Cellular RespirationCellular Energy Unit Part II

Heterotrophs

• Consumers• Cellular respiration• Use organic compounds such as

glucose and oxygen to make cellular energy (ATP)

• Waste: CO2 and H2O

Aerobic Cellular Respiration

Glycolysis

• Glucose + ATP → Pyruvate + ATP + NADPH + H2O

• Occurs in the cytoplasm• Multistep process that can be divided

into two phases: Investment and Payoff.

• It takes 2 ATP to rearrange glucose so it can be broken down into pyruvate. The breakdown yields 4ATP for a net gain of 2ATP.

• The ATP is used for cellular energy and the NADPH goes on to power the electron transport chain and the Krebs cycle. The pyruvate enters the Krebs cycle to be broken down into carbon dioxide to create more ATP and NADPH.

• Water is waste.

Mitochondira

• Mitochondria are the sites of the Krebs cycle and the electron transport chain.

• Mitochondria are double membrane organelles. The folded membranes provided a lot of surface area for respiration.

• Cristae are the folds in the inner membrane. The folded membranes provided a lot of surface area for electron transport chain.

• Matrix is the thick gelatinous substance that fills the mitochondria. It is the site of the Krebs cycle.

The Krebs Cycle

• Pyruvate + NADP+ + ADP→ 3CO2 + ATP + NADPH

• Occurs in the matrix of mitochondria. • Since each glucose produces 2 pyruvates

after glycolysis, it takes 2 turns of the Krebs cycle to break down 1 glucose.

• Each turn produces 3 CO2 which enter the lungs via diffusion.

• Each turn will produce 1 ATP and 4 NADPH

• In total the Krebs cycle produces 6 CO2, 2 ATP, and 8 NADPH

• The CO2 is waste, the ATP powers cellular processes and the NADPH goes on the power the electron transport chain.

Electron Transport Chain

• A series of molecules that pass electrons from NADPH to produce a H ion gradient which ATP synthase uses to make ATP from ADP.

• Occurs in the inner membrane of mitochondria.

• NADPH + ADP + O2 → H2O + ATP and NADP+

• NADP+ is recycled and reused in the respiration process. • Oxygen is the end electron acceptor and water is produced. (in photosynthesis the ETC cleaved

water, in respiration the ETC makes water.)

Anaerobic Cellular Respiration

• NO OXYGEN!• Occurs in the cytoplasm• Since oxygen isn’t there

to accept the electrons of the electron transport chain they have to be funneled down another pathway.

• Pyruvate

FermentationLactic Acid • Since pyruvate can’t go through

the Krebs cycle because there is not oxygen to accept the electrons at the end of the ETC, then it is fermented into lactate.

• Occurs in happen in the cytoplasm

Alcohol• Same thing goes except the

pyruvate is cleaved and CO2 is released. (yeast)

• Creates ethanol.• Occurs in the cytoplasm.

Cellular Respiration

• Overall reaction: Glucose + O2→ ATP + CO2 + H2O• Aerobic: Involves glycolysis, krebs cycle, and the electron

transport chain. Can make up to 38 ATP’s per glucose• Occurs in the cytoplasm (glycolysis) and the mitochondria

(krebs and e- chain). • Uses glucose and oxygen• Makes ATP that is used to power all cellular processes. • Carbon dioxide and water are the waste products.

• Anaerobic: Can be lactic acid or alcohol fermentation• Occurs in the cytoplasm• Uses glucose (pyruvate) to make ATP• Either Lactic acid (lactate) or alcohol and carbon dioxide

are waste.