Enzymes
What are enzymes made of and what do they do?
Proteins that act as catalysts, speeding up reactions by lowering activation energy.
What does ATP stand for?
Adenosine Triphosphate
Where does photosynthesis occur?
In the chloroplast.
Where does cellular respiration occur?
In the mitochondria.
What type of energy does photosynthesis store?
Light energy converted to chemical energy.
What happens to an enzyme when temperature or pH is too extreme?
It becomes denatured, losing its shape and function.
Where is energy stored in an ATP molecule?
In the bond between the last two phosphate groups.
What is the overall equation for photosynthesis?
6CO₂ + 6H₂O + light → C₆H₁₂O₆ + 6O₂
What is the equation for cellular respiration?
C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + ATP
How are photosynthesis and respiration related?
The products of one are the reactants of the other.
What is the term for the specific area where a substrate binds to an enzyme?
The active site.
What happens when ATP breaks a bond?
It becomes ADP + P, and energy is released
What are the two stages of photosynthesis?
Light-dependent reactions and the Calvin Cycle.
What are the three main stages of aerobic respiration?
Glycolysis, Krebs Cycle, Electron Transport Chain.
What is the energy flow through these processes?
Sunlight → Glucose → ATP → Cell work.
How do enzymes affect the rate of chemical reactions?
They speed them up by lowering activation energy.
What cellular processes use ATP?
Muscle contraction, active transport, and biosynthesis.
What is produced in the light-dependent reactions?
ATP, NADPH, and O₂.
What is the total ATP yield from one glucose molecule?
About 36–38 ATP.
How do matter and energy move differently in these cycles?
Matter (CO₂, H₂O) cycles; energy flows one-way from sunlight.
Why is enzyme shape important?
The shape determines specificity — only one substrate fits (lock-and-key model)
Describe the ATP–ADP cycle.
ATP releases energy, becoming ADP + P; energy from food rebuilds ATP again.
How are the two stages of photosynthesis connected?
ATP and NADPH from light reactions power the Calvin Cycle to make glucose
How does aerobic respiration differ from anaerobic respiration?
Aerobic uses O₂ and produces more ATP; anaerobic (fermentation) occurs without O₂ and makes less ATP.
Why are both processes essential for life?
They depend on each other — photosynthesis provides food & O₂; respiration releases ATP for cell functions.