Cellular Respiration Review Flashcards
Chem. rxns. where electrons are transferred from one molecule to another
Redox Reactions
Molecules that can donate electrons; results in a decrease in potential energy
Reducing Agents
Molecules that can accept electrons; results in an increase in potential energy
Oxidizing Agents
Molecules that gain electrons after rxn.
Reduced
Molecules that lose electrons after rxn.
Oxidized
Most of the energy used to fuel cell function is in the form of what?
High-energy electrons
Loss of phosphate group from a molecule
Dephosphorylation
Why are phosphate groups inherently unstable?
They are negatively charged and repel one another when arranged in a series
What is the process of adding a phosphate group to a molecule?
Phosphorylation
Are phosphorylated molecules less stable?
Yes
How is ATP generated?
ADP undergoes phosphorylation (ADP + Pi = ATP)
What produces 90% of ATP?
Chemiosmosis (Oxidative Phosphorylation)
What is the equation for cellular respiration?
C6H12O6 + 6O2 = 6CO2 + 6H2O + about 36 ATP
What are the metabolic pathways involved in cellular respiration?
Glycolysis, Pyruvate Oxidation, Citric Acid Cycle, and Oxidative Phosphorylation (ETC & Chemiosmosis)
How does glucose enter a cell?
Secondary active transport against a concentration gradient or GLUT proteins (facilitated diffusion)
Where does glycolysis take place?
Cytoplasm
What are the inputs for glycolysis?
1 glucose, 2 NAD+, 2 ATP, and 4 ADP
What are the outputs for glycolysis?
2 pyruvate, 2 NADH, 4 ATP, and 2 ADP
After the first half of glycolysis, why can’t glucose leave the cell via glucose transport proteins?
Negatively charged phosphate won’t allow glucose to cross plasma membrane
What converts one isomer to another?
Isomerase
How is glycolysis an example of end product inhibition?
More active when ADP is high and less active when ATP is high
What are the 3 net changes in glycolysis?
- Glucose converted to 2 molecules of pyruvate
- 2 molecules of ADP converted to ATP
- 2 molecules of NAD+ reduced to NADH
What happens to pyruvate if O2 is present?
Oxidized to acetyl CoA which enters CAC
What happens to pyruvate if O2 is not present?
Reduced to oxidize NADH back to NAD+ for fermentation
Where does pyruvate oxidation take place in eukaryotes?
Mitochondria
Where does pyruvate oxidation take place in prokaryotes?
Plasma Membrane
What are the inputs of pyruvate oxidation?
2 pyruvate, 2 NAD+, 2 coenzyme A
What are the outputs of pyruvate oxidation?
2 CO2, 2 NADH, 2 acetyl CoA
Why are the steps of the CAC a closed loop?
Last part of the pathway regenerates compounds needed in first step, allowing cycle to run continuously when reactants are present
Outputs per glucose at the end of CAC
4 ATP, 6 CO2, 10 NADH, 2 FADH2
What happens to glucose at the end of the CAC
It’s completely oxidized; all possible electrons have been removed
Outputs of CAC
2 ATP, 4 CO2, 6 NADH, 2 FADH2
What is the only pathway where O2 is an input?
Oxidative Phosphorylation
What provides the energy to power chemiosmosis?
H+ concentration gradient created by the ETC
What is the electron transport chain?
Series of e- transporters embedded in inner mitochondrial membrane
What does the ETC do?
Shuttle e- from NADH and FADH2 to O2
What happens to O2 in the ETC?
Reduced to form H2O
How does chemiosmosis form ATP?
Uses KE from protons falling down H+ gradient to form ATP from ADP + Pi
How much ATP is generated by cellular respiration per glucose?
30-36
Why must cellular respiration be regulated?
- Provide balanced amt. of energy in form of ATP without being wasteful
- Generate a number of intermediate compounds that are used in forming macromolecules
How are carbs stored for short-term use in animals?
As glycogen in liver and muscle tissue
What dietary sugars produce the same number of ATP molecules as glucose?
Fructose & Galactose
