Chapter 4 : Bacterial Culture and Growth

Question 1

what are the three ways that microbes respond to their resources being depleted?

Answer 1

they can (1) die, (2) evolve to use what resources remain, or (3) cannibilize other microorganisms

Question 2

what type of nutrients must an organism import from the immediate environment, otherwise it will not grow?

Answer 2

essential nutrients

Question 3

what are nutrients that are needed in large quantities?

Answer 3

macronutrients

Question 4

what are the 6 main macronutrients that are needed to make carbs, lipids, protein and nucleic acids in a cell?

Answer 4

C, N, P, H, O, N, and S

Question 5

what are cofactors in terms of nutrients?

Answer 5

cations for specific enzymes (ex. Mg2+, Fe2+, K)

Question 6

what type of nutrients are required in trace amounts, including Co, CU, Mn, Mb, Ni, and Zn?

Answer 6

micronutrients

Question 7

what process breaks down multicarbon(organic) nutrients to CO2?

Answer 7

heterotrophy

Question 8

what process reassembles CO2 into multicarbon nutrients thereby reducing CO2 to make carbohydrates that are consumed by heterotrophs?

Answer 8

autotrophy

Question 9

what is the process wherein organic carbon sources are broken down in ways that generate energy through oxidation?

Answer 9

organotrophy

Question 10

what are the two types of autotrophs?

Answer 10

photoautotrophs and chemolithotrophs

Question 11

what do photoautotrophs do?

Answer 11

use light energy to fix CO2 into biomass

Question 12

what do chemolithotrophs do?

Answer 12

fix CO2 using chemical reactions without light(Calvin cycle)

Question 13

what do lithotrophs use for energy?

Answer 13

inorganic chemicals that they oxidize

Question 14

what do organotrophs use for energy?

Answer 14

organic compounds that they oxidize

Question 15

if a compound is more reduced, will it have a higher or lower potential energy yield?

Answer 15

higher, because it has more e- to give up

Question 16

how is a membrane potential made?

Answer 16

chemical or light energy is used to pump protons outside of the cell, making cation concentration greater outside the cell

Question 17

why can most organisms not use atmospheric N2?

Answer 17

its triple bonds are highly stable and require a lot of energy to break

Question 18

what is a symbiont?

Answer 18

an organism that lives with another organism

Question 19

what is the process wherein nutrients are transported from areas of higher to lower concentration (into a cell)?

Answer 19

facilitated diffusion

Question 20

is facilitated diffusion an example of active or passive transport?

Answer 20

passive, as it does not use energy

Question 21

for what type of molecule is facilitated diffusion generally used?

Answer 21

compounds that are too large or too polar to diffuse on their own

Question 22

what is the name of the important membrane protein family that is responsible for transporting water and other small, polar molecules?

Answer 22

aquaporins

Question 23

what process imports nutrients into the cell against a concentration gradient?

Answer 23

active transport

Question 24

why is active transport important in aquatic and soil habitats?

Answer 24

in aquatic habitats, nutrient concentration is low; in soil habitats, competition for nutrients is fierce b/c of microbial abundance

Question 25

how is active transport generally achieved?

Answer 25

ion gradient

Question 26

what is symport in regards to ion gradient?

Answer 26

the two molecules involved in the "coupled transport" travel in the same direction

Question 27

what is antiport in regards to ion gradient?

Answer 27

the two molecules involved in the "coupled transport" travel in the opposite direction

Question 28

what are ABC transporters?

Answer 28

ATP-binding cassette transporters that use ATP to move molecules across the cell membrane

Question 29

what do ABC transporters consist of?

Answer 29

two hydrophobic membrane proteins and two cytoplasmic proteins

Question 30

what are secreted by the cell to bind ferric iron(Fe3+) and transport it into the cell where it is reduced?

Answer 30

siderophores

Question 31

what type of growth covers the entire agar surface?

Answer 31

confluent growth

Question 32

what type of medium is nutrient rich but poorly defined?

Answer 32

complex medium

Question 33

what type of medium is a complex medium with specific nutrients added

Answer 33

enriched medium

Question 34

what type of medium favors the growth of one organism over another?

Answer 34

selective medium

Question 35

what type of medium exposes biochemical differences between organisms?

Answer 35

differential medium

Question 36

what are specific nutrients that are not required by other species?

Answer 36

growth factors

Question 37

when the growth curve is exponential, the growth rate is said to be proportional to the ________.

Answer 37

population size

Question 38

what is the equation to find the number of organisms after a certain number of generations, given the initial population size?

Answer 38

N(final) = N(initial) x 2^n n = number of generations

Question 39

what is generation time?

Answer 39

amount of time it takes for a bacterial population to double; i.e., time required for one bacterial cell to divide into two daughter cells through binary fission

Question 40

what is the formula to find generation time?

Answer 40

g = t / n g = generation time t = time elapsed n = number of generations

Question 41

what does the growth rate constant show?

Answer 41

rate of exponential growth

Question 42

what is the formula to find the growth rate constant?

Answer 42

k = n / t

Question 43

what are the four stages of a batch culture lifecycle?

Answer 43

1. lag phase 2. log phase (and late log phase if you count it) 3. stationary phase 4. death phase

Question 44

what occurs during the lag phase?

Answer 44

cells that are transferred to new medium prepare for growth by making new enzymes to adjust to new nutrient sources and environment

Question 45

what occurs during log phase?

Answer 45

exponential growth phase, balanced constant rates of growth, linear

Question 46

what occurs during the late log phase?

Answer 46

rate of doubling slows, cells sense presence of others

Question 47

what occurs during stationary phase?

Answer 47

cell density is too high compared to nutrient density, resulting in a plateau of population size on the curve

Question 48

what occurs during death phase?

Answer 48

death rate is proportional to population size; exponential decline

Question 49

what is a biofilm?

Answer 49

bacteria in nature that form specialized, surface-attached, collaborative communities

Question 50

Pseudamonas aeruginose growing on the surfaces of the lungs in CF patients is an example of what?

Answer 50

biofilm

Question 51

what are microbial spores?

Answer 51

they are secreted by cells and do not grow or need nutrients until germination; they have increased chemical and heat resistance