lesson four

Question 1

endotoxin

Answer 1

• part of the cell structure-anchored in outer membrane
• lipid molecule
• released from the cell when the cell dies and disintegrates

Question 2

exotoxin

Answer 2

• produced by the bacterial cells, not a part of the cell strucuture
• released from cell in many ways, damages other cells
• protein
• three functional types: enterotoxin, neurotoxin and cytotoxin

Question 3

bacterial metabolism

Answer 3

sum total of all chemical reactions within an organism
- catabolic: release energy
anabolic: store energy
- catabolism: chemical reactions that release energy, breakdown of organic compounds

Question 4

anabolism

Answer 4

chemical reactions that require energy, building of complex organinc molecules from simpler compounds (stores ATP)

Question 5

reaction rates

Answer 5

temperature dependent,
higher the temp, higher the reaction rate
- drawback: high temperature may kill cells (denaturation of proteins)

Question 6

enzymes

Answer 6

Large protein molecules (biological catalysts)
* Make chemical reactions happen 100,000,000 X faster
* Substrate specific (what they work on)
* Have suffix “ase”
* May need cofactors – e.g. metal ions like zinc, magnesium
* Recyclable, unchanged during reaction

Question 7

what cellular controls affect function of enzymes

Answer 7

• temp
• pH
• saturation
• salt concentration
• inhibitors (mercury, silver)

Question 8

energy production

Answer 8

• most microbes use carbohydrates as number 1 source for production of energy
• glucose the most common nutrient source

Question 9

Two processes by which glucose is used

Answer 9

a. cellular respiration (aerobic, anaerobic)
b. fermentation
both processes need ATP to run

Question 10

energy sources other than glucose

Answer 10

• lipids: broken down by lipases
  protiens: broken down by proteases

Question 11

physchrophiles

Answer 11

-5 to +15 C

Question 12

pyschrotrophs

Answer 12

20-30 C (listeria)

Question 13

mesophiles

Answer 13

25-45 C

Question 13

thermophiles

Answer 13

45-70 C

Question 14

hyperthermophiles

Answer 14

70-110 C

Question 15

Listeria monocytogenes

Answer 15

• gram +, non-spore forming
• facultatively anaerobic, motile
• wide temp range: 3-42 C
• wide pH range: 5.5-9.5
• grow in high concentrations of salt (10%)

Question 16

listeria growth/survival

Answer 16

• survives in low temp, high acidity and salt concentrations

Question 17

listeria habitat

Answer 17

• soil, animal intestine through contaminated feed

Question 18

listeria symptoms in animals

Answer 18

CNS infections, goats, cattle (circling disease)

Question 19

listeria symptoms in man

Answer 19

• food borne disease
• CNS infections/death
• abortion

Question 20

how listeria causes disease

Answer 20

ingestion of contaminated food
- invasion of bacteria through gastric epithelial cells
- gene ActA codes for this protein- an “invasin”
- grows in macrophages, destroys the phagolysosome with listerolysin
- intracellular and extracellular growth

Question 21

listeria clinical infection

Answer 21

meningitis, encephalitis, septicemia
-incubation period may be as long as 2 months
-elderly and immunocompromised at risk
mortality of CNS infections 20-50%
pregnant women can cause abortion or stillbirth

Question 22

listeria transmission

Answer 22

• fecal-oral
• foods implicated as a vehicle of infections: coleslaw, soft unpasteurized cheeses, turkey wieners, cold cuts, mushrooms and prepackaged salads, milk

Question 23

listeria epidemiology

Answer 23

• hard to track because of long incubation period
• responsible for 1700 cases of invasive disease
  fatal in about 1/3 of cases even with antibiotics

Question 24

listeria treatment

Answer 24

antibiotics for treatment but you have to diagnose the infection in time

Question 25

physical factors: pH

Answer 25

5-8 usual activity zone for human pathogens

Question 26

physical factors: osmotic pressure

Answer 26

- isotonic solution is balenced - hypotonic: cell swells - hypertonic: cell shrinks, plasmolysis

Question 27

gaseous requirements for growth

Answer 27

- strict aerobe: needs oxygen - facultative anaerobe: can be exposed to some oxygen - strict anaerobe: no oxygen - aerotolerant anaerobe: can have oxygen or not - microaerophile: small amounts of oxygen

Question 28

chemical factors

Answer 28

- sources of C,N,O,S,P and trace elements - sources of organic growth factors (yeast extract in artificial media, cysteine or other amino acids)

Question 29

environmental factors: intracellular

Answer 29

- evade WBC - need antibiotics that penetrate host cell membranes - some cannot be grown on artificial media - may be dependent on host cell for energy

Question 30

bacterial reproduction

Answer 30

binary fission

Question 31

bacterial generation time

Answer 31

- dependent on media and growth conditions - aerobic bacteria usually grow faster than anaerobic (higher productions of ATP)

Question 32

bacterial growth kinetics

Answer 32

lag phase, log phase, stationary phase, death phase

Question 33

biofilms

Answer 33

- bacteria like to live in communities dynamic: bacteria are not stuck, they can leave the biofilm and start a new focus of infection - slimy matrix with polysaccharides, proteins, DNA, bacteria - antibiotics ineffective against biofilms

Question 34

how to grow bacteria in the lab

Answer 34

- nutrient material - agar: complex polysaccharide from algae for solid culture - bacteria grow in “colonies” – piles of bacteria where the original bacteria was placed on the surface of the agar filled plate

Question 35

hemolysis

Answer 35

breakdown of blood cells in agar plates - used for presumptive bacterial identification of streptococcus species

Question 36

Alpha

Answer 36

partial breakdown of RBC (greening) around and under colony

Question 37

Beta

Answer 37

total breakdown (clearing) of RBC around and under colony

Question 38

gamma

Answer 38

no breakdown of RBC around or under colony

Question 39

complex media

Answer 39

used for growing human pathogens

Question 40

differential media

Answer 40

ingredients in media allow us to tentatively identify bacteria into major groups