Micro CH 3 Flashcards
Defining the requirements for life ?
- 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)
Catabolism and Anabolism
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
Free energy (metabolic requirement)
- 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)
Catabolic Pathways (free energy)
- Exergonic cellular processes that generate free energy
- Free energy produced is conserved by synthesizing energy-rich molecules like ATP
- linked with anabolic
Anabolic pathways (free energy)
- endergonic cellular processes in which cellular synthesis requires energy (energy comes from hydrolysis of ATP)
- linked with anabolic
Reducing Power (redox reactions)
- 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
Oxidation Reaction (reducing power)
- 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
Reduction Reaction (reducing power)
- 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
Metabolic Classes of Microorganisms
- the means by which a microbe obtains the energy and nutrients it needs to live and reproduce
- Phototrophs, Chemotrophs, Heterotrophs, Autotrophs, Chemoheterotrophs, Chemoautotrophs,
Phototrophs (metabolic class)
- obtain energy from light (plants)
- do not require chemicals as a source of energy
- Oxygenic and an oxygenic photosynthesis
Chemotrophs (metabolic class)
- Obtain energy from chemical reactions
- example: aerobic reactions, anaerobic reactions, anaerobic respiration and fermentation
- Can be organic or inorganic
Heterotrophs (metabolic class)
- obtain carbon from organics (humans, dog, fish, and birds)
Autotrophs (metabolic class)
- obtain carbon from CO2
- producers that prepare their own food
- primary producers, synthesizing organic matter from inorganic carbon ( bacteria and algae)
Chemoheterotrophs and Chemoautotrophs
Chemoheterotrophs - obtain energy and reducing power from organics
Chemoautotrophs - obtain energy and reducing power from inorganics
The Redox Tower
- 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)
NAD+ / NADH Cycling
- 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
Energy-rich Compounds
- 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
Mechanisms of Energy Conservation
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
Oxidative and Substrate-level Phosphorylation
Substrate-level Phosphorylation
- substrate - P + ADP –> ATP
Oxidative phosphorylation
- ADP + P —> ATP
Differentiate the metabolic pathways
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
Catabolic Pathways (Aerobic (O2) and Anaerobic resp (Other) )
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
Stage 1 Glycolysis
-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
Stage 2 Acetyl CoA Formation
- Pyruvate (3 carbon) → ? → Acetyl CoA (2 carbon)
- Consumed CoA produced CO2
- Consumed NAD+ to produce NADH to generate OP
Organism Classification based on O2 Requirements
- 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
