Cellular Respiration (pdbio exam 3) Flashcards
Cellular respiration is the process by which cells metabolize _____.
glucose
What is the equation for cellular respiration?
C6H12O6 + 6O2»_space; 6C02 + 6H2O + energy
What elements are oxidized in cellular respiration?
C6H12O6 oxidized to CO2
What elements are reduced in cellular respiration?
6O2 is reduced to 6H2O
What are the 4 metabolic pathways of cellular respiration? briefly describe
- glycolysis: glucose (6C) is broken down to pyruvate (3C)
- pyruvate oxidation: (3C) pyruvate is oxidized to form acetyl CoA (2C)
- krebs cycle: Acetyl CoA is oxidized to CO2
- chemiosmosis (oxidative phosphorylation): compounds that were reduced in steps 1-3 are oxidized in reactions leading to ATP production
Where does glycolysis occur?
In the cytoplasm
What happens in glycolysis?
Products?
ATP production?
6C sugar is broken down into 2 pyruvate (3C).
2NADH and 2ATP
Process requires 2 ATP, and 4 ATP is formed, therefore there is a net production of 2 ATP.
Which metabolic pathway can occur without oxygen?
Glycolysis
What happens in pyruvate oxidation?
Products?
ATP production?
2 pyruvate are transferred to the mitochondrial matrix. Pyruvate loses a carbon in the form of CO2 and the remaining two carbons are attached to a coenzyme creating acetyl CoA.
Products are 2 NADH and 2 CO2
ATP production = 0
Where does pyruvate oxidation occur?
the mitochondrial matrix
Where does the Krebs cycle take place?
The mitochondrial matrix
What happens in the Krebs cycle?
Products?
ATP production?
Acetyl is removed from Acetyl CoA and attacked to oxaloacetate to form citrate (aka citric acid). Through multiple oxidation redox reactions, a carbon is released one at a time.
Products in total are 4 CO2, 2 ATP, 6NADH, and 2 FADH2.
ATP production = 2 ATP total
Excess glucose can be polymerized into….
starch/glycogen
Excess acetyl CoA can be used in metabolic pathways to generate…
fats and phospholipids
If more of any products used in glycolysis or the Krebs cycle are added…
more downstream products will be produced
Where does chemiosmosis take place?
In the mitochondrial matrix
What happens during chemiosmosis?
Products?
ATP production?
High energy electrons are removed from NADH and FADH2 to make ATP. THIS PROCESS REQUIRES OXYGEN. Electrons are oxidized through multiple protein complexes embedded in the inner mitochondrial membrane in a linear manner. The movement of electrons generates an H+ electrochemical gradient between membranes ending finally with OXYGEN. Protons pass through the ATP synthase in a rotary motion that makes ATP as it spins. NADH oxidation makes most of the ATP.
Products: ATP
ATP production: depends on the H+ pushed through the ATP synthase - the greater concentration gradient = more ATP made
What is the net yield of ATP?
Varies on the textbook, but 30 - 34 ATP
Why does the net yield of ATP differ?
Because NADH is also used in anabolic pathways and H+ gradients for other purposes
What is the final electron acceptor in the ETC?
Oxygen
What happens if oxygen isn’t available?
Fermentation
Without oxygen, cells must find another way to turn ____ back to ____
NADH, NAD+
What are the two principle forms of fermentation?
- lactic acid fermentation
2. alcohol fermentation
What is the equation for lactic acid fermentation?
Where does it occur?
pyruvate + NADH»_space; lactic acid + NAD+
Occurs in humans
What is the equation for alcohol fermentation?
Where does it occur?
pyruvate + NADH»_space; ethyl alcohol + NAD+ + CO2
Occurs in yeasts
What is the primary source/substrate for cellular respiration?
Carbohydrates (glucose)
What are alternative sources/substrates for cellular respiration?
Fats and proteins
During glycolysis, one molecule of ____ is broken down in to two molecules of pyruvate, driving the synthesis of ATP.
glucose
As a result of the reactions of the citric acid cycle, the carbons from acetyl CoA are released as ____.
CO2
During oxidative phosphorylation, ATP synthesis is coupled to…
the removal of high-energy electrons from NADH and FADH2
The structural components of the ETC include:
protein complexes and small organic molecules
During oxidative phosphorylation, ATP is produced by the enzyme ____
ATP synthase
In the 1st reaction of the citric acid cycle, oxaloacetate, which contains ____ carbons, is combined with acetyl CoA, which contains ____ carbons in its acetyl group, to produce citric acid which contains ____ carbons.
4
2
6
When electrons are transferred to oxygen in the final step of the ETC, a mole of ___ is produced.
H2O
The flow of electrons through the ETC is ____.
exergonic
In eukaryotic cells, the ETC is located in the:
inner mitochondrial membrane
During the chemical reactions of oxidative phosphorylation ____ is oxidized and ___ is produced.
NADH is oxidized
ATP is produced
T/F: The flow of electrons through the ETC requires an input of energy.
False
Which molecules are used as energy sources by living organisms?
sugars, amino acids, fatty acids
In aerobic respiration O2 is reduced to ____.
H20
Feedback Inhibition: When ATP concentrations are high, glycolysis…
When ATP concentrations are low, gylcolysis…
shuts down
continues
