Cellular Respiration Flashcards
Cellular Respiration (purpose)
- Provide energy (ATP) for cells by breaking down organic compounds (glucose) through a series of biochemical pathways.
- 3 stage process: Glycolysis, Krebs cycle, Electron Transport Chain (ETC).
- To make as much usable energy (ATP) then use it and release energy from organic compounds.
ATP - ADP Immediate Energy
- When ADP is reloaded, a phosphate (Pi) is added. Process is called phosphorylation.
- Making energy by taking off the carbons from glucose to then use the energy to make ATP from ADP.
- Loading ADP to ATP.
Aerobic Respiration
- Chemically reverse of photosynthesis thesis.
- Aerobic respiration actually involves many steps and is can be divided into Glycolysis, Krebs cycle, Electron Transport Chain (ETC).
Stage 1: Glycolysis
- Occurs in the cytosol.
- Glucose is broken down into pyruvate, 2 ATP is generated (2 ATP put in and 4 ATP is released so 2 ATP is gained), NAD+ picks up H+ ions and carries them to a later stage.
- After glycolysis, depending on oxygen availability then the process will continue through the next two stages of aerobic cellular respiration.
- If no oxygen, fermentation occurs and only means a little energy and carbon is produced.
Glycolysis: Inputs and Outputs
Inputs: Glucose, 2 ADP, 2 NAD+
Outputs: 2 ATP, 2 NADH, 2 pyruvate
Coenzymes: NAD+ and FAD+
NAD+, FAD+ (unloaded acceptors) –> NADH, FADH2 (loaded acceptors)
- NADH molecule carries H+ ions and electrons to later stages to release them to generate more ATP.
- FADH2 is produced during stage 2 by collecting 2 hydrogen atoms per molecule.
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Stage 2: Krebs Cycle
- Occurs in the mitochondria, matrix.
- The second stage of cellular respiration that’s takes place in the matrix.
- The matrix is the inner compartment of the mitochondria which is the liquid inside.
- Pyruvate and NADH is transported into the matrix.
Krebs Cycle: Inputs and Outputs
Inputs: 2 pyruvate, 2ADP, 8NAD+, 2FAD+
Outputs: 6CO2, 2ATP, 8NADH, 2FADH2
Stage 3: Electron Transport Chain
- Occurs in the mitochondria cristae, in the matrix.
- It is the 3rd stage and is where most of ATP is created
- Energy in the loaded acceptors (NADH and FADH2) molecules is converted into ATP. Both loaded acceptors feed the ETC the H+ ions and electrons.
- High energy protons and electrons are shuffled down the membrane to produce 26/28 ATP.
- The high charged H+ particles are combined with an oxygen molecule to form water.
- The proton gradient allows ADP and Pi undergoes ATP synthase to make ATP.
- Once hydrogen gets to the other side (in between the two membranes) oxygen is added to make water.
Electron Transport Chain: Inputs and Outputs
Inputs: 6NADH, 2FADH, 6O2, 26/28 ATP
Outputs: 6H2O, 6NAD+, 2FAD+, 26/28
Anaerobic Fermentation
- Occurs outside the mitochondria.
- Is the breakdown of glucose in the absence of oxygen.
- The electron transport chain will not function.
- NAD+ –> NADH and the Krebs cycle slows and pyruvate accumulates.
- Some protists, fungi and animals (muscle cells) can still continue at low oxygen levels with enzymes that convert pyruvate to lactic acid which allows loading of NAD+.
Anaerobic Fermentation in animals (Lactic acid fermentation)
- Occurs during strenuous activity and in the cytosol.
- Enzymes convert pyruvate to lactic acid which then leaves the cell.
- Enzymes will then unload NADH –> NAD+.
- Extracted energy to make 2 ATP, every glucose you get 2 ATP.
- It is the same as glycolysis, and lactate is produced.
- Preventing the build up of pyruvate.
Anaerobic Fermentation in yeast (Alcohol fermentation)
- Occurs in the cytosol.
- Enzymes convert pyruvate to ethanol and CO2.
- Enzymes can then unload NADH → NAD+
- Start with glucose and making pyruvate producing ethanol
- If you have oxygen you will have more energy ATP produced
Temperature on Respiration
- Very similar to all enzyme based reactions.
Glucose and Oxygen Availability
- Glucose is needed in constant supply
- Organisms store complex carbohydrates to supply glucose
- Can also access lipids and proteins to generate glucose
- Presence of oxygen gives a much greater and faster yield of ATP.
Biomass for Biofuel
- Biomass is the idea of using living things such as plants or yeasts as fuel or to produce biofuel that can be used.
- For example, growing trees then burning the wood would be biomass.
- It is difficult to make something like a car run on wood, however, ethanol is something that is already added to fuels, and yeast naturally produces this.
Biofuel
- Biofuels such as ethanol have many advantages over biomass such as crops, such as being better able to be stored, and easier to use when needed.
- Yeast can be used to convert easy to grow biomass into biofuel.
- Yeast could be fed other things, such as waste products, not just plants specifically grown to be turned into biofuel.
Ethanol Conversion
- Ethanol can be used as an input source for other biofuels, such as biodiesel. (exact mechanisms are not necessary to know, just that it can be done).
Aerobic Respiration Equation
Glucose + Oxygen –> Carbon dioxide + Water + Energy
OR
C6H12O6 + 6O2 –>8 6CO2 + 6H2O + 30/32 ATP
