Chapter 13 Flashcards
Catabolism
- breakdown of complex molecules into smaller one
- provides energy for anabolism.
- some chemical energy is lost as heat
Anabolism
reactions that build molecules and cells
Energy
- the ability to do work.
- Chemical energy is present in bonds
- Cells use energy to assemble simple, disordered molecules into complex, ordered forms
Entropy
-is a measure of the disorder or randomness of a system (heat)
open systems
- obtain energy from their environment
- Energy can be converted from one form to another
- All energy transformation lose some energy as heat
photosynthetic microbes
- solar radiation reaches Earth, a small fraction is captured
- Largely in the range of visible light, which can be absorbed by organic molecules
energy carriers
- Many of the cell’s energy transfer reactions
- Molecules that gain or release small amounts of energy in reversible reactions
- Examples: NADH and ATP
Electron donor
reducing agent, e.g., NADH
Electron acceptor
oxidizing agent, e.g., NAD+
ATP can transfer energy to cell processes in three different ways
- Hydrolysis, releasing phosphate (Pi)
- Hydrolysis, releasing pyrophosphate (PPi)
- Phosphorylation of an organic molecule
Nicotinamide adenine dinucleotide (NADH)
- carries two to three times as much energy as ATP.
- It also donates and accepts electrons.
- NADH is the reduced form.
- NAD+ is the oxidized form.
- NAD+ consumes two hydrogen atoms to make NADH
Flavine adenine dinucleotide (FADH2)
- another related coenzyme that can transfer electrons.
- FADH2 (reduced form) versus FAD (oxidized form)
Enzymes
- catalyze biological reactions
- Lower the activation energy (Ea) allowing rapid conversion of reactants to products
- Does not change delta G
Fermentation
- partial breakdown of organic food without net electron transfer to an inorganic terminal electron acceptor
- do not generate ATP beyond that produced by substrate-level phosphorylation
Respiration
complete breakdown of organic molecules to CO2 with electron transfer to a terminal electron acceptor such as O2
Photoheterotrophy
catabolism is conducted with a “boost” from light
three main routes to catabolize glucose
- Glycolysis (Embden-Meyerhof-Parnas (EMP) pathway)
- Entner-Doudoroff (ED) pathway
- Pentose phosphate pathway (PPP), also known as the pentose phosphate shunt
Homolactic fermentation
Produces two molecules of lactic acid
Ethanolic fermentation
Produces two molecules of ethanol and two CO2
Heterolactic fermentation
Produces one molecule of lactic acid, one ethanol, and one CO2
Mixed-acid fermentation
Produces acetate, formate, lactate, and succinate, and others, as well as ethanol, H2, and CO2
Swiss cheese production
- involves two fermentation stages:
- Stage 1: Lactobacillus ferments lactose sugar into lactic acid
- Stage 2: bacteria converts lactate to propionate, acetate, and CO2
diagnostic microbiology
- important application of fermentation
- To quickly identify the microbe causing a disease and prescribe an effective antibiotic, hospitals use rapid and inexpensive biochemical tests
Krebs cycle
- also known as TCA cycle or citric acid cycle
- In prokaryotes, it occurs in the cytoplasm.
- In eukaryotes, it occurs in the mitochondria
- Glucose catabolism connects with the TCA cycle through pyruvate breakdown to acetyl-CoA and CO2
Acetyl-CoA
-enters the TCA cycle by condensing with the 4-C oxaloacetate to form citrate
For each pyruvate oxidized
- 3 CO2 are produced by decarboxylation.
- NADH and FADH2 are produced by redox reactions
- ATP is produced by substrate-level phosphorylation
oxidative phosphorylation
-overall process of the electron transport system (ETS) and ATP generation by the proton motive force (PMF)
Aromatic Pollutants
- Many microbes are decomposers in the environment
- Catabolism of aromatic molecules by bacteria and fungi recycles lignin (from wood) and other substances within ecosystems.
- Toxic pollutants are also degraded
