Cellular Respiration Chapter 8 Cellular Respiration Chapter 8.
Cellular Respiration Bio2
description
Transcript of Cellular Respiration Bio2
CELLULAR RESPIRATIONand FERMENTATION
Energy Harvest
• Fermentation – partial breakdown w/o oxygen
• Cellular Respiration – most efficient, oxygen consumed, mitochondria
• Cells recycle ATP• Redox reactions (oil/rig); reducing agent –
electron donor; oxidizing agent – acceptor• Cell Resp: glucose oxidized – H removed;
oxygen reduced – accepts H
Energy flow and chemical recycling in ecosystems
NAD+ electron shuttle
• Nicotinamide adenine dinucleotide
• Coenzyme, oxidizing agent, reduced form NADH
• NADH shuttles electrons to ETC
ETC – proteins, cytochromes in cristae, series of smaller steps, stores released energy to make ATP, oxygen combines w/ electrons and proton
Glycolysisglucose pyruvate; cytosol
Krebs cyclemitochondrial matrix, pyruvate acetyl CoA
& CO2
PHOSPHORYLATION
• OXIDATIVE – ATP synthesis powered by redox
reactions– Electron transport chain– Requires oxygen (final electron acceptor)
• SUBSTRATE LEVEL– ATP synthesis from transfer of phosphate
group from substrate to ADP– Glycolysis and Krebs cycle
Substrate level Phosphorylationin glycolysis
GLYCOLYSIS
• Splitting of glucose
• C6H12O6 → 2 C3H3O3
• Uses 2 ATP’s
• Makes 4 ATP’s
• Net 2 ATP’s
• 2 NADH & 2 H+
← SUMMARY
GLYCOLYSIS
Glucose → 2PGAL → 2 PGA → 2 pyruvates
↑ ↑ ↑
requires 2 NAD+ generates
2 ATP’s reduced 4 ATP’s
2 NADH
Oxidation of Pyruvate•Occurs in mitochondrion, requires transport protein & coenzyme A•Yields Acetyl CoA, 1 NADH & 1 H+
from each pyruvate (2 total)•Waste – carbon dioxide
KREBS CYCLE• Occurs in mitochondrial
matrix
• 1 cycle/pyruvate• 2 cycles/glucose
• Acetyl CoA (2-C) + oxaloacetate (4-C) → citrate (6-C)
• 7 more steps: 2CO2 removed, 3NADH & H+, 1FADH2
• 1 ATP – substrate phosphorylation
ELECTRON TRANSPORT
• Cristae of mitochondrion – foldings ↑ surface area
• Electron carriers (proteins) embedded in membrane
• NADH “delivers” electrons to first molecule in chain (3 ATP’s); FADH2 adds electrons at lower level (2 ATP’s)
• Last cytochrome passes electrons to ½O2 + H2 → H2O
CHEMIOSMOSIS• Energy coupling• ATP synthase
– Generates ATP– Molecular mill– Powered by proton flow
• Uses exergonic flow of electrons to pump H+ (protons) from matrix into intermembrane space, they flow back through ATP synthase
• H+ gradient couples redox reactions of ETC to ATP synthesis
SUMMARY
FERMENTATION
• Anaerobic glycolysis followed by break down of pyruvates
• Substrate level phosphorylation• Regenerates NAD+ from NADH• Alcoholic: yeast, bacteria, produces – 2 ATP, 2
CO2 & 2 ethanol from pyruvates
• Lactic acid: fungi, human muscle cells, bacteria, produces – 2 ATP & 2 lactates from pyruvate
• Acetic acid: bacteria, 2 ATP, 2 CO2 & 2 acetic acids from pyruvates
• Other metabolic pathways
• Versatility of catabolism
• Biosynthesis
FEEDBACK
MECHANISMS
CONTROL
CELLULAR RESPIRATION