Lecture 10 [Exam 3]

Question 1

Microbes need the following to grow:

Answer 1

*Carbon source *Energy source

Question 2

True or False: Microbes have a remarkable plasticity of microbial genomes

Answer 2

True

Question 3

What are compounds that microbes must need from the environment (they cannot make them)?

Answer 3

Essential nutrients

Question 4

What are 2 types of essential nutrients?

Answer 4

 Macronutrients
 Micronutrients

Question 5

What are some macronutrients (needed in large amounts)?

Answer 5

Carbon (C), Nitrogen (N), Oxygen (O), Phosphorus (P), Sulfur (S), Hydrogen (H)

Magnesium (Mg2+), Iron (Fe2+), Potassium (K+), Calcium (Ca+)

Question 6

What are some micronutrients (needed in small amounts)?

Answer 6

Cobalt (Co2+), Copper (Cu), Manganese (Mn2+), Molybdenum (Mo2+), Nickel (Ni2+), and Zinc (Zn2+)

Question 7

Which macronutrients are found in macromolecules (i.e. carbohydrates, lipids, nucleic acids, and proteins)?

Answer 7

Carbon (C), Nitrogen (N), Oxygen (O), Phosphorus (P), Sulfur (S), Hydrogen (H)

Question 8

Which macronutrients are found in enzyme cofactors and regulatory molecules?

Answer 8

Magnesium (Mg2+), Iron (Fe2+), Potassium (K+), Calcium (Ca+) (VITAMINS)

Question 9

What are micronutrients typically used for?

Answer 9

Components of enzyme cofactors

Question 10

What element are all of Earth’s life forms based on?

Answer 10

Carbon

Question 11

______________ use CO2 as a carbon source and assemble into organic molecules (mainly sugars).

Answer 11

Autotrophs

Question 12

_____________ consume the organic compounds made by autotrophs to gain carbon (some are converted to CO2 as waste)

Answer 12

Heterotrophs

Question 13

The carbon cycle requires both ____________ and _____________.

Answer 13

Autotrophs and Heterotrophs

Question 14

All organisms require an ________________.

Answer 14

energy source

Question 15

_____________ obtain energy from chemical reactions triggered by LIGHT.

Answer 15

Phototrophs

Question 16

______________ obtain energy from OXIDATION-REDUCTION REACTIONS.

Answer 16

Chemotrophs

Question 17

What are the two classes of chemotrophs?

Answer 17

*lithotrophs *organotrophs

Question 18

What class of chemotrophs se inorganic molecules as a source of electrons?

Answer 18

Lithotrophs

Question 19

What type of molecules do lithotrophs use as a source of electrons?

Answer 19

H2, H2S, NH4+, NO2–, and Fe2+

Question 20

What class of chemotrophs use organic molecules (sugar) as electron donors?

Answer 20

Organotrophs

Question 21

What form of energy is contained in the high-energy phosphate bonds in adenosine triphosphate (ATP)?

Answer 21

Chemical energy

Question 22

What form of energy is stored in the form of an electrical potential generated between compartments separated by a membrane and is known as the membrane potential (more negative inside than outside)?

Answer 22

Electrochemical energy

Question 23

____________ is a type of electrochemical energy that is generated when chemical (or light) energy is used to pump protons
outside of the cell.

Answer 23

Membrane potential

Question 24

The H+ gradient plus the charge difference
form an electrochemical potential called
the _______________.

Answer 24

Proton Motive Force (PMF)

Question 25

What processes does the proton motive force (PMF) drive?

Answer 25

transportation of nutrients, flagellar rotation, and synthesis of ATP via F1FO ATP synthase

Question 26

What element comprises 79% of Earth's atmosphere, but is unavailable for use by most organisms?

Answer 26

Nitrogen

Question 27

What type of bond between two nitrogen atoms (N2) is highly stable and takes considerable energy to break?

Answer 27

Triple

Question 28

____________ possess nitrogenase, which converts N2 to ammonium ions (NH4+).

Answer 28

Nitrogen fixers

Question 29

What is is used to make amino acids and other nitrogen- containing compounds needed for growth?

Answer 29

Ammonium NH4+

Question 30

What are 2-types of nitrogen fixing bacteria?

Answer 30

Non-symbiotic and symbiotic

Question 31

____________ are free-living in soil or water and fix majority of nitrogen (i.e. cyanobacteria/blue-green algae)

Answer 31

Non-symbiotic

Question 32

____________ form symbiotic associations with plants.

Answer 32

Symbiotic

Question 33

What are some examples of symbiotic bacteria (specifically symbionts with leguminous plants like soybeans, chickpeas, and clover)?

Answer 33

 Rhizobium, Sinorhizobium, and Bradyrhizobium

Question 34

Once fixed into organic compounds, how does nitrogen get back into the atmosphere?

Answer 34

Nitrification and Denitrification (via the nitrogen cycle)

Question 35

_______________ oxidize ammonia to nitrate (NO3–)

Answer 35

Nitrifiers

Question 36

What are some examples of bacteria that oxidize ammonia to nitrate?

Answer 36

Nitrosomonas, Alcaligenes, Nitrobacter

Question 37

____________ convert nitrate to N2.

Answer 37

Denitrifiers

Question 38

What type of bacteria performs denitrification?

Answer 38

Paracoccus

Question 39

What are the three steps in the nitrogen cycle?

Answer 39

1)Nitrogenase fixes atmospheric nitrogen to ammonia 2) Nitrifiers oxidize NH4+ to generate energy 3) Denitrifiers use oxidized forms (i.e. nitrate) as alternative electron (-) acceptors

Question 40

How do we capture bacteria and study them?

Answer 40

They must be grown separately in pure culture for detailed studies

Question 41

After almost 140 years of trying, what percentage of bacteria have we have succeeded in culturing?

Answer 41

less than 1%

Question 42

Bacteria are grown in 2 main types of culture media:

Answer 42

Liquid (broth) or Solid

Question 43

What are liquid (broth) or solid culture useful for?

Answer 43

studying the growth characteristics of a pure culture

Question 44

_______________ is a culture containing only a single strain or species of microorganisms.

Answer 44

Pure culture

Question 45

Why are solid cultures (usually plated with agar) useful?

Answer 45

separate mixed cultures from clinical specimens or natural environments

Question 46

_____________________ contain only those nutrients that are essential for growth of a given microbe.

Answer 46

Minimal defined medium

Question 47

______________ is a complex media to which specific blood components are added (some microbes are fastidious)

Answer 47

Enriched medium

Question 48

___________________ favor the growth of one organism over another.

Answer 48

Selective medium

Question 49

A solid medium containing bile salts and crystal violet is a selective media that favors the growth of _______________.

Answer 49

Gram negative (-)

Question 50

__________________ exploit differences between two species that grow equally well (usually by exposing biochemical differences).

Answer 50

Differential media

Question 51

Several media used in clinical microbiology can be both _____________________.

Answer 51

selective and differential

Question 52

What is an example of a selective and differential medium used in clinical microbiology?

Answer 52

MacConkey medium

Question 53

List characteristics of the MacConkey medium.

Answer 53

*Only Gram-negative bacteria grow (selective) *Only a species capable of fermenting lactose produces pink colonies (differential)

Question 54

___________________ produce acid from lactose and absorb neutral red (stays red at acidic pH)

Answer 54

Lactose fermenting bacteria

Question 55

__________________make alkaline products, neutral red is colorless at alkaline pH so it does not alter appearance of the medium

Answer 55

Lactose non-fermenting bacteria

Question 56

Most bacteria divide by ______________.

Answer 56

Binary fission

Question 57

What happens during binary fission?

Answer 57

One parent cell splits into two equal daughter cells.

Question 58

True or False: Some microbes divide ASYMMETRICALLY in binary fission.

Answer 58

True

Question 59

_____________ divides by budding and releases a smaller cell from a stalked parent.

Answer 59

Hyphomicrobium

Question 60

Exponential growth never lasts indefinitely in which type of culture?

Answer 60

Batch culture

Question 61

List all of the characteristics of a batch culture.

Answer 61

*A liquid medium within a closed system *No fresh medium is added during incubation *Nutrient consumption and toxic by-products accumulation occur *Greatly affect bacterial physiology and growth. *Illustrates the remarkable ability of bacteria to adapt to their environment.

Question 62

Plotting culture growth versus incubation time, makes it possible to do what?

Answer 62

See the effect of changing conditions on generation time as well as reveal the stages of growth.

Question 63

In what culture do all cells in a population achieve a steady state which allows detailed study of bacterial physiology?

Answer 63

Continuous culture

Question 64

What is a continuous culture system that ensures logarithmic growth by constantly adding and removing equal amounts of culture medium?

Answer 64

Chemostat

Question 65

True or False: The human gastrointestinal tract is a crude chemostat.

Answer 65

True

Question 66

What happens to bacteria when they are faced with environmental stress?

Answer 66

They undergo complex molecular reprogramming that includes changes in cell structure

Question 67

What are examples of some bacteria that undergo complex changes in response to environmental stress?

Answer 67

*Endospores of certain Gram-positive bacteria *Heterocysts of cyanobacteria *Fruiting bodies of Myxococcus xanthus *Aerial hyphae and arthrospores of Streptomyces

Question 68

What species can produce dormant spores that are heat and desiccation resistant?

Answer 68

Clostridium and Bacillus

Question 69

Starvation initiates an elaborate 8-hour genetic program (sporulation) that involves:

Answer 69

An asymmetrical cell division process and production of a forespore (ultimately an endospore)

Question 70

__________ is divided into discrete stages based on morphological appearance.

Answer 70

Endospore formation

Question 71

The process of ___________________ wakes the dormant cell, dissolves the spore coat, and releases a viable vegetative cell once proper nutrient requirements are met.

Answer 71

Germination

Question 72

Spore resistance to heat and chemical insults:

Answer 72

- The thick covering -The synthesis of Dipicolinic acid stabilizes and protects spore DNA -The uptake of calcium into the coat of the spore

Question 73

Desiccation:

Answer 73

-have only 10–30% of a vegetative cell’s water content -Packed with small acid-soluble proteins (SASPs) -Bind and protect DNA from damage by ultraviolet light and various toxic chemicals

Question 74

True or False: Only gram positive bacteria form endospores in the genuine sense.

Answer 74

True

Question 75

Cyanobacteria are:

Answer 75

-Filamentous and multicellular -Carry out photosynthesis -Fix nitrogen anaerobically into specialized cells called heterocysts.

Question 76

What is nitrogenase?

Answer 76

-the enzyme required to fix nitrogen -very sensitive to oxygen (by product of photosynthesis)

Question 77

Heterocysts:

Answer 77

-A tightly regulated genetic program converts every tenth photosynthetic, vegetative cell to a heterocyst -Form a specialized envelope as a barrier to atmospheric 02 -Degrade the photosynthesis machinery that produces O2 -Supplies nitrogen compounds to the adjacent vegetative cells, which, in turn, send carbon sugars to the heterocyst

Question 78

What is Myxococcus xanthus?

Answer 78

-Gram-negative, soil-dwelling bacteria -uses gliding motility (involving a type of pilus) -travel on surfaces as individuals or move together as a mob

Question 79

__________ triggers the aggregation of approx. 100,000 cells.

Answer 79

Starvation

Question 80

Over the course of 72 hours of starvation myxcoccus xanthous rises into a ______________.

Answer 80

fruiting body

Question 81

Specialized, surface-attached, collaborative communities formed by bacteria in nature are called _________________.

Answer 81

Biofilms

Question 82

The mixture of facultative and anaerobic bacteria (Streptoc occi) form ________________.

Answer 82

dental plaque

Question 83

True or False: Bacterial biofilms form when nutrients are plentiful

Answer 83

True

Question 84

True or False: Once nutrients become scarce, individuals detach from the community to forage for new sources of nutrients.

Answer 84

True

Question 85

The formation can be signaled by different environmental parameters such as:

Answer 85

pH, iron concentration, temperature, oxygen availability, and the presence of certain amino acids

Question 86

Chemical signals allow bacteria to communicate within the biofilm is also called ____________.

Answer 86

Quorum sensing

Question 87

The Gram-negative bacterium Pseudomonas aeruginosa can form a single-species biofilm on _______________, _____________, and _______________.

Answer 87

-the lungs of cystic fibrosis patients -medical implants -ventilators used to assist respiration