Chp 17 - Glycolysis / TCA / ETC OVERVIEW Flashcards
What is cellular respiration
Cellular respiration is the release of energy from molecules such as glucose accompanied by the use of this energy to synthesize ATP molecules
- Aerobic – requires O2
- Gives off CO2
What are the phases of cellular respiration
Phases of Cellular Respiration
- Glycolysis (Cytoplasm)
- Preparatory Reaction (Mitochondria)
- Citric Acid Cycle (Mitochondria)
- Electron Transport Chain (Mitochondria)
Expalain the 3 important stages of cellular respiration
There are 3 important stages of celluar respiration:
- Glycolysis: Glucose is split into two molecules called pyruvate and 2 ATP molecules are generate per molecule of glucose as well as 2 molecules of NADH. Glycolysis takes place in the cytoplasm of the cell and does not require oxygen.
- Krebs Cycle (also known as the Citric Acid Cycle): Uses the pyruvate molecules from Glycolysis to generate 2 ATP as well as several molecules of FADH2 and NADH for the electron transport chain. Krebs Cycle takes place in the mitochondrial matrix and requires oxygen.
- Electron transport chain (ETC): Using the NADH and FADH2 molecules formed during Glycolysis and Krebs Cycle, the electron transport chain creates a proton gradient that ultimately leads to the production of about 32 molecules of ATP. The ETC takes place in the mitochondrial matrix and requires oxygen.
What are the important players in cellular respiration?
Important Players in Cellular Respiration
Glucose: A simple, 6 carbon sugar that serves as the primary energy source in the body.
ATP (Adenosine triphosphate): The major energy currency of the cell. ATP is a high-energy molecule that stores and transports energy within cells.
NADH: High energy electron carrier used to transport electrons generated in Glycolysis and Krebs Cycle to the Electron Transport Chain.
FADH2: High energy electron carrier used to transport electrons generated in Glycolysis and Krebs Cycle to the Electron Transport Chain.
what is the structure of glucose
What is the formula for pyruvate?
Pyruvate or pyruvic acid
C3H4O3
What is the formula for glucose?
Glucose ————– C6H12O6
Explain aerobic respiration
Aerobic respiration - the process by which a cell uses O2 to “burn” molecules and release energy
The reaction:
C6H12O6 + 6O2 >> 6CO2 + 6H2O
What is the reaction of aerobic respiration
The reaction: C6H12O6 + 6O2 >> 6CO2 + 6H2O
The reaction of aerobic respiration takes place over the course of 3 major reaction pathways, what are these 3 major reaction pathways?
Aerobic respiration -
The reaction: C6H12O6 + 6O2 >> 6CO2 + 6H2O
This reaction takes place over the course of three major reaction pathways
- Glycolysis
- The Krebs Cycle
- Electron Transport Phosphorylation (chemiosmosis)
Explain where in the cell do the phases of cellular respiration occurs
Glycolysis (Cytoplasm)
Preparatory Reaction (Mitochondria)
Citric Acid Cycle (Mitochondria)
Electron Transport Chain (Mitochondria)
What is the net energy differences between anaerobic and aerobic respiration?
Note differences -
anaerobic respiration - 2 ATP’s produced (from glycolysis),
aerobic respiration - 36 ATP’s produced (from glycolysis, Krebs cycle, and Oxidative Phosphorylation)
What is the net energy production for the entire process of aerobic respiration?
Net Engergy Production from Aerobic Respiration
Net Energy Production: 36 ATP!
What is the net energy production for each of the steps of aerobic respiration
Net Engergy Production from Aerobic Respiration
Glycolysis: 2 ATP
Krebs Cycle: 2 ATP
Electron Transport Phosphorylation: 32 ATP
- Each NADH produced in Glycolysis is worth 2 ATP (2 x 2 = 4) - the NADH is worth 3 ATP, but it costs an ATP to transport the NADH into the mitochondria, so there is a net gain of 2 ATP for each NADH produced in gylcolysis
- Each NADH produced in the conversion of pyruvate to acetyl COA and Krebs Cycle is worth 3 ATP (8 x 3 = 24)
- Each FADH2 is worth 2 ATP (2 x 2 = 4)
- 4 + 24 + 4 = 32
** Net Energy Production: 36 ATP!**
What is the NET energy production of glycolysis?
Net Engergy Production from Aerobic Respiration
Glycolysis: 2 ATP
What is the net energy production for the TCA or the krebs cycle?
Net Engergy Production from Aerobic Respiration
Krebs Cycle: 2 ATP
What is the net energy production for the electron transport chain?
Net Engergy Production from Aerobic Respiration
Electron Transport Phosphorylation: 32 ATP
How do you achive net energy of 32 ATP during the electron transport chain?
Electron Transport Phosphorylation: 32 ATP
- Each NADH produced in Glycolysis is worth 2 ATP (2 x 2 = 4) - the NADH is worth 3 ATP, but it costs an ATP to transport the NADH into the mitochondria, so there is a net gain of 2 ATP for each NADH produced in gylcolysis
- Each NADH produced in the conversion of pyruvate to acetyl COA and Krebs Cycle is worth 3 ATP (8 x 3 = 24)
- Each FADH2 is worth 2 ATP (2 x 2 = 4)
- 4 + 24 + 4 = 32
What is the goal of anaerobic respiration?
Anaerobic Respiration
Goal: to reduce pyruvate, thus generating NAD+
Where does anaerobic respiration occur in the cell?
Anaerobic Respiration
Where: the cytoplasm
Why does anaerobic respiration occur in the cell?
Anaerobic Respiration
Why: in the absence of oxygen, it is the only way to generate NAD+
What are the 2 different types of anaerobic respiration?
Alcohol Fermentation -
- occurs in yeasts in many bacteria
- The product of fermentation, alcohol, is toxic to the organismLactic Acid Fermentation -
- occurs in humans and other mammals
- The product of Lactic Acid fermentation, lactic acid, is toxic to mammals
- This is the “burn” felt when undergoing strenuous activity
Explain each different type of anaerobic respiration
Alcohol Fermentation -
- occurs in yeasts in many bacteria
- The product of fermentation, alcohol, is toxic to the organismLactic Acid Fermentation -
- occurs in humans and other mammals
- The product of Lactic Acid fermentation, lactic acid, is toxic to mammals
- This is the “burn” felt when undergoing strenuous activity
What is the only goal of fermentation?
The only goal of fermentation reactions is to convert NADH to NAD+ (to use in glycolysis).
No energy is gained
Explain what glycolysis is
- Glycolysis is the anaerobic catabolism of glucose.
- It occurs in virtually all cells.
- In eukaryotes, it occurs in the cytosol.
- It converts a molecule of glucose into 2 molecules of pyruvic acid.
- C6H12O6 + 2NAD+ -> 2C3H4O3 + 2NADH + 2H+
- The free energy stored in 2 molecules of pyruvic acid is somewhat less than that in the original glucose molecule.
- Some of this difference is captured in 2 molecules of ATP.
Explain the pathway of glycolysis
What is the fate of pyruvate or pyruvic acid in mitochondria?
- In Mitochondria Pyruvic acid is oxidized completely to form carbon dioxide and water.
- The process is called cellular respiration.
What does glycolysis do?
- Breakdown of glucose to two molecules of pyruvate
- One six-carbon molecule into two three-carbon molecules
- Oxidation by removal of hydrogens releases enough energy to make Four ATP
- Net gain is only two
Does glycolysis require oxygen
NO. Glycolysis doesn’t require oxygen
What are the energy investments steps of glycolysis?
Energy-Investment Steps
- Energy from two ATP is used to activate glucose
- Glucose is split into two 3-carbon glyceraldehyde 3-phosphate G3P molecules
What are the energy harvesting steps of glycolysis
Energy-Harvesting Steps
- Oxidation of G3P by removal of hydrogen atoms
- Hydrogen atoms are picked up by NAD+ to form NADH + H+
- Oxidation of G3P and further substrates yields enough energy to produce 4 ATP by direct substrate-level ATP synthesis
Explain the following things for glycolysis pathway:
- input
- Output
- Net energy
Explain Pyruvate
Pyruvate
- Pivotal metabolite in cellular respiration
- If no oxygen is available, pyruvate is reduced to lactate (in animals) or ethanol fermentation results in a net gain of two ATP/glucose
Explain the Preparatory (Prep) Reaction
Preparatory (Prep) Reaction
Pyruvate (3-carbon) oxidized to acetyl CoA (2-Carbon)
carbon dioxide is removed
Occurs inside the Mitochondria
Prep reaction occurs twice because glycolysis produces two pyruvates
Explain the Tricarboxylic Acid Cycle
Tricarboxylic Acid Cycle
- Acetyl CoA is converted to citric acid and enters the cycle
- Cyclical series of oxidation reactions that produces one ATP and carbon dioxide per turn
- Tricarboxylic acid turns twice because two acetyl CoA’s are produced per glucose
- Occurs in matrix of mitochondria
- Oxidation reactions where CO2 are produced
Expalain the Electron Transport Chain
Electron Transport Chain
- Series of electron carrier molecules
- Electrons passed from one carrier to another
- As the electrons move from a higher energy state to a lower one, energy is released to make ATP
- Under aerobic conditions 32-34 ATP per glucose molecule can be produced
Explain Fermentation
- Occurs when O2 is not available
- Animal cells convert pyruvate to lactate
- Other organisms convert pyruvate to alcohol and CO2
- Fermentation regenerates NAD+ which keeps glycolysis and substrate-level ATP synthesis going
What are the advantages and disadvantages of Fermentation
Advantages and Disadvantages of fermentation
- Provides a rapid burst of ATP
- Provides a low but continuous supply of ATP when oxygen is limited and only glycolysis can function
- Lactate is potentially toxic to muscles, lowering pH and causing fatigue
How is the cristae organized?
Organization of Cristae
- Electron carriers are located in the cristae
- As electrons are passed, energy is used to pump H+ into the intermembrane space of mitochondrion
- As H+ moves back into the matrix, energy is released and captured to form ATP by ATP synthase complexes
- Process is called chemiosmosis
What is chemiosmosis?
Where are the electron carriers located within the mitochondria?
Electron carriers are located in the cristae
