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Glycolysis & Cellular Respiration: The Biology of Energy (6)…
Glycolysis & Cellular Respiration:
The Biology of Energy
1) ATP Molecules Store Energy in Cells
ATP: universal currency of energy in plant & animal cells
ATP molecules formed: high energy bond joining inorganic phosphate group to ADP molecules
Energy to be used -> transfer energy to ATP molecules
Energy is stored in bond between phosphate group and ADP molecule
ATP molecules energy storage-> immediate availability for urgent cellular processes
Processes to form new high energy ATP molecules: glycolysis and cellular respiration
2) Glycolysis & Cellular Respiration: An Overview
Glycolysis
Without oxygen
Takes place in cytosol
Provides energy for short bursts of energy
Actions suddenly: cells not oxygenated rapidly enough for heart and lungs to support cellular respiration
Not efficient: releases 2% of energy in glucose = 2 ATP molecules for every glucose molecule metabolized
Cellular Respiration
With oxygen
Efficient: releases 37% of energy in glucose= 36 or 38 ATP molecules for every glucose molecule metabolized
4) Glycolysis breaks apart Glucose molecules
Glycolysis= to break apart glucose
Glucose->pyruvic acid: two stages
glucose activation
energy 2 ATP molecules
glucose->fructose diphosphate
energy harvest
fructose diphosphate breaks apart ->2 PGAL molecules
2PGAL-> 2 pyruvic acid molecules
2PGAL->2ATP (NET gain)
2 PGAL->NADH molecules provide energy for cellular respiration
11) conclusion
Glycolysis: 2 ATP per glucose molecule
Cellular respiration: 34-36 ATP
total: 36-38 ATP per glucose molecule
3) Cellular Respiration Reverses Photosynthesis
Breaking apart glucose for energy: start glycolysis
anaerobic (without oxygen)-> fermentation: glycolysis repeats
aerobic (with oxygen)-> cellular respiration:release energy
5)Fermentation enables glycolysis to coninue anaerobic conditions
NAD+ runs out->glycolysis stops
Fermentation NAD+ molecules regenerated->glycolysis continues
Two types of Fermentation
Lactic acid fermentation
restored NAD+ molecules free to accept electrons during glycolysis
electrons and hydrogen from NADH energy source
muscle cells: pyruvic acid->lactic acid
After: lactic acid->pyruvic acid
Alcoholic fermentation produces alcohol & CO2
Micro organisms
hydrogen from NADH
Ethanol-> alcohol and CO2 from pyruvic acid
8) Electrons deposited on electron transport system by carrier molecules
carrier molecules deposit energetic electron pairs in electron transport system in bedded in inner mitochondria membrane
energetic electron mover molecule to molecule along electron transport system
energy released during transfer used to pomp hydrogen ions mitochondrial matrix->inner membrane compartment
mitochondrial matrix -> negatively changed, inter-membrane compartment-> positively changed
creates source of energy
positively charged hydrogen ions flow back through channel proteins due electrical attraction negative mitochondrial matrix
10)ATP transported to cytoplasm powers cellular processes
Final step in cellular respiration is ATP transport
Outer mitochondrial membrane permeable to ATP, ADP & inorganic phosphate molecules
Proteins inner mitochondrial membrane exchange ATP matrix with ADP and phosphate groups -> diffused into inner membrane compartment
ATP in outer membrane diffuse into cytoplasm
ATP provides energy needed for activities
7) Krebs Cycle: energetic electrons attach to carrier molecules
acetyl CoA+2-oxaloacetic acids
2 carbon acetyl+ 4 carbon oxaloacetic acids-> 2-citric acids
CoA recycled
enzymes mitochondria+ 2-citric acids->regenerate 2-oxaloacetic acids
during process: 4CO2 and energy 2 acetyl groups ->8 electron carrier molecules(2FADH2 and 6NADH)
cell only gained 4ATP up till now BUT capture energetic electrons and attach to carrier molecules
2 NADH (glycolysis), 2 NADH(acetyl CoA formation), 6NADH(krebs cycle), 2FADH2 (krebs cycle)
each pair energetic electrons
9) Flow of H+ ions powers ATP synthesis
enzymes channel proteins use energy flow hydrogen ions to create ATP by adding phosphate based molecules to ADP
end of transport system: enzymes take hydrogen atoms combine them oxygen to H2O
clears system open for more electrons
without oxygen, electrons pile up in transport system
hydrogen wouldn't be prompt across inner membrane into membrane compartment
Flow hydrogen ions through ATP synthesizing enzymes produced by each molecule of glucose broken down creates energy
energy enough to synthesize 32-34 ATP molecules by combining 32-34 ADP to phosphate groups in Matrix
each pair electrons provided by NADH or FADH2 molecule travelling down electron transport system pomp enough hydrogen ions across inner membrane to provide energy 3 ATP molecules
6) Cellular Respiration occurs in Mitochondria
oygen available->no fermentation
cellular respiration: break glucose into CO2 & H2O
Mitochandria have two membranes:inner membrane->inner compartment-> mitochondrial matrix and outer membrane->inter membrane compartment
1st step cellular respiration: glycolysis
Pyruvic acids-> mitochondrial matrix
2 pyruvic acid->CO2 + acetylgroup
acetyl group+co enzyme A->acetyl CoA molecules
during reactions: energetic electron & hydrogen transferred NAD+ forming 1 energy NADH per acetyl CoA
2 acetyl CoA -> krebs cycle
large pores outer membrane permeable pyruvic acid, inner membrane-> proteins
