Photosynthesis and Chloroplast Structure

Vocabulary flashcards covering chloroplast anatomy, photosynthetic pigments, energy molecules, light-dependent reactions, and the Calvin cycle.

Photosynthesis

An anabolic pathway occurring in chloroplasts that converts light energy into chemical energy in the form of glucose, represented by the formula $6\text{CO}_2 + 6\text{H}_2\text{O} + \text{light energy} \rightarrow \text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2$.

Photons

Packets of light energy that come in various wavelengths and energy levels.

Blue Photons

Photons characterized by short wavelengths that carry high energy.

Red Photons

Photons characterized by long wavelengths that carry low energy.

Chlorophyll

The green pigment in plants located in thylakoid membranes that absorbs red and blue light while reflecting green light.

Chlorophyll A

The photosynthetic pigment that directly transfers light energy into the process of photosynthesis.

Chlorophyll B

An accessory pigment that absorbs light and transfers energy to chlorophyll A.

Chloroplast Structure

A plant organelle enclosed by outer and inner membranes, containing stroma, disc-like thylakoids arranged in grana stacks, and interconnecting lamellae.

Thylakoid

A flattened, disc-shaped membrane sac containing chlorophyll where light-dependent reactions take place.

Grana

Stacks of thylakoid discs inside the chloroplast where the light-dependent reactions occur.

Stroma

The gel-like, fluid-filled space inside the inner membrane of the chloroplast containing DNA; site of the Calvin cycle (light-independent reactions).

Light-Dependent Reactions

Processes occurring across the thylakoid membrane that utilize inputs of $\text{H}_2\text{O}$, $\text{ADP} + \text{P}_\text{i}$, and $\text{NADP}^+$ to generate outputs of $\text{O}_2$, $\text{ATP}$, and $\text{NADPH}$.

Photolysis

The splitting of water ($\text{H}_2\text{O} \rightarrow \frac{1}{2}\text{O}_2 + 2\text{H}^+ + 2e^-$) to replace electrons lost from Photosystem II, releasing $\text{O}_2$ as a byproduct.

NADPH

An electron carrier synthesized via the reaction $\text{NADP}^+ + \text{H}^+ + 2e^- \rightarrow \text{NADPH}$ at NADP reductase, acting as a reducing agent in photosynthesis.

Chemiosmosis

The movement of hydrogen ions ($\text{H}^+$) across a selectively permeable membrane, where electron transport powers the pumping of $\text{H}^+$ to generate energy that powers light-independent reactions.