AP Biology - Chapter 8: Photosynthesis

Photosynthesis equation

6CO₂ + 6H₂O + Light Energy→C₆H₁₂O₆ + 6O₂

Stroma

Fluid-filled space surrounding thylakoids where light-independent reactions (Calvin Cycle) occur

Thylakoid

Membrane-bound sacs where light reactions occur

Grana

Stacked thylakoids

Where the Calvin cycle (light-independent reactions) takes place

Stroma

Thylakoid membrane

Where light-dependent reactions occur

Chloroplast Outer Membrane

Permeable to small molecules

Two stages of photosynthesis

light-dependent and light-independent reactions

Light-Dependent reaction input

Light energy, H2O, NADP+, ADP, and inorganic phosphate

Light-Dependent reaction output

O2, ATP, and NADPH

Photolysis

Water is split into oxygen, protons, and electrons

Electron Transport Chain (ETC)

Electrons move through proteins in the thylakoid membrane, generating a proton gradient

ATP Synthesis

Protons flow through ATP synthase to generate ATP from ADP

NADPH Formation

Electrons reduce NADP+ to form NADPH

Light-Independent reactions input

CO2, ATP, and NADPH

Light-Independent reactions output

G3P (glyceraldehyde-3-phosphate), used to form glucose

Carbon Fixation

First step in the Calvin Cycle: CO2 is fixed by rubisco to form a 6-carbon compound that splits into two 3-carbon molecules

Reduction

Second step in the Calvin Cycle: ATP and NADPH are used to reduce the 3-carbon molecules into G3P.

Regeneration of RuBP

Final step in the Calvin Cycle: Some G3P molecules are used to regenerate RuBP, allowing the cycle to continue

Chlorophyll b

Assists chlorophyll a in capturing light.

Carotenoids

Accessory pigments that protect the plant by absorbing light in different wavelengths

Photosystem II (P680)

Uses light energy to split water molecules and release oxygen, initiating the electron transport chain

Photosystem I (P700)

Uses light energy to boost electrons to a higher energy level and ultimately reduce NADP+ to NADPH

Electron Transport

Electrons move through various proteins in the thylakoid membrane, generating a proton gradient that drives ATP synthesis, pumps H⁺ from a low to high concentration gradient

Chloroplast Inner Membrane

Contains the thylakoid membrane, where light-dependent reactions occur

Photosynthesis is what type of reaction?

Anabolic

Cellular Respiration is what type of reaction?

Catabolic

Cellular Respiration equation

C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + ATP

Heterotrophs

Organisms that obtain food by consuming other organisms

Autotrophs

Organisms that make their own food through photosynthesis

Photophosphorylation

The process of generating ATP from ADP using light energy