lecture 28

Question 1

how much of the earths biomass are microbes

Answer 1

50%

Question 2

why can bacteria develop good antimicrobial resistance

Answer 2

because they can divide very quickly, so many divisons make for high and fast mutation rate

Question 3

whats the bacterias and archaea way of replication

Answer 3

binary fission

Question 4

does binary fission involve mitosis before occuring

Answer 4

not it does not

Question 5

explain process of binary fission

Answer 5

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.

Question 6

where in bacteria does the DNA replication start

Answer 6

, this place being called the origin of replication

Question 7

binary fission is what type of cell division

Answer 7

asexual

Question 8

how long have bacteria existed

Answer 8

3.5 billion years

Question 9

whats a closed batch culture system

Answer 9

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

Question 10

bacterial growth diagram has four phases, what are they

Answer 10

lag phase, exponential phase, stationary phase, death phase

Question 11

explain lag phase

Answer 11

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

Question 12

explain the exponential phase

Answer 12

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

Question 13

explain the stationary phase

Answer 13

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.

Question 14

what can occur during the stationary phase

Answer 14

cryptic growth. this is when some bacterial organisms are growing off of the components of lysed and dead cells.

Question 15

at stationary phase, the population is what

Answer 15

the population is dynamic as the cells are dying as fast as grow

Question 16

what happens in the death phase

Answer 16

there is net cell death, as bacteria dies faster than the population grows. so the equilibrium is skewed toward death.

Question 17

what three things do prokaryotes need in order to grow

Answer 17

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+.

Question 18

whats an autotroph

Answer 18

an organism which makes organic substances which it uses for energy from carbon dioxide

Question 19

what are heterotrophs

Answer 19

organisms that get their organic nutrition substances from other carbon using sources

Question 20

whats an auxotroph

Answer 20

an organism that is unable to synthesize one or more essential growth factors, and it will not grow unless factor is provided

Question 21

whats cross-feeding or syntrophy

Answer 21

when one species gains metabolic products of another species.

Question 22

why is it hard to culture most organisms alone

Answer 22

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

Question 23

whats the microbiome

Answer 23

The complete collection of microorganisms and their genes within an environment.

Question 24

whats a microbiota

Answer 24

an individual microbial species of a biome