energy transformation: cellular respiration outline
TRANSCRIPT
Energy Transformation: Cellular Respiration Outline
1. Sources of cellular ATP2. Turning chemical energy of covalent bonds between C-C into energy for cellular
work (ATP)3. Importance of electrons and H atoms in oxidation-reduction reactions in
biological systems4. Cellular mechanisms of ATP generation5. The four major central metabolic pathways
Glycolysis- FermentationTransition step Krebs CycleElectron Transport chain and oxidative phosphorylation
4. Poisons of cellular respiration and their mechanisms of action.5. Control of cellular respiration6. Use of biomolecules other than glucose as carbon skeletons & energy sources7. Sources of energy and carbon for living cells
http://health.howstuffworks.com/sports-physiology3.htm
Muscle cells have enough ATP to last for about three seconds
Phosphagen system
Glycogen- glucoselactic acid system
Glucose- AerobicRespiration
Phosphagen System https://www.unm.edu/~lkravitz/Exercise%20Phys/PhosphagenSystem.html
https://ib.bioninja.com.au/higher-level/topic-8-metabolism-cell/untitled/phosphagen-system.html
Breakdown of glucose in presence of oxygencomplete breakdown
C6H12O6 + 6O2 ……………… 6CO2 + 6H2O + ATP + (heat)
C-C-C-C-C-C + O2 ……………… CO2 + H2O + ATP +(heat)
During cellular respiration the potential energy in the chemical bonds holding C atoms in organic molecules in turned into ATP.
In presence of oxygencomplete breakdown
C-C-C-C-C-C + O2……………… CO2 + H2O + ATP + heatlarge amount
In absence of oxygenincomplete breakdown
C-C-C-C-C-C ……………… 2 C-C-C + ATP + heatsmall amount
Cellular respiration: ATP is produced aerobically, in the presence of oxygen
Fermentation: ATP is produced anaerobically, in the absence of oxygen
Chemical bonds of organic molecules
Chemical bonds involve electrons of atoms
Electrons have energy
Chemical bonds are forms of potential energy
If a molecule loses an electron does it lose energy?
When a chemical bond is broken sometimes electrons can be released
• Oxidation: removal of electrons.• Reduction: gain of electrons.• Redox reaction: oxidation reaction paired with a
reduction reaction.
Oxidation-Reduction (OIL-RIG)
The electrons associated with hydrogen atoms; biological oxidations are often dehydrogenations
Soluble electron carriersNAD+, and FAD (ATP generation) NADP+ (biosynthetic reactions)
Electron Carriers in Biological Systems
Nicotinamide Adenine Dinucleotide (NAD+) a co-enzyme that acts as an electron shuttle (Niacin/B3)
NAD+
Nicotinamide (oxidized form)
Dehydrogenase
2 e– + 2 H+2 e– + H+
NADH H+
H+
Nicotinamide (reduced form)
+ 2[H](from food)
+
Flavin Adenine Dinucleotide (FAD+) is another co-enzyme that acts as an electron shuttle (Vitamin B2)
In cells, energy is harvested from an energy source (organicmolecule) through the central metabolic pathways, a series ofcoupled oxidation/reduction reactions (redox) that involve dehydrogenation.
becomes oxidized
becomes reduced
Dehydrogenase
An overview of the central metabolic pathways
• Glycolysis• Transition step• Tricarboxylic acid cycle (TCA or Krebs cycle)• The Electron Transport Chain and oxidative
phosphorylation
GlycolysisTransition stepTricarboxylic acid cycle, citric acid cycle (TCA or Krebs cycle)Transition Step & The Krebs CycleThe Electron Transport Chain and oxidative phosphorylation
An overview of the central metabolic pathways
Glycolysis
• Cytosolic multi – step breakdown of glucose into intermediates
• Turns one glucose (6-carbon) into two pyruvate (3-carbon) molecules
• Generates a small amount of ATP (substrate-level phosphorylation)
• Generates reducing power - NADH + H+
1. Substrate-level phosphorylation
Generation of ATP
-Transfer of a high-energy PO4 from an organic molecule to ADP- Different enzymes- During glycolysis and theTCA or Krebs cycle
-
Energy investment phase
Glucose
2 ATP used2 ADP + 2 P
4 ADP + 4 P 4 ATP formed
2 NAD+ + 4 e– + 4 H+
Energy payoff phase
2 NADH + 2 H+
2 Pyruvate + 2 H2O
Net2 Pyruvate + 2 H2O
2 ATP
2 NADH + 2 H+
Glucose
4 ATP formed – 2 ATP used
2 NAD+ + 4 e– + 4 H+
Glycolysis Citricacidcycle
Oxidative phosphorylation
ATPATPATP
The energy input and output of glycolysis
Transition step
• Under aerobic conditions, the pyruvate produced during glycolysis is directed to the mitochondrion.
• A multi-enzyme complex, spanning the 2 mitochondrial membranes, turns pyruvate (3-carbon) into Acetyl-CoA (2-carbon) and releases one CO2molecule
• Uses coenzyme A (Vit B derivative)• Generates reducing power NADH + H+
Figure 9.10 Conversion of pyruvate to acetyl CoA, the junction between glycolysis and the Krebs cycle
Krebs or TCA Cycle
• A cyclical pathway• Accepts – acetyl – CoA• Generates 2 – CO2 molecules (for every acetyl-CoA• Generates reducing power NADH + H+ and FADH2
• Generates a small amount of ATP (substrate-level phosphorylation)
2. Oxidative phosphorylation/ Chemiosmosis
ATP Generation during aerobic cellular respiration
• ADP and inorganic PO-4
• ATP synthase• Cellular respiration in mitochondria• Electron Transport Chain
Electron Transport Chain and ATP generation
Electron transport chain:• membrane-embedded or
bound electron carriers• Mostly proteins with non-
protein groups.• NADH vs. FADH2
• No direct formation of ATP• Pumps H+ into the inter-
membrane space
Oxidative Phosphorylation and ATP generation
ATP Generation :• Membrane-embedded protein complex , ATP
synthase• Proton-motive force• Direct formation of ATP by Chemiosmosis
Chemiosmosis: the coupling of the transport ofH+ across membrane by facilitated diffusionwith chemical reaction producing ATP
Electron Transport chains and oxidative phosphorylationhttp://highered.mcgraw-hill.com/sites/0072437316/student_view0/chapter9/animations.html#
ATP Synthase Gradient: The Moviehttp://vcell.ndsu.edu/animations/at pgradient/movie.htm
Chemiosmosis
Oxidative Phosphorylation
Oxidative Phosphorylation: Couples the electron transport chain tpChemiosmosis
Certain poisons interrupt critical events in cellular respiration• Block the movement of electrons• Block the flow of H+ through ATP synthase• Allow H+ to leak through the membrane
H+
H+
H+
H+
H+
H+ H+ H+ H+
+2 H+
H+
H+H+
1 O22
H O2 ADP + P ATP
NADH
FADH2
NAD+
FAD
Rotenone Cyanide, carbon monoxide
Oligomycin
DNP
ATPSynthase
Electron Transport Chain Chemiosmosis
DNP toxicity https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3550200/
After a person is exposed to an electron transport inhibitor, a series of events will occur which will diminish the production of ATP by oxidative phosphorylation. Using the items listed below, determine the correct order of these events.
1. The number of electrons transported to ATP synthase would decrease
2. The number of hydrogen ions pumped into the intermembrane space would decrease
3. The amount hydrogen ions that flow through ATP synthase would decrease
4. The number of electrons moving through the electron transport chain would decrease
Choose from these ANSWERS:A. 3, 4, 2 B. 4, 1, 2, 3 C. 1, 2, 4 D. 4, 2, 3 E. 4, 1, 2
Fermentation
• An extension of glycolysis• Takes place in the absence of oxygen (anaerobic)• Regenerates NAD+ from NADH + H +
• ATP generated by substrate - level phosphorylation during glycolysis
• Does not use the Krebs cycle or ETC (no oxidative -phosphorylation)
• A diversity of end products produced (i.e. lactic acid, alcohols, etc.)
Energy yield: How many ATP molecules are generated during cellular respiration of a single glucose molecule?
Needs 2 ATPs
36 ATP
Food for Thought!!!
You have a friend who lost 15 pounds of fat on a diet. Where did the fat go (how was it lost)?
Sources of cellular glucose
• glucose from food in the intestine• glycogen supplies in the muscles• breakdown of the Liver's glycogen into
glucose
The Catabolism of various food molecules
Beta oxidation
http://www.brookscole.com/chemistry_d/templates/student_resources/shared_resources/animations/carnitine/carnitine1.html
• Triglycerides consist of glycerol and fatty acids• Fatty acids broken down into through beta
oxidation
Simple lipids
Proteins
Protein Amino acidsExtracellular proteases
Krebs cycle and glycolysis Transition step
Deamination, decarboxylation,dehydrogenation Organic acid
Feedback control of cellular respiration
PhosphofructokinaseAllosteric enzymeActivity modulated by inhibitors and activatorsAdjustment of cellular respiration in response to demand
OXIDATIVE PHOSPHORYLATION(Electron Transport and Chemiosmosis)
Food, such as peanuts
Carbohydrates Fats Proteins
Sugars Glycerol Fatty acids Amino acids
Amino groups
Glucose G3P Pyruvate Acetyl CoA
CITRIC ACID CYCLE
ATP
GLYCOLYSIS