Prokaryotic Growth Flashcards

1
Q

Prokaryotic cells divide by what process?

A

Binary Fission

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2
Q

What is the Generation time?

A

Time it takes for population to double (varies among species)

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3
Q

How can bacterial population growth be calculated (formula)?

A

Nt = N0 x 2n
(Nt ) number of cells in population
(N0 ) original number of cells in the population
(n) number of divisions

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4
Q

How are Biofilms Formed?

A
  1. Attachment~ Formation begins when planktonic bacteria attach to surfaces
  2. Expansion~ Other bacteria attach and grow on initial layer
  3. Maturation/ Resistance~ Secretion of slime layer (glycocalyx)
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5
Q

What are some characteristics of biofilms?

A
  1. Complex, channels for diffusion and exchange of nutrients, gases etc.
  2. Resistant to antimicrobial agents
  3. Persistent
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6
Q

What is a pure culture?

A

A population of organisms descended from a single cell and therefore separated from all other species

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7
Q

Why do we seek pure cultures in the lab?

A

Prokaryotes in the environment grow in close association with many different species, but this is too hard to study, so we isolate them.

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8
Q

Which scientist tried potatoes and gelatin as mediums before discovering agar?

A

Koch

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9
Q

What does growth within a batch system involve?

A

No new input of nutrient and no release of waste

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10
Q

What pattern does a population of cells follow?

A

A growth curve

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11
Q

What are the 5 growth curve stages?

A
  1. Lag stage
  2. Exponential or log stage
  3. Stationary stage
  4. Death stage
  5. Phase of prolonged decline
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12
Q

What features characterize the Lag Phase on a growth curve?

A
  1. Number of cells does not increase

2. Cells prepare for growth (“tooling up”)

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13
Q

What features characterize the Log Phase on a growth curve?

A
  1. Period of exponential growth (Doubling of population with each generation)
  2. Early~ Produce primary metabolites (Compounds req’d for growth)
  3. Late~ Synthesize secondary metabolites
    (Used to enhance survival, ex antibiotics)
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14
Q

What features characterize the Stationary Phase on a growth curve?

A
  1. Overall population remains relatively stable
  2. Cells exhausted nutrients
  3. Cell growth = cell death
  4. Dying cell supply metabolites for replicating cells
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15
Q

What features characterize the Death Phase on a growth curve?

A
  1. Total number of viable cells decreases

2. Decrease at constant rate

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16
Q

What features characterize the Phase of Prolonged Decline on a growth curve?

A
  1. Once nearly 99% of all cells dead
  2. Marked by very gradual decrease in viable population
  3. Phase may last months or years
17
Q

How much Oxygen do Obligate aerobes require for growth?

A

Absolute requirement for oxygen

~ Use for energy production

18
Q

How much Oxygen do Obligate anaerobes require for growth?

A

No multiplication in presence of oxygen

~ May cause death

19
Q

How much Oxygen do Facultative anaerobes require for growth?

A

Grow better with oxygen but can grow in absence of oxygen

20
Q

How much Oxygen do Microaerophiles require for growth?

A

Require oxygen in lower concentrations

~ Higher concentration inhibitory

21
Q

How much Oxygen do Aerotolerant anaerobes

require for growth?

A

Indifferent to oxygen, grow with or without

~ Do not use oxygen to produce energy

22
Q

Which bacteria can’t synthesize their own macromolecules?

A

fastidious bacteria

23
Q

Which “trophes” use organic carbon as nutrient source

A

Heterotrophs

24
Q

Which “trophs” use inorganic carbon (CO2) as carbon source?

A

Autotrophs

25
Q

Which “trophs” use light as source of energy?

A

Phototrophs

26
Q

Which “trophs” depend on oxidation-reduction reactions of inorganic or organic compounds for energy?

A

Chemotrophs

27
Q

Which “trophs” are primary producers?

A

Photoautotrophs

28
Q

Which “trophs” Use sunlight and atmospheric carbon (CO2) as carbon source?

A

Photoautotrophs

29
Q

Which “trophs” get energy from sunlight, carbon from organic compounds?

A

Photoheterotrophs

30
Q

Which “trophs” use inorganic chemicals for energy and use CO2 as carbon source?

A

Chemoautotrophs

31
Q

Which “trophs” use organic compounds for energy and carbon source?

A

Chemoheterotrophs

32
Q

Which “troph” type is the most common among humans and other animals?

A

Chemoheterotrophs

33
Q

How is complex media defined?

A

Complex media contains a variety of ingredients

~ ex. Nutrient broth, Blood agar, Chocolate agar

34
Q

How is chemically defined media described?

A

Chemically defined media is composed of precise amounts of pure chemicals

35
Q

Why do research labs use chemically defined media?

A

Generally not practical for routine laboratory use but invaluable in research because does not introduce experimental variable

36
Q

How is selective media defined?

A

It inhibits the growth of unwanted organisms and allows only sought after organisms to grow
~ ex. MacConkey agar, for isolation of Gram negative bacteria

37
Q

How is differential media defined?

A

It contains substance that bacteria change in recognizable way
~ ex. Blood agar: Certain bacteria produce hemolysin to break down RBC (Hemolysis)
~ ex. MacConkey agar: Contains pH indicator to identify bacteria that produce acid