Cellular respiration 2018

Cellular respiration - process that releases energy from food in the presence of oxygen.

Autotrophs and heterotrophs must have food turned into energy by cellular respiration.

Energy in food is expressed by units called calories Energy in food is expressed by units called calories. calorie – amount of energy needed to raise the temperature of 1 gram of water 1 degree Celsius.

cellular respiration equation 6 O2 + C6H12O6  6 CO2 + 6 H2O + Energy

Three Stages of cellular respiration: glycolysis Kreb’s Cycle Electron transport chain

Location of the stages Glycolysis – cytoplasm of cell Krebs cycle – mitochondria Electron transport chain – inner mitochondrial membrane

Oxygen requirements aerobic - in air anaerobic – without air Glycolysis – anaerobic in cytoplasm Krebs cycle and electron transport chain- aerobic in mitochondria

Photosynthesis vs. Cellular respiration puts carbon dioxide back in atmosphere uses oxygen to release energy from food Removes carbon dioxide from atmosphere Releases oxygen into atmosphere

Comparing Cellular respiration Photosynthesis

9.2 The Process of Cellular Respiration 10. During glycolysis, 1 molecule of glucose, a 6 ­carbon compound, is transformed into 2 molecules of pyruvic acid, a 3­ carbon compound. (254) ATP and NADH are also produced. The process takes place in the cytoplasm where there is no oxygen. Therefore, glycolysis is an anaerobic process.

Glycolysis C6H12O6, glucose is turned into 2 molecules pyruvic acid (pyruvate) in the cytoplasm. ATP and NADPH are produced too

Glycolysis ATP production: 2 ATP molecules are needed to start it 4 ATP molecules are produced, for a net gain of 2 ATP per molecule of glucose in glycolysis. These 2 ATP molecules go in to the mitochondria and are used in the Kreb’s cycle

NADH Production in Glycolysis NAD+ – electron carrier found in the cytoplasm of mitochondria NADH – NAD+ joined with 2 high energy electrons NADH carries these electrons to the electron transport chain.

Krebs cycle in mitochondria matrix results in pyruvic acid being broken down into carbon dioxide, NADH, ATP, and FADH2. FAD – electron carrier FADH2 - FAD with 2e- and a H+ ion

Mitochondria matrix – innermost compartment of the mitochondrion Contains oxygen

After glycolysis: Pyruvic acid enters matrix and reacts to form acetyl- CoA which then enters the Krebs cycle.

Krebs cycle acetyl CoA joins with other carbon molecules in the matrix to form citric acid. a molecule of CO2 is produced and 2 high energy electrons are passed to NAD+ to produce NADH.

Citric acid is broken down through many reactions into a 4 and 5 carbon compound. The 4 carbon compound recycle in matrix.

the Krebs cycle turns twice for each glucose molecule that enters glycolysis.

Notice how much energy goes to electron transport chain from glycolysis and Krebs cycle:

Three Steps Kreb’s Cycle Glycolysis 2 ATP 32 2 NADH 6 NADH Acetyl CoA 2 FADH2 2 NADH 2 NADH 6 NADH Acetyl CoA Kreb’s Cycle Electron Transport Chain Glycolysis 2 ATP 2 ATP 32

electron transport chain in the inner mitochondrial membrane. Membrane has electron carriers and ATP synthase aerobic process.

Intermembrane space is between the inner membrane and the outer membrane of the mitochondria. Has build up of hydrogen ions during ETC

23. Steps of electron transport chain: NADH and FADH2 give off high energy electron to pass down the ETC through electron carriers Oxygen in mitochondria accepts hydrogen ions and electrons to make water

H+ ions move across the inner mitochondrial membrane and into the intermembrane space because of energy released by electrons.

When concentration of hydrogen ions build up in the intermembrane space, they pass through ATP synthase when the synthase molecule rotates a phosphate is added to ADP, making ATP

Electron transport chain – makes 32 ATP

36 molecules of ATP per molecule of glucose made from all 3 stages of cellular respiration.

Electron Transport Chain Mitochondria inner membrane Reactants Products Glycolysis Cytoplasm outside mitochondria C6H12O6 2 ATP 4 molecules ATP Net gain only 2 2 pyruvate molecules NADH Krebs Cycle In matrix of mitochondria 4CO2 2ATP NADH & FADH2 6O2 32 ATP 6 H20 Electron Transport Chain Mitochondria inner membrane

9.3 What happens if no oxygen in a cell? Fermentation is a way to release energy from food molecules by producing ATP without oxygen. Two types Alcoholic fermentation Lactic acid fermentation

What are the similarities? Glycolysis – anaerobic Reactants – pyruvic acid and NADH One product – NAD+ which cycles back into the cytoplasm

What are the differences What are the differences? Alcohol fermentation produces ethyl alcohol and CO2 Lactic Acid fermentation produces Lactic acid

fermentation occurs when mitochondria in muscles run out of oxygen due to overuse Bacteria can’t perform cellular respiration because they don’t have mitochondria

Both produce energy for yeast, microorganisms and eukaryotic cells out of oxygen

Other uses for fermentation Alcoholic Lactic Acid yeast & microorganisms produce alcoholic beverages & yeast bread Certain foods use the lactic acid for flavoring; cheese, yogurt, buttermilk, sour cream, pickles & sauerkraut

Photosynthesis Cellular respiration No. of steps Names of steps Alternate pathways 2 3 Light independent cycle Glycolysis Krebs cycle Electron Transport Cycle Light dependent cycle C4 and CAM Lactic acid fermentation Alcohol fermentation

9.1 assessment a. Review Why do all organisms need food? to gain energy to undergo processes of life b. Relate Cause and Effect Why do macromolecules differ in the amount of energy they contain? chemical structures differ in carbs, proteins, and fats so therefore the energy contained in their chemical bonds, differ.

2. a. Review Write the overall reaction for cellular respiration. 6O2 + C6H12O6 → 6CO2 + 6H2O + Energy b. Apply Concepts How does the process of cellular respiration maintain homeostasis at the cellular level? Remember plasma membrane controls homeostasis Things need to get in and out of cell to maintain homeostasis and some of them need the energy from break down of food to move things in and out of cell

3. a. Review In what ways are cellular respiration and photosynthesis considered opposite processes? Cellular respiration breaks down glucose; photosynthesis builds it Cellular respiration uses oxygen; photosynthesis breaks H20 and releases oxygen. b. Use Analogies How is the chemical energy in glucose similar to money in a savings account? Chemical energy is stored in the bonds of glucose, just as money is stored in a savings account

9.2 assessment 2 molecules of pyruvic acid 2 molecules of NADH 1a. Review What are the products of glycolysis? 2 molecules of pyruvic acid 2 molecules of NADH a net gain of 2 ATP molecules

b. Compare and Contrast How is the function of NAD+ similar to that of NADP+? Both electron carriers

2. a. Review What happens to pyruvic acid in the Krebs cycle 2. a. Review What happens to pyruvic acid in the Krebs cycle? Pyruvic acid is broken down into carbon dioxide

b. Interpret Visuals Look at Figure 9–5 and list the products of the Krebs cycle. What happens to each of these products? CO2 is expelled in exhalation. The ATP molecules are used to power cellular activities. The NADH and FADH2 molecules are used in the electron transport chain to generate more ATP.

3. a. Review How does the electron transport chain use the high energy electrons from glycolysis and the Krebs cycle? to power the “pumping” of H+ ions against a concentration gradient from the matrix to the intermembrane space

3.b. Relate Cause and Effect How does the cell use the charge differences that build up across the inner mitochondrial membrane during cellular respiration? The charge differences force protons through ATP synthase, which powers the conversion of ADP to ATP.

4. a. Review How many molecules of ATP are produced in the entire breakdown of glucose? about 36 molecules of ATP per molecule of glucose b. Use Analogies How is the cell like a furnace? It can “burn” many different types of fuels, not just glucose. Also, a cell releases heat energy through the breakdown of glucose that heats the organism, just as a furnace releases energy to heat a building

9.3 assessment a. Review Name the two main types of fermentation. Lactic acid fermentation and alcoholic fermentation b. Compare and Contrast How are alcoholic fermentation and lactic acid fermentation similar? Both forms provide energy to the cell in the absence of oxygen, and both produce NAD+. How are they different? They are different in that alcoholic fermentation produces alcohol and carbon dioxide, while lactic acid fermentation produces lactic acid.

2.a. Review Why do runners breathe heavily after a sprint race? When the race is over, the only way to get rid of lactic acid is through a chemical pathway that requires extra oxygen. b. Sequence List the body’s sources of energy in the order in which they are used during a long-distance race. ATP already in muscles ATP made by lactic acid fermentation ATP produced by cellular respiration