4.2 Energy Metabolism Flashcards
Where does the energy to make ATP come from?
Chemical bonds in food molecules
In cells, energy can be extracted from food molecules where…
Electrons are shared equally by covalent bonds
Examples of food molecules that can be used for energy
Carbon-carcon bonds and
Carbon-Hydrogen bonds
Found in lipids, carbs, AAs and nucleotides
Oxygen is the ______, once O is in a covalent bond with carbon or hydrogen, energy _______ be extracted
Ground state
CAN NOT
More carbons and more bonds =
More available energy (E)
More atoms and electrons bonding =
More energy
How do cells extract energy from foods?
Oxidation-reduction chemical reactions
Are redox reactions always 100% efficient?
No, some energy is ALWAYS lost as heat
Reduction is…
A molecule gaining energy
Oxidation is…
When a molecule loses energy
Are redox reactions always paired?
Yes, if a molecule gets oxidized, something simultaneously gets reduced
NAD+ + Energy –>
NADH
reduction
NADH oxidation
NAD+ + Energy
OIL RIG
Oxidation is loss (of e-)
Reduction is gain
(of e-)
What is NADH doing?
Storing energy
All 6 C’s in glucose are..
Oxidized to CO2
When glucose is oxidized to CO2..
Energy is released
ADP–>ATP
Oxygen reduced to H2O
What percentage of energy is captured to make ATP?
30-40%
When does aerobic cellular respiration occur?
When there is adequate oxygen supply (lungs, CV system, and RBCs can keep up with demand)
Products of Aerobic cellular respiration
CO2 + H2O
36 ATP / glucose
Anaerobic cellular respiration occurs when there is..
Inadequate oxygen
Products of anaerobic cellular respiration
Lactic acid
2 ATP / glucose
4 Stages of aerobic cellular respiration
- Glycolysis
- Acetyl-CoA formation
- Kreb’s Cycle
- Electron transport chain and oxidative phosphorylation
Start and end of glycolysis
6C Glucose 3C Pyruvate (x2)
Energy captured by reduction in glycolysis
2 ATP
2 NADH
What happens if regeneration of NAD+ stops?
Glycolysis stops
During pyruvate oxidation, what is pyruvate oxidized to?
Acetyl CoA (Produces 2)
Per 1 glucose in pyruvate oxidation…..
- 2 CO2 released by oxidation
- 2 NADH produced by reduction
After pyruvate oxidation, there is a…
Decision point!
If cell needs ATP after pyruvate oxidation
Acetyl CoA proceeds to step 3: Kreb’s Cycle
If there is plenty of ATP after Kreb’s cycle…
Acetyl CoA goes into long term energy storage (adipose tissue, triglycerides)
If you burn fat for energy, you release..
Acetyl CoA
Overall effect of Kreb’s Cycle
Oxidation of remaining acetyl-coA to CO2
Reduction of NAD+ to NADH
After the Kreb’s Cycle, what has the cell made
6 CO2
4 ATP
10 NADH
2 FADH2
During ETC and OP, high energy electrons from _____ are used to fuel _______ ion pumps
NADH
H+
H+ ion pumps create H+ ion ________, flow of ions used to make ____
Gradient
ATP
Oxygen is the ground state in the ETC and OP, meaning that..
Electrons flow down towards it
Issue with glycolysis and anaerobic cellular respiration
Regenerating NAD+ from NADH to keep glycolysis running smoothly
Without NAD+, glycolysis…
Stops cold (but is usually not a problem since oxygen is around)
Solution to NAD+ problem in anaerobic cellular respiration
NADH electrons dropped onto Pyruvate (reduces it), frees up NAD+ to go back and keep glycolysis running
Result of reducing pyruvate…
Creates lactate or lactic acid (in animals)
Or yeast / ethanol in plants
