Name: light-harvesting in photosynthesis
Uploaded: 2025-08-20T08:43:35.000Z
Duration: 1 min 15 s
Channel: JoVE

K12 Standards

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NC K-12 Science Standard Course of Study

9-12

Biology

from-molecules-to-organisms-structures-and-processes

From Molecules to Organisms- Structures and Processes

LS.Bio.3.2

The Antenna Complex

The reaction center of a photosystem alone is not efficient enough to meet the energy demand of the electron transport chain.So, it is assisted by a surrounding antenna or light-harvesting complex, which comprises several hundred pigment molecules, including chlorophyll a, b, and other accessory pigments.Unlike the reaction center, the photochemically inactive antenna complex pigments cannot directly convert light energy into chemical energy.However, these pigments absorb photons of varying wavelengths and rapidly transfer energy to the adjacent pigments.These antenna pigments are positioned close to each other by a protein scaffold, forming an energy-efficient complex.As a result, the energy absorbed by the antenna complex is channeled through a network of pigment molecules to the reaction center.Finally, a special pair of chlorophyll molecules in the reaction center absorbs these photons.The reaction center can now transmit an adequate number of electrons to the electron transport chain, enhancing its yield.

the antenna complex

Plants and other photosynthetic organisms comprise pigments capable of absorption of direct sunlight. These pigments are present in the reaction center - the main site of photochemical reactions as well as in the antenna complex. Under average light conditions, the rate at which reaction center pigments absorb light is far below the electron transport chain's capacity. As a result, the reaction center alone cannot provide enough energy to drive photosynthesis. The photosynthetic efficiency can be increased with an antenna complex where hundreds of pigment molecules absorb different wavelengths of light. The energy thus accumulated over a larger surface is then transferred to the reaction center.
The antenna complex, also known as the light-harvesting complex (LHC), comprises hundreds of chlorophyll molecules and dozens of carotenoids. The antenna pigments are organized into protein scaffolds that hold the pigments in the right position and orientation. The major function of the antenna complex is to transfer excitation energy to the reaction center. Another important function is to safely dissipate excess absorbed energy as heat.
In plants and most algae, the chlorophyll a and b molecules are integral components of the light-harvesting complex. The relative concentration of chlorophyll a and chlorophyll b is used as an indicator of the antenna size. Seasonal changes in light intensity may cause variation in the ratio of chlorophyll a/b, thus altering the antenna size. For instance, in LHCII (for photosystem II), low light conditions trigger the synthesis of chlorophyll b. As a consequence, the antenna size increases, allowing increased absorption of available light. In contrast, the antenna size must be reduced under high-light intensities to prevent excess light capture.

Plants and other photosynthetic organisms comprise pigments capable of absorption of direct sunlight. These pigments are present in the reaction center - ...

Education

JoVE Core

Cell Biology

Unit 1

Chloroplasts and Photosynthesis

KEY TERMS AND CONCEPTS

light-harvesting in photosynthesis

Light-harvesting in photosynthesis depends on the antenna complex, also called the light-harvesting complex (LHC). Plants and other photosynthetic organisms use this system to collect direct sunlight with pigments in both the reaction center and the antenna complex. The reaction center is the main site of photochemical reactions.

Under average light conditions, the reaction center pigments absorb light more slowly than the electron transport chain can use it. The reaction center alone cannot supply enough energy to drive photosynthesis. The antenna complex solves this by spreading light capture across hundreds of pigment molecules that absorb different wavelengths.

The antenna complex contains hundreds of chlorophyll molecules and dozens of carotenoids. These pigments are arranged on protein scaffolds that keep them in the correct position and orientation. The absorbed energy is then transferred to the reaction center. The antenna complex also helps safely release excess absorbed energy as heat.

In plants and most algae, chlorophyll a and chlorophyll b are key parts of the light-harvesting complex. The relative amount of chlorophyll a and chlorophyll b can show antenna size. Seasonal changes in light intensity can shift this ratio and change how large the antenna is.

In LHCII, the light-harvesting complex of photosystem II, low light triggers the production of chlorophyll b. This increases antenna size and helps the plant absorb more available light. Under high-light conditions, the antenna size must be reduced to avoid capturing too much light.

Light-Harvesting in Photosynthesis

what is photosynthesis?

Photosynthesis Powers the Food Chain

Photosynthesis powers the food chain by turning sunlight into usable chemical energy. It is the only biological process that can capture energy from sunlight and convert it into chemical energy that organisms use to support metabolism. Photosynthesis also provides the oxygen needed by many living things. Organisms are often grouped by how they get food. Autotrophs are organisms that make their own food. Plants, algae, and cyanobacteria are autotrophs, and because they use light to make...

the anatomy of chloroplasts

How Chloroplasts Power Photosynthesis

Chloroplasts are the organelles that power photosynthesis in green algae and plants. They are found in green stems and unripe fruit as well as in leaves. Inside chloroplasts, the two stages of photosynthesis work together to turn sunlight, carbon dioxide, and water into chemical energy. The light-dependent reactions capture sunlight and release oxygen. They also make ATP and NADPH, which are energy-rich molecules. The light-independent reactions then use ATP and NADPH to capture CO2 and build...

the calvin benson cycle

Photorespiration, C4, and CAM Pathways

Photorespiration and the C4 and CAM pathways change how plants handle carbon dioxide during photosynthesis. These processes matter because RuBisCo, the enzyme that starts carbon dioxide fixation, works very slowly. A typical enzyme can process about a thousand molecules per second, but RuBisCo fixes only around three carbon dioxides per second. To make up for this slow rate, photosynthetic cells produce very large amounts of RuBisCo. That is why it is the most abundant single enzyme on Earth. <br...

the photochemical reaction center

Light-Harvesting Antennas in Reaction Centers

Light-harvesting antennas and reaction centers work together in photosynthesis. A reaction center is a pigment-protein complex that starts the conversion of light energy into chemical energy. The term photochemical reaction center is more precise because these complexes carry out the first light-driven chemical step. Robert Emerson and William Arnold gave the first experimental evidence for these centers. They showed that nearly 2,500 chlorophyll molecules were involved in the release of just...

Light-harvesting in photosynthesis depends on the antenna complex, also called the light-harvesting complex (LHC). Plants and other photosynthetic organisms use this system to collect direct sunlight with pigments in both the reaction center and the antenna complex. The reaction center is the main site of photochemical reactions. Under average light conditions, the reaction center pigments absorb light more slowly than the electron transport chain can use it. The reaction center alone cannot...

photosystems

Photosystems in Light Reactions

Photosystems are pigment-rich protein complexes that help drive the light reactions of photosynthesis in plants, algae, and cyanobacteria. They are embedded in the thylakoid membrane inside the chloroplast. Their job is to capture light energy and pass it along for chemical use. Each photosystem contains many pigment molecules, including chlorophylls and carotenoids. These pigments are arranged in two parts: the antenna complex and the reaction center. The antenna complex absorbs photons and...

the z-scheme of electron transport in photosynthesis

the-z-scheme-of-electron-transport-in-photosynthesis

How Electron Flow Powers the Z-Scheme

The Z-scheme explains how electrons move through the light reactions of photosynthesis. In this process, light energy drives electrons from water to NADP+, and oxygen is released when water splits. Because water is hard to oxidize, the reaction needs a strong oxidizing agent. That role is filled by oxidized P680, also called P680+. It is the first product of the light reactions and is known as the most powerful oxidizing agent in biology. After it gains an electron from water-splitting, P680+...

key terms and concepts

Learn how the antenna complex helps plants capture light, transfer energy to the reaction center, and adjust antenna size with changing light levels.

Light-Harvesting in Photosynthesis | JoVE K12

cell biology

JoVE Core Cell Biology illustrates complex cellular processes in easy-to-understand yet comprehensive animated video lessons. This collection focuses on the essential components and functions of cells, including organelles and membranes, cellular transport, and cell energetics. It is complemented by scientist-in-action videos that demonstrate the application of cell biology in real-world research experiments.

Pennsylvania State Academic Standards

Life Science

matter-and-energy-in-organisms-and-ecosystems

Matter and Energy in Organisms and Ecosystems

3.1.9-12.E

3.1.9-12.J

3.1.9-12.K

Louisiana Student Standards for Science

High School

Life Sciences

From Molecules To Organisms: Structures And Processes

HS-LS1-5

ecosystems-interactions-energy-and-dynamics

Ecosystems: Interactions, Energy And Dynamics

HS-LS2-1

Environmental Science

HS-LS2-4

ohios-learning-standards-and-model-curriculum

Ohio’s Learning Standards and Model Curriculum

Cells

Cellular processes

Tennessee Academic Standards

From Molecules to Organisms: Structures and Processes

BIO1.LS1.8

Virginia  Standards of Learning

HIgh School

BIO.2

BIO.2.e

Minnesota Academic Standards in Science

3.1.1 9L.3.1.1.2

3.2.1 9L.3.2.1.3

new-jersey-student-learning-standards-for-science

New Jersey Student Learning Standards for Science

Arizona Science Standards

HS.L2

HS.L2U1.21

HS+B.L2

HS+B.L2U1.8

Alabama Course of Study Science

9-12.B.1.5.b

Next Generation Science Standards

Florida Department of Education

SC.912.L.18

SC.912.L.18.7

south-carolina-college-and-career-ready-science-standards

South Carolina College and Career Ready Science Standards

B-LS1-5

Georgia Standards of Excellence

Botany

SBO1.

Photosynthesis

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Light-Harvesting in Photosynthesis

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