prokaryotic growth

Question 1

structure of a prokaryote

Answer 1

• no nucleus or membrane bound organelles
• genetic info in a nucleoid
• extra chromosome called plasmid
• flagella

Question 2

define phototophs and chemotrophs

Answer 2

Photo: use light as energy source
chemo: obtain energy from oxidation of compounds

Question 3

define lithotrophs and organottrophs

Answer 3

lithotrophs: use reduced inorganic substances as electron source
organotrophs: extract electrons from reduced organic compounds

Question 4

define autotrophs and heterotrophs

Answer 4

auto: use carbon dioxide as sole carbon source
hetero: use reduced organic molecules as carbon source

Question 5

explain classifications of microorgansims by metbaolism

Answer 5

1. energy source = phototroph or chemotrophs
2. electron source = lithotrophs or organotrophs
3. carbon source = autotroph or heterotroph

Question 6

what are the five TYPES of microorganisms based on combination of energy sources

Answer 6

1. photolithoautotroph
2. photoorganoheterotroph
3. chemolithoautotroph
4. chemolithoheterotroph
5. chemoorganoheterotroph

Question 7

explain binary fission process

Answer 7

1. DNA rep
2. cell elongation
3. cell division (septum forms)

Question 8

If the starting populaion of cells is 5.5x10^6 cells/mL, the incubation time is 1 hour and the generation time is 20 minutes, what is the final cell concentration

Answer 8

• 5.5x10^6 x 2^3
• 3 x 20 mins in an hour, thus 3 generations
• every generation = x 2 of population
• thus 2^3 (2 ^ number of generations)
  = 4.4 x 10^7 cell/mL

Question 9

what are the 5 phases of bacterial growht and breifly explain

Answer 9

1. lag phase - cells alive but population does not increase (synthesising components and adjusting to new conditions)
2. log/exponential phase
   - cells growing and diving at maximum rate.
   - Mean generation time measured
   - constant growth rate
3. stationary phase - constant number of cells (death and growth balance)
4. death phase - viable cells decline

Question 10

What is MGT

Answer 10

-mean generation time
- time required for one generation of bacteria to double

Question 11

how to calculate MGT

Answer 11

find two points where cell number doubles and calculate the time between the two points

Question 12

what is bacterial cell growth dependent on?

Answer 12

• speicies
• growth medium
• environmental conditions

Question 13

how can bacterial growth be measured

Answer 13

• turbidity - scattering of light (increased absorbance)
• dry weight
• viable cell count - agar
• direct cell count - microscope
• protein measurement

Question 14

cell state in a hypertonic soln, isotonic, and hypoonic

Answer 14

hyper = shrivelled
iso = normal
hypo = lysed (burst)

Question 15

why is temperature so important to bacteria

Answer 15

• no insulation so bacteria are SAME temp as environment
• impacts enzymes
• impacts membrane structure (bonds)