Bacterial Physiology And Metabolism

Question 1

Bacterial physiology and metabolism can be

Answer 1

Bacterial metabolism 
Growth requirements 
Bacterial enzymes
Bacterial pigments and toxins
Bacterial growth curve

Question 2

Bacterial metabolism definition

Answer 2

Metabolism means the chemical processes that occur within a cell. Bacteria needs energy to grow. Energy is brought through respiration, photosynthesis or fermentation

Question 3

Respiration definition and pathway

Answer 3

Respiration is an energy yielding process in which oxidation is followed by reduction.
Glucose in the cell - 2 hydrogen atoms gives gluconate
Gluconate + carbon dioxide + 2 hydrogen + Energy gives hydrogen peroxide
Catalase enzyme converts hydrogen peroxide to water and oxygen

Question 4

In aerobic organisms, the ultimate electron acceptor is ……… because they have ……….

Answer 4

oxygen …………………… peroxidase enzyme

Question 5

In anaerobic organisms, the ultimate electron acceptor is …… and converted to ……

Answer 5

Nitrate or sulphate ……………………. Nitrite or sulfite

Question 6

Main elements needed for bacterial nutrition

Answer 6

Carbon and nitrogen

Question 7

Autotrophs definition and examples

Answer 7

Bacteria can assimilate carbon and nitrogen from simple inorganic sources
Utilize CO2 and ammonium salts
Many saprophytic bacteria

Question 8

Heterotrophs definition and examples

Answer 8

Require pre-formed sources of nutrition
Glucose and amino acids
Most pathogenic bacteria are examples

Question 9

Gaseous requirements of bacteria

Answer 9

All bacteria need carbon dioxide to grow. Some depend on oxygen too

Question 10

According to bacterial need for oxygen, bacteria can be divide to

Answer 10

Obligatory aerobes
Obligatory anaerobes
Aerobe facultative anaerobe
Micro aerophilic

Question 11

According to the need of carbon dioxide, bacteria can be divided to

Answer 11

• bacteria that grow normally in 0.04% carbon dioxide concentration
• bacteria that need 5-10% carbon dioxide concentration (Capnophilic bacteria)

Question 12

Capnophilic bacteria examples

Answer 12

Pneumococci
Gonococci
Brucella abortus

Question 13

Micro aerophilic bacteria definition and examples

Answer 13

Grow best in presence of a trace of O2 (5%) and often prefer high concentration of CO2
Ex: Campylobacter

Question 14

Aerobe facultative anaerobes definition and examples

Answer 14

Grow well in the presence of O2 and in its absence

Ex: Most pathogenic bacteria like Staphylococcus and E.coli

Question 15

Obligatory anaerobes definition and examples

Answer 15

Grow only in absence of O2

Ex: Clostridium

Question 16

Obligatory aerobes definition and examples

Answer 16

Grow only in presence of O2 (21%)

Ex: Mycobacterium tuberculosis and pseudomonas

Question 17

Moisture effect on bacteria

Answer 17

Drying is dangerous for many bacteria eg gonococci but some bacteria can survive dry places like:
T.b
Bacillus 
Spores
Clostridium

Question 18

Optimum temperature for bacterial growth

Answer 18

37 degrees

Question 19

Optimum pH for bacteria (neutral, acidic and alkaline)

Answer 19

Most pathogenic bacteria can grow at pH of 7.5 with a range of 7.2 to 7.6
Some bacteria prefer acidic media like Lactobacilli
Some bacteria prefer alkaline media like Vibro cholera

Question 20

Bacterial enzymes definition

Answer 20

Enzymes are biological catalysts which initiate and accelerate chemical reactions without themselves being changed.

Question 21

Types of bacterial enzymes

Answer 21

Can be:

• Constitutive enzymes
• Inducible enzymes

Question 22

Constitutive enzymes definition and examples

Answer 22

They are enzymes that are synthesized irrespective of the environmental conditions
Essential for fundamental metabolic pathways and growth of the bacteria
Like respiratory enzymes

Question 23

Inducible enzymes definition and examples

Answer 23

They are enzymes produced only in the presence of an inducer

Eg proteolytic enzymes

Question 24

Bacterial pigments types

Answer 24

• endopigment

- exopigment

Question 25

Endopigments characteristics and examples

Answer 25

Non-diffusible. Best demonstrated when the organism is grown on the surface of solid media. Color appears within the colonies e.g. golden yellow pigment of staph. aureus

Question 26

Exopigments characteristics and examples

Answer 26

Soluble or diffusible to the surrounding media Colonies do not change color e.g. Pseudomonas aeruginosa produce many types of pigments e.g. (pyocyanin and pyoverdin pigments) which turn the medium greenish(-blue).

Question 27

Factors affecting pigment production

Answer 27

Pigment production is better in aerobic conditions and room temperature

Question 28

Functions of the pigments

Answer 28

Help in identifying the bacteria

Question 29

Bacterial toxins definition

Answer 29

They are highly poisonous substances produced by certain bacterial species and lead to tissue damage

Question 30

Types of bacterial toxins

Answer 30

Endotoxin | Exotoxin

Question 31

Bacterial growth curve definition and how is it represented graphically

Answer 31

The definitive course of bacterial growth when cultivated in vitro in suitable medium and incubated at suitable temperature Represented graphically by plotting the log of number of bacteria against the time in hours

Question 32

Bacterial growth curve phases

Answer 32

Lag phase Log phase Stationary phase Decline phase

Question 33

Endotoxins properties and examples | DHN FATS

Answer 33

``` Diffusability: Non-diffuasble Heating: Stable Nature: Lipopolysaccharide produced only by gram -ve bacteria as they have Lipid A Formaline effect: NOt detoxified Antigenicity: Poor Toxicity: Low Specificity: Non-specific, generalised action Examples: Salmonella Typhi ```

Question 34

Exotoxin properties and examples | DHN FATS

Answer 34

Diffusability: Diffusable Heating: Destroyed Nature: Protein in nature mainly secreted by grame +ve bacteria but can be secreted by Gram -ve Formaline effect: Converted to toxoid Antigenicity: Strong Toxicity: High Specificity: Selective action Examples: In gram +ve like: Clostrodium tetani and C.diphtheria In Gram -ve like: Vibro cholera

Question 35

Factors affecting the length of the lag phase:

Answer 35

1- The nature of the organism (E.coli has short lag phase while T.B has long lag phase) 2- Size of the inoculum: The bigger, the shorter the phase 3- Stage from which the inoculum was taken: if taken from the log phase, the lag phase will be slow 4- Suitability of the medium: The more suitable the medium the shorter the lag phase

Question 36

Lag phase corresponds with:

Answer 36

Incubation period of the disease

Question 37

Log phase corresponds with:

Answer 37

Acute phase of the disease

Question 38

Stationary phase corresponds with:

Answer 38

Chronic phase of the disease

Question 39

Decline phase corresponds with:

Answer 39

Convalescent phase ends with complete cure

Question 40

Sample taken from specimen and grown on a plate?

Answer 40

Culture

Question 41

Sample taken from a plate to be grown on a second plate?

Answer 41

Sub-culture