Mbio 4

Front 1

what is bacterial growth?

Back 1

more numbers

Front 2

how do bacteria reproduce?

Back 2

bacterial fission (elongates -> divides in two identical cells)

Front 3

what does exponential growth mean?

Back 3

population of bacteria cells double with every generation

Front 4

what is generation time?

Back 4

time required for population to double

Front 5

what is E. coli generation time?

Back 5

20 mins

Front 6

what is mycobacterium tuberculosis generation time?

Back 6

24 hrs

Front 7

what is culture?

Back 7

microbes growing in a medium

Front 8

what is inoculation?

Back 8

introducing microbes into a medium to start a culture

Front 9

what is batch culture?

Back 9

closed system; no added nutrients after it starts growing, eventually it stops growing after nutrients are gone

Front 10

continuous culture

Back 10

open system; nutrients are continuously added + wastes removed -> indefinite growth

Front 11

growth curve in batch culture?

Back 11

1. lag phase

2. exponential/log phase

3. stationary phase

4. death phase

5. phase of prolonged decline

Front 12

what is lag phase?

Back 12

adaptation period; cells adjust and prepare to grow

Front 13

what is exponential/log phase?

Back 13

maximal reproduction period; used to calculate generation time

Front 14

what is stationary phase?

Back 14

cells reached max population density; no increase in cell number

Front 15

what is death phase?

Back 15

toxic waste products accumulated, cells die at a uniform rate

Front 16

what is phase of prolonged decline?

Back 16

sometimes a few cells survive death phase; may eat nutrients from dying cells -> selected as strongest cells in the population

Front 17

what is the range of temperature requirements?

Back 17

minimum (lowest temp), optimum (best temp), maximum (highest temp)

Front 18

temperature range of psychrophiles?

Back 18

cold-loving

grow between -5°C and 15°C

killed at 20°C

Front 19

temperature range of psychrotrophs?

Back 19

broad temp. range

min: about -5°C

optimum: 15-30°C

max: 30-45°C

these microbes caused spoiled food in your fridge

Front 20

temperature range of mesophiles?

Back 20

min: about 10°C

optimum: about 25-45°C

max: about 45°C

most bacteria are mesophiles

Front 21

what is temp. optimum of pathogens (disease-causing microbes)?

Back 21

37°C

Front 22

temperature range of thermophiles?

Back 22

min: about 40°C

optimum: about 65°C

max: about 80°C

Front 23

temperature range of hyperthermophiles?

Back 23

min: about 75°C

max: up to 121°C

deep water where it's very hot

Front 24

how to use temperature for food safety?

Back 24

- heat kills mesophiles and psychotrophes

- cold slows growth ie. only psychotrophs grow in a fridge, slowly

Front 25

oxygen requirements

Back 25

some organisms need O2, some find it toxic

Front 26

which microbe need O2 for respiration (energy generation) aka to grow?

Back 26

obligate aerobes

Front 27

which microbe can use O2 for respiration, but can also grow without it?

Back 27

facultative anaerobes

Front 28

which microbe cannot use O2 and is killed by it?

Back 28

obligate anaerobes

Front 29

which microbe can use a little bit of O2 but dies if there's too much?

Back 29

microaerophiles

Front 30

which microbe cannot use O2, but is not killed by it?

Back 30

aerotolerant anaerobes

Front 31

what pH level do most bacteria grow?

Back 31

pH 6.5 - 7.5

Front 32

what are bacteria that grow at very low pH called?

Back 32

acidophiles

Front 33

what are bacteria that grow at high pH called?

Back 33

alkaliphiles

Front 34

what is osmosis?

Back 34

the movement of solvent molecules across a semi-permeable barrier

eg. water moving thru cytoplasmic membrane

Front 35

what is hypertonic solution?

Back 35

- high solute concentration

- water flows out of cell

- cell dries up (plasmolysis)

Hint 35

hyper = over

Front 36

what is hypotonic solution?

Back 36

- low solute solution

- water flows into cell

- cell bursts (osmotic lysis)

Hint 36

hypo = under

Front 37

what is isotonic solution?

Back 37

solute concentration inside cell = outside cell

Hint 37

iso = same/equal

Front 38

what are bacteria that adapted to life in high salt concentrations called?

Back 38

extreme halophiles

Hint 38

halo = salt in greek

Front 39

salt concentration of blood

Back 39

0.9%

Front 40

nutritional factors that influence growth

Back 40

1. Carbon

2. Nitrogen, Sulfur, and Phosphorus

3. Trace elements

4. Energy

Front 41

what are heterotrophs?

Back 41

take carbon from organic matter

eg. sugars

Hint 41

hetero = other

trophe = nourishment

Front 42

what are autotrophes?

Back 42

use inorganic carbon (produce its own food)

eg. CO2

Hint 42

auto = self

trophe = nourishment

Front 43

what needs nitrogen, sulfur, and phosphorus?

Back 43

required in smaller amounts for synthesis of cellular material

eg. protein, nucleic acids, phospholipids

Front 44

what needs trace elements?

Back 44

required in very small amounts

eg. iron, zinc, molybdenum

essential to certain enzymes' function

Front 45

what needs energy?

Back 45

organisms need it to build cell material and drive cellular processes

Front 46

what are chemotrophs?

Back 46

acquire energy from chemical compounds, may be in/organic

eg. sugars

Hint 46

chemo = chemicals?

troph = food

Front 47

what are phototrophs?

Back 47

harvest energy from sunlight

Hint 47

photo = light

trophe = nourishment

Front 48

what are photoautotrophs?

Back 48

use sunlight for energy + CO2 as a carbon source = photosynthesis

includes: some bacteria, algae, plants

Hint 48

photo = light

auto = self

trophe = nourishment

Front 49

what are photoheterotrophes?

Back 49

use sunlight for energy + obtain organic carbon

includes: some bacteria

Hint 49

photo = light

hetero = other

trophe = nourishment

Front 50

what are chemoautotrophs?

Back 50

obtain energy from inorganic chemicals (eg. H2, H2S) + use CO2 as carbon source

only done by some bacteria

Hint 50

chemo = chem

auto = self

trophe = nourishment

Front 51

what are chemoheterotrophes?

Back 51

obtain energy from organic chemicals + use those for carbon source

includes: all animals, fungi, protozoa, most bavteria, all medically relevant bacteria)

Hint 51

chemo = chem

hetero = other

trophes = nourishment

Front 52

solid media (agar petri plates)

Back 52

- add agar

- allows growth of colonies (genetically identical cell population)

- allows isolation of pure cultures

Front 53

chemically defined

Back 53

exact chemical composition of medium is known aka minimal media

Front 54

chemically undefined

Back 54

contains rich organic ingredients (so the chemical composition is not known) aka complex media

Front 55

selective media

Back 55

prevents unwanted organisms from growing, only desired ones allowed

inhibits growth of all gram positive and most gram negative bacteria

Front 56

differential media

Back 56

used to distinguish different bacteria

all can grow but certain colonies look diffedent on the plate

Front 57

direct count

Back 57

(live and dead) cells counted using a light microscope, inaccurate

Front 58

viable counts

Back 58

only live cells counted

Front 59

how are counts expressed?

Back 59

cfu per ml

colony forming units