UNIT 6 CELLULAR RESPIRATION Flashcards
Why does glucose have such lots of energy?
Because it has a lot of C-H bonds, which allows electrons to hold a maximum of energy.
The potential of energy in molecule is released by?
Oxidation
Oxidation
loss of electrons
Reduction
Gain of electrons
Redox word to remember.
OIL-RIG, Oxidation Is Loss, Reduction Is Gain.
Why is O2 an electron receptor in redox reactions?
Because it has a high electronegativity.
Why can we see cellular respiration is like controlled combustion?
Because the oxidation of glucose results in the transfer of electrons to O, making CO, water, and the release of energy.
Why does CO2 contains no usable energy?
Because it is fully oxidized.
Dehydrogenases
Enzymes that facilitate the transport of electrons from food to the molecule. They act as an energy carrier (NAD+).
3 parts of cellular respiration
- Glycolysis
- Citric acid Cycle
- Electron transport chain and chemiosmosis.
Glycolysis
Breakdown of glucose into 2 molecules of pyruvate, some ATP and NADH is synthesized.
Citric Acid Cycle
Pyruvate oxidizes and forms Acetyl CoA. It then oxidizes to CO2. SomeATP and NADH is synthesized.
Electron transport and chemiosmosis
NADH formed in the previous stages is oxidized and the electrons liberated from it are passed in the transport chain and transferred to O2, making H2O. The free energy released during the transport establish a proton gradient across the membrane and this is what synthesize the rest of ATP.
Mitochondrion is only in
eukaryotes.
inter membrane compartment
area between the inner and outer membrane
Matrix
The inside of both membranes, inside of mitochondria,
Where happens glycolysis in eukaryotes?
In the cytosol of the cell
Where happens the citric acid cycle in eukaryotes?
in the mitochondrial matrix
Where happens the electron transport chain?
In the inner mitochondrial membrane
Glycolysis net gain?
2 ATP and 2 NADH
Glycolysis
Converts one 6-carbon glucose molecule into two 3-carbon molecules of pyruvate and the product of this process is 2 ATP and 2 NADH.
2 phases of glycolysis
- energy-requiring phase
- energy-releasing phase
Energy requiring phase
The glucose molecule gets 2 phosphate group, making it unstable and split in half, making two 3-carbon sugar. The 2 phosphate group used come from ATP so 2 ATP is used.
Energy releasing phase
Each of the two 3-carbon sugar is converted into pyruvate. This reaction makes 4 ATP and 2 NADH.
Does glycolysis require O2?
No, that’s why it’s considered an ancient pathway, back in time there was no O2 and it was still happening.
Pyruvate oxidation
The pyruvate molecules made in the glycolysis are transported in the mitochondrial matrix where they are converted into Acetyl-CoA. In that process, 1 NADH is formed.
Citric-Acid Cycle
Bunch of enzyme-catalyzed reactions that oxidizes the Acetyl group to CO2 and the synthesis of 1 ATP, 3 NADH and 1 FADH2.
Oxydative phosphorylation
Type of ATP synthesis that is linked by the oxydation of energy-rich molecules by an electron transport chain.
How does oxidative phosphorylation works?
The electron transport chain transport electrons from NADH and FADH2 to O2. But NADH has more electrons than O2, the extra electrons are released from the transport chain and are used to transport protons with protons pumps. This will create a chemical gradient and when it’s done, the protons will diffuse back with help of ATP synthase. Which synthesize ATP.
How many reactions in the citric acid cycle?
8
2 types of electron shuttle in the electron transport chain?
- Ubiquinone
- Cytochrome c
Ubiquinone
hydrophobic molecule found in the core of the membrane. Carries complex 1 , 2 and 3.
Cytochrome C
Located in the inter membrane . Carries complex 3, 4 and 5.
Proton-motive force
Produced electrochemical gradient that created potential energy.
Chemiosmosis
Ability of cells to use the proton-motive force
Oxidative phosphorylation relies on?
ATP synthase
ATP synthase is?
Multiprotein complex that span the inner mitochondrial membrane.
ATP synthase form?
Its base is embeded in the membrane and forms a channel. The stalk connects to the headpiece which goes into the matrix.
What powers ATP synthesis?
The flow of protons from the headpiece
Uncoupling of electron transport and chemiosmosis
Occur with mechanisms that prevent the formation of the proton-motive force by making the membrane permeable to protons.
What makes the membrane permeable to protons in chemiosmosis?
Inophores, they are uncouplers because they form channels across membranes.
What is the efficiency of cellular respiration?
32%
How is cellular respiration regulated?
by feedback inhibition with supply and demand
Feedback inhibition
The end product of the pathway inhibits an enzyme early in the pathway.
Catabolism of carbs
starch is broken in glucose, which can enter glycolysis
Catabolism of fats
triglicerydes are hydrolyzed in glycerol and fatty-acids.
Catabolism of protein
Hydrolyzed into amino-acids before oxidation
The intermediate of the citric acid cycle and glycolysis are utilized for anabolic reactions like?
They are used for synthesis of amino-acids, pyrimidine and purine bases. They supply the carbon backbone for hormones.
Fermentation
If little O2, pyruvate stays in cytosol and is reduced consuming NADH.
2 types of fermentation
- Lactic acid fermentation
- alcohol fermentation
Lactic acid fermentation
Pyruvate is converted to lactate. The reaction is reversed when O2 becomes available.
Lactic acid fermentation happens in
The cytosol of muscle cell during strenuous activity. When ATP demand is higher than the rate t which O2 can be supplied.
Alcohol fermentation
Happens in microorganisms such as yeast
Alcohol fermentation works by?
The pyruvate being reduced to a molecule of CO2and a molecule of acetyl alcohol while NADH is converted to NAD+
Common electron acceptors that do not use O2 as the terminal electron receptor.
sulfate, nitrate, ferric ion.
Strict anaerobe
Needs an oxygen free environment to survive.
facultative anaerobe
switch between fermentation and oxydative pathways depending on the O2 supply.
Strict aerobe
Need oxygen to survive.
