LESSON 1: are split, releasing electrons, protons
(H⁺), and oxygen (O₂) as a byproduct.
PHOTOSYNTHESIS
Plants, algae, and some bacteria
converts light energy to chemical
reactions in the form of sugar
2. Electron Transport Chain: The
PHOTOAUTOTROPH excited electrons move through a
series of proteins, including the
Produces its own food using light
cytochrome b₆f complex (b₆f). As they
energy (i.e plants)
move along this chain, their energy is
ATP (ADENOSINE TRIPHOSPHATE) used to pump H⁺ ions from the stroma
(outside) into the thylakoid lumen
Primary energy carrier in living things (inside), creating a high concentration
CHLOROPLAST of H⁺ ions within the lumen.
Plant cell structure where
photosynthesis occurs
THYLAKOIDS
3. Photosystem I (PSI): The
Disc-like structure that helps absorb electrons eventually reach PSI (P700),
light where they are re-energized by
another photon of light. These
GRANA electrons are then transferred to a
Stack of thylakoids in a chloroplast protein called ferredoxin (FD).
CHLOROPHYLL
Pigment found in thylakoid; uses it to
produce carbohydrates 4. NADP⁺ Reduction: The electrons
STROMA are used to reduce NADP⁺ to NADPH
with the help of an enzyme called
Fluid-filled space around the grana ferredoxin-NADP⁺ reductase (FNR).
LESSON 2: NADPH is an energy carrier molecule
that will be used in the Calvin cycle to
LIGHT-DEPENDENT REACTIONS IN help produce sugars.
PHOTOSYNTHESIS (THYLAKOID
MEMBRANE OF CHLOROPLASTS)
1. Photosystem II (PSII): light
energy is absorbed by PSII, which
excites electrons (e-) in the chlorophyll
(P680). These high-energy electrons
are passed to a molecule called
plastoquinone (PQ). To replace the
lost electrons, water (H₂O) molecules
5. ATP Synthesis: Due to the high regeneration process uses additional
concentration of H⁺ ions in the lumen, ATP. So, the Calvin Cycle turns CO₂,
they flow back into the stroma through ATP, and NADPH into sugars like
an enzyme called ATP synthase. This glucose, storing energy from sunlight
flow of H⁺ ions provides the energy in a form that the plant can use for
needed to convert ADP to ATP, which growth and maintenance.
is another energy carrier for the Calvin
cycle.
LESSON:4 CELLULAR RESPIRATION
Cellular respiration has two main
types: aerobic (with oxygen) and
anaerobic (without oxygen).
In summary, the light-dependent 1. Aerobic Respiration (with
reactions convert light energy into oxygen)
chemical energy in the form of ATP
This type occurs in the mitochondria of
and NADPH, while also producing
cells and includes several stages:
oxygen as a byproduct. These energy
molecules are then used in the Calvin Glycolysis (in the cytoplasm):
cycle to synthesize glucose.
Glucose is broken down into two
LESSON: 3 molecules of pyruvate. This process
generates 2 ATP and 2 NADH
CALVIN CYCLE
molecules.
1. Carbon Fixation: Three molecules
Pyruvate Oxidation (in the
of CO₂ are combined with three
mitochondria):
molecules of a five-carbon compound
called ribulose bisphosphate (RuBP), Each pyruvate is converted into
catalyzed by the enzyme Rubisco. This acetyl-CoA, releasing CO₂ and
reaction forms six molecules of a producing NADH.
three-carbon compound called 3-
phosphoglycerate (3-PGA).
2. Reduction: Each of the six 3-PGA Krebs Cycle (Citric Acid Cycle):
molecules is converted into a higher- Acetyl-CoA enters the Krebs cycle,
energy molecule using energy from where it’s further broken down.
ATP and electrons from NADPH. This
step produces six molecules of This cycle generates 2 ATP, 6 NADH,
glyceraldehyde-3-phosphate (G3P). and 2 FADH₂, and releases CO₂ as a
waste product.
3. Regeneration of RuBP: Out of the
six G3P molecules, only one exits the
cycle to eventually form glucose and Electron Transport Chain (ETC):
other sugars. The remaining five G3P
molecules are used to regenerate NADH and FADH₂ donate electrons to
three molecules of RuBP, which the ETC, which powers ATP synthesis.
enables the cycle to continue. This
Oxygen is the final electron acceptor, Alcohol Fermentation:
forming water.
Occurs in yeast and some plants.
The ETC produces about 32-34 ATP.
Pyruvate is converted into ethanol and
CO₂.
Total ATP from Aerobic Like lactic acid fermentation, it
Respiration: Approximately 36-38 produces 2 ATP per glucose, with no
ATP per glucose molecule. additional ATP generated beyond
glycolysis.
Summary: Aerobic respiration is
efficient and produces a high amount Summary: Anaerobic respiration is less
of ATP by fully breaking down glucose efficient, producing only 2 ATP per
in the presence of oxygen. glucose. It’s a backup method used in
low-oxygen situations but leads to
byproducts like lactic acid or alcohol.
2. Anaerobic Respiration (without
Comparison:
oxygen)
When oxygen is unavailable, cells
switch to anaerobic processes to Aerobic: High energy yield (36-38
produce energy. ATP), requires oxygen, produces CO₂
and water.
This happens in the cytoplasm and
includes two main types: Lactic Acid
Fermentation and Alcohol
Anaerobic: Low energy yield (2 ATP)
Fermentation.
does not require oxygen, produces
lactic acid or alcohol as byproducts.
Lactic Acid Fermentation:
Common in animal cells (like muscles)
and some bacteria.
Glucose undergoes glycolysis to
produce pyruvate, which is then
converted into lactic acid.
This process generates 2 ATP per
glucose molecule, but no additional
ATP beyond glycolysis.
