Cellular Respiration

Question 1

Cellular Respiration (purpose)

Answer 1

• 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.

Question 2

ATP - ADP Immediate Energy

Answer 2

• 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.

Question 3

Aerobic Respiration

Answer 3

• Chemically reverse of photosynthesis thesis.
• Aerobic respiration actually involves many steps and is can be divided into Glycolysis, Krebs cycle, Electron Transport Chain (ETC).

Question 4

Stage 1: Glycolysis

Answer 4

• 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.

Question 5

Glycolysis: Inputs and Outputs

Answer 5

Inputs: Glucose, 2 ADP, 2 NAD+
Outputs: 2 ATP, 2 NADH, 2 pyruvate

Question 6

Coenzymes: NAD+ and FAD+

Answer 6

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.
-

Question 7

Stage 2: Krebs Cycle

Answer 7

• 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.

Question 8

Krebs Cycle: Inputs and Outputs

Answer 8

Inputs: 2 pyruvate, 2ADP, 8NAD+, 2FAD+
Outputs: 6CO2, 2ATP, 8NADH, 2FADH2

Question 9

Stage 3: Electron Transport Chain

Answer 9

• 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.

Question 10

Electron Transport Chain: Inputs and Outputs

Answer 10

Inputs: 6NADH, 2FADH, 6O2, 26/28 ATP
Outputs: 6H2O, 6NAD+, 2FAD+, 26/28

Question 11

Anaerobic Fermentation

Answer 11

• 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+.

Question 12

Anaerobic Fermentation in animals (Lactic acid fermentation)

Answer 12

• 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.

Question 13

Anaerobic Fermentation in yeast (Alcohol fermentation)

Answer 13

• 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

Question 14

Temperature on Respiration

Answer 14

• Very similar to all enzyme based reactions.

Question 15

Glucose and Oxygen Availability

Answer 15

• 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.

Question 16

Biomass for Biofuel

Answer 16

• 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.

Question 17

Biofuel

Answer 17

• 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.

Question 18

Ethanol Conversion

Answer 18

• 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).

Question 19

Aerobic Respiration Equation

Answer 19

Glucose + Oxygen –> Carbon dioxide + Water + Energy
OR
C6H12O6 + 6O2 –>8 6CO2 + 6H2O + 30/32 ATP