Catabolic Pathways Flashcards
Catabolic pathways
Release energy by breaking down big molecules into smaller compounds
Aerobic respiration
Oxygen is consumed with organic fuel. Electrons from glucose are transferred to O2 to make H2O
Anaerobic respiration
Organic fuel is broken down without oxygen
Final e- acceptor is not oxygen
Fermentation
Partial breakdown of organic fuels without oxygen
Does not have an ETC or oxygen as the final e- acceptor
Is cellular respiraton aerobic or anaerobic?
Both, but mostly aerobic
Redox reactions (LEO goes GER)
The transfer of electrons from one molecule to another
Loss of electrons = oxidization
Gain of electrons = reduction
What does NAD+ do?
An electron transporter during the breakdown of glucose. It is a coenzyme and an oxidizing agent
What does NAD+ cycle between?
NAD+ (oxidized) and NADH (reduced)
What would happen if the transfer of electrons was uncontrolled?
There would be one big release of energy with LOTS of heat loss
What are the two ways ATP is made?
- Substrate level phosphorylation: uses an enzyme to transfer a phosphate group from ADP to make ATP
- Oxidative phosphorylation: H+ gradient to drive the protein ATP synthase
How much ATP is made from substrate level phosphorylation?
10%
How much ATP is made from oxidative phosphorylation?
90%
Where does glycolysis and the citric acid cycle occur?
The cytosol
What is glycolysis?
The splitting of glucose into two three-carbon sugars
The sugars are then oxidized and rearranged to form 2 pyruvates
The pyruvates are used for the next step in cellular respiration
What is the overall net gain of Glycolysis?
2 ATP and 2 NADH
Is there a carbon loss in glycolysis?
No
Will glycolysis occur with or without oxygen?
Yes
After glycolysis, pyruvate is _____ transported into the mitochondria
Actively
Pyruvate is converted into ____ .
Acetyle CoA
How many ATP is generated per cycle of the citric acid cycle?
1
2 total because there are 2 pyruvates going through the cycle
What is the total yield per glucose?
6 NADHs, 2FADH2, 2ATP
Together, glycolysis and the citric acid cycle yield?
4 ATP per glucose
What is the electron transport chain?
A collection of proteins within the inner membrane of the mitochondrion
How does the electron transport chain work?
Each component becomes reduced when it accepts electrons from its “uphill” neighbour
The transporters then return to the oxidized state and starts the cycle again to pick up more electrons
Electrons from _____________ are transferred from NADH to the ETC complex l.
Glycolysis and the citric acid cycle
Which complexes have cytochromes?
Complexes lll and lV
The cytochromes pass the electron to _____ which picks up 2 electrons and 2 protons to form _______.
Oxygen
Water
Electrons acquired from the citric acid cycle from FADH2 join the ETC at complex ______?
ll
FADH2 converts about _______ less energy than NADH
1/3
Where is ATP synthase found?
The inner membrane of the mitochondrion
ATP synthase makes ATP from _____ and ______
ADP and inorganic phosphate
Chemiosmosis
The movement of hydrogen ions across the membrane via ATP synthase via an energy- coupling mechanism
What helps change the shape of the protein so that it spins? (ATP synthase)
Rotor
The turning of the _______ activates catalytic sites that produce ATP and ADP in the knob
Rod
The ________ of the electrons in the ETC provides the energy to pump H+ ions from the _______ into the ________.
Exergonic flow
Mitochondrial matrix
Intermembrane space
For each glucose what is the tally of everything produced?
Glycolysis:
2 ATP via SLP
2 NADH
2 pyruvate
Pyruvate oxidation
2 NADH
Citric acid cycle
2 ATP via SLP
6 NADH
2 FADH2
ETC
112 protons
10 NADH
2 FADH2
28 ATP via OP
How many protons does it take to make 1 ATP?
4
What is the total number of ATP produced during cellular respiration?
32
Is fermentation considered cellular respiration?
No
What ensures that ATP is produced if oxygen is not present?
Fermentation
By recylcing NAD+ from NADH during glycolysis
What is alcohol fermentation?
Pyruvate is converted to ethanol
What is lactic acid fermentation?
Pyruvate is reduced directly by NADH to form lactic acid
During exercise, muscle cells are starved of oxygen, how does cellular respiration continue?
Lactic acid fermentation
Do all three cellular respiration methods generate ATP and use glycolysis to oxidize glucose to make pyruvate?
Yes
Do all three methods use NADH as the oxidizing agent?
No. NAD+ is the oxidizing agent
Fermentation uses ______ as the final electron acceptor to oxidize NADH
An organic molecule
Pyruvate in lactic acid
Acetaldehyde in alchohol fermentation
Cellular respiration uses ETC to regenerate ________
NAD+
Fermentation yields ____ ATP via substrate level phosphorylation
2
Obligate anaerobes
Only carry out fermentation or anaerobic respiration
Facultative anaerobes
Use both fermentation and cellular respiration to make enough ATP
How does glycolysis and the citric acid cycle connect to other metabolic pathways?
Proteins provide the _____, ________, and ________
Carbohydrates are the _________
Fats get broken down into ________ to make ________ and the ________ for Acetyl-CoA
Coenzymes, enzymes, and amino functional groups
Sugar sources
Glycerol monomers, G3P, fatty acids
