4) Bacterial metabolism, growth and reproduction

Question 1

various biological processes that convert food and other substances into energy and other metabolic byproducts

Answer 1

Metabolism

Question 2

Biodegradation of large organic molecules into simple molecules

Answer 2

Catabolism

Question 3

Assimilation of nutrients to form new

and functional units (biosynthesis)

Answer 3

Anabolism

Question 4

To be able to grow and multiply, every microorganism must have a source of

Answer 4

carbon (to build up their structural and functional molecules)

nitrogen (for vital nitrogenous molecules e.g. amino acids, proteins, DNA, and RNA)

energy (to drive both anabolic - building- or catabolic –degrading- reaction)

Question 5

In addition to suitable environmental conditions such as;

Answer 5

Temperature,
pH,
Oxygen concentration,
moisture and salt concentrations

Question 6

A growth environment can be;

Answer 6

Natural: the microorganism’s natural habitat (also called niche)

Artificial: culture media of natural or synthetic component.

Question 7

catabolic

Answer 7

energy releasin

Question 8

anabolic:

Answer 8

energy requiring

Question 9

macronutrients include :

Answer 9

C, 
N, 
P, 
S, 
K, 
Ca, 
Mg, 
Fe

Question 10

micronutrients include =

Answer 10

trace elements, growth factors

Question 11

Bacterial metabolism:

Answer 11

1. Glycolysis: 2. Kerb’s cycle: 3. Electron transport chain

Question 12

Energy Source= Light

Carbon Source= CO2

Nutritional Type ?

Examples?

Answer 12

‏Photoautotrophs

…….

Cyanobacteria,

some Purple

and Green Bacteria

Question 13

Energy Source = light

Carbon Source = Organic compounds

Nutritional Type ?

Examples ?

Answer 13

Photoheterotrophs

…

Some Purple and Green Bacteria

Question 14

Energy Source = Inorganic compounds, e.g. H2, NH3, NO2, H2S

Carbon Source = CO2

Nutritional Type ?

Examples ?

Answer 14

Chemoautotrophs

….

A few Bacteria and many Archaea

Question 15

Energy Source = Oxidation of organic compounds

Carbon Source = Organic compounds

Nutritional Type ?

Examples ?

Answer 15

Chemoheterotrophs

…..
Most Bacteria, some Archaea

Question 16

cold-loving organisms able to grow at temp as low as zero °C.

Answer 16

Psychrophiles

Question 17

psychrophiles that have an optimum temp of 10-20 °C.

Answer 17

Psychrotrophs

Question 18

organisms with an optimum temp around 37°C.

Answer 18

Mesophiles

Question 19

organisms with an optimum temp of 45-70 °C

Answer 19

Thermophiles

Question 20

some archaea with optimum temp of 90 °C and a maximum of 110 °C.

Answer 20

Extreme thermophiles

Question 21

grow at optimum pH below 7 e.g. (Lactobacillus acidophilus)

(Moulds ) prefer a pH of 5.5 while (yeasts ) prefer a pH of 4.5.

Answer 21

Acidophiles

Question 22

grow best at neutral pH e.g. most bacteria. .

Answer 22

Neutrophiles

Question 23

grow best under alkaline conditions e.g. (Streptococcus pneumoniae.)

Answer 23

Alkaliphiles

Question 24

The pH varies from 0.5 in the ………..

to 10 in the ……….

Answer 24

1) most acidic soil

2) most alkaline lakes

Question 25

The pH of the human body ranges from 1 (………….) to 8 (……..)

Answer 25

• in the stomach

- in the intestine

Question 26

Fungi prefer …………..

while bacteria grow well (……..)

Answer 26

• slightly acidic medium

- around neutrality (pH7)

Question 27

each organism has

-

pH values as described above.

Answer 27

minimum

optimum

maximum

Question 28

Microorganisms are named according to their response to salt (NaCl) into :

Mild halophiles =

Moderate halophiles=

Extreme halophiles=

Answer 28

require 1-6% salt

require 6-15% salt

require 15-30% salt.

Question 29

is an organism that grows best at salt concentrations where most microorganisms are inhibited

Answer 29

A true halophile

Question 30

The term ……….. refer to microorganisms that are able to live in environments with high sugar concentrations

Answer 30

Osmophiles

Question 31

The concept of lowering water activity in order to prevent microbial growth is the basis for

Answer 31

preservation of foods by drying (using sunlight or evaporation)

Or

by addition of high concentrations of salts or sugars

Question 32

Reproduction

Cell Division

Answer 32

Binary fission

Vegetative bacterial -> Binary
fission
(=asexual reproduction)

Generation time

time for duplication of bacteria.
•17 min in E. coli
•up to 900 min in Mycobacterium
tuberculosis

Colonies

Question 33

seen <24H (E. coli) for

up to 3 weeks (M. tuberculosis)

Answer 33

Colonies

Question 34

Bacterial Growth Curve =

Answer 34

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

Question 35

• adapt to new environment

* high biosynthesis

Answer 35

1-Lag phase

Question 36

• Rapid exponential growth

* Maximum nutrients metabolism

Answer 36

2.Log phase

Question 37

• caused by depletion nutrients
 • ↓ metabolic activity and consume non-
essential cellular proteins 
• ↑expression of genes of repair,
antioxidant metabolism and nutrient
transport

Answer 37

3.Stationary phase

Question 38

• There is decrease in number (not a
growth phase(

Answer 38

4. Death phase

Question 39

a dormant, tough, non-reproductive

structure to resist environmental stress

Answer 39

Spore

Or

spores

Question 40

Corynebacterium

Answer 40

No spores

Question 41

Bacillus

Clostridium

Answer 41

Spores

Question 42

Resistance of spores due to:

Answer 42

• Low water content.
• Low permeability of spore wall.
• Dipicolinic acid + Ca2+.
• Low metabolic activity.

Question 43

Measurements of bacterial growth :

Answer 43

1- Turbidity

2- Direct microscopic count

3- Standard plate count

Question 44

The turbidity of a broth culture is determined using a

Answer 44

spectrophotometer

Question 45

The instrument detects the (............) 
by a (..............)

Answer 45

amount of light scattered

bacterial suspension of cells.

Question 46

The amount of light scattered (……….)

is a function of the cell number (…………)

Answer 46

• the optical density

- (the more cells present , the more light is scattered).

Question 47

A standard curve can be generated (………..) in other situations.

Answer 47

to measure the cell number

Question 48

Direct microscopic count using =

Answer 48

specially designed slide and

a known sample of the culture.

Question 49

Turbidity and Direct microscopic count =

Answer 49

Both methods will count both dead and live cells.

Question 50

gives an indication of cell mass

Answer 50

Dry weight

Question 51

indication of metabolic activity and therefore cell number

Answer 51

Oxygen uptake

Question 52

Standard plate count:

Answer 52

Bacterial culture is (diluted )

And

samples of dilutions are placed in (agar plates)

Question 53

Each cell will undergo multiple rounds of binary fission to =

Then

each cell is called (………)

Answer 53

produce a separate colony on the plate consequently

……….

colony forming unit.

Question 54

Standard plate count as it measures (………..);

Because this it is another name is (………)

Answer 54

the living cells only (which can divide)

it is known as “Viable count” technique.