Cellular Respiration & Fermentation

Cellular Respiration & Fermentation 4.4, & 4.6

4.4 & 4.6 – Overview of Cellular Respiration & Fermentation • Key Concept: • The overall process of cellular respiration converts sugar into ATP using oxygen. • 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)

STOP & REVIEW • 1. What is the main reason that an organism needs to go through cellular respiration (to make what)? • 1. ATP • 2. What word means does not require oxygen? • 2. Anaerobic • 3. What word means requires oxygen? • 3. Aerobic • 4. What step of cellular respiration happens first and is anaerobic? • 4. Glycolysis • 5. What 2 steps happen next in cellular respiration and are aerobic? • 5. Krebs Cycle & ETC

1. mitochondrion 1 matrix (area enclosed by inner membrane) Glycolysis: Anaerobic process in cytoplasm that splits glucose into two 3C molecules Makes 2 ATP ATP 3. Kreb’s Cycle Takes place in: matrix of mitochondria; produces 2 ATP and 4. 6CO2 5. Energy transferred to 2nd stage (aerobic stage) 2. 2 Pyruvates ATP inner membrane 6. ETC: energy from glycolysis and6O2 enter ATP 4 7. 6 H2O produced and a large amount of ATP (32)

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)

STOP & REVIEW • 1. Glycolysis (the first step in C.R.) takes place where? • 1. Cytoplasm • 2. One glucose is split into 2? • 2. Pyruvates • 3. How many ATP does the cell actually gain from this part? • 3. 2 ATP • 4.Can prokaryotes and eukaryotes go through glycolysis? Why or why not? • 4.Yes, they both have cytoplasm, so both types of cells can go through glycolysis.

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 • Total products of Kreb’s cycle (because of 2 pyruvates): • 2 ATP

STOP & REVIEW • 1. The Kreb’s Cycle (second step) takes place where? • 1.Matrix of mitochondria • 2. The 2 pyruvates from glycolysis are broken down here to make how many total ATP’s? • 2.2 ATP • 3. So, with the last step (glycolysis) and this step (Kreb’s) how many total ATP have been made so far? • 3. 4ATP

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 • Oxygen and hydrogen ions combine to form water (released as a waste product) • 32 ATP are made

STOP & REVIEW • 1. The third step (ETC) takes place where? • 1. Inner membrane of mitochondria • 2. Why is the inner membrane folded? • 2. To create more surface area to make more ATP. • 3. What combines here and gets released as waste? • 3. H and O combine to make/release water. • 4. How many ATP are made by just this step? • 4. 32 ATP • 5. How many total ATP have been made by all three steps together? • 5. 36 ATP

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

Allows glycolysis to continue making ATP without oxygen

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)

STOP & REVIEW • 1. Why does fermentation occur? • 1. Because too little or no oxygen is available. • 2.Out of all 3 steps of cellular respiration, which one does fermentation only use? Why? • 2. Glycolysis (only one that is anaerobic) • 3. Which form of fermentation occurs in animals when not enough oxygen is consumed? • 3. Lactic Acid Fermentation (produces lactic acid) • 4. How many ATP are made by this form of fermentation? • 4. 2ATP (glycolysis only makes 2) • 5. Which form of fermentation do bacteria and yeast use? • 5. Alcoholic Fermentation • 6.What are the byproducts of this form of fermentation (produced)? • 6. Alcohol, 2 ATP, CO2

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Cellular Respiration & Fermentation