(LE2) Microbial Metabolism

Question 1

What are the two source categories all organisms need for proper metabolism function?

Answer 1

Carbon source and energy source

Question 2

What are the two processes organisms acquire carbon?

Answer 2

Autotrophy: carbon comes from CO2 in the air
Heterotrophy: Carbon comes from consuming other organic matter

Question 3

What are the processes organisms acquire energy?

Answer 3

Chemotrophy: From chemical processes
Phototrophy: light is energy source

Question 4

What category of metabolism do plants fall into?

Answer 4

Photoautotrophs

Question 5

What classification of metabolism are pathogens, most bacteria, fungi, protozoans, and all animals?

Answer 5

Chemoheterotrophs

Question 6

What phase of metabolism is shown in the image? Explain this phase. Provide an example

Answer 6

Anabolism: building polymers from monomers
- energy is needed to build chemical bonds
- e.g. protein synthesis

Question 7

What phase of metabolism is shown in the image? Explain this phase. Provide an example

Answer 7

Catabolism: breaking down polymers into monomers
- energy is released by breaking chemical bonds
- e.g. digestion

Question 8

What is Collision Theory?

Answer 8

• substrates must make physical contact in order for a chemical reaction to occur
• All molecules have kinetic energy

Question 9

What is activation energy?

Answer 9

• the amount of energy required to get a reaction started

Question 10

What is reaction rate?

Answer 10

the frequency of collisions containing sufficient energy to bring about a reaction

Question 11

How can we increase reaction rates?

Answer 11

1. Increase kinetic energy by adding heat
2. Lower activation energy requirements

Question 12

What are enzymes?

Answer 12

Biological catalysts that speed up the rate of chemical reactions without being used

Question 13

How do enzymes speed up the rate of chemical reactions?

Answer 13

1. Decrease activation energy for reactants to reach high energy transition state
2. Ensure reactants are in the proper orientation

Question 14

What is turnover number?

Answer 14

number of substrates converted to products per second

Question 15

ID and define what’s indicated in the image

Answer 15

Holoenzyme: the entire structure of the enzyme

Question 16

ID and define what’s indicated in the image

Answer 16

Cofactor: (sometimes) inorganic component, often a metal ion (e.g. HgB and Fe)

Question 17

ID and define what’s indicated in the image

Answer 17

Apoenzyme: protein component

Question 18

ID and define what’s indicated in the image

Answer 18

Coenzyme: organic non-protein component, often derived from vitamins. Forms part of the active site

Question 19

ID and define what’s indicated in the image

Answer 19

Catalytic site

Question 20

What are the steps for the metabolism of enzyme action?

Answer 20

1. Substrate(s) bind active site of enzyme
2. Enzyme-substrate complex forms. Substrates are in proper orientation. “Transition state”
3. Substrate is converted to product
4. Products released
5. Enzyme is unchanged during reaction. Ready to catalyze another reaction

Question 21

What factors influence enzyme activity?

Answer 21

1. Temperature
2. pH
3. Substrate concentration
4. Enzyme inhibition
5. Feedback inhibition
6. Enzyme activation

Question 22

Why does temperature affect enzyme activity?

Answer 22

High temp denatures (unfold) protein.
Enzymes work better at higher temp in their range. (b/c substrates move faster)

Question 23

Why does pH affect enzyme activity?

Answer 23

Low and high pH denature protein

Question 24

What is the effect on bacteria when the temperature is colder than their optimum temperature for growth? Hotter?

Answer 24

Colder - Bacteriostasis: enzymes are too slow for growth
Hotter - Bacteriocidal: kills enzyme and bacteria

Question 25

How does substrate concentration affect enzyme activity?

Answer 25

Enzyme activity can slow if there are less substrates Enzyme has max reaction rate when saturated substrate concentration is reached

Question 26

What are the two types of enzyme inhibitors?

Answer 26

Competitive Inhibitors Non-competitive Inhibitors

Question 27

How do competitive inhibitors influence enzyme activity?

Answer 27

They are substrate analogs, so they compete for the active site

Question 28

What happens if there are more competitive inhibitors than substrates?

Answer 28

Enzyme activity slows

Question 29

Will increasing the substrate amount increase the reaction rate against competitive inhibitors? Increasing enzyme levels?

Answer 29

Increasing [S] will work. Increasing [E] will not because substrates will still be outcompeted by greater number of inhibitors

Question 30

How do non-competitive inhibitors influence enzyme activity?

Answer 30

It binds to the allosteric site, not the active site which unfolds (changes shape) the active site

Question 31

How can you increase the reaction rate against noncompetitive inhibitors?

Answer 31

Increase [E] Not increase [S]

Question 32

What is feedback inhibition? What is an example?

Answer 32

When the end-product of an enzymatic pathway inhibits one of the earlier reactions. e.g., Threonine converting into Isoleucine, then Isoleucine binding to the allosteric site of the enzyme until enough isoleucine is created.

Question 33

What are two types of enzyme activation? Provide examples

Answer 33

1. Covalent modification (covalent bond; e.g. phosphorylation/dephosphorylation) 2. Conformational change: enzyme needs to unfold to allow substrate to fit in active site. e.g. pepsinogen interacting with HCl to become Pepsin

Question 34

What are the three types of ATP production?

Answer 34

1. Substrate-level phosphorylation 2. Photophosphorylation 3. Oxidative phosphorylation

Question 35

What method of ATP production is shown? What organisms perform this method?

Answer 35

Substrate-level phosphorylation: done in glycolysis e.g. fermenters -> slow growth. 2 ATP/glucose molecule

Question 36

What method of ATP production is shown? How does it work? What organisms perform this method? What is the energy yield?

Answer 36

Oxidative phosphorylation - electron energy captured in redox reaction to form phosphate bond. e.g. aerobic/anaerobic respiration. Electron transport chain produces 34 ATP/glucose

Question 37

What are redox reactions?

Answer 37

Transfer of e- Reduction: gain e- (gain energy) Oxidation: loss of e- (lose energy)