Chapter 6: How Cells Harvest Chemical Energy

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Chapter 6: How Cells Harvest Chemical Energy by Mind Map: Chapter 6: How Cells Harvest Chemical Energy

1. 6.6 Overview: Cellular respiration occurs in three main stages

1.1. Stage 1: Glycolysis

1.1.1. Occurs in the cytoplasm, and breaks glucose into two molecules called pyruvate

1.2. Stage 2: The citric acid cycle

1.2.1. Takes place in the Mitochondria, takes the derivative of pyruvate and transforms to CO2

1.2.2. Both Stage 1 and Stage 2 create a small amount of ATP, but rather prepare Stage 3 to has a massive production of ATP

1.3. Stage 3: Oxidative phosphorylation

1.3.1. Materials needed: Electron Transport Chain (Embedded in the Mitochondrial Membrane), NADH and FADH (Electron Carriers)

1.3.2. Takes the electrons to the electron transport chain and releases energy through the downward fall of electrons from NADH and FADH to O2, to Phoshorylate ADP. This works by pumping the H+ ions across the membrane into the narrow inter-membrane space, this is a concentration gradient In chemiosmosis, the potential energy of this concentration gradient is used to make ATP Chemiosmosis uses proteins called ATP Synthasis which when H+ ions go through them, ATP is produced

2. 6.7 Glycolysis harvests chemical energy by oxidizing glucose to pyruvate

2.1. Glycolysis literally means the splitting of sugar

2.2. Starts with 1 molecule of Glucose -> And becomes two molecules of Pyruvate

2.2.1. Pyruvate is the ionized form of pyruvic acid

2.2.2. The carbon atoms get divided into 3 and 3 for both of the pyruvates

2.2.3. There are 9 chemical steps from glucose to pyruvate. During these steps the cell transforms NAD+ to NADH and creates 2 ATP molecules through Substrate Level Phosphorylation Substrate Level Phosphorylation Enzyme takes phosphate group from substrate molecule, and then attaches this to ADP making ATP Small amount of ATP Compounds that form between the initial reactant, glucose, and the ending product, pyruvate, are known as intermediates Steps 1-4 are the energy investment phase Steps 5-9 are the energy payoff phase

3. 6.8 Pyruvate is chemically groomed for the citric acid cycle

3.1. Pyruvate on its own can not enter the citric acid cycle, instead it must be groomed to enter

3.2. Carboxyl group is removed from pyruvate and given off as CO2 (First time CO2 is released as part of cellular respiration)

3.3. The 2 carbon molecule is oxidized, and NAD+ -> NADH

3.4. Coenzyme A from a B vitamin joins with the two carbon group to create acetyl coenzyme A

3.5. For each molecule of Glucose two molecules of Acetyl CoA are produced

4. 6.9 The citric acid cycle completes the oxidation of organic molecules creating many, NADH, and FADH2, molecules

4.1. Citric Acid Cycle is also called the Krebs Cycle

4.2. The citric acid cycle starts with the Acetyl CoA molecule, which once entered loses the CoA part.

4.3. The acetyl ground binds with 4 more carbons (called a citrate), which when processed through a redox reaction, loses 2 CO2 molecules

4.4. The 4 carbon molecule is regenerated, making a cycle

4.5. One glucose molecule makes 2 ATP, 6 NADH, and 2 FADH2

5. 6.10 Most ATP production occurs by oxidative phosphorylation

5.1. The electron carriers in the membrane use the energy from redox reactions for a H+ concentration gradient in chemiosmosis, to drive ATP synthesis

5.2. Oxygen has an important role in Cellular Respiration, accepting electrons from the chain and picking up two hydrogen ions creating H20

5.3. Hydrogen ions are transported from the matrix of the mitochondria to the inter-membrane space

5.4. The mitochondrial membrane is not permeable to H+ ions which is why there is a need for carrier proteins

6. 6.11 Certain poisons interrupt critical events in cellular respiration

6.1. Poisons block the electron transport chain. Rotenone binds tightly in the first protein carrier molecules in the first protein comple. This prevents electrons from passing to the next carrier molecule

6.1.1. Rotenone is often used to kill pest insects and fish.

6.1.2. Rotenone starves a cell of its energy by blocking the electron transport chain close to its start - preventing ATP synthesis

6.1.3. Cyanide and carbon monoxide: bind with an electron carrier in the in the fourth proetein complx.

6.2. Oligomycin blocks H+ from traveling through the channel in ATP synthase

6.2.1. Oligomycin: An antibiotic used on skin to combat fungal diseases

6.3. Uncouplers make the membrane of the mitochondria leaky to hydrogen ions.

6.3.1. ATP cannot be made because H+ ions leaking through the membrane destroy the H+ gradient.

7. 6.12 Review: Each molecule of glucose yields many molecules of ATP

7.1. Glycolysis (occurring in the cytoplasmic fluid) and the citric acid cycle (occurring in the mitochondrial matrix) contribute a net total of 4 ATP per glucose molecule by substrate-level phosphorylation.

7.1.1. More energy is harvested from NADH and FADH2 - glycolysis, grooming of the pyrucate, and citric acid cycle Energy of the electrons makes 34 molecules of ATP using the electron transport chain and chemiosmosis in oxidative phosphorylation.

7.2. Up to 40% of a molecule's potential energy can be harvested from glucose

8. 6.1 Photosynthesis and cellular respiration provide energy for life

8.1. def. and photo

8.2. Cellular Respiration - The process of taking in Glucose and O2 Molecules to create ATP + C02 + H20

9. 6.2 Breathing supplies oxygen to our cells for use in cellular respiration and removes carbon dioxide

9.1. Cellular Respiration (def) - The aerobic harvesting of energy from food molecules by cells

9.2. Relationship with the Runner:

9.3. She takes in O2 through her mouth

9.4. The O2 Goes to the lungs

9.5. Hemoglobin carries the O2 to the muscle cells

9.6. The mitochondria uses the O2 for cellular respiration

9.7. The lungs and blood take the wastes such as CO2, and expels them

10. 6.3 Cellular respiration banks energy in ATP molecules

10.1. Cellular Respiration Formula:

10.2. Exergonic Process of efficiency 40% > than average automobile efficiency. Can produce up to 38 ATP molecules per glucose.

11. 6.4 The human body uses energy from ATP for all its activities

11.1. Energy is required to stay alive

11.2. Maintain body temperature, keep heart pumping, etc.

11.3. Brain requires 120g of glucose per day, uses about 15% of oxygen consumed

11.4. Maintaining brain cells and keeping you alive can use up to 75% of daily energy

11.5. Kilocalorie (kcal): the quantity of heat required to raise the temperature of 1 kilogram of water by 1 degree Celsius.

12. 6.5 Cells taps energy from electrons "falling" from organic fuels to oxygen

12.1. How do cells extract energy from glucose?

12.1.1. Electrons are transferred to oxygen as the carbon-hydrogen bonds of glucose are broken and the hydrogen-water bonds of water form.

12.1.2. Oxygen strongly attracts electrons and the electrons lose their potential energy because they are "bound" to the oxygen. This is called electrons "falling".

12.1.3. Redox reaction: the movement of electrons from one molecule to another is an oxidation-reduction of reaction Oxidation: The loss of electrons from one substance Reduction: The addition of electrons to another substance

12.1.4. Electron transfer requires both a donor and an acceptor

13. 6.13 Fermentation enables cells to produce ATP without oxygen

13.1. Lactic Acid Fermentation

13.1.1. Regenerate NAD+

13.1.2. NADH is oxidized to NAD+ as pyruvate is reduced to lactate

13.1.3. Lactate builds up in muscle cells during strenuous exercising Transported through blood to the liver and converted back into pyruvate

13.1.4. Lactate: The ionized form of lactic acid

13.1.5. Used to make cheese and yogurt

13.2. Alcohol Fermentation

13.2.1. Used in brewing, wine-making, and baking

13.2.2. Yeasts: single-celled fungi that normally use aerobic respiration to process their food Turn NAD+ back into NADH while converting pyruvate into CO2 and ethanol The CO2 provided the the air bubbles in beer and champagne, and also in bread when baking Ethanol is toxic to the organisms that produce it

13.2.3. Obligate Anaerobes: Prokaryotes which live in stagnant ponds and deep in soil, require anaerobic conditions, and are poisoned by oxygen

13.2.4. Facultative anaerobes (yeasts and other bacteria): Can make ATP by fermentation or oxidative phosphorylation Muscle cells are anaerobes

14. 6.14 Glycolysis evolved early in the history of life on Earth

14.1. Prokaryotes used glycolysis ONLY to produce ATP for almost a billion years

14.1.1. Until O2 was available

14.2. The fact that it takes place in the mitochondria suggests that it does not require any membrane bound organelles of eukaryotic cells, which means it developed before eukaryotic cells even existed.

14.3. First stage in the breakdown of organic molecules by cellular respiration

15. 6.15 Cells use many kinds of organic molecules as fuel for cellular respiration

15.1. Many carbohydrates can be hydrolyzed to sugars and then be used in glycolysis

15.1.1. Proteins are digested into amino acids

15.1.2. The amino acids are used to make proteins in the cell

15.1.3. The excess amino acids can be converted by enzymes into intermediates for glycolysis or the citric acid cycle

15.1.4. Energy is harvested by cellular respiration

15.1.5. During the conversion, the amino acids are stripped and later disposed of in urine