Lecture 1 Flashcards
What is the equation for exponential growth of microbes
2^n
When does exponential growth take place
When all conditions for growth are optimal, including food, lack of waste
What are the 2 major shapes of microbes and the 2 main ways the cells arrange
Cocci and rods, forming into chains or clusters
What cell divisions cause what cell arrangement
Division in 1 plane- diplococcus, division in 2 plane-streptococcus/chains, division in many planes- cluster
What are the environmental Physical Factors that influence growth
Gaseous environment, Temperature, pH, Osmotic pressure
Whats the difference between aerobes and anaerobes
aerobes- require oxygen, in e- chain final e- is oxygen OR an oxidant
anaerobes- do anaerobic respiration OR fermentation. ANA: in e- chain final e- is EXOgenous like nitrate or sulphate. FERM: no e- chain ATP made by sub level phos and e- acceptor is ENDOgenous/pyruvate
what conditions do facultative anaerobes grow in
With or without oxygen however grows better with
What conditions do microaerophiles grow in
2-10% oxygen/require lower levels of oxygen that atmospheric
What conditions do capnophiles grow in
increased levels of CO2
Why can oxygen be toxic
It can be converted by enzymes into highly reactive derivatives that are damaging to cells eg. superoxide free radical
Why can the aerobes tolerate oxygen
They can break down the superoxide free radical into Hydrogen peroxide with the use of superoxide dismutase. then down further with the use of catalase or peroxidase
Why can’t the anaerobes tolerate the oxygen
They cannot break down the superoxide free radical due to lacking both superoxide dismutase and catalase therefore resulting in the microbes to be destroyed
Describe the 3 osmotic pressures
Isotonic- the most favoured, same concentration in cell and out
hypertonic- higher concentration of water inside therefore it leaves. Can result in plasmolysis which kills the cell by pulling the cytoplasmic membrane away
hypotonic- Water concentration inside is lower so water diffuses inside. Can cause cell swelling
Name the chemical environmental factors that influence growth
Water(influenced by temp and osmotic p from the physical factors), Energy and electron source, Carbon source, Marco and micronutrients
What are the micros
Zinc, cobalt, molybdenum, copper, manganese
What are the cations and anions required for life
cations: K+, Na+, Mg2+, Ca2+, Fe2+
anion: Cl-
