MT1 > Ecology of Bacteria and Viruses

Question 1

What 2 main factors differentiate Bacteria/Archaea from Viruses?

Answer 1

Bacteria/Archaea:

1. Are unicellular living organisms with no organelles
2. Have a complete set of RNA (rRna, tRNA)

Question 2

What environments can support bacterial growth?

Answer 2

Almost every environment on earth, even extreme ones.

Question 3

What are the 6 main characteristics of bacteria (+Archaea)?

Answer 3

1. Self-feeding
2. Self-replicating (growth)
3. Differentiation (sporulation)
4. Chemical signalling (quorum sensing)
5. Movement
6. Evolution

Question 4

Describe the characteristics of an autotrophic organism.

Answer 4

Derives energy from light or chemical oxidation. Derives carbon from CO2 or carbonate.

Question 5

Describe the characteristics of a heterotrophic organism.

Answer 5

Derives energy from oxidation of organic molecules. Derives carbon from metabolic intermediates.

Question 6

What does Liebig’s Law of the Minimum stipulate?

Answer 6

Growth is not controlled by the total amount of resources available, but by the scarcest resource (limiting factor).

Question 7

What is a real world example of Liebig’s Law of the Minimum at work?

Answer 7

Plant growth often is not limited by water or sunlight, but rather by nitrogen or phosphate in the soil.

Question 8

How can iron act as a limiting factor (as in Liebig’s Law of the Minimum)?

Answer 8

Iron is critical for several metalloproteins in the body, and several bacteria have evolved iron carriers to take advantage of ferric iron in the body.

Question 9

What 2 principles constrain Liebig’s Law of the Minimum?

Answer 9

1. Only applicable under steady-state conditions (non-transitioning ecosystem)
2. Limiting factor may change according to interaction of environmental variables

Question 10

What does Shelford’s Law of Tolerance stipulate?

Answer 10

Success of an organism relies not only on the availability of nutrient but also that organism’s tolerance to the environment. Optimal and minimal conditions exist.

Question 11

What differentiates eurytypic organisms from stenotypic organisms?

Answer 11

Eury: grow within a wide range of a specific condition (ex: temp)
Steno: grow only in a narrow range of a specific condition (ex: temp)

Question 12

What is meant by “quorum sensing”?

Answer 12

Cells reach a certain density and can start expressing proteins which can affect the surrounding population.

Question 13

How much ferric iron is contained in the human body?

Answer 13

Only 5g!

Question 14

What is “diauxic growth”?

Answer 14

Cell growth in 2 phases. Caused by the organism switching from one nutrient source to another more beneficial one.

Question 15

What are 4 examples of environmental factors that might affect bacteria growth?

Answer 15

1. Water
2. Sodium
3. Light
4. Temperature

Question 16

In what 3 main ways does temperature affect the growth and survival of organisms?

Answer 16

1. Rate of chemical reactions
2. Denaturation of proteins
3. Climate

Question 17

At what temperatures do mesophilic bacteria thrive?

Answer 17

~ 39C

Question 18

At what temperatures do thermophilic bacteria thrive?

Answer 18

~ 60C

Question 19

At what temperatures do hyperthermophilic bacteria thrive?

Answer 19

~88C or even greater

Question 20

At what temperatures do psychrophilic bacteria thrive?

Answer 20

~ 4C

Question 21

What temperature range do pathogenic bacteria usually prefer?

Answer 21

Mesophiles who prefer temperatures in a narrow range ~37C (the normal temp of the human body).

Question 22

Describe the oxygen relationship of a bacteria which is an “obligate aerobe”.

Answer 22

Requires oxygen for aerobic respiration.

Question 23

Describe the oxygen relationship of a bacteria which is a “facultative aerobe”.

Answer 23

Oxygen helpful, but not required. Can do aerobic or anaerobic respiration, as well as fermentation.

Question 24

Describe the oxygen relationship of a bacteria which is a “microaerophile”.

Answer 24

Requires oxygen for aerobic respiration, but at lower than atmospheric levels.

Question 25

Describe the oxygen relationship of a bacteria which is "aerotolerant".

Answer 25

Oxygen has no effect. Uses fermentation for energy.

Question 26

Describe the oxygen relationship of a bacteria which is an "obligate anaerobe".

Answer 26

Oxygen harmful or lethal. Can do anaerobic respiration and fermentation.

Question 27

What sorts of energy metabolisms did organisms likely use prior to the appearance of oxygen?

Answer 27

Organisms where likely chemoautotrophic or fermentative.

Question 28

How would you define a biological population?

Answer 28

All organisms of the same species living in the same place and time.

Question 29

How does statistics define a population?

Answer 29

"The totality of individual observations about which inferences are to be made, existing anywhere within a defined sampling area and time."

Question 30

What 3 strategies have prokaryotes used to adapt to higher temperatures?

Answer 30

1. Changing hydrophobic interactions 2. Changing hydrogen bonding 3. Adding more salt bridges

Question 31

What did bacteria use to create energy before there was water?

Answer 31

Sulfur.

Question 32

What differentiates a stable population from an unstable one?

Answer 32

Stable: population does not change over time Unstable: population fluctuates over time according to other factors

Question 33

What are examples of tools which can be used to count cells?

Answer 33

- Microscope (EM or light) - Epifluorescence - Petri dishes - Spectrophotometer - Quantitative PCR

Question 34

What are the 6 growth phases of a bacterial population as described by Monod's experiments?

Answer 34

1. Lag 2. Acceleration 3. Exponential 4. Retardation 5. Stationary 6. Declining

Question 35

In bacteriology, which phase is used to define a microbial population?

Answer 35

The exponential phase. A population is described by its constant rate of growth rather than an actual count.

Question 36

What effects do mixing populations in natural systems have on population growth and survival?

Answer 36

Interactions can have positive, negative, or no effect on growth and survival.

Question 37

What is the definition of a biological community?

Answer 37

A system of organisms living together and linked by the effect they have on each other and their shared environment.

Question 38

Define "neutralism".

Answer 38

Lack of interaction between two populations.

Question 39

Define "commensalism".

Answer 39

One organism lives off the leftover nutrients of another.

Question 40

Define "synergism".

Answer 40

Two populations both benefit from a non-obligatory relationship.

Question 41

Define "mutualism".

Answer 41

Two populations benefit each other and depend on one another for survival.

Question 42

Define "competition".

Answer 42

Two populations use the same limiting resource. Both are negatively affected.

Question 43

Define "amensalism".

Answer 43

One population produces a substance toxic to competing populations, thus gaining an advantage.

Question 44

What does the competitive exclusion principle stipulate?

Answer 44

That two populations cannot occupy the same niche. One will out-compete and eliminate the other.

Question 45

Define "parasitism".

Answer 45

One population steals nutrients from another, indirectly harming it.

Question 46

Define "predation".

Answer 46

One population consumes members of another for energy.

Question 47

What is an example of organisms living in a mutualistic (symbiotic) relationship?

Answer 47

Cyanobacteria/algae and lichen co-exist to form lichen. Rhizobium fixes nitrogen for plants in return for nutrients.

Question 48

What is an example of a way the competitive exclusion principle has been used in epidemiology?

Answer 48

The PCV-7 vaccine was introduced in BC to out-compete streptococcus pneumoniae.

Question 49

What is an example of an organism which exhibits amensalism?

Answer 49

Penicillium produces beta-lactam which prevents the growth of nearby bacteria.

Question 50

What differentiates an ectoparasite from an endoparasite?

Answer 50

Ecto: remain outside the cells of the host Endo: penetrate into the cells of the host

Question 51

What is the term used to describe a virus which targets bacteria?

Answer 51

A bacteriophage.

Question 52

What is an "r-strategist" organism?

Answer 52

Organisms which favour rapid reproduction and low investment in offspring. Tend to be small and have short lifespans.

Question 53

What is a "k-strategist" organism?

Answer 53

Organisms which invest heavily in offspring and favour survival. Tend to be larger and have longer lifespans.

Question 54

What kinds of biological gradients exist which can drive population succession?

Answer 54

- Altitude - Depth - Fresh>salt water - etc.

Question 55

What is the definition of an ecosystem?

Answer 55

A community and its environment treated together as a functional system of a complementary relationship, and transfer/circulation of energy and matter.

Question 56

What is the smallest unit used in ecology?

Answer 56

An ecosystem.

Question 57

What are the 4 phylodynamic categories of RNA viruses?

Answer 57

1. Short infection w/ strong cross immunity 2. Short infection w/ partial cross immunity 3. Infection w/ immune enhancement 4. Persistent infection

Question 58

Who developed the Ro # for vaccinations? When?

Answer 58

Robert May and Roy Anderson in the late 80s.

Question 59

When was smallpox eradicated?

Answer 59

1980.

Question 60

What is meant by a "nosocomial disease"?

Answer 60

A disease that is transmitted at the hospital.

Question 61

What type of infectious agent is gonorrhea?

Answer 61

Bacteria.

Question 62

What type of infectious agent is streptococcus pneumonia?

Answer 62

Bacteria.

Question 63

What type of infectious agent is malaria (plasmodium falciparum)?

Answer 63

Protozoa.

Question 64

What mutation caused some people to not contract HIV when exposed? Which gene is it a part of?

Answer 64

Delta 32, in the CCR5 gene.

Question 65

What type of infectious agent is HIV?

Answer 65

Virus.

Question 66

What type of infectious agent is influenza?

Answer 66

Virus.

Question 67

What type of infectious agent is Creutzfeldt-Jakobs?

Answer 67

Prions.

Question 68

What are the 2 proteins on the influenza virus?

Answer 68

1. Hemagluttinin | 2. Neuraminidase

Question 69

Which of the 2 inlfuenza proteins is the better target for treatment?

Answer 69

Hemagluttinin.

Question 70

What is the function of Hemagluttinin in the influenza virus?

Answer 70

Attaches to salycilic acid and allows viral genome insertion.

Question 71

What is the function of Neuraminidase in the influenza virus?

Answer 71

Allows the virus to detach from the host cell.

Question 72

How did Thomas Brock advance bacterial research?

Answer 72

He showed that bacteria could grow at extremely high temperatures by analyzing colonies from geysers in Yellowstone.

Question 73

What differentiates the IPV and OPV vaccines?

Answer 73

IPV: developed by Salk, injected OPV: developed by Sabin, oral (can lead to paralysis)

Question 74

What is the name of the iron carriers in cyanobacteria and bacteria?

Answer 74

Siderophores, which solubilize iron for transport.

Question 75

What is enterobactin?

Answer 75

A siderophore. Transports iron and attaches to receptor, allowing bacteria to uptake iron.

Question 76

Describe Martin's experiment.

Answer 76

Dumped iron into sea water and observed rampant chlorophyll growth.

Question 77

Hemacytometer is for blood cells what _____ is for bacteria.

Answer 77

Petrof-Hauser.

Question 78

At what salinity do nonhalophilic bacteria thrive?

Answer 78

Can't tolerate any salt.

Question 79

At what salinity do halotolerant bacteria thrive?

Answer 79

Need a little salt.

Question 80

At what salinity do halophilic bacteria thrive?

Answer 80

Like moderate levels of salt.

Question 81

At what salinity do extreme halophilic bacteria thrive?

Answer 81

Like being salty AF.

Question 82

Place the following in order of when they increase during bacterial growth: Cell numbers, DNA, RNA, Proteins.

Answer 82

First RNA increases, then proteins, then DNA, and finally cell numbers.