Cellular Respiration: (Step 1: Glycolysis)

Question 1

Glycolysis uses what type of respiration?

Answer 1

Both aerobic and anaerobic cellular respiration.

Question 2

Cellular respiration involves 3 phases:

Answer 2

•stage 1: glycolysis- a 10 step process occurring in the cytoplasm.
•stage 2: Kreb’s cycle (citric acid cycle)- an 8 step cyclical process occurring inside the mitochondria.
•stage 3: electron transport chain/oxidative phosphorylation/chemiosmosis- a multi-step process occurring inside the mitochondria.

Question 3

Glucose (C6H12O6):

Answer 3

•glucose is oxidized to form CO2.
•O2 is reduced to form H2O.
•hydrogen is transferred from glucose to oxygen bringing electrons with it which provide energy for ATP synthesis.
•by oxidizing glucose, respiration takes energy out of storage and makes it available for ATP synthesis.

Question 4

Glucose is oxidized and oxygen is reduced:

Answer 4

C6H12O6 — + 6O2 ~~~ —> —> 6CO2 (becomes oxidized) + ~~> 6H2O (becomes reduced) + Energy.
-arrows are showing the movement of electrons.

Question 5

Glycolysis “sugar-splitting”:

Answer 5

•occurs in cytoplasm.
•glucose is split into two 3-carbon sugars (PGAL) which are then oxidized to form 2 pyruvate molecules.
•released energy will create ATP and NADH.
•only 40% of this energy is useful.

Question 6

Energy investment stage:

Answer 6

-2 ATP molecules split glucose (C6).
-resulting in 2 x C3 molecules.

Question 7

Energy pay-off phase:

Answer 7

•oxidation of the intermediate C3 now occurs:
•2 e- + 2 H+ + 2 NAD+ —> 2 NADH.
•4 ADP + 4 pi —> 4ATP.
•2 ATP were put in to split glucose, 4 ATP were formed from the oxidation of the intermediate, so 2 ATP net were formed.
•4-2=2.
•product is 2 C3 molecules of pyruvate.

Question 8

Glycolysis inputs:

Answer 8

•1 glucose.
•2 NAD+.
•2 ATP.
•4 ADP + 4 Pi.

Question 9

Glycolysis outputs:

Answer 9

•2 pyruvate.
•2 NADH.
•4 ATP (2 ATP net).
•2 H2O.

Question 10

Glycolysis inputs and outputs:

Answer 10

-inputs:
•1 glucose.
•2 NAD+.
•2 ATP.
•4 ADP + 4 Pi.
-outputs:
•2 pyruvate.
•2 NADH.
•4 ATP (2 ATP net).
•2 H2O.

Question 11

Summary:

Answer 11

•start of aerobic cellular respiration (and fermentation).
•happen in the cytoplasm.
•generates small amount of ATP.
•glucose (6 carbons) is broken into pyruvate (3 carbons).
•If not enough oxygen available—> fermentation.
•If enough oxygen is available, pyruvate moves into the mitochondria and enter the Kreb’s cycle, makes molecules with reducing power (NADH and FADH2).
•••
•during glycolysis, a small amount of ATP is generated, and NAD+ is reduced to NADH.
•ATP is actually used at the start of this process.
•still leads to a net production of 2 ATP and some NAD+ is reduced to produce NADH.
-(which can make more ATP via the ETC).

Question 12

Phosphorylation:

Answer 12

ADP + Pi—> ATP.

Question 13

Intermediate:

Answer 13

Coming between two things in place.