Cellular Respiration

C6H12O6 + O2 CO2 + H2O + energy

Glucose + oxygen carbon + water + ATP

dioxide

Glycolysis• Glucose is converted into 2 pyruvate.• NAD+ becomes NADH• Net 2 ATP• Water made as waste product.http://www.mcgrawhill.ca/school/applets/

abbio/quiz/ch05/how_glycolysis_works.swfhttp://instruct1.cit.cornell.edu/courses/biomi290/ASM/glycolysis.dcrhttp://programs.northlandcollege.edu/biology/Biology1111/animations/glycolysis.html

Reduction of NAD+

• http://www.mcgrawhill.ca/school/applets/abbio/quiz/ch05/how_nad_works.swf

Krebs Cycle

• First Pyruvate converted to Acetyl-CoA.

• NAD + converted to NADH

• FAD converted to FADH2

• CO2 given off as waste product

• ATP produced

http://www.mcgrawhill.ca/school/applets/abbio/quiz/ch05/how_the_krebs_cycle_wor.swf

Electron Transport Chain and Chemiosmosis

• NADH converted to NAD+ releasing high energy electrons.

• FADH2 converted to FAD releasing high energy electrons.

• H+ pumped to intermembrane space by high energy electrons.

• H+ reenters matrix joining with electrons and O2 to produce water.

• This converts ADP to ATP.

• When ETC is operating pH matters.

• The H+ gradient that results is called the proton motive force.

• Force is an electrochemical gradient.– The concentration of protons (chemical gradient).– Voltage across the membrane because of a

higher concentration of positively charged charged protons on one side (electrical gradient).

• Oxidative and photo phosphorylation.

• http://highered.mcgraw-hill.com/olcweb/cgi/pluginpop.cgi?it=swf::535::535::/sites/dl/free/0072437316/120071/bio11.swf::Electron%20Transport%20System%20and%20ATP%20Synthesis

These take time to load…• http://vcell.ndsu.nodak.edu/animations/etc/movie.htm• http://vcell.ndsu.nodak.edu/animations/atpgradient/

movie.htmProkaryotes• http://www.mcgrawhill.ca/school/applets/abbio/quiz/

ch05/electron_transport_syst38.swf

ATP Total from Cell Respiration

• 38 ATP prokaryotes

• 36 ATP eukaryotes (b/c 2 used for active transport of NADH into mitochondria)

• 2 ATP Glycolysis;

• 2 ATP Krebs Cycle;

• 32 ATP ETC and Chemiosmosis

Regulation of Aerobic Respiration

3 points of feedback inhibition

1. Large amounts of ATP or citrate (from the Krebs cycle) bind to and stop enzyme phosphofructokinase from allowing glycolysis to continue. These are allosteric inhibitors.

2. Also, large amounts of NADH inhibit pyruvate dehydrogenase from converting pyruvate to acetyl-CoA.

3. Finally, large amounts of ADP activate the enzyme phosphofructokinase of glycolysis.

Oxidation without O2 Anaerobic Respiration

• Some prokaryotes use S, N, CO2, and inorganic metals as final e- acceptors in place of O2. Less ATP produced but enough to be called respiration.

• Methanogens are part of Archaea and use CO2 as e- acceptor. They convert it into CH4 or methane.

• Some prokaryotes use SO2 or other sulfates as e- acceptor. They convert it into H2S.

Fermentation

• Process in which electrons stored in NADH from glycolysis are recycled or donated to organic molecules. This converts NADH to NAD+ and allows glycolysis to run continuously.

• Bacteria can carry out many different types of fermentation.

Organic molecule + NADH

reduced organic molecule + NAD+

Ethanol Fermentation

• Occurs in yeast after glycolysis.

• Yeast enzymes remove CO2 as a waste product from pyruvate through decarboxylation.

• The other product from decarboxylation is a 2C molecule acetaldehyde which accepts electrons from NADH. This produces ethanol and NAD +.

Lactic Acid Fermentation

• The enzyme lactate dehydrogenase converts pyruvate into lactic acid and converts NADH into NAD+.

• Usually blood can remove the lactate, however if this does not happen muscle fatigue results.

Catabolism of Proteins and Fats

Catabolism of Proteins

• Broken down into amino acids.

• Deamination removes side amine group.

• New proteins can be made from these amino acids.

• Some enter glycolysis or Krebs cycle to become intermediate molecules.

Catabolism of Fats

• Broken down into fatty acids and glycerol.

• Fatty acids are converted to form acetyl-CoA by –oxidation.

• Produce more energy per gram than glucose.

Key intermediates connect metabolic pathways

• Many enzymatic pathways can be used to break down macromolecules (catabolism) or to build up macromolecules (anabolism).

Evolution of Metabolism(important events)

1. Obtaining chemical energy from breaking down organic molecules.

2. Evolution of glycolysis.

3. Evolution of photosynthesis to generate ATP.

4. The substitution of H2O for H2S to produce O2 during photosynthesis.

5. The evolution of aerobic respiration.

6. Nitrogen fixation makes N available to organisms.