AP Biology Unit 4: Respiration Notes

UNIT 4: RESPIRATION

Cellular Respiration and Fermentation (Ch. 7)
●​ The general equation for cellular respiration
-​ C6H12O6 + 6O2 ⇒ 6CO2 + 6H2O + ATP
●​ The three main stages of cellular respiration and locations of these stages
-​ Glycolysis (cytoplasm) (anaerobic) ⇒ link reaction (inner matrix of mitochondria)
(anaerobic) ⇒ Krebs Cycle (mitochondrial matrix)(aerobic) ⇒ Electron Transport
Chain (mitochondriaal inner membrane)

●​ The general equation for each variation of fermentation
-​ Fermentation: ​
→ Lactic acid fermentation: glucose → glycolysis → 2 pyruvate → fermentation → 2
lactic acid
→ Lactic acid fermentation: glucose → glycolysis → 2 pyruvate → fermentation → 2
ethanol

●​ The start and end products of glycolysis
Glucose is broken down to produce energy
Glucose + 2NAD+ + 2ADP + 2Pi → 2 Pyruvate + 2NADH + 2ATP + 2H2O + 2H+
-​ Glycolysis can split into: aerobic and anaerobic processes
-​ Aerobic: glycolysis → link reaction → kreb’s cycle → ETC
-​ Anaerobic: glycolysis → fermentation (alcoholic or lactic acid fermentation)

➔​ Glucose (C6H12O6) → (2ATP ⇒ 2ADP) → PGAL x2 → (2 NAD+ + 2H+ + 2PI ⇒ 2NADH) → 1,3 BPG
x2 → (4ADP ⇒ 4ATP) → 2 Pyruvate
➔​ Link reaction: pyruvate is actively transported into inner matrix of mitochondria
(pyruvate is oxidized) → CO2 is released → (NAD+ ⇒ NADH produced) → Coenzyme A is
added → Acetyl CoA
-​ 1 pyruvate ⇒ 1 Acetyle CoA, 2 pyruvates ⇒ 2 Acetyle CoA
●​ The start and end products of the Krebs cycle aka Citric Acid cycle
1.​ Acetyl CoA from the pyruvate (glycolysis)
2.​ Six carbon molecule from acetyl CoA (2 from acetyl CoA and 4 from four carbon
acceptor in #9)
3.​ NAD+ changes into NADH + CO2 (1 carbon is lost as CO2)
4.​ Five carbon molecule from acetyl CoA
5.​ NAD+ changes into NADH + CO2 (another carbon is lost as CO2)
6.​ Four carbon molecule from acetyl CoA
7.​ GDP → GTP (energy carrying molecule equivalent to ATP)
8.​ FAD → FADH2 ( reduced electron carrier similar to NADH2)
9.​ Four carbon acceptor molecule ( regenerated in each cycle)
-​ 1 turn of citric acid cycle = 2 CO2 molecules, 3 NADH, 1 FADH2, 1 ATP
-​ Four carbon acceptor combines with acetyl CoA and restarts the cycle
-​ Krebs Cycle: 2 Acetyl CoA ⇒ Coenzyme A → Citrate → (NAD+ ⇒ NADH) -> (CO2 is
produced) → a Ketoglutarate → (NAD+ ⇒ NADH) (ADP + PI ⇒ ATP) → ( CO2 is produced) →
Succinate → (FAD ⇒ FADH2) (NAD+ ⇒ NADH) → Oxaloavetate ​
- in total (2 turns): 2ATP, 6NADH, 2FADH2, 4CO2

●​ The start and end products of the electron transport chain
1.​ Electrons in protein complex I change NADH ⇒ NAD+
2.​ H+ ion is powered through membrane into intermembrane space from the matrix
(active transport)
3.​ Electrons move into other protein complex II, changes FADH2 into FAD