Cellular Respiration & Fermentation. 4.4, 4.5, & 4.6. 4.4 – Overview of Cellular Respiration. Key Concept: The overall process of cellular respiration converts sugar into ATP using oxygen. 4.5 – Cellular Respiration in Detail. Key Concept:
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Cellular Respiration & Fermentation 4.4, 4.5, & 4.6
4.4 – Overview of Cellular Respiration • Key Concept: • The overall process of cellular respiration converts sugar into ATP using oxygen. 4.5 – Cellular Respiration in Detail • Key Concept: • Cellular respiration is an aerobic process with two main stages.
Purpose of Cellular Respiration • To make ATP from the energy stored in glucose • Glucose 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)
Glycolysis • Takes 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 this • 4 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 mitochondrion • Each pyruvate is broken down to create 1 ATP, 3 CO2, NADH, & FADH2 • Total products of Kreb’s cycle (because of 2 pyruvates): • 2 ATP • 6 CO2 • NADH • FADH2 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 cycle • 32 ATP from ETC • GAIN 36 ATP from one glucose molecule
Equation for Cellular Respiration C6H12O6 + 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
Lactic Acid Fermentation • Anaerobic • Occurs in muscle cells • Produces burning feeling in muscles • Occurs 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 • Anaerobic • Occurs in some bacteria and yeast • Produces CO2, ethyl alcohol, and 2 (net) ATP • Used in food production (bake bread and make wine)