Photosynthesis Flashcards

Flashcards about Photosynthesis.

Photoautotrophs

Organisms that use sunlight to make food from inorganic molecules.

Chemoautotrophs

Organisms that capture energy from inorganic compounds to produce organic compounds.

Heterotrophs

Organisms that rely on the sugars produced by autotrophs for their energy needs.

Photosynthesis

The process that uses solar energy to produce sugar from carbon dioxide and water, with oxygen as a waste product.

Stomata

Small pores on the leaf underside where gas exchange occurs.

Mesophyll cells

Cells in the interior of leaves where high densities of chloroplasts occur.

Light reaction and The Calvin Cycle

The two metabolic pathways of photosynthesis.

Light reaction

Converts light energy to chemical energy, making ATP and NADPH.

Calvin cycle

Uses ATP and NADPH to make sugar (food).

Thylakoid membranes

The location of the light reaction.

Stroma

The location of the Calvin cycle.

Grana

Stacks of thylakoids

Lumen

The space inside the thylakoid.

Light energy

Electromagnetic energy composed of photon particles that travel as waves.

Visible range

The range of light energy visible to humans.

Nanometers (nm)

The measurement of wavelengths of light.

Photosynthetic pigments

Pigments that absorb specific wavelengths of light.

Chlorophyll a, chlorophyll b, and β-carotene

The main pigments of the thylakoid membranes.

β-carotene

Helps to protect photosystems by dissipating excess energy.

Photosystems II and I

Sites of light absorption in the thylakoid membranes.

Electron Transport Chain (ETC)

A series of molecules in the thylakoid membrane that transport electrons.

NADP reductase and ATP synthase

Two enzyme complexes in the thylakoid membranes.

Photosystems II and I

Consists of a light-harvesting complex and a reaction center.

Light-harvesting complex

Passes light energy to two special chlorophyll a molecules in the reaction center.

First electron acceptor

The first electron acceptor of the ETC in the reaction center.

Photosystem II

Where the electron comes from the splitting of water, which releases oxygen as a waste product.

Photosystem I

Where the electron comes from the ETC.

Plastoquinone Qb, Cytochrome b6f, and Plastocyanin

Transports e- from PS II to PS I.

Ferredoxin

Transports e- from PS I to NADP reductase.

NADP+

The final e- acceptor of the light reaction.

Chemiosmosis

The process by which ATP synthase uses a H+ gradient to generate ATP.

Rubisco

Enzyme that adds CO2 to RuBP to generate two 3-PGA molecules.

RuBP (ribulose bisphosphate)

The molecule to which CO2 is added in the Calvin Cycle.

Reduction

The stage of the Calvin Cycle where ATP and NADPH are used to add e- and make sugar (G3P).

Regeneration

The stage of the Calvin Cycle where RuBP is regenerated from G3P.

Three

The number of cycles required to make one G3P.

Carbon Fixation

The conversion of inorganic carbon (carbon dioxide) to organic compounds by living organisms.

Photoautotrophs (examples)

Plants, algae, and cyanobacteria.

Chemoautotrophs (examples)

Thermophilic bacteria in deep sea vents.

Heterotrophs (examples)

Animals, fungi, and most bacteria.

Mesophyll

The interior tissue of a leaf, containing many chloroplasts.

Stroma (chloroplast)

The fluid-filled space surrounding the thylakoids inside a chloroplast.

Thylakoids

Disc-shaped structures inside chloroplasts where the light-dependent reactions occur.

Pigment

Molecule that absorbs light energy in photosynthesis.

Chlorophyll a

Primary pigment in plants that absorbs blue and red light.

Chlorophyll b

Accessory pigment in plants that absorbs blue and red light.

Carotenoids

Accessory pigment that reflects yellow and red light

Electron Transport Chain

Series of protein complexes that transfer electrons.

ATP Synthase

Protein complex that uses a proton gradient to produce ATP.

NADP+

Molecule that accepts electrons and protons to form NADPH.

NADPH

High-energy electron carrier that provides electrons for carbon fixation.

Chemiosmosis

Process in which ATP is generated using a proton gradient.

Carbon Fixation

First phase of the Calvin cycle, in which carbon dioxide is incorporated into an organic molecule.

Rubisco

Enzyme that catalyzes the first step of the Calvin cycle.

3-PGA (3-phosphoglycerate)

Three-carbon molecule formed in the first step of the Calvin cycle.

Reduction Phase (Calvin Cycle)

Phase of the Calvin cycle in which ATP and NADPH are used to convert 3-PGA to G3P.

G3P (glyceraldehyde-3-phosphate)

Three-carbon sugar formed in the Calvin cycle

Glucose

sugar molecules for plant use

Regeneration Phase (Calvin Cycle)

Phase of the Calvin cycle in which RuBP is regenerated.

photons

Light is composed of these

wavelength

Distance between crests in a wave

Thylakoid membrane

Location of the Photosystems and the Electron Transport Chain

Electrons

The splitting of water provides these for Photosystem II

Electron Transport Chain

Electrons move from Photosystem II to Photosystem I via these

Thylakoid Lumen

Proton (H+) concentration is higher here

NADPH

NADP+ becomes this when it accepts electrons

ATP Synthase

This enzyme uses the proton gradient to make ATP

G3P

CO2, ATP, and NADPH are used to make this in the Calvin Cycle

Carbon Fixation

Rubisco adds CO2 to RuBP in this process