Cellular Respiration Flashcards
Anabolic
Use of energy to build macromolecules (Endergonic)
Catabolic
The breakdown of complex organic molecules to generate energy: releases energy (Exergonic)
–>Think of cat tearing the cat tower
Cellular Respiration
The major CATABOLIC pathway to produce energy from food
Oxidation
LOSS of electrons
(INCREASES CHARGE)
Reduction
GAINS electrons
(REDUCES/Decreases CHARGE)
Cell Respiration General Formula
Sugar + O2 —> H2O + CO2 + Energy
Sugar –> CO2 = Oxidation
O2 –> Water = Reduction
In cell respiration, sugar is…
OXIDIZED (Loses electrons which releases energy)
NAD+
Nicotinamide Adenine Dinucleotide –> A COENZYME
NAD+ vs NADH
NAD+ = Oxidized form (loss of electron)
NADH = Reduced form (gain of electron)
NADH
An energy storage molecule (stores electrons) that is tapped to produce ATP
Dehydrogenase
Enzyme that convert NAD+ to NADH
NAD+ –> NADH =
Reduction
NADH –> NAD+ + H+ =
Oxidation
4 main steps to cellular respiration:
1) Glycolysis
2) Intermediate Step (Pyruvate Oxidation)
3) Kreb’s Cycle
4) Oxidative Phosphorylation
Glycolysis
The splitting of sugar
Steps of glycolysis
10 steps total:
–> First 5 steps = energy investment phase (uses 2 ATP)
–> Second 5 steps = Energy Payoff Phase (produces 4 ATP)
Glycolysis Products
1) 2 NET ATP
2) 2 NADH
3) 2 Pyruvate
Pyruvate
A 3 carbon molecule that is the product of glycolysis
–>In the presence of oxygen, pyruvate is further broken down to produce more energy
Substrate-Level Phosphorylation
An enzyme transfers a phosphate group (NOT Pi) from an organic molecule (substrate) to ADP = produces ATP
Last Step of Glycolysis (example of substrate-level phosphorylation)
PEP + ADP –> Pyruvate + ATP
(mediated by pyruvate kinase)
Pyruvate Kinase
Takes phosphate from PEP to convert ADP to ATP (while also producing pyruvate)
Intermediate Step
(AKA Pyruvate Oxidation) –> The conversion of pyruvate to Acetyl-CoA
Intermediate Step PROCESS
1) Pyruvate is translocated to mitochondrion
2) Pyruvate is oxidized to release CO2
3) Acetalaldehyde remains (2C) and is oxidized to convert NAD+ to NADH
4) Acetyl group is left and this combines with Coenzyme A to produce Acetyl-CoA
Intermediate Step Products
1) 2 Acetyl CoA
2) 2 NADH
3) 2 CO2
CO2 is FIRST produced when/where in cell respiration?
In the oxidation of pyruvate (intermediate step)
Coenzyme A
CoA: a sulfur containing compound that binds to acetyl to produce Acetyl-CoA
Kreb’s Cycle
8 total steps that oxidizes pyruvate products completely to produce materials needed for the ETC and OXPHOS
Kreb’s Cycle takes in the following molecules:
1) Acetyl-CoA
2) ADP
3) NAD+
4) FAD+
Kreb’s cycle produces:
1) 4 CO2
2) 6 NADH
3) 2 ATP
4) 2 FADH2
Kreb’s cycle occurs how many times per one molecule of glucose?
2 times
Electron Transport Chain
A collection of molecules that donate and accept electrons: Produces a proton gradient that powers ATP synthase
–> Creates conditions needed for ATP synthesis (BUT DOES NOT PRODUCE ATP ITSELF)
Oxygen serves as a __________ in the electron transport chain
Oxygen acts as the final electron acceptor in the ETC which produces water (waste product)
Oxidative Phosphorylation
Occurs in Complex V or ATP synthase which converts ADP to ATP (powered by the proton gradient created from the ETC)
ETC proton gradient creation
The complexes of the ETC pump H+ protons from the MT matrix into the IMS
–> These protons then come back to the matrix by diffusing through ATP synthase and thus powering the production of ATP
Uncoupling
AKA Uncoupled Respiration
–> When the ETC is disconnected from OXPHOS = Minimal to no ATP production BUT gradient still forms
Uncoupling can occur do to (2 possibilities):
1) ATP synthase is inhibited
2) Membrane permeabilizes (has holes) which leads to proton leak
Proton Leak
H+ protons leak back into the matrix through holes rather than through ATP synthase
–> Causes the proton gradient to not be able to be maintained
Benefits of uncoupled respiration
Uncoupled respiration still produces energy but in a different form: HEAT
–> Used in brown fat which contains THERMOGENIN (uncoupler) to increase heat production in hibernating animals and newborns
Cell Respiration in Prokaryotes
**ETC STILL OCCURS SARAH
–> Their ETC simply occurs on their plasma membrane
–> More energy efficient because it does not require NADH to be trafficked into mitochondria (which uses ATP)
Fermentation
Anaerobic respiration: Energy produced without using O2
–> Mainly just glycolysis
Why does the ETC not function without O2?
Because O2 is the final electron acceptor, without this the ETC cannot run –> Therefore OXPHOS cannot go
Lactic Acid Fermentation
Pyruvate is reduced BY NADH DIRECTLY (no further breakdown of Pyruvate!!!)
(NADH is oxidized to NAD+)
–> Produces lactate as a waste product
Alcohol Fermentation
1) Pyruvate is broken down to acetalaldehyde (2C)
(RELEASES CO2)
2) Acetalaldehyde is reduced by NADH = ETHANOL production
(NADH is oxidized to NAD+)
Which fermentation process produces CO2?
Alcohol Fermentation
Pyruvate represents a __________ in the energy producing system that controls where the process goes
FORK –> Energy production can either go in aerobic or anaerobic directions
Phosphofructokinase (PFK)
An enzyme (early in the glycolysis process)
–> Involved in feedback regulation of respiration
PFK is inhibited by
1) ATP
2) Citrate
–> Stops glycolysis from happening and thus stops the energy production process as a whole
PFK is activated by
AMP
PFK is regulated by ___________
Allosteric regulation
> AMP when…
< ATP
