MIcrobes and Growth

Question 1

Process where nutrients are acquired from the environment for metabolism and growth.

Answer 1

Nutrition

Question 2

What are the nutrients that:

• Required in very large amounts
• Required in small quanitities for growth/reproduction

Answer 2

• Macronutrients
• Micronutrients

Question 3

Explain the steps to Binary Fission (five steps):

Answer 3

1. Cell elongates
2. New matieral synthesized
3. Chromosome replicated
4. Septum forms
5. Cell divided into two progeny​

Question 4

What are the three phases of binary fission?

Answer 4

1. Period of growth
2. Chromosome replication (partioning)
3. Cytokinesis

Question 5

Name these terms involved in chromosome replication:

1. site where replication starts
2. DNA replication machinery
3. site where replication ends

Answer 5

1. Origin of replication
2. Replisome
3. Terminus

Question 6

Name these terms involved in Cytokinesis:

1. Cytoskeletal proteins
2. All proteins involved in cell division
3. Formation of cross wall between two daughter cells

Answer 6

1. Z ring
2. Divisome
3. Septation

Question 7

Time needed for complete fission cycle:

Answer 7

Generation time

Question 8

After each fission cycle, how much do bacteria replicate by?

Answer 8

By a factor of 2

Question 9

What does a growth curve do?

What are its 4 phases?

Answer 9

Plots number of microorganisms in population over time

1. Lag phase
2. Log Phase
3. Stationary phase
4. Death phase

Question 10

What is the:

• Lag phase
• Log phase

of the growth curve?

Answer 10

• Cells adjust to environment (not reproducing)
• Exponential growth (continues as long as nutrients available)

Question 11

What is the:

• Stationary phase
• Death phase

of growth curve?

Answer 11

• Survival phase (replication=death rate)
• Nutrients depleted, cells die

Question 12

What is a viable plate count (measurement of growth)?

Answer 12

A direct method that counts the number of colony forming units from media

Question 13

What are microscopic counts (measurement of growth)?

Answer 13

A direct method of measurement where a small amount is added to a microscope with a grid

Question 14

What are electron counters (measurement of growth)?

Answer 14

A direct method that measure culture as it passes through a detector

Question 15

What is metabolic activity (measurement of growth)?

Answer 15

indirect method that determines the proportion of nutrients and waste production to number of microbes.

Question 16

What is dry weight (measurement of growth)?

Answer 16

indirect method where bacteria is filtered from media, dried, and weighed

Question 17

What is turbidity (measurement of growth)?

Answer 17

indirect method that determines how clody a tube of media becomes

more cloudy=more microbes

Question 18

Explain these terms that related to Oxygen requirements:

1. Obligate aerobe
2. Obligate (strict) anaerobe

Answer 18

1. Grow only in the presence of oxygen
2. Die in the presence of oxygen

Question 19

Explain these terms that have to do with oxygen requirements:

1. Facultative anaerobe
2. Aerotolerant anaerobe

Answer 19

1. Do not require oxygen, but grow better with it
2. Grow equally well with or without oxygen

Question 20

What are microaerophiles (oxygen requirement)?

Answer 20

Require low oxygen (damaged by normal amounts

Question 21

Explain these terms (environmental factors):

1. halophile
2. Osmophile

Answer 21

1. Require high levels of sodium chloride to grow
2. Require high levels of sugar to grow

Question 22

Explain these terms (environmental factors)

1. Osmotolerant
2. Xerophile

Answer 22

1. Grow optimally at high water activity
2. Grow optimally at low water activity

Question 23

Name these terms (Environmental factors):

1. Optimal growth at 15ºC or lower
2. Optimal growth between 20-30°C

Answer 23

1. Psychrophile
2. Psychrotolerant

Question 24

Name these terms (environmental factors):

1. optimal growth between 20-45°C
2. optimal growth at 55°C or higher
3. optimal growth between 85-120°C

Answer 24

1. Mesophile
2. Thermophile
3. Hyperthermophile

Question 25

Name these environmental factors: 1. Optimal growth between pH 0-5.5 2. Optimal growth between pH 5.5-8 3. optimal growth between pH 8-11.5

Answer 25

1. Acidophile 2. Neutrophile 3. Alkaphile

Question 26

Name these environmental factors: 1. increased pressure adversely affects them, **but not completely** 2. •maximal growth is at higher pressure (\> 1 atm)

Answer 26

1. Barotolerant 2. Barophilic

Question 27

Name these environmental factors (radiation) 1. **Very short** wavelengths and high energy **results in mutation**

Answer 27

Ionizing radiation

Question 28

Name this environmental factor (radiaition) **Short wavelength** and high energy. **Results in DNA damage**

Answer 28

UV radiation

Question 29

Name this environmental factor (radiation) **Photosensitizer** absorb lights, transfers energy to O2 to become singlet O2 * How do microorganisms counter this effect?

Answer 29

Visible light * Carotenoids

Question 30

What are biofilms? How do they form?

Answer 30

Complex, slime-encased community of microbes Form on _any_ substrate through **Extracellular Polymeric Substances**

Question 31

What purpose do biofilms serve?

Answer 31

1. More resistant to antimicrobials 2. Serve as reservoir for infection

Question 32

What do microbes use to communicate in Biofilms?

Answer 32

Molecule called: ## Footnote **Quorum sensing**