+

Cellular Respiration & Fermentation4.4, 4.5, & 4.6

+4.4 – Overview of Cellular RespirationKey Concept:

The overall process of cellular respiration converts sugar into ATP using oxygen.

4.5 – Cellular Respiration in DetailKey Concept:

Cellular respiration is an aerobic process with two main stages.

+ Purpose of Cellular Respiration

To make ATP from the energy stored in glucoseGlucose comes from an organism

doing photosynthesis themselves or from eating foods containing glucose

Remember: the purpose of photosynthesis was just to get glucose

+Cellular Respiration has 2 parts

Anaerobic (does not require oxygen)Glycolysis

Aerobic (requires oxygen)Kreb’s Cycle (Citric acid Cycle)Electron Transport Chain (ETC)

+ GlycolysisTakes place in cytoplasm (eukaryotes and

prokaryotes do this step since all cells have cytoplasm)

Splits one glucose molecule into two pyruvate molecules

Costs the cell 2 ATP molecules to do this4 ATP molecules are produced (only gain 2 ATP)2 NADH molecules are formed

+Kreb’s Cycle (Citric Acid Cycle)Takes place in matrix of mitochondria (only

in eukaryotes)2 pyruvate (made during glycolysis) enter the

mitochondrionEach pyruvate is broken down to create 1 ATP, 3

CO2, NADH, & FADH2

Total products of Kreb’s cycle (because of 2 pyruvates):2 ATP6 CO2NADHFADH2

Will carry energy to the next step

+Electron Transport Chain (ETC)

Takes place in inner membrane of mitochondria (cristae) Folded to create more surface area for reactions to produce

more ATP in a small space NADH & FADH2 (from Kreb’s) donate their energy (electrons) to the

electron transport chain Oxygen is the final electron acceptor and it picks up hydrogen ions Oxygen and hydrogen ions combine to form water (released as a

waste product) 32 ATP are made

+

+ ATP from Cellular Respiration

4 from Glycolysis (uses up 2, so really only gain 2 ATP)

2 ATP from Kreb’s cycle32 ATP from ETCGAIN 36 ATP from one glucose molecule

+Equation for Cellular RespirationC6H12O6 + 6O2 6CO2 + 6H2O + 36ATP

Like the reverse of photosynthesis

+ What happens when there’s no/not enough oxygen or there

are no mitochondria? Answer: Fermentation

Two Kinds: Lactic Acid Fermentation Alcoholic Fermentation

+

Allows glycolysis to continue making ATP without oxygen

+Lactic Acid FermentationAnaerobicOccurs in muscle cells

Produces burning feeling in musclesOccurs when body is worked to the point

that more oxygen is being used than what is being taken in

This is why you breathe harder when you’re exercising is to get more oxygen to keep making ATP

Produces Lactic Acid and 2 (net) ATP

+Alcoholic Fermentation

AnaerobicOccurs in some bacteria and yeastProduces CO2, ethyl alcohol, and 2 (net)

ATPUsed in food production (bake bread and

make wine)