Lecture 1: physical and chemical requirements of microbial growth

Question 1

microbial growth def

Answer 1

increase in bacterial numbers

Question 2

what is the septum

Answer 2

the dividing wall that forms across the middle of a bacterial cell, effectively splitting it into two daughter cells during the process of cell division

Question 3

what causes the shape and arrangement of bacterial cells

Answer 3

the plane of division that has occurred during binary fission

Question 4

shapes and arrangements of bacterial cells

Answer 4

shapes = cocci and rod
arrangements = chains and clusters

Question 5

what does division in one plane form

Answer 5

diplococcus

Question 6

what does division in two planes form

Answer 6

streptococcus

Question 7

what does division in many planes form

Answer 7

cluster

Question 8

what cell size is advantageous

Answer 8

a smaller cell size as there is a larger surface to volume ratio

Question 9

physical factors that influence microbial growth

Answer 9

• gaseous atmosphere
• temperature
• ph
• osmotic pressure

Question 10

chemical factors that influence microbial growth

Answer 10

• water
• energy and electron source
• carbon
• micronutrients
• macronutrients

Question 11

gaseous atmosphere

Answer 11

microbes vary in their need for and tolerance of oxygen

Question 12

aerobes

Answer 12

require molecular oxygen (aerobic respiration)
–> electron transport chain, then final electron acceptor is oxygen

Question 13

anaerobes

Answer 13

prefer the absence of oxygen (anaerobic respiration or fermentation)
–> anaerobic respiration uses electron transport chain, the final electron acceptor is exogenous

Question 14

what happens during fermentation

Answer 14

• there is no electron transport chain (or generation of PMF)
• ATP is synthesised by substrate level phosporylation, electron acceptor is endogenous

Question 15

capnophiles

Answer 15

require increased levels of carbon dioxide (around 5% which is more than what is in the environment naturally)

Question 16

obligate aerobes

Answer 16

need oxygen

Question 17

facultative anaerobe

Answer 17

prefer oxygen

Question 18

aerotolerant anaerobe

Answer 18

tolerate oxygen

Question 19

strict anaerobe

Answer 19

oxygen is toxic

Question 20

microaerophile

Answer 20

2-10% oxygen

Question 21

how can oxygen be toxic

Answer 21

• it can be converted by metabolic enzymes into highly reactive derivatives
• aerobes can tolerate it bc they convert the toxic substances using enzymes
• anaerobes do not possess these enzymes and so cannot tolerate oxygen

Question 22

reactive oxygen species (ROS)

Answer 22

superoxide and hydrogen peroxide

Question 23

5 different bacteria species and their temp preference (coldest to hottest)

Answer 23

psychrophiles
psychrotolerants
mesophiles
thermophiles
hyperthermophiles

Question 24

different pH solutions

Answer 24

• isotonic
• hypertonic
• hypotonic

Question 25

why dont bacterial cells burst

Answer 25

because they have a rigid wall

Question 26

how is water impacted and what does it impact

Answer 26

Impacts osmotic pressure And is impacted by temperature

Question 27

categories of organism based on their energy source

Answer 27

- phototrophs - chemotrophs

Question 28

phototrophs

Answer 28

derive energy from sunlight

Question 29

chemotrophs

Answer 29

energy derived from oxidation of chemical compounds (organic or inorganic)

Question 30

electron source may be from

Answer 30

reduced inorganic subastances = lithotrophs reduced organic compounds = organotrophs

Question 31

two terms used to characterise organisms according to the carbon sources which they utilise

Answer 31

- autotrophs - heterotrophs

Question 32

autotrophs

Answer 32

utilise only inorganic carbon in the form of carbon dioxide

Question 33

heterotrophs

Answer 33

utilise organic carbon (proteins, carbs and lipids)

Question 34

chemo organoheterotrophs

Answer 34

the combined terms for energy, electron and carbon source

Question 35

macronutrients

Answer 35

Def: a type of food required in large amounts in the diet eg: carbon, hydrogen, nitrogen, oxygen, phosphorus, sulphur

Question 36

micronutrients

Answer 36

Def: a chemical element or substance required in trace amounts for the normal growth and development of living organisms Eg: zinc, cobalt, molybdenum, copper, manganese