Cellular Respiration

Cellular respiration

• Oxidation

• Is respiration creating or reusing P groups?

Converting ORGANIC MOLECULES (lipids, fats, ect…) into usable cellular energy (ATP)

• Catabolic / Exergonic

• Oxidation = converting

• REUSING

Where does cellular respiration occur in…

Eukaryotes

Prokaryotes

Mitochondria

Cytosol

AEROBIC cellular respiration

• Requires oxygen

• More efficient

• MITOCHONDRIA

• 1 glucose = 38 ATP

ANAEROBIC cellular respiration 

• Doesn’t need oxygen 

• Less efficient 

• CYTOSOL

• 1 glucose = 2 ATP (limits bacteria size)

Obligate

Can only do ONE form of respiration

• Obligate AEROBIC

• Obligate anaerobic

Facultative

Can do BOTH modes of respiration

• Facultative AEROBIC (switch BUT default AEROBIC)

• Facultative anaerobic

Flow chart

Glucose → 2 Pyruvate (Glycolysis) → Aerobic (Citric Acid Cycle/Krebs Cycle/TCA cycle → Oxidative Phosphorylation (ETC & Chemiosmosis)) OR Anaerobic (Lactic Acid Fermentation OR Ethanol Fermentation)

Glycolysis

• Gross & Net production

ALL ORGANISMS ON PLANET DO THIS

SPLITTING GLUCOSE INTO TWO PYRUVATE

• In Cytosol

• 10 steps

• Gross : +4 ATP & +2 NADH

• Net : +2 ATP & +2 NADH (loses 2 ATP to activation energy since reaction is CATABOLIC)

Redox process

Reaction where e- are exchanged

• LEO : Loose electrons oxidation

• GER : Gain electrons reduction

• THESE CANNOT EXIST SEPARATELY

Aerobic respiration equation

C6H12O2 + O2 → CO2 + H2O + ATP

• Glucose is OXIDIZED into CO2

• Oxygen is REDUCED into H2O

Electron carriers 

NAD + → NADH 

FAD → FADH2

• 1st are EMPTY, then gain +2 e-, then final forms are carrying electrons 

1 NADH : 3 ATP 
1 FADH : 2 ATP 

When do anaerobic reactions occur

When theres limited O2 OR when supply doesn't meet demand

Lactic Acid Fermentation

• Goal:

• Product:

Occurs in MUSCLE CELLS & certain bacterias

• Goal: Regenerate NAD+ to continue glycolysis

• Product: Lactic Acid & NAD+

Ethanol Fermentation 

• Goal:

• Product:

Carried out by YEAST

• Goal: Regenerate NAD+

• Product: Ethanol, NAD+, CO2

Citric Acid Cycle:

Where?

Purpose?

Products?

MATRIX (mitochondria)

COMPLETE OXIDATION of glucose (pyruvate)

6 CO2 , 2 ATP , 8 NADH , 2 FADH2

Electron Transport Chain

• NADH & FADH2 _____ e- to _____ ____ of ETC

• ____ energy is used to pump ____ from matrix to _______, which creates…

• ____ is the final e- acceptor, combining with ___ to form ____

Series of proton pumps located on INNER MEMBRANE

• Donate ; proton pumps

• E- ; protons ; intermembrane space … high proton gradient in intermembrane space

• Oxygen ; 2 protons ; H2O

Chemiosmosis 

• Protons diffuse ____ to matrix through ____ ____

• Drives ______ of ADP + P → ATP

Diffusion of protons 

• Back ; ATP synthase 

• Phosphorylation 

Versatility of Catabolism

• Catabolic pathways funnel e- from many kinds of organic molecules into cellular respiration

• Glycolysis accepts a wide range of carbs

• Proteins digested into amino acids → amino acids feed glycolysis or CAC

Biosynthesis (Anabolic Pathway)

Body uses small molecules to build other substances

• Small molecules come directly from food, glycolysis, or CAC

Feedback Mechanism 

Feedback inhibition is the most common mechanism for control

• If ATP concentration begins dropping, respiration will speed up & vice versa 

• Control of catabolism is based mainly on regulating activity of enzymes at strategic points in catabolic pathway