Microbial Population Growth Flashcards
Why are prokaryotes so dominant
Fast growth rate (as low as 13 minute doubling time)
Fast growth allows for fast evolution
What is binary fission
Chromosomes replication begins
One copy of the origin is now at each end of cell
Replication finishes
Cell devices into two (cytokinesis)
Two clone daughter cells
What is the genetic makeup of daughter cells of binary fission
Genetically identical
Why are prokaryotes so diverse
Fast growth + 3.5 billion years allowed colonisation of all ecosystems
Prokaryotes were sole inhabitants for 1.7 billion years
Most habitats were colonised
Extreme ecological and metabolic diversity
Outline the cellular requirements of microbial cells and eukaryotes
Microbes need same building blocks, just in different amounts
If we supply them with all required materials the can reproduce
What is a closed batch culture
A form of cell culturing
Defined amount/supply of nutrients is provided
Once used, cells cannot proliferate
Standard method of studying microorganisms in culture
Dictated by method, not shape of flask
What are the feast and famine phases of microbial growth
Feast: Lots of nutrients to grow on
Famine: nutrients devoid environment
What is the lag phase of cellular growth
Length depends on history of the inoculum, time is required to get bio synthetic reactions running. Generally characterised by metabolic activity but not growth
What is the exponential phase (log growth) of cellular growth
Cells are actively dividing and nothing is limiting growth. Population is doubling at constant time interval
What is stationary phase of cellular growth
Cells stop growing and cryptic growth is observed
What is cryptic growth
Organisms survive by consuming lyses cell constituents of other dead dells within population
Population is not static, but is dynamic. Equilibrium between growing and dying cells
What causes stationary phase of bacteria growth
Run out of nutrients to sustain expanding population
Competition for resources
Produce toxic end products (closed system, are not removed)
What is cell death phase
Cell death. Equilibrium between growing and dying cells is skewed towards cell death
What 3 things do microorganisms need to grow
A carbon source = building blocks for macro molecular synthesis
An energy source = energy (electrons) to drive anabolic (making) and catabolic (breaking) reactions in cell
Reducing power = carriers of energy/electrons (NAD+/NADP+)
What does the photosynthetic electron transport chain produce for the cell
Transforms light energy into carbs, NADPH, and APT
Where do microbes harvest carbs from
Microbes harvest carbs from autotrophs as sources of carbon/energy
How do microorganisms harvest energy
Molecules = natures batteries (glycolysis)
Chemical energy stored in bonds
Breaking of bonds releases energy that can be captured in new bonds (ATP)
ATP bonds can later be token to release energy
What is a photoautotroph
Organisms that use light energy and inorganic carbon to produce organic materials
What is a photoheterotroph
organisms that use light for energy, use organic compounds as their sole carbon source
What is a chemoautotroph
Organism that used chemical energy, and fixation of inorganic substances for carbon
What is a chemoheterotroph
Organisms that use chemical energy, carbon from organic compounds
What is a genomic strain when studding communities
Wild type strain might have all genes necessary, can be grown in isolated pure culture
Auxotroph got be lacking/defective in one or more essential genes
Cannot grow unless missing factor is supplied (might be supplied by other organism in wild)
What % of microorganism are auxotrophs, and how do the survive in the wild
98% of all microorganism sequenced so far lack essential pathways or key genes for synthesis of Amin acids
Something else provides missing substance in wild
What is an auxotroph
An organism that is unable to synthesise one or more essential growth factors, and cannot grow unless this is provided
What is cross feeding
When one species gains metabolic products off another species
Allows for survival of auxotrophs by harvesting resources generated by other organisms
Interactions can benefit one, or both partners
What is a microbiome
Complete collection of mircoorganisms and there genes within a particular environment
What is a microbiota
Individual microbial species in a biome
What are the 3 ways of studying the microbiome
Metagenomics
Metatranscriptonics
Metabiomics
What are the pros and cons of studying the microbiome using culture dependant methods
Pros: Allows access to phenotype, can study one organism at a time, can manipulate conditions to see response of organism
Cons: Not all organism can be cultured, Too many species to grow them all, culturing requires precise conditions to match microbes needs, does not match real world conditions
What are the pros and cons of studying microbiome using culture independent methods
Pros: Allows access to all genotypes, can study many organisms at a time, shows communities as they are in nature, can target non culturable organisms, provides access to unknown information/species
Cons: No pure culture so no ability to manipulate, expensive and complex methods
