Microbial metabolism

Question 1

Are archae autotrophs or heterotrphs

Answer 1

• Autotrophs
• they convert abiotic subtances into energy

Question 2

What is a hyperthermophile and why does the group of microorganisms not cause disease in humans

Answer 2

• Likes extreme temperatures
• Their ideal temperature is well above the human body temperature
• Members of archae

Question 3

Name a metabolite produced by a commensal microbe, that is beneficial to the host organism

Answer 3

1. Gut microbiome
2. Short chain fatty acids
3. Skin flora

Question 4

What is the function of isomerase, acetyltransferase, and ligase

Answer 4

1. Isomerase - converts one isomer into another
2. Acetyltransferase - catalyses acetylation
3. Ligase - joins molecules together (DNA synthesis)

Question 5

What type of macrobacterium gains energy from fermentation in the absence of oxygen?

Answer 5

Anaerobes and facultative anaerobes

Question 6

What are the products of fermentation

Answer 6

Acids and alcohols from carbohydrate substrates (sugar)

Question 7

What is the theoretical yield of ATP molecules per glucose molecule in each step of aerobic respiration cycle

Answer 7

Glycolysis = 2

Krebs = 2

Electron transport cycle = 34

Question 8

What happens following glycolysis in anaerobic respiration

Answer 8

Pyruvate is reduced to lactate

Or pyruvate is converted to acetaldehyde and the to alcohol

Krebs and ETC does not occur

Question 9

What are obligate aerobes

Answer 9

Cannot survive without oxygen

Question 10

What are facultative aerobes

Answer 10

Primarily anaerobic, but can respire using oxygen

Question 11

What are obligate anaerobes

Answer 11

Vegetative cells cannot grow in the presence of oxygen

Question 12

What are facultative anaerobes

Answer 12

Primarily aerobic, but can respire anaerobically

Question 13

What are microaerophilic organisms

Answer 13

Requires oxygen, but only tolerates a very small amount

Question 14

What are capnophilic organisms

Answer 14

Tolerates only a small concentration of oxygen. Requires an atmosphere enriched with CO2

Question 15

Define autotrophs

Answer 15

Can produce its own food

Acquire carbon via CO2

e.g. plants, some bacteria, algae, phytoplankton

Question 16

Define heterotrophs

Answer 16

Does not make its own food

Acquires carbon via sugars, aa, nitrogenous bases, fatty acids

e.g. animals, fungi

Question 17

What are photoheterotrophs

Answer 17

Photoheterotrophs obtain energy from light but acquire carbon from organic sources

Question 18

What are chemoheterotrophs

Answer 18

chemoheterotrophs derive both their energy and carbon from organic sources

Question 19

What are 3 essential nutrients for microbes and how are they used

Answer 19

1. Phosphorus – nucleic acids; phospholipids
2. Sulphur – aa, vitamins and enzymes
3. Potassium – enzymes for protein synthesis

Question 20

What are siderophores (iron chelators/hydroxamates)

Answer 20

• Iron binding molecules
• bacteria use siderophores to harvest iron from other bacteria
• siderophores tend to occur in environmental microbes

Question 21

What is the urease test used for

Answer 21

• Some bacteria possess the urease enzyme
• breaks down urea into ammonia
• pH change turns the phenol red indicator (yellow) into pink

Question 22

What is the citrate-utilisation test for

Answer 22

• Some bacteria use citrate as a nutrient
• by-product is alkaline
• pH change changes the colour of agar green to blue

Question 23

What is the lactose test for

Answer 23

• acid and gas are produced as bacteria grow in lactose
• broth changes from pale yellow to pink
• and gas bubbles form
• same for glucose test

Question 24

What is mannitol salts agar helpful for

Answer 24

• detecting presumptive staphylococci (staph aureus)
• appears yellow

Question 25

How were the alcohol and lactic acid by-products beneficial to these microbes

Answer 25

- reduces competition - lower energy expenditure - survives better as it can sustain being in its own toxic waste