Bacteriology 1

Question 1

What are bacteria?

Answer 1

One of the three domains of life in the classification (Taxonomy) or organisms

Question 2

Bacteria

Answer 2

Also prokaryotes; unicellular organisms that lack a membrane-bound nucleus and other membrane bound organelles of eukaryotes; thus are smaller and less complex than eukaryotic cells

Question 3

What are some other characteristics of bacterial that are unique?

Answer 3

A rigid cell wall containing peptidoglycan layer
nucleus is not bound by a nuclear membrane, is usually singular and circular
do not have an nucleolus, mitochondria, endoplasmic reticulum, or golgi apparatus
multiply by binary fission
exhibit considerable morphologic diversity but are usually <5micrometer

Question 4

Bacteria Taxonomy

Answer 4

bacteria and other organisms are classically further divided into biological taxonomic units
the main division we are interested in are genus/species (occasionally family)

Question 5

How do we classify bacteria?

Answer 5

morphology
biochemical reactions
serology
nucleic acid profiles

Question 6

Structures in Bacteria

Answer 6

Cell envelope
capsule or slime
cell wall
cytoplasmic membrane
Cytoplasm
nucleoid, ribosomes
Other structures in bacteria
flagella, pili, spores, biofilms

Question 7

Capsule or Slime Layer

Answer 7

Amorphous, gelatinous materials lying outside the cell wall (goop)
most commonly carbohydrates but some are polypeptides (sticky goop)
very variable (antigenically diverse)
help adherence
anti-phagocytic
may prolong survival in environment

Question 8

Cell wall

Answer 8

20% of total dry weight of bacteria
Gives bacteria their shape and rigid structure
Differs in structure and chemical composition between different bacteria, which influences their pathogenicity and staining characteristics
Gram positive
Gram negative
Acid fast
Others

Question 9

Gram positive bacteria

Answer 9

simpler structure of gram negative
thicker more uniform cell wall
predominantly composed of peptidoglycan and teichoic acid
the peptidoglycan desiccates on decolorization (gram stain) making it less permeable to dye complex
thicker wall also more resistant to mechanical damage
peptidoglycan is a target for some antibiotics and also lysozymes

Question 10

Gram negative bacteria

Answer 10

more complex of gram positive
outer membrane (OM) which has-lipopolysaccharides (LPS) (virulence factor) and porins
periplasmic space containing smaller amount of peptidoglycan
due to its structure the OM excludes hydrophobic molecules and renders gram negative bacteria resistant to some detergents

Question 11

Process of Gram staining

Answer 11

fixation
crystal violet
iodine treatment
decolorization
counter stain safranin

Question 12

Why is it helpful to know if a bacteria is gram + or -

Answer 12

help with diagnosis
help with treatment

Question 13

Flagella

Answer 13

important as confer motility

Question 14

fimbriae (phili)

Answer 14

important for adherence

Question 15

spores

Answer 15

important for long term survival and physical resistance

Question 16

Biofilms

Answer 16

planktonic (Free)
sessile (attached)
quorum sensing-communicating with another
pathogenesis of bacterial infection
aiding colonization
avoiding phagocytosis
avoiding antibiotics

Question 17

how does bacteria grow

Answer 17

binary fission, where generation time is length of time required for a single bacterium to yield two daughter cells

Question 18

Clonal expasnion

Answer 18

the number of colonies is directly related to the number of bacteria
optimal pH is neutral to alkaline
optimal tonicity is isotonic to hypotonic

Question 19

temperature

Answer 19

98.6

Question 20

(strict or obligate) aerobes

Answer 20

requires O2 for growth

Question 21

(Strict or obligate) anaerobes

Answer 21

killed by O2

Question 22

Facultative anaerobes

Answer 22

can grow aerobically or anaerobically

Question 23

microaerophiles

Answer 23

requires O2 some also like increase Co2