Bacterial growth and metabolism

Question 1

What is Metabolism?

Answer 1

Metabolism refers to all the biochemical reactions that occur in a cell or organism.

Question 2

What is bacterial metabolism?

Answer 2

Bacterial metabolism focuses on the chemical diversity of substrate oxidations and dissimilation reactions (reactions by which substrate molecules are broken down), which normally function in bacteria to generate energy.

The bacterial cell is a highly specialized energy transformer

Question 3

What is heterotrophic metabolism?

Answer 3

Heterotrophic metabolism is the biologic oxidation of organic compounds, such as glucose, to yield ATP and simpler organic (or inorganic) compounds, which are needed by the bacterial cell for biosynthetic or assimilatory reactions

Question 4

What is respiration?

Answer 4

Respiration is a type of heterotrophic metabolism that uses oxygen and in which 38 moles of ATP are derived from the oxidation of 1 mole of glucose, yielding 380,000 cal.

Question 5

What is fermentation?

Answer 5

In fermentation, another type of heterotrophic metabolism, an organic compound rather than oxygen is the terminal electron (or hydrogen) acceptor.

Less energy is generated from this incomplete form of glucose oxidation, but the process supports anaerobic growth.

Question 6

What is the Krebs Cycle?

Answer 6

The Krebs cycle is the oxidative process in respiration by which pyruvate (via acetyl coenzyme A) is completely decarboxylated to CO2. The pathway yields 15 moles of ATP (150,000 calories).

Question 7

What is the Glyoxylate Cycle?

Answer 7

The glyoxylate cycle, which occurs in some bacteria, is a modification of the Krebs cycle. Acetyl coenzyme A is generated directly from the oxidation of fatty acids or other lipid compounds.

Question 8

Electron Transport and Oxidative Phosphorylation

Answer 8

In the final stage of respiration, ATP is formed through a series of electron transfer reactions within the cytoplasmic membrane that drive the oxidative phosphorylation of ADP to ATP. Bacteria use various flavins, cytochrome, and non-heme iron components as well as multiple cytochrome oxidases for this process.

Question 9

What are Heterotrophs and Autotrophs?

Answer 9

> Heterotroph
an organism that obtains carbon in an organic form made by other living organisms

Autotroph
> an organism that uses CO2 (an inorganic gas) as its carbon source
> not dependent on other living things

Question 10

What are the types of Heterotrophs?

Answer 10

1. Saprobes

2. Parasites/pathogens

Question 11

What are the ways of nutritional movement in Bacteria?

Answer 11

1. Osmosis
2. Facilitated diffusion
3. Active transport
4. Endocytosis
   > Phagocytosis
   > Pinocytosis

Question 12

What is extracellular digestion?

Answer 12

> digestion of complex nutrient material into simple, absorbable nutrients

> accomplished through the secretion of enzymes (exoenzymes) into the extracellular environment

Question 13

What are the environmental influences on microbial growth?

Answer 13

1. temperature
2. oxygen requirements
3. pH
4. Osmotic pressure
5. UV light
6. Barophiles

Question 14

Temperature types

Answer 14

1. Minimum temperature
   the lowest temperature that permits a microbe’s growth and metabolism
2. Maximum temperature
   the highest temperature that permits a microbe’s growth and metabolism
3. Optimum temperature
   promotes the fastest rate of growth and metabolism

Question 15

What are the temperature adaptation groups?

Answer 15

1. Psychrophiles
   optimum temperature 15oC
   capable of growth at 0 - 20oC
2. Mesophiles
   optimum temperature 40oC
   Range 10o - 40oC (45)
   most human pathogens
3. Thermophiles
   optimum temperature 60oC
   capable of growth at 40 - 70oC
4. Hyperthermophiles
   Archaea that grow optimally above 80°C
   hot-water vents

Question 16

1. Psychrophiles

Answer 16

optimum temperature 15oC

capable of growth at 0 - 20oC

Question 17

2. Mesophiles

Answer 17

optimum temperature 40oC
Range 10o - 40oC (45)
most human pathogens

Question 18

3. Thermophiles

Answer 18

optimum temperature 60oC

capable of growth at 40 - 70oC

Question 19

4. Hyperthermophiles

Answer 19

Archaea that grow optimally above 80°C

hot-water vents

Question 20

What are the different Oxygen requirements and degrees of dependence?

Answer 20

1. Aerobe
   - requires oxygen
2. Obligate aerobe
   - cannot grow without oxygen
3. Anaerobe
   - does not require oxygen
4. Obligate anaerobes die in the presence of oxygen
5. Aerotolerant bacteria
   
   • not affected at all by oxygen, evenly spread along the test tube.
6. Facultative anaerobe and aerobe
   - capable of growth in the absence OR presence of oxygen.

Question 21

The pH scale

Answer 21

The pH Scale

-Ranges from 0 - 14

-pH below 7 is acidic
[H+] > [OH-]

-pH above 7 is alkaline
[OH-] > [H+]

-pH of 7 is neutral
[H+] = [OH-]

Question 22

What are the different types of organisms that have different pH optimum levels?

Answer 22

1. Acidophiles
   optimum pH is relatively to highly acidic
2. Neutrophiles
   optimum pH ranges about pH 7 (plus or minus)
3. Alkaphiles
   optimum pH is relatively to highly basic

Question 23

How does Osmotic pressure influence microbial growth?

Answer 23

-Bacteria are 80% water, so they Require water to grow.

-Sufficiently hypertonic media at concentrations greater than those inside the cell cause water loss from the cell
>Osmosis
> The fluid leaves the bacteria causing the cell to contract = Causes the cell membrane to separate

Plasmolysis
Cell shrinkage

Extreme or obligate halophiles
Adapted to and require high salt concentrations

Question 24

Plasmolysis

Answer 24

Cell shrinkage

Question 25

What are extreme or obligate halophiles?

Answer 25

Adapted to and require high salt concentrations

Question 26

How does UV light affect microbial growth?

Answer 26

-UV light is great for killing bacteria - Damages the DNA (making little breaks) - in sufficient quantities, the breaking can kill the organisms - in a lower range causes mutagenesis > Endospores tend to be resistant and can survive much longer exposures

Question 27

How do Barophiles affect microbial growth?

Answer 27

-Bacteria in oceans grow at moderately high hydrostatic pressures. >membranes and enzymes depend on pressure to maintain their three-dimensional, functional shape 1. Barotolerants Grows at pressures from 100-500 2. Barophilic 400-500 3. Extreme barophilic Higher than 500

Question 28

Microbial association can be: 2 types

Answer 28

1. Symbiotic | 2. Non-symbiotic

Question 29

Symbiotic associations

Answer 29

When organisms live in close nutritional relationships

Question 30

What are the types of symbiotic associations? (3)

Answer 30

1. Mutualism Obligatory Dependent Both members benefit 2. Commensalism One member benefits Other member not harmed 3. Parasitism Parasite is dependent and benefits Host is harmed

Question 31

What are the types of Non-symbiotic associations?

Answer 31

When organisms are free-living, relationships not required for survival

Question 32

Synergism

Answer 32

members cooperate and share nutrients

Question 33

Antagonism

Answer 33

some members are inhibited or destroyed by others

Question 34

What are BIOFILMS?

Answer 34

Complex relationships among numerous microorganisms. Develop an extracellular matrix which: 1. Adheres cells to one another. 2. Allows attachment to a substrate. 3. Sequesters nutrients. 4. May protect the individual population of bacteria in the biofilm.

Question 35

What is BINARY FISSION?

Answer 35

> Prokaryotes reproduce asexually > one cell becomes two: basis for population growth ``` Process: parent cell enlarges duplicates its chromosome forms a central septum divides the cell into two daughter cells ```

Question 36

What is the process of binary fission?

Answer 36

``` Process: 1. parent cell enlarges 2. duplicates its chromosome 3. forms a central septum divides the cell into two daughter cells ```

Question 37

In population growth: what is Generation/doubling time?

Answer 37

Generation/doubling time: - Is the time required for a complete fission cycle. - Length of the generation time is a measure of the growth rate of an organism. - Some populations can grow from a small number of cells to several million in only a few hours!!

Question 38

In Prokaryotic growth: What are the phases in the Bacterial Growth curve?

Answer 38

1. Lag phase 2. Logarithmic phase 3. Stationary phase 4. Decline phase

Question 39

Bacterial Growth Curve + describe their phases

Answer 39

1. lag phase no cell division occurs while bacteria adapt to their new environment 2. logarithmic (log) phase The exponential growth of the population occurs Human disease symptoms usually develop 3. stationary phase When reproductive and death rates equalize 4. decline (exponential death) phase accumulation of waste products and scarcity of resources

Question 40

What are the other Methods of Analyzing Population Growth?

Answer 40

1. Turbidity 2. Direct microscopic count 3. Coulter counting

Question 41

Turbidity - describe

Answer 41

.

Question 42

Direct microscopic count - describe

Answer 42

.

Question 43

Electric counting - describe

Answer 43

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