Micro CH 3

Question 1

Defining the requirements for life ?

Answer 1

• Metabolism: all Biochemical reactions needed for life (catabolism and anabolism)
• Energy is either created or destroyed (generate ATP)
• metabolic requirements (water, carbon, free energy, reducing power)

Question 2

Catabolism and Anabolism

Answer 2

Catabolism- (breakdown of organic compounds to obtain energy, uses energy to break down (ADP to ATP), large to small, energy releases, oxidation reaction, aerobic respiration

Anabolism- (consumption of energy to synthesize organic compounds, requires energy to grow and build (ATP to ADP), small to large, require energy, amino acids to proteins, reduction, photosynthesis

Question 3

Free energy (metabolic requirement)

Answer 3

• Some reactions release energy (catabolism) and others require energy (anabolism)
• determines how systems change and how much work they put into it
• Change in free energy referred to as ^G
  
  • Endergonic reactions have a +G and requires energy, non spontaneous (reduction)
  • Exergonic reactions have a -G and release energy, spontaneous (oxidative)

Question 4

Catabolic Pathways (free energy)

Answer 4

• Exergonic cellular processes that generate free energy
• Free energy produced is conserved by synthesizing energy-rich molecules like ATP
• linked with anabolic

Question 5

Anabolic pathways (free energy)

Answer 5

• endergonic cellular processes in which cellular synthesis requires energy (energy comes from hydrolysis of ATP)
• linked with anabolic

Question 6

Reducing Power (redox reactions)

Answer 6

• Reducing power is the ability to donate electrons during electron transfer reactions
• Redox reactions
  
  • Electron donor: transfers electrons (oxidized)(catabolism)
  • Electron acceptor: adds electrons (reduced) (anabolism)
• Reduction potential: affinity of substance for electrons
• metabolic reactions depend on electron flow from electron donor to electron acceptor

Question 7

Oxidation Reaction (reducing power)

Answer 7

• oxidation a loss in - e (electron donor)
• decrease in C-H bonds, increases in C-O bonds
• Example: C6H12O6 –> CO2
• losses hydrogen gives a electron

Question 8

Reduction Reaction (reducing power)

Answer 8

• reduction a gain in e- (electron acceptor)
• increase in C-H bonds or decrease in C-O bonds
• Example: O2 –> H2O
• gains hydrogens accepts a electron

Question 9

Metabolic Classes of Microorganisms

Answer 9

• the means by which a microbe obtains the energy and nutrients it needs to live and reproduce
  
  • Phototrophs, Chemotrophs, Heterotrophs, Autotrophs, Chemoheterotrophs, Chemoautotrophs,

Question 10

Phototrophs (metabolic class)

Answer 10

• obtain energy from light (plants)
• do not require chemicals as a source of energy
• Oxygenic and an oxygenic photosynthesis

Question 11

Chemotrophs (metabolic class)

Answer 11

• Obtain energy from chemical reactions
• example: aerobic reactions, anaerobic reactions, anaerobic respiration and fermentation
• Can be organic or inorganic

Question 12

Heterotrophs (metabolic class)

Answer 12

• obtain carbon from organics (humans, dog, fish, and birds)

Question 13

Autotrophs (metabolic class)

Answer 13

• obtain carbon from CO2
• producers that prepare their own food
• primary producers, synthesizing organic matter from inorganic carbon ( bacteria and algae)

Question 14

Chemoheterotrophs and Chemoautotrophs

Answer 14

Chemoheterotrophs - obtain energy and reducing power from organics

Chemoautotrophs - obtain energy and reducing power from inorganics

Question 15

The Redox Tower

Answer 15

• represents the range of possible reduction potentials with the most negative and positive potentials
• Strongest electron donors at the top (-0.50) (oxidation)
• Strongest electron acceptors at bottom (+0.80)(reduction)
• The greater the difference in reduction potential between electron donor and electron acceptor, greater the free energy released
• those that have negative reduction potential have a stronger reduction potential
• -G is proportional to E (but opposite in sign)

Question 16

NAD+ / NADH Cycling

Answer 16

• Electron movements proceeds through consecutive reactions
• good electron carriers
• NADH good electron donor
• NAD+ weak electron acceptor
• reduction requires 2 e- and 1 H+
• NAD+/NADH are coenzymes, allows from many different electron donors and acceptors to interact
• redox reaction in which two different enzymes are linked by their requirement for NAD+ and NADH

Question 17

Energy-rich Compounds

Answer 17

• several others have energy-rich phosphate or sulfur bonds
• cells need compounds where G < -31.8 / mol to synthesize ATP
• Coenzyme A derivatives have energy-rich thirster bonds

Question 18

Mechanisms of Energy Conservation

Answer 18

ATP generates through 1or 3 mechanisms
- Substrate-level phosphorylation: energy-rich substrate bond hydrolyzes directly to drive ATP formation

-Oxidative phosphorylation: Movement of electrons generates proton motive force used to synthesize ATP

• Photophosphorylation: light used to form proton motive force

Question 19

Oxidative and Substrate-level Phosphorylation

Answer 19

Substrate-level Phosphorylation
- substrate - P + ADP –> ATP
Oxidative phosphorylation
- ADP + P —> ATP

Question 20

Differentiate the metabolic pathways

Answer 20

Aerobic respiration: complete breakdown of energy sources with O2 as terminal e- acceptor ( 38 ATP) Example: Glucose –> CO2 (1/2 O2 –> H2O)

Anaerobic respiration: same as aerobic respiration, but something other than O2 as terminal e- acceptor, such as NO3-, SO4-2-, CO2 (less 38 ATP)
Example: Glucose –> CO2 (NO3-,NO2-)

Fermination: Partial breakdown of energy source with glycolysis end product, pryuvate, as e- acceptor (2 ATP)
Example: Glucose –> pyruvate –> lactate

Question 21

Catabolic Pathways (Aerobic (O2) and Anaerobic resp (Other) )

Answer 21

Stage 1 of respiration- Glycolysis (can do Fermentation) located in the cytoplasm

Stage 2 of respiration- Acetyl CoA form, located in the cytoplasm

Stage 3 of respiration- Citric Acid Cycle, located in the cytoplasm

Stage 4 of respiration- Oxidative phosphorylation (ATP synthesis), located plasma membrane, E-transportation, Phosphorylation

Question 22

Stage 1 Glycolysis

Answer 22

-Yield: 2 pyruvate, 2NADH, 2ATP
-Glucose (6 carbons) → ? → pyruvate (3 Carbons)
- split into two phases
- First Phase (Energy Investment Phase): 2ATP –> 2ADP
- Second Phase (Energy payoff phase):
- NAD+ –> NADH x 2
- 2ATP –> 2ATP

Question 23

Stage 2 Acetyl CoA Formation

Answer 23

• Pyruvate (3 carbon) → ? → Acetyl CoA (2 carbon)
• Consumed CoA produced CO2
• Consumed NAD+ to produce NADH to generate OP

Question 24

Organism Classification based on O2 Requirements

Answer 24

• Obligated aerobic: Aerobic, requires O2, growth concentration on top
• Microaeroophile: Aerobic, growth concentration on top
• Facultative aerobes: aerobic, anaerobic, and termination, growth concentration on top and dispersed throughout
• Obligated anaerobic: Anaerobic and fermentation, growth concentration on bottom
• Aerotolerant anaerobe: Anaerobic and fermentation, growth concentration dispersed throughout