Requirements for microbial growth – Part 2

Question 1

what do microbes need to make new cell material

Answer 1

carbon

Question 2

what do microbes need for growth

Answer 2

an energy source

Question 3

where do phototrophs get their energy from

Answer 3

from the light

Question 4

where do chemotrophs get their energy from

Answer 4

obtain energy from oxidation & reduction of chemicals

Question 5

Chemoorganotrophs?

Answer 5

organic chemicals

Question 6

Chemolithotrophs?

Answer 6

inorganic chemicals

Question 7

what do autotrophs require

Answer 7

only c02 as a carbon source

Question 8

what do hetrotrophs require

Answer 8

require organic forms of carbon

Question 9

what are the 4 nutritional categories of organisms

Answer 9

Photoautotrophs
Photoautotrophs
Chemolithoautotrophs
Chemolithoautotrophs

Question 10

For chemotrophs, two mechanisms for energy generation & conservation are known:

Answer 10

Respiration & fermentation

Question 11

what is fermentation?

Answer 11

anaerobic catabolism of organic compounds (generally carbohydrates

Question 12

summarise fermentation?

Answer 12

Simple method of generating energy

Oxidation & reduction of organic chemicals

Absence of usable terminal electron acceptor

Question 13

what is respiration?

Answer 13

anaerobic or aerobic catabolism

Question 14

summarise respiration?

Answer 14

Generation of energy with terminal electron acceptor

Oxygen if aerobic respiration

Electron acceptor other than oxygen if anaerobic

Question 15

what does glycolsis produce?

Answer 15

atp and reduces NAD to NADH

Question 16

what does the krebs cycle produce

Answer 16

produces some ATP by substrate-level phosphorylation,

Question 17

what happens in the ETC

Answer 17

the energy of the
electrons is used to
produce a great deal of
ATP by oxidative
phosphorylation

Question 18

WHAT HAPPENS IN FERMENTATION?

Answer 18

In fermentation, the pyruvic acid and the electrons carried by NADH from glycolysis are incorporated into fermentation end-products.

Question 19

why is respiration more efficient that fermentation

Answer 19

Fermentative microbes grow slowly
A far higher yield of ATP is possible with respiration

Question 20

what is microbial nutrion about?

Answer 20

all about supplying cells with the chemical tools, or nutrients, that they need to make monomers

Question 21

in nature what does microbes use for nutrients for growth

Answer 21

host tissues/food

Question 22

Organic tissues & food have complex heterogeneous structures therefore their chemical properties vary widely
what does this result in?

Answer 22

the characteristics of tissue/food components dictates the microbial flora that may grow

Question 23

what enzymes act on what/

Answer 23

Amylases act on starches
Proteases act on proteins
Lipases act on lipids/fats

Question 24

what are macronutrients

Answer 24

Macronutrients – nutrients required in large amounts

Question 25

what are micronutrients

Answer 25

Micronutrients – nutrients required in trace amounts

Question 26

why is nitrogen important in cells

Answer 26

Integral component of proteins, nucleic acids, phospholipids & cell wall

Question 27

where is nitrogen most abundant

Answer 27

forms but the bulk of available nitrogen is in inorganic form

Question 28

what is phosphrus used for>

Answer 28

required by the cell primarily for the synthesis of nucleic acids & phospholipids inorganic phosphates (PO43-)

Question 29

what is sulphur used for?

Answer 29

structural role in the amino acids cysteine & methionine & present in vitamins (e.g. thiamine & biotin) & coenzyme A (sulphate (SO42−), sulphide (HS−) )w

Question 30

what is potassium used for?

Answer 30

required by all organisms as many enzymes require potassium for activity various K salts or K+ in solution

Question 31

what is magnesium used for?

Answer 31

functions to stabilise ribosomes, membranes & nucleic acids

Question 32

what is calcium used for?

Answer 32

helps stabilise cell walls & plays a key role in the heat stability of endospores

Question 33

what is sodium used for?

Answer 33

– required by some but not all microbes. Typically a reflection of the habitat

Question 34

what is the role of iron?

Answer 34

Plays major role in cellular respiration

Question 35

what does iron form under anoxix conditions?

Answer 35

generally ferrous (Fe2+) form & soluble

Question 36

what does iron form under oxic conditions

Answer 36

generally ferric (Fe3+) form in insoluble minerals

Question 37

what does iron also produce?

Answer 37

produce siderophores (iron-binding agents) to obtain iron from insoluble mineral form & from animal iron-binding proteins

Question 38

what does a poor iron environment mean to some bacteria

Answer 38

requires certain bacteria to express siderophores for survival (e.g. aquachelin)

Question 39

what do trace elements play a role in?

Answer 39

components of enzymes or as vitamin cofactors

Question 40

what micronutrietns called/

Answer 40

called trace elements because they are only required in tiny or trace amounts

Question 41

what are growth factors

Answer 41

Growth factors – organic compounds needed in relatively small amounts by certain organism (requirements vary)

Question 42

what are some examples of growth factors?

Answer 42

Vitamins – function as coenyzmes. Most commonly required growth factors Amino acids – for synthesis of proteins Purines & pyrimidines – for synthesis of nucleic acids (DNA & RNA)

Question 43

what are some psychical requirements for microbial growth

Answer 43

Temperature pH Osmotic effects Oxygen Pressure

Question 44

what are some chemical requirements for microbial growth

Answer 44

Macronutrients Micronutrients (trace elements) Growth factors