Photosynthesis and Cellular Respiration

Vocabulary practice flashcards covering photosynthesis, light reactions, the Calvin cycle, chloroplast morphology, cellular respiration, and mitochondrial structure.

Photosynthesis

An anabolic process performed by plants, algae, protists, and some bacteria that traps radiant solar energy and converts it into chemical energy stored as glucose, following the reaction $6CO_2 + 6H_2O + \text{energy} \rightarrow C_6H_{12}O_6 + 6O_2$.

Cellular Respiration

A catabolic process performed by plants and animals/consumers that breaks down the chemical energy stored in the bonds of glucose into usable energy in the form of $\text{ATP}$.

Anabolic Pathway

A metabolic pathway that synthesizes larger, more complex molecules from smaller ones and requires an input of energy (such as photosynthesis constructing glucose).

Catabolic Pathway

A metabolic pathway that breaks down larger molecules into smaller ones, releasing energy in the process (such as cellular respiration breaking down glucose).

Plant Dry Mass Origin

The added dry mass of a growing plant or tree, which originates primarily from carbon dioxide ($CO_2$) absorbed from the air and fixed into organic molecules.

Chlorophyll a

The primary light-absorbing pigment directly involved in photosynthesis, absorbing blue-violet and red wavelengths while reflecting green light.

Chlorophyll b

An accessory photosynthetic pigment that absorbs additional wavelengths of light to broaden the overall range of light a plant can capture.

Carotenoids

Accessory pigments in photosynthetic organisms that absorb additional wavelengths of light and protect cells against excess light.

Action Spectrum

A graph showing the rate of photosynthesis produced by an organism across different wavelengths of visible light.

Absorption Spectrum

A graph displaying the relative amounts of light absorbed at various wavelengths by individual photosynthetic pigments.

Chloroplast

A double-membrane organelle found in plant and algae cells that serves as the site of photosynthesis.

Thylakoid

A flattened, disc-shaped sac within a chloroplast whose membrane contains embedded chlorophyll and is the site of the light-dependent reactions.

Granum

A stack of thylakoid discs inside a chloroplast (plural: grana).

Lamellae

Skeletal channel structures that connect adjacent stacks of grana within the chloroplast.

Stroma

The gel-like aqueous fluid surrounding the grana inside a chloroplast, containing enzymes and chemicals used to synthesize glucose during the Calvin cycle.

Lumen

The fluid-filled interior space enclosed by the thylakoid membrane where protons ($H^+$) accumulate during electron transport.

ATP (Adenosine Triphosphate)

The principal energy molecule of the cell that transfers usable energy to cellular processes, produced during light-dependent reactions and consumed in the Calvin cycle.

NADPH (Nicotinamide Dinucleotide Phosphate)

A high-energy electron carrier formed when $NADP^+$ accepts one hydrogen atom and $2\,e^-$, providing reducing power to the Calvin cycle.

Oxidation

A chemical reaction in which an atom or molecule loses one or more electrons.

Reduction

A chemical reaction in which an atom or molecule gains one or more electrons, resulting in a higher energy state.

Reducing Power

The stored chemical energy characteristic of molecules in their reduced form, allowing them to donate electrons to reduce other compounds.

Photosystems

Arrangements of chlorophyll and other light-absorbing pigments embedded in the thylakoid membrane (specifically Photosystem I and Photosystem II) that capture photon energy.

Photolysis

The light-driven splitting of water molecules within the thylakoid membrane according to the equation $2H_2O + \text{energy} \rightarrow 4H^+ + 4e^- + O_2$, replenishing electrons in the photosystems.

ATP Synthase Complex

A specialized membrane protein complex that uses energy derived from the passive flow of $H^+$ ions down their gradient out of the lumen into the stroma to synthesize $\text{ATP}$.

Calvin Cycle

The light-independent stage of photosynthesis occurring in the stroma where carbon dioxide ($CO_2$) is fixed into sugars using energy from $\text{ATP}$ and reducing power from $\text{NADPH}$.

RuBisCO

The enzyme (RuBP carboxylase) that catalyzes the first stage of the Calvin cycle by attaching carbon dioxide ($CO_2$) to ribulose bisphosphate (RuBP).

G3P (Glyceraldehyde 3-Phosphate)

The three-carbon sugar formed during the reduction phase of the Calvin cycle, used to synthesize glucose and regenerate RuBP.

Paper Chromatography

A laboratory technique used to separate and analyze the individual photosynthetic pigments present in plant tissue based on size, charge, polarity, and solubility.

Rf Value (Reference Flow)

A metric used in chromatography to determine pigment solubility, calculated as $\text{Rf} = \frac{\text{distance travelled by pigment}}{\text{distance travelled by solvent}}$.

Mitochondria

Double-membraned cellular organelles that serve as the site of cellular respiration and aerobic $\text{ATP}$ production.

Mitochondrial Matrix

The fluid-filled space within the inner mitochondrial membrane containing enzymes and an appropriate pH to support the Krebs cycle and breakdown of glucose products.

Cristae

The inner folds of the inner mitochondrial membrane that expand the available surface area for oxidative phosphorylation and $\text{ATP}$ synthesis.

Steps of Aerobic Cellular Respiration

The four sequential stages through which glucose is disassembled to extract energy: 1. Glycolysis, 2. Pyruvate Oxidation, 3. Krebs Cycle, and 4. Electron Transport Chain and Chemiosmosis.