What is binary fission?
- single parent cell divides into identical daughter cells
- sectum begins to form –> then fully forms –> and then cell separates –> cycle continues
Cell numbers increase ___. What is mean generation time? How is microbial growth typically plotted?
- “Exponentially”
- time it takes for single cell to divide and the whole population
- Logarithmic plot
What is cell arrangement? What are the 3 types?
- Determined by number of planes that cell division occurs in, repeatable
- Chains, clusters, rods
What is division in one plane (of cocci)? one plane but second division? Many planes?
- diplococcus –> two
- streptococcus –> chains formed
- cluster
What are the physical factors that influence microbial growth?
- gaseous atmosphere
- temperature
- pH
- osmotic pressure
What are the chemical factors that influence microbial growth?
- water
- energy and electron source
- carbon
- macronutrients and micronutrients
What are aerobes? What is aerobic respiration? What is the FEA? Has what enzymes?
- require oxygen for aerobic respiration which uses the ETC and has oxygen as the final electron acceptor
- +SOD, +Catalase
What are anaerobes? What is anaerobic respiration? Fermentation? What are the FEAs? Has what enzymes?
- prefer no oxygen for anaerobic respiration
- AR uses ETC and has exogenous final electron acceptor (found from outside cell)
EX: nitrate - fermentation does NOT use ETC and instead ATP is synthesized through substrate level phosphorylation and has endogenous FEA (found inside the cell)
EX: pyruvate - -SOD, -Catalase
What are facultative anaerobes? Has what enzymes?
- grow with or without oxygen, prefers oxygen
- +SOD, +Catalase
What are microaerophiles? Has what enzymes?
- growth with little oxygen, not too much
- +SOD, low levels of +/-Catalase
What are capnophiles? Has what enzymes?
- require increased carbon dioxide levels
Why is oxygen a toxic substance?
- it gets converted into highly reactive derivatives –> damages cells
How does oxygen become non-toxic to some organisms? (What gets converted into what, using what) Why can’t anarobes tolarate oxygen?
- Aerobes and facultative organisms can convert superoxide free radical into hydrogen peroxide using the enzyme superoxide dismutase
- Further broken down by other enzymes (catalase or peroxidase)
- Anarobes don’t have these enzymes
If an organism can just tolerate oxygen what enzymes does it have?
+SOD, -Catalase
What are the toxic products from oxygen?
- Superoxide radical, hydrogen peroxide, and hydroxyl radical
What are protective enzymes produced?
- Superoxide dismutase (SOD)
- Catalase
- Peroxidase
What happens to growth at the minimum temperature? Maximum? Optimal?
- Longer generation time –> longer for enzyme reactions, metabolism is slowed
- Cell death
- Quickest growth, main generation time is short
What pH for growth? What acient group grows at extreme pH?
- most around neutral
- some are acid tolerant and can grow at extreme pH (called archaea)
What are some examples of extreme conditions for growth?
- Hot springs
- Tube worms on ocean floor
- Solar evaporation pond
How does osmotic pressure play a role in growth/what media is preferred?
- Isotonic media (ion concentration same inside and outside) = preferred
- Hypertonic (more ions outside the cell) = shrivelled cell
- Hypotonic (more ions inside the cell) = burst cell
Role of water in growth? What is it affected by/what does it affect?
- essential
- bacteria are 90% water
- temperature affects avaliablility of water and water affacts osmotic pressure
What are autotrophs? What are heterotrophs?
- Autotrophs utilize inorganic carbon in the form of CO2
- Heterotrophs utilize organic carbon like proteins, carbs, and lipids
What are chemoorganoheterotrophs? Ex?
- Electron and carbon sources are combined
- Most nonphotosynthetic microbes
- Ex: most pathogens, fungi, protists, archaea
What are some macronutrients? (they make up 96% of living organisms)
- CHONSP
- Carbon, hydrogen, oxygen, nitrogen, sulfur, phosphorus
- And other elements that aren’t major components (potassium, sodium, magnesium, calcium, iron, chlorine)
