Lectures 8-10

Question 1

What is Metabolism?

Answer 1

1) The energy needed to build cells
2) Metabolism = Catabolism + Anabolism

Question 2

What is Catabolism?

Answer 2

Exergonic reactions that breakdown molecules

Question 3

What is Anabolism?

Answer 3

Endergonic reactions that build molecules

Question 4

Primary producers, grazers, predators, and decomposers are all a part of the general food web. What are their roles?

Answer 4

The primary objective is nutrient cycling.
1) Primary Producers - Produce energy through photosynthesis
2) Grazers - Consume primary producers, gaining ~10% of energy
3) Predators - Consume other consumers, gaining ~0.1-1% energy
4) Decomposers - Feed on dead organisms, and cycle CO2 and minerals for primary producers

Question 5

What is the difference between phototrophs and chemotrophs?

Answer 5

Phototrophs gain their energy from the sun while chemotrophs gain their energy from chemical compounds

Question 6

What are autotrophs and what are the different types of autotrophs?

Answer 6

Autotrophs are organisms who produce their own “food” (energy)
1) Photoautotrophs - Acquire energy through photosynthesis
2) Chemoautotrophs - Acquire energy through oxidizing inorganic molecules

Question 7

What are heterotrophs and what are the different types of heterotrophs?

Answer 7

Heterotrophs are organisms who are unable to produce their own energy, leading them to consume other organisms for energy
1) Photoheterotrophs - Utilize light for energy, but cannot use CO2 as their sole carbon source
2) Chemoheterotrophs - Obtain energy from organic compounds

Question 8

True or False: Phototrophs can also be heterotrophic

Answer 8

True - Diatom and photosynthetic algae are some organisms that are both.

Question 9

True or False: Heterotrophic organisms are often also organotrophic (use organic compounds as a source of electrons and carbon)

Answer 9

True

Question 10

What is the nitrogen cycling process?

Answer 10

1) Nitrogenase fixes atmospheric nitrogen into ammonia
2) Nitrifiers (ex. Nitrosomonas) oxide ammonia to generate energy
3) Denitrifiers (ex. Paracoccus) use oxidized forms of nitrogen (ex. nitrate) as alternative electron acceptors

Question 11

True or False: Bacteria play key roles in the nitrogen cycle, one of which being that all bacteria can fix nitrogen

Answer 11

False: Though bacteria does play key roles in the nitrogen cycle, only few bacteria can fix nitrogen such as Rhizobium, a nitrogen-root endosymbiont in plants

Question 12

What is the process of Binary Fission?

Answer 12

1) The parent cell’s DNA replicates
2) FtsZ proteins form a ring which directs the formation of the septum division
3) The cell separates into two equal daughter cells

Question 13

What is Asymmetrical Budding?

Answer 13

A process in which an unidentical “bud” (daughter cell) develops from an existing organism (parent cell)

Question 14

What bacterial species has the fastest generation time?

Answer 14

Clostridium perfringens; ~10 minutes

Question 15

What species has the slowest known generation time?

Answer 15

Mycobacterium leprae; ~14 days

Question 16

True or False: All microbes are culturable in pure culture

Answer 16

False: Less than 1% of microbes are culturable in pure culture

Question 17

What is the importance of understanding nutrient requirements of microbes?

Answer 17

1) Characterization
2) Optimized usage of beneficial microbes (ex. enzymes)
3) Increased understanding of detrimental/undesirable microbial impacts - “How do threats grow and what are they after?”

Question 18

What are some of the reasons as to why the majority of prokaryotes are uncultured?

Answer 18

1) They depend on factors provided by other species that cohabit their niche
2) They evolved to live inside other cells (intracellular parasites)
3) They cannot survive separated from their partners (ex. lichen and algae)

Question 19

What are the two main forms of culture media?

Answer 19

1) Liquid Media - Cells are in suspension, best used for studying the growth characteristics of a pure culture and obtaining a large numbers of cells
2) Solid Media - Cells are gelled/solidified, best used for trying to separate bacteria in samples and studying diversity

Question 20

What are the different types of microbial culture media?

Answer 20

1) Complex/Rich Media - Nutrient rich, but undefined composition
2) Minimal Defined Media - Only contain the essential nutrients for the given microbe
3) Enriched Media -Complex media to which specific factors (that cannot be grown by the microbe) are added
4) Selective Media - Favour the growth of one organism over the other
5) Differential Media - Exploit the biomedical/physiological differences between two species that grow equally well

Question 21

What is the purpose of Pure Culture Isolation?

Answer 21

To obtain well isolated single colonies

Question 22

What are the two techniques for Pure Culture Isolation?

Answer 22

1) Dilution Streaking
2) Spread Plating

Question 23

What is the process of Dilution Streaking?

Answer 23

1) A sterilized loop picks up a small amount of the sample
2) The sample is dragged across the surface of an agar plate
3) A flame is used to sterilize the loop
4) Touch the end of the sample and repeat the streaking
5) Repeat sterilization and streaking as necessary

Question 24

What is the process of Spread Plating?

Answer 24

1) Set up 10-fold serial dilutions in liquid culture
2) Dispense a small amount (ex. 0.1mL) of each dilution on an agar plate and spread it
3) Incubate the dilution

Question 25

What are the methods for microbe counting?

Answer 25

1) Haemocytometry
2) Plate counting
3) Optical Density

Question 26

What are the four phases of growth during the Microbial Growth Cycle?

Answer 26

1) Lag Phase - The bacteria adapt themselves to the conditions and begin maturing. The synthesis of RNA, enzymes, etc. also occurs
2. a) Early Exponential Phase - Cells grow at the maximum rate physiologically possible based on available conditions
2. b) Late Exponential Phase - Growth rate slows due to cell density, competition for nutrients, etc., causing a decrease in slope
3) Stationary Phase - Depletion of essential nutrients and/or formation of an inhibitory product causes the overall population growth to plateau
4) Death Phase - Cells die off