cellular respiration

Question 1

balanced equation

Answer 1

C6H12O6 + 6O2 —> 6CO2 + 6H2O

Question 2

glycolysis

Answer 2

• Occurs in cytoplasm
• First 10 reactions of cellular respiration
• Each step is catalyzed by a specific enzyme
• It is anaerobic (no oxygen required)
• 1 glucose molecule makes 2 pyruvates and each pyruvate contains one ATP.
• Substrate-level phosphorylation

Question 3

pyruvate oxidation

Answer 3

• 2 pyruvate + 2NAD+ + 2 CoA 2 acetyl-CoA + 2 NADH + 2H+ + 2CO2
• The carboxyl group is removed from pyruvate to form CO2. This is called a decarboxylation reaction. CO2 is waste and is eventually exhaled from the body.
• Remaining 2C molecule is oxidized (by intermediate enzyme reactions) which produces an acetyl group. In the process, dehydrogenation reactions transfer 2 electrons and 2 H+ to NAD+, reducing it to NADH + H+. This is a redox reaction: pyruvate is oxidized and NAD+ is reduced.
• A sulfur-containing compound called Coenzyme A (CoA) bonds to the acetyl group, producing Acetyl-CoA. The Acetyl-CoA molecule will then enter the Citric Acid Cycle/Krebs Cycle.

Question 4

krebs cycle

Answer 4

2 oxaloacetate + 2Acetyl-CoA + 2ADP + 2Pi + 6NAD+ + 2FAD -> 2CoA + 2ATP + 6NADH + 6H+ + 2FADH2 + 4CO2 + 2oxaloacetate

• Produces 2 ATP
• 1 ATP from one cycle and since there are 2 acetyl-CoA, the cycle occurs twice = 2 ATP
• Substrate-level phosphorylation

Question 5

ETC

Answer 5

• Oxygen begins the movement of electrons by interacting with Complex IV – 2 electrons are removed
• As oxygen reacts with the 2 electrons, it also reacts with 2 H+ from the matrix to from H2O
• A chain reaction is now triggered: Oxidation of NADH
  The electrons from Complex III move to Complex IV via cyt c
  The electrons from Complex 1 move to Complex III via UQ
  The electrons from NADH move to Complex I

Question 6

chemiosmosis

Answer 6

• There are more H+ in the intermembrane space than in the mitochondrial matrix. This means that there is potential energy stored that can be harnessed to do work
• CHEMIOSMOSIS: the ability of the cell to used the proton-motive force to do work
• Chemiosmosis can refer to ATP synthesis, but can also refer to other energy consuming activities, such as the rotation of flagella that prokaryotes use for motion.

Question 7

ATP synthase

Answer 7

• A large multiprotein complex that spans the IMM
• The proton-motive force moves H+ through the protein down the concentration gradient, and into the matrix (because the cell wants to be balanced)
• ATP Synthase has specialized components that catalyze the formation of one ATP from ADP + Pi
• 3 H+ are required to form 1 ATP molecule

Question 8

importance of oxygen

Answer 8

The human body can’t survive without oxygen for a few minutes because oxygen is necessary for aerobic cellular respiration as it’s the final electron acceptor. It initiates the electron transport chain which then creates the proton motive force and gradient causing oxidative phosphorylation to occur, synthesizing a majority of the ATP required. This lack of oxygen would cause cell death and organ failure. ETC would shut down and glycolysis would only occur since it is aerobic which doesn’t produce enough ATP to sustain cells (2 ATP).

Question 9

krebs ATP yeild

Answer 9

2 from glycolysis
2 from Citric Acid Cycle
32-34 from ETC/Chemiosmosis
= 36-38 ATP/glucose molecule