College · BIO 101
Cell Biology & Energy (BIO 101) — study guide & practice questions
Respiration, photosynthesis and the organelles that run them.
Study guide
Cell Structure & Compartmentalization
- The fluid mosaic membrane, endomembrane system, and cytoskeleton together organize the cell's chemistry.
- Mitochondria (cristae, matrix) and chloroplasts (thylakoids, stroma) each carry their own DNA, supporting endosymbiotic origins.
Bioenergetics Basics
- Negative ΔG reactions are spontaneous; cells couple ATP hydrolysis to endergonic reactions to drive them.
- Redox reactions move electrons via NAD⁺/NADH and FAD/FADH₂; enzymes speed reactions without changing their ΔG.
Glycolysis
- An investment phase (2 ATP) destabilizes glucose; a payoff phase yields 4 ATP and 2 NADH, for a net of 2 ATP and 2 pyruvate per glucose.
- Phosphofructokinase (PFK) is the main regulatory point, inhibited by ATP/citrate and activated by AMP.
Pyruvate Oxidation & the Citric Acid Cycle
- Each pyruvate becomes acetyl-CoA (releasing CO2, making NADH) before entering the cycle, which runs twice per glucose.
- Per glucose, this stage yields 8 NADH, 2 FADH₂, and 2 ATP total — mostly electron carriers, not direct ATP.
Oxidative Phosphorylation & the Electron Transport Chain
- The ETC pumps protons using electrons from NADH/FADH₂; chemiosmosis through ATP synthase converts that gradient into ATP.
- Oxygen is the final electron acceptor; total yield is about 30–32 ATP per glucose (~2.5 ATP/NADH, ~1.5 ATP/FADH₂).
Photosynthesis: The Light Reactions
- Photosystem II splits water (releasing O2) to replace electrons lost to an ETC that pumps protons for photophosphorylation.
- Photosystem I re-energizes those electrons and reduces NADP⁺ to NADPH; ATP and NADPH then power the Calvin cycle.
Photosynthesis: The Calvin Cycle & Adaptations
- Rubisco fixes CO2 onto RuBP; ATP and NADPH reduce the product to G3P, most of which regenerates RuBP.
- C4 and CAM plants separate carbon fixation from the Calvin cycle (by space or by time) to limit photorespiration and water loss.
Fermentation, Metabolic Integration & Regulation
- Fermentation regenerates NAD⁺ without oxygen so glycolysis can continue, at a much lower ATP yield.
- Fats (via beta-oxidation) and proteins feed into these same pathways; energy charge (ATP/ADP/AMP levels) regulates them throughout.
Course modules
8 foundation modules free to read here. Every module ends with a quiz in the app.
1. Cell Structure & Compartmentalization Free
The membrane, organelle system, and cytoskeleton that organize a eukaryotic cell's chemistry.
Read the 4 lessons →2. Bioenergetics Basics Free
The thermodynamics, ATP chemistry, and redox reactions underlying every metabolic pathway.
Read the 4 lessons →3. Glycolysis Free
The universal first stage of sugar breakdown: investment, payoff, net yield, and regulation.
Read the 4 lessons →4. Pyruvate Oxidation & the Citric Acid Cycle Free
How pyruvate is fully dismantled to CO2, harvesting electron carriers for the payoff stage to come.
Read the 4 lessons →5. Oxidative Phosphorylation & the Electron Transport Chain Free
Where the vast majority of ATP is actually made: electron transport, chemiosmosis, and total yield.
Read the 4 lessons →6. Photosynthesis: The Light Reactions Free
How chlorophyll captures light energy and converts it into ATP, NADPH, and oxygen.
Read the 4 lessons →7. Photosynthesis: The Calvin Cycle & Adaptations Free
How captured energy builds sugar from CO2, and how some plants avoid wasting it in hot, dry climates.
Read the 4 lessons →8. Fermentation, Metabolic Integration & Regulation Free
What cells do without oxygen, how other fuels feed into these pathways, and how it's all kept in balance.
Read the 4 lessons →Sample practice questions
From module 1, Cell Structure & Compartmentalization. Pick your answers, then check them in the app, with an explanation for every question.
1. Which cytoskeletal filament forms the mitotic spindle?
2. What is the folded inner membrane of the mitochondrion called?
Sample flashcards
4 of the cards in this course's deck. Tap a card to flip it.
Cellular RespirationWhat are the three stages of cellular respiration, and where does each occur?
Glycolysis (cytoplasm), the citric acid / Krebs cycle (mitochondrial matrix), and oxidative phosphorylation (inner mitochondrial membrane).
GlycolysisWhat is the net ATP yield of glycolysis per glucose molecule?
2 ATP net (4 are made, 2 are invested in the preparatory phase), plus 2 NADH and 2 pyruvate.
Electron TransportWhat is oxygen's role in the electron transport chain?
It is the final electron acceptor: it combines with electrons and H⁺ to form water, which lets electrons keep flowing through the chain.
Electron TransportHow does ATP synthase make ATP?
Protons flow down their gradient from the intermembrane space into the matrix through ATP synthase. The rotation this drives joins ADP + Pi into ATP (chemiosmosis).
The full course is in LectureMate's Course Library: every module quiz with explanations, the complete flashcard deck with spaced repetition, and a 6-step strategy for Cell Biology & Energy questions. Foundation modules are free; advanced modules need Pro.