Energy Transformation: Cellular RespirationLeila A. Allado-Ombat, PhDBiology DepartmentCollege of Arts and SciencesCaraga State University, Butuan City
Learning ObjectivesAt the end of this session, the learner be able to:differentiate aerobic from anaerobic respiration (STEM_BIO11/12-IIa-j-6).explain the major features and sequence the chemical events of cellular respiration (STEM_BIO11/12-IIa-j-7).distinguish major features of glycolysis, Krebs cycle, electron transport system, and chemiosmosis (STEM_BIO11/12-IIa-j-8). describe reactions that produce and consume ATP (STEM_BIO11/12-IIa-j-9).describe the role of oxygen in respiration and describe pathways of electron flow in the absence of oxygen (STEM_BIO11/12-IIa-j-10).compute the number of ATPs needed or gained in photosynthesis and respiration (STEM_BIO11/12-IIa-j-11).
REVIEW OF PREVIOUS TOPICWhat is ATP?What does ATP do for you?How do we get energy from ATP?How ATP re-made?When is ATP made in the body?
AnswerWhat is ATP?
AnswerWhat does ATP do for you?
It supplies you energy.
AnswerHow do we get energy from ATP?
By breaking the high energy bonds between the last two phosphates in ATP through hydrolysis (adding of water)
How the breaking of bond happens?
ATPaseWith the aid of ATPase (enzyme)
AnswerHow ATP re-made?
ADP uses energy and gain an extra Phosphate and is recharged back to ATP with the help of ATP synthetase (an enzyme)
AnswerWhen is ATP made in the body?
During a Process called Cellular Respiration that takes place in both Plants & Animals
Physical exercise for 10 minutes
Question to Answer:
What do you call the gas inside the bag?Aside from the gas, what else inside the bag?What other things you observed in your body after you exercise?How those things are produce by your body?What do you call the process of producing carbon dioxide, water and energy in your body?What cell organelle is responsible for that process?Are all living organisms have mitochondria?
Cellular RespirationIncludes pathways that require oxygenGlucose is oxidized and O2 is reducedGlucose breakdown is therefore an oxidation-reduction reactionBreakdown of one glucose results in 36 to 38 ATP molecules
Overall Equation of Cellular RespirationRaw Materials
6CO2 + 6H20 + e- + 36-38ATPsC6H12O6 + 6O2
What Type of Reaction is Cellular Respiration?An Oxidation-Reduction Process or REDOX ReactionOxidation of GLUCOSE --> CO2 + H2O (e- removed from C6H12O6)Reduction O2 to H2O (e- passed to O2)
What Carries the electron?
NAD+ (nicotinadenine dinucleotide) acts as the energy carrierNAD+ is a coenzymeIts Reduced to NADH when it picks up two electrons and one hydrogen ion
Are there any Electron Carrier?Yes the FAD another co-enzymeFAD+ (Flavin adenine dinucleotide)Reduced to FADH2
Where Does Cellular Respiration Take Place?It actually takes place in two parts of the cell:
Glycolysis occurs in the Cytoplasm
Krebs Cycle & ETC Take place in the Mitochondria
Review of Mitochondrion Anatomy
Smooth outer MembraneFolded inner membraneFolds called CristaeSpace inside cristae called the Matrix
Cumulative Process of Cellular RespirationGlycolysis (Anaerobic)Breaks down glucose into two molecules of pyruvate in cytoplasmThe citric acid cycle (Aerobic)Completes the breakdown of glucose in the matrix of mitochondrionOxidative phosphorylationIs driven by the electron transport chain in inner mitochondrial membraneGenerates ATP
An Overview of Cellular Respiration
Overall process of cellular respiration
Video on cellular respiration
In the CytoplasmGlycolysis consists of two major phasesEnergy investment phaseEnergy payoff phase
Energy Investment PhaseEnergy Pay off Phase
FermentationIn the absence of O2 (e.g. in plant roots in flooded soil), fermentation regenerates the NAD+ needed for glycolysis.
- glycolysis can then be the main source of energy
Transition between glycolysis andKrebs CycleBefore the citric acid cycle can beginPyruvate must first be converted to acetyl CoA, which links the cycle to glycolysis in the mitochondrion
Krebs Cycle/TCA/Citric Acid CycleReactions and enzymes of the Citric Acid Cycle
Electron Transport System (ETC)Catalyzes a flow of electrons from NADH to O2Electron transport is coupled with formation of proton gradient used for ATP synthesisConsists of 5 complexes:Complex I (NADH dehydrogenase)Complex II (succinate dehydrogenase)Complex III (Cytochrome bc1 complex)Complex IV (Cytochrome c oxidase)Complex V (ATP synthase)
Electron Transport ChainPlant mitochondria contain additional enzymes (in green), which do not pump protons.
Number of ATPs produced per GlucoseThere are three main processes in this metabolic enterprise
Consumption of ATPATP powers most energy-consuming activities of cells, such as:anabolic (synthesis) reactions, such as:joining transfer RNAs to amino acids for assembly into proteinssynthesis of nucleoside triphosphates for assembly into DNA and RNAsynthesis of polysaccharidessynthesis of fatsactive transport of molecules and ionsconduction of nerve impulsesmaintenance of cell volume by osmosisaddition of phosphate groups (phosphorylation) to different proteins (e.g., to alter their activity in cell signaling)muscle contraction beating of cilia and flagella (including sperm)bioluminescence
Extracellular ATPIn mammals, ATP also functions outside of cells. ATP is released in the following examples:
from damaged cells to elicit inflammation and painfrom the carotid body to signal a shortage of oxygen in the bloodfrom taste receptor cells to trigger action potentials in the sensory nerves leading back to the brainfrom the stretched wall of the urinary bladder to signal when the bladder needs emptying