Cellular Respiration Flashcards
Exergonic
Catabolic breakdown of organic molecules- releases energy
Aerobic respiration
Consumes organic molecules and O2 and yields ATP
Fermentation
A partial degradation of sugars that occurs without O2 (anaerobic)
Cellular respiration
Includes both aerobic and anaerobic respiration but is often used to refer to aerobic respiration
The catabolism of glucose free energy change
-686 kcal / mol
Phosphorylation
Transferring the terminal phosphate group to another molecule
Transfer of electrons
The transfer (relocation) of electrons during chemical reactions releases energy stored in organic molecules
Synthesis of ATP
The release energy from the transfer of electrons is used to synthesize ATP
Oxidation-reduction/redox reaction
Chemical reactions that transfer electrons between reactants
Oxidation
Substance loses electrons (OIL)
Reduction
A substance gains electrons (RIG)
Reducing agent
The electron donor
Oxidizing agent
The electron receptor
Enzymes
In cellular respiration, glucose and other organic molecules are broken down in a series of steps- each catalyzed by a specific enzyme
NAD+
A coenzyme- Electrons from organic compounds are usually first transferred to NAD+
Electron carriers
NADH and FADH; Hydrogen atoms are stripped from glucose and passed to these electron carriers
Electron transport chain
NADH passes electrons to the electron transport chain
Glycolysis
Occurs in the cytoplasm; Breaks down glucose into two molecules of pyruvate
Citric acid / Krebs cycle
- Completes the breakdown of glucose (pyruvate -> CO2)
- Oxidizes organic fuel derived from pyruvate, generating 1 ATP, 3 NADH, and 1 FADH2 per turn
Oxidative phosphorylation
(Powered by redox reactions of the ETC, inorganic P added to ADP) accounts for almost 90% of the ATP generated by cellular respiration
Substrate-level phosphorylation
Phosphate group transferred from a organic substrate to ADP- forms small amount of ATP in glycolysis and the citric acid cycle
Glucose -> ATP
For each molecule of glucose degraded to CO2 and water by respiration, the cell makes up to 32 molecules of ATP
Energy investment phase
One of glycolysis major phases (how many put in?)
Energy payoff phase
One of glycolysis major phases (how many released?)
Electron transport chain (ETC)
- Electrons are removed- passed to electron carriers (NADH) and taken to ETC
- Citric acid cycle: NADH & FADH2 relay electrons from food to the ETC
Oxygen in glycolysis
Glycolysis occurs whether oxygen is present or not
Oxidation of glucose
If O2 is present pyruvate enters the mitochondrion (in eukaryotic cells) where the oxidation of glucose is completed
Coenzyme A (acetyl CoA)
Before the citric acid (Krebs) cycle can begin, pyruvate must be converted to acetyl Coenzyme A (acetyl CoA), which links glycolysis to the citric acid cycle
Steps of the citric cycle
[8 steps]
- A acetyl group of acetyl CoA joins the cycle by combining with oxaloacetate, forming citrate
- The next seven steps decompose the citrate back to oxaloacetate, making the process a cycle
Chemiosmosis couple (ETC -> ATP synthesis)
Following glycolysis and the citric acid cycle, NADH and FADH2 accounts for most energy extracted from food -> electron carrier donate electrons to ETC -> powers ATP synthesis via oxidative phosphorylation
Cristae
The inner membrane of the mitochondrion where ETC is location
Final electron acceptor (ETC)
Carriers alternate reduced and oxidized states until electrons drop free energy and are passed to the final electron acceptor: O2, forming H2O
Cytochromes
Proteins that electrons are passed through (each with an iron atom) to O2
Mitochondrial matrix
Pumps H+ due to proteins from electron transfer in the ETC to the intermembrane space
ATP synthase
Protein that H+ passes through after moving back across the membrane
Phosphorylation
ATP synthase uses the exergonic flow of H+ to drive phosphorylation of ATP
Chemiosmosis
The use of energy in a H+ gradient to drive cellular work
Proton-motive force
The H+ gradient, energy stored in a H+ gradient across a membrane couples the redox reactions of ETC -> ATP synthesis
Cellular respiration sequence
Glucose -> NADH -> electron transport chain -> proton-motive force -> ATP
Alcohol fermentation
Pyruvate is converted to ethanol in two steps
- First releasing CO2
Alcohol fermentation by yeast is used in brewing, winemaking, and baking
Lactic acid fermentation
Pyruvate is reduced to NADH, forming lactate as an end product, with no release of CO2
Human muscle cells
Human muscle cells use lactic acid fermentation to generate ATP when O2 is scarce
Obligate anaerobes
Carry out fermentation or anaerobic respiration and cannot survive in the presence of O2
Facultative anaerobes
Yeast and many bacteria, meaning that they can survive using either fermentation or cellular respiration
Amino acids
Proteins must be digested to amino acids; amino groups can feed glycolysis or the citric acid cycle
Glycerol
Used in glycolysis from fats that are digested
Fatty acids
Used in generating acetyl CoA from fats that are digested
