Glycolysis Groundwork
Where in the cell does glycolysis take place?
Cytoplasm
Where in the cell does the Krebs cycle occur?
Mitochondrial matrix
What does ETC stand for?
Electron Transport Chain
What is fermentation?
An anaerobic process that allows ATP production without oxygen
What does ATP stand for?
Adenosine Triphosphate
What is the starting molecule of glycolysis?
Glucose
What molecule enters the Krebs cycle from glycolysis?
Pyruvate (converted into Acetyl-CoA)
Where is the electron transport chain located in eukaryotic cells?
Inner mitochondrial membrane
Name one type of fermentation.
Lactic acid fermentation or alcoholic fermentation
How many ATP are produced from one glucose molecule in aerobic respiration (approximate)?
About 36–38 ATP
How many ATP are invested and how many are produced in glycolysis?
2 invested, 4 produced, net gain of 2 ATP
How many CO₂ molecules are released from one turn of the Krebs cycle?
2 CO₂ per turn
How do NADH and FADH₂ contribute to the ETC?
They donate high-energy electrons that power proton pumps
Compare what is produced by alcoholic fermentation and lactic acid fermentation.
Alcoholic fermentation produces ethanol and CO₂; lactic acid fermentation produces lactic acid
Explain the difference between substrate-level phosphorylation and oxidative phosphorylation.
Substrate-level directly transfers phosphate to ADP; oxidative uses proton gradient + ATP synthase
Explain why glycolysis is considered anaerobic.
It does not require oxygen to occur
Identify two electron carriers produced during the Krebs cycle.
NADH and FADH₂
What role does oxygen play in the electron transport chain?
Final electron acceptor, forming water
Why is fermentation important when oxygen is unavailable?
It regenerates NAD⁺ so glycolysis can continue producing ATP
How is energy efficiency different between aerobic and anaerobic respiration?
Aerobic yields ~18x more ATP per glucose than anaerobic
Predict what would happen to cellular respiration if glycolysis did not occur.
No pyruvate would be produced, so the Krebs cycle and ETC could not proceed, halting ATP production
Explain how the Krebs cycle connects to other cellular processes.
It supplies energy carriers for the ETC and provides intermediates for biosynthesis of amino acids, nucleotides, and lipids
Analyze why cyanide, which blocks the ETC, is lethal to cells.
Electrons cannot flow, no proton gradient forms, ATP production stops, leading to cell death
Evaluate the advantages and disadvantages of fermentation vs. aerobic respiration.
Advantage: quick ATP without oxygen; Disadvantage: much less efficient (2 ATP vs. ~36 ATP per glucose)
Construct an argument for why multicellular organisms rely on aerobic respiration instead of fermentation for most of their energy.
They require large, sustained amounts of ATP to power growth, movement, and complex functions that fermentation alone could not provide