lecture 28 Flashcards
how much of the earths biomass are microbes
50%
why can bacteria develop good antimicrobial resistance
because they can divide very quickly, so many divisons make for high and fast mutation rate
whats the bacterias and archaea way of replication
binary fission
does binary fission involve mitosis before occuring
not it does not
explain process of binary fission
initiated when the DNA of the bacterial chromosome begins to replicate at a specific place on the chromosome. There are two copies of this one origin. As the chromosome continues to replicate, one origin moves rapidly toward the opposite end of the cell. While this is happening the cell elongates. When this replication finishes the bacteria reaches a length of about twice its initial. Once this has occurred the plasma membrane pinches inward, dividing the e coli parent into two daughter cells. This division occurs at a very specific place so that one set of each whole chromosome is placed in each cell.
where in bacteria does the DNA replication start
, this place being called the origin of replication
binary fission is what type of cell division
asexual
how long have bacteria existed
3.5 billion years
whats a closed batch culture system
its the classical way of culturing a system, it involves a defined [limited amount] supply of
nutrients being provided
v Once used [become limited] cells
cannot proliferate
bacterial growth diagram has four phases, what are they
lag phase, exponential phase, stationary phase, death phase
explain lag phase
when the bacteria is introduced to the culture and there is a lag in growth as the bacteria must initiate biosynthetic reactions before growth starts
explain the exponential phase
this is after the cells have their metabolism going, so they can grow exponentially and interrupted as there are no limiting factor. population doubles every Tc if conditions perfect
explain the stationary phase
this is when there is no longer an excess of nutrients, so cells begin to die. cell death in this phase is going at the same rate as growth. so there is no net growth.
what can occur during the stationary phase
cryptic growth. this is when some bacterial organisms are growing off of the components of lysed and dead cells.
at stationary phase, the population is what
the population is dynamic as the cells are dying as fast as grow
what happens in the death phase
there is net cell death, as bacteria dies faster than the population grows. so the equilibrium is skewed toward death.
what three things do prokaryotes need in order to grow
a carbon source: this carbon source providing building blocks for macromolecule synthesis
An energy source: energy in the form of electrons is used to drive anabolic and catabolic reactions in the cell.
Reducing power: carries of electron energy, these carries are the same as humans, NAD+ and NADP+.
whats an autotroph
an organism which makes organic substances which it uses for energy from carbon dioxide
what are heterotrophs
organisms that get their organic nutrition substances from other carbon using sources
whats an auxotroph
an organism that is unable to synthesize one or more essential growth factors, and it will not grow unless factor is provided
whats cross-feeding or syntrophy
when one species gains metabolic products of another species.
why is it hard to culture most organisms alone
These auxotrophs cant grow in pure culture, as there must be something they are missing provided. and we dont know exactly what the missing thing is that we must provide
whats the microbiome
The complete collection of microorganisms and their genes within an environment.
whats a microbiota
an individual microbial species of a biome
