negative organism

Question 4

the layer just outside the bacterial cytoplasmic membrane is the
-present on what bacteria?

Answer 4

peptidoglycan layer or cell wall

-gram neg and gram positive bacteria

Question 5

the enzyme that cross links amino acid residues coming from the disaccharides in the bacterial cell wall is called

-where is it located?

Answer 5

transpeptidase

-located in the inner cytoplasmic membrane

Question 6

what does penicllin disrupt

Answer 6

transpeptidase

Question 7

gram positive cell wall

Answer 7

thick outer peptidoglycan layer with teichoic acid, and polysaccharides as well

Question 8

bacterial cytoplasmic membrane contains no

Answer 8

cholesterol or other sterols

Question 9

what is an important antigenic determinate of gram positive bacteria

Answer 9

techoic acid

Question 10

gram negative cell envelope has 3 layers

Answer 10

cytoplasmic memrbane
(periplasmic space with proteins and enzymes)
peptidogylcan layer (cell wall that is thin)
-murein lipoprotein extends from this layer to the
Outer membrane
-composed of 2 layers, outermost portion has LPS

Question 11

LPS has 3 components

Answer 11

O-specific side chain (carbs)

core polysaccharide

Lipid A (endotoxin)

Question 12

function of porin and what bacteria

Answer 12

embedded in gram neg outer membrane which allows passage of nutrients

Question 13

which bacteria are vulnerable to lysozyme and penicillin attack

Answer 13

gram positive bacteria

Question 14

what contirbutes to the blue color of gram positive stains

Answer 14

the violet stain gets trapped in the thick cross linked cell wall

Question 15

bacterial shapes: spherical

Answer 15

cocci

Question 16

bacterial shapes: rods

short ones

Answer 16

bacilli

short bacili = coccobacilli

Question 17

comma-shaped, S-shaped, spiral-shaped

Answer 17

spiral

Question 18

lacking a distinct shape (like jello)

Answer 18

pleomorphic

Question 19

3 gram positivie cocci

Answer 19

streptococcus
enterococcus (form strips)
staphylocossus (form clusters)

Question 20

2 gram positive rods that produces spores

Answer 20

bacillus
clostridium

BC SPOREts

Question 21

2 gram positive rods that do not form spores

Answer 21

corynebacterium (core I Knee)

listeria

Question 22

only 2 groups of gram negative organisms that are cocci

Answer 22

both diplococci

• neisseria
• moraxella

Question 23

1 group of spiral shaped organisms in gram negative bacteria

Answer 23

spirochetes

bacterium treponema pallidum –>causes syphilis

Question 24

exceptions: mycobacteria

Answer 24

weak gram positive but stain better with acid-fast stain

-tuberculosis and leprosy

Question 25

exceptions: spirochetes

Answer 25

gram neg cell wall but too small to be seen with light microscope
-need darkfield microsceope

-slender and tightly coiled

• like normal Gram negative cell envelope but have additional phospholipid-rich outer membrane with few exposed proteins
• protects from immune recognition

specialized periplasmic flagella

• run sideways along spirochete under outer membrane sheath
• rotation propells them forward

Question 26

exceptions mycoplasma

Answer 26

no cell wall

only simple cell membrane

-neither gram positive or gram negative

Question 27

bacterial ribosome subunits and the antibiotics that attack them

Answer 27

50S blocked by erythromoycin

30S blocked by tetracycline

Question 28

enzymes that bacteria have to break down oxygen

Answer 28

catalase (H202)
peroxidase (H2O2)
superoxide dismutase (breaks down superoxide anion)

Question 29

obligate aerobes have which enzymes

Answer 29

all 3, use glycolysis, TCA, and ETS

have peroxidase and catalase

Question 30

facultative anaerobes

Answer 30

can grow with or without oxygen

-without oxygen they use fermentation for energy but perfor aerobic conditions

Question 31

microaerophilic bacteria (aerotolerant anaerobes)

Answer 31

use fermentation
no ETS
can tolerate low oxygen bc have superoxide dismutase

Question 32

obligate anaerobes

Answer 32

hate oxygen and have no enzymes to defend against it

Question 33

autotrophs

Answer 33

organisms that use chemical sources that are inorganic

Question 34

organisms that use chemical sources that are organic carbon sources called

Answer 34

heterotrophs

Question 35

all medically important bacteria are

-based on energy source

Answer 35

chemnoheterotrophs

Question 36

obligate intracellular organisms

Answer 36

can’t produce own ATP, must steal from host
cannot survive without hose

chlamydia and rickettsia