Understanding Photosynthesis

• Photosynthesis needs sunlight, water, and carbon dioxide
• Photosynthesis produces glucose and oxygen
• Photosynthesis occurs in two main stages

Light Independent Reactions (Calvin Cycle)

• Occurs in the stroma of chloroplasts
• Does not require light directly, but uses ATP and NADPH from the light reactions
• Produces glucose (C6H12O6), which plants use for energy and growth
• Rubisco is involved

Light Dependent Reactions

• Occurs in the thylakoid membranes of the chloroplasts
• Requires sunlight to excite electrons in chlorophyll
• Splits water molecules (H2O), producing oxygen (O2) as a byproduct
• Converts light energy into ATP (adenosine triphosphate) and NADPH, which store energy for the next stage
• Photosystem I (PSI) and Photosystem II (PSII) are two protein-pigment complexes in the thylakoid membrane
• PSI and PSII drive the light-dependent reactions of photosynthesis, converting light energy into chemical energy

Electron Transport Chain (ETC)

• Series of protein complexes in the thylakoid membrane that transfers electrons from Photosystem II (PSII) to Photosystem I (PSI)

• Generates ATP and NADPH, which power the Calvin cycle

• Photosystem II splits water (H2O) and starts the electron transport chain

• Photosystem I produces NADPH

Chloroplasts

• Organelles found in plant cells and some algae
• Photosynthesis occurs here, converting sunlight into chemical energy (glucose) while releasing oxygen
• Contains thylakoids, which are complex proteins needed for photosynthesis
• Chlorophyll inside the thylakoid membrane absorbs light energy

Cellular Respiration

• Cells break down glucose into usable energy
• Mainly takes place in mitochondria
• Breaks down glucose
• Produces energy in the form of ATP
• Needs glucose and oxygen
• Has 3 stages

Glycolysis

• Occurs in the cytoplasm
• Anaerobic process
• Breaks down glucose (C6H12O6) into two molecules of pyruvate (C3H4O3)
• Produces 2 ATP and 2 NADH (energy carriers)

Krebs Cycle

• Occurs in the mitochondrial matrix
• Pyruvate is converted into Acetyl-CoA, which enters the cycle
• Releases CO2 as a waste product
• Produces 2 ATP, NADH, and FADH2 (electron carriers)

Oxidative Phosphorylation

• NADH & FADH2 donate electrons to the ETC
• Electrons move through protein complexes, pumping protons (H+) into the intermembrane space, creating a proton gradient
• Oxygen (O2) acts as the final electron acceptor, forming water (H2O)
• ATP Synthase uses the proton gradient to generate ~34 ATP

ATP

• Contains adenine (a nitrogenous base)
• Contains ribose (a five-carbon sugar)
• Contains three phosphate groups (Triphosphate)
• Energy currency for life

ADP

• Contains adenine (a nitrogenous base)

• Contains ribose (a five-carbon sugar)

• Contains two phosphate groups (Diphosphate)

• Metabolism includes all chemical reactions that occur in cells

• Anabolism and catabolism

NADPH

• Energy carrier
• Can store and transfer high-energy electrons
• Essential molecule in photosynthesis and other cellular processes that is an electron carrier
• Provides high-energy electrons for biosynthesis and energy production

ATP Synthase

• Enzyme that produces ATP (Adenosine Triphosphate)

• Plays a crucial role in both photosynthesis and cellular respiration by converting ADP and inorganic phosphate (Pi) into ATP using a proton gradient

• Anaerobic: without oxygen

• Aerobic: with oxygen

Enzymes

• Molecules that speed up chemical reactions

• Substrates are molecules that react to form new products

• Active site is a region on an enzyme that binds to a protein or other substance during a reaction

• Induced fit describes how enzymes and proteins change shape to bind to substrates

• Fermentation uses microorganisms to break down organic compounds into simpler molecules