Topic 8.2: Cellular respiration Flashcards
How are organic molecules broken down?
Via a number of discrete processes
a) By staggering the breakdown, the energy requirements are reduced
b) Released energy is transferred to electron carriers via redox reactions.
Reduction reactions
a) Gain of electrons / hydrogen
b) Loss of oxygen
Oxidation reactions
a) Loss of electrons / hydrogen
b) Gain of oxygen
Function of electron carriers
Transfer chemical energy via redox reactions
a) Organic molecules are oxidized to form reduced carriers
b) Reduced carriers are oxidized to form ATP
Examples of electron carriers
a) NAD+ + 2H+ + 2e– → NADH + H+
b) FAD + 2H+ + 2e– → FADH2
Definition of ATP
High energy molecule that works as an immediate source of energy for cell processes
Function of ATP
a) Energy currency of the cell by releasing energy when hydrolyzed to ADP
b) Transfer a PO4 3- to an organic molecule, make them less stable and more reactive
Glycolysis
a) Site
b) Conditions
a) Cytoplasm
b) Absence of hydrogen
Reactants of glycolysis
a) Carbohydrates
b) Lipids
c) Proteins
Steps of glycolysis
a) Phosphorylation
b) Lysis
c) Oxidation
d) ATP formation
Phosphorylation
a) Glucose is phosphorylated by 2 molecules of ATP, forming an hexose biphosphate
b) This makes the molecule less stable
Lysis
Hexose biphosphate is split into two triose phosphates
Oxidation
a) Hydrogen atoms are removed from each of the 3C sugars to reduce NAD+
b) Two molecules of NADH are produced in total
ATP formation
a) Some of the energy released from the sugar intermediates is used to synthesize ATP
b) Four molecules of ATP are produced in total via substrate level phosphorylation
Products of glycolysis
a) 4 ATP molecules (2 net ATP)
b) 2 NADH + H+
c) 2 Pyruvate
Site of link reaction
Matrix of the mitochondria
Type of chemical reactions in link reaction
Oxidative decarboxylation
Steps of link reaction
a) Pyruvate is transported from the cytosol into the mitochondrial matrix
b) Pyruvate is decarboxylated (CO2 produced)
c) 2C compound loses hydrogen atoms via oxidation (reduction of NADH)
d) Coenzyme A binds to acetyl to form Acetyl CoA
Products of Link Reaction
a) 2 NADH + H+
b) 2 CO2
c) 2 Acetyl CoA
Site of Krebs Cycle
Matrix of the mitochondria
Steps in Krebs Cycle
a) Acetyl CoA transfers its acetyl group to oxaloacetate to make citrate (CoA is released)
b) Two C atoms are released via decarboxylation to form molecules of CO2
c) Multiple oxidation reactions (4) result in the reduction of electron carriers (NAD + FAD)
d) One molecule of ATP is produced via substrate level phosphorylation
Products of Krebs Cycle
a) 4 CO2
b) 2 ATP
c) 2 FADH2
d) 6 NADH + H+
Site of electron transport chain
Inner mitochondrial membrane
What happens in oxidative phosphorylation?
Energy within the reduced hydrogen carriers is released to synthesize ATP via oxidation reactions
Process in Electron Transport Chain
a) Generating a proton motive force
b) ATP synthesis via chemiosmosis
c) Reduction of oxygen
Generating a proton motive force (1)
a) Electron carriers are oxidized and release high energy electrons and protons
b) Electrons are transferred to electron carriers, which consist of various transmembrane proteins
c) As electrons pass through the chain, they lose energy which is used to pump protons from the matrix
d) The accumulation of protons within the intermembrane space creates an electrochemical gradient
ATP synthesis (2)
a) The electrochemical gradient causes H+ to diffuse back into matrix through ATP synthase
b) As protons move through ATP synthase, they trigger the synthesis of ATP from ADP + Pi
Reduction of oxygen (3)
a) Oxygen acts as the final electron acceptor from the ETC, preventing the chain from becoming blocked
b) Oxygen binds with free protons to form water, Maintaining the hydrogen gradient
Products of electron transport chain
32 ATP
6 H2O
Function of mitochondria
Synthesize large amounts of ATP via aerobic respiration
Structure of mitochondria
a) Outer membrane
b) Inner membrane
c) Cristae
d) Intermembrane space
e) Matrix
f) Ribosome 70S
g) Loops of DNA
Adaptation
A change in structure so that something carries out its function more efficiently
Function of outer membrane in mitochondria
Separates the contents of the mitochondrion from the cytosol
Function of inner membrane in mitochondria
Contains ETC and ATP synthase used for oxidative phosphorylation
Function of cristae in mitochondria
Inner membrane is arranged into folds that increase the SA:Vol ratio
Function of intermembrane space
Small space to easily accumulate protons in chemiosmosis
Function of Ribosome 70S / Loops of DNA
Expression of mitochondrial proteins
Definition of electron transport chain
Series of electron carriers, located in the inner membrane of the mitochondrion
Definition of chemiosmosis
Generation of ATP using energy released by the movement of hydrogen ions across a membrane
