bio 6A

Question 1

what is cellular respiration?

Answer 1

a process that allows cells to break down large molecules (e.g. glucose) and produces substantial amount of energy (ATP) from a series of biochemical reactions

Question 2

what is aerobic respiration?

Answer 2

in the presence of oxygen

Question 3

what are the inputs of Glycolysis?

Answer 3

1x C6H12O6
2x ADP + Pi
2x NAD+ + 2H+

Question 4

what is the process of glycolysis?

Answer 4

• it occurs in the cytosol
  i. glucose (6-carbon) is broken down into 2x pyruvate via ten enzyme-regulated reactions
  ii. energy is released as glucose breaks down (ATP + NADH are formed)
• H+ comes from the breakdown of glucose and the pyruvate and NADH form can make more ATP in the next two stages
  iii. NADH molecules are transported to the mitochondria (each molecule transports electrons and protons to the ETC to make more ATP)
  iv. the two pyruvate molecules are transported to the mitochondria to be modified and broken down further in the Krebs cycle

Question 5

what are the outputs of Glycolysis?

Answer 5

2x pyruvate
2x ATP
2x NADH

Question 6

what is the link reaction?

Answer 6

occurs after glycolysis: Pyruvate (3-carbon) enters the mitochondrion and CO2 is removed from the pyruvate (exits into atmosphere) and Coenzyme A is added to form Acetyl CoA (2-carbon)

Question 7

what is the process of the Krebs cycle?

Answer 7

• occurs in the matrix of the mitochondria (inner membrane)
  i. energy is extracted from the ‘acetyl’ component of the Acetyl-CoA when it breaks down (Coenzyme A is recycled to be used for more link reactions)
• protons and electrons are released and are loaded onto NAD+ and FAD to form NADH and FADH2
  ii. the Krebs cycle forms 2x CO2 for every 1x Acetyl-CoA. this produces 2x ATP
• all carbons from the original 1x glucose molecule are accounted for as the 2x pyruvate undergoing the link reaction forms 2x CO2 + the 4x CO2 formed from the 2x Acetyl-CoA breaking down into CO2

Question 8

what are the inputs of the Krebs cycle?

Answer 8

2x Acetyl-CoA
2x ADP + Pi
6x NAD+ + 6H+
2x FAD + 4H+

Question 9

what are the outputs of the Krebs cycle?

Answer 9

4x CO2 molecules
2x ATP
6x NADH
2x FADH2

Question 10

what is the process of the Electron Transport Chain?

Answer 10

• occurs in the cristae of the mitochondria (peaks and folds)
  i. energy from the electrons is unloaded by the NADH and FADH2 which generates a proton gradient and drives ATP production
• NADH + FADH2 are converted back to NAD+ and FAD to be recycled
  ii. this leads to a build-up of free-roaming electrons in the intermembrane space and this causes a steep concentration gradient across the inner mitochondrial membrane
• to move the concentration gradient, the protons must travel through special channels (ATP synthase - the enzyme spins like a turbine due to this)
• the kinetic energy that builds up from the spinning powers the reaction of ADP + Pi into ATP (26/28 for each glucose molecule)

Question 11

what are the inputs for the electron transport chain?

Answer 11

6x O2 + 12x H+
26/28x ADP + Pi
10x NADH
2x FADH2

Question 12

what are the outputs of the electron transport chain?

Answer 12

6x H2O
26/28x ATP
10x NAD+ + 10H+
2x FAD + 4H+

Question 13

why is oxygen important in the electron transport train?

Answer 13

oxygen is able to bind to the free-roaming electrons and protons to create water in order to prevent the creation of dysfunctional proteins/damaged DNA/interference with enzyme reactions