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Chloroplast

In brief

A chloroplast is a photosynthetic organelle of plants and algae. Its thylakoid membranes and surrounding stroma perform complementary tasks: light-driven electron transport helps produce ATP and NADPH, while carbon-fixation reactions use them to build organic compounds. Different compartments bring these reactions together in one organelle. [6] [7] [8] [9] [10]

Evidence for this statement

Source-based explanation

Where to check this statement

biology59-plastids
Chloroplast envelope, stroma, thylakoid membrane and proton gradient paragraphs
biology59-carbon
Chloroplasts Capture Energy from Sunlight and Use It to Fix Carbon; carbon-fixation cycle paragraphs
biology59-overview
Basic Photosynthetic Structures: envelope, thylakoid membranes, grana, lumen and stroma
biology59-light
How Light-Dependent Reactions Work; Figure8.17 explanatory text: PSII/PSI, ATP, NADPH and proton gradient; no figure reused
biology59-fixation
The Calvin Cycle; Stages1–3: fixation, reduction and regeneration; no quantitative ATP/NADPH lifetime or evolutionary dating claim used
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Where light energy becomes chemical work

Example: Arabidopsis thaliana, first leaf of control seedling grown without added NaCl; Figure 3A
Example: Arabidopsis thaliana, first leaf of control seedling grown without added NaCl; Figure 3ATeaching material · Peharec Štefanić, Koffler, Adler & Bar-Zvi (2013) · CC-BY-4.0 · Original and attribution

The electron micrograph shows a chloroplast from a control Arabidopsis seedling in a particular study. The original figure retains a 1 μm scale; it does not show a spruce chloroplast.

[1] [2] [3]
Evidence for this statement

Source-based explanation

Where to check this statement

go-chloroplast
Captured GO ontology JSON: results[].id and definition.text
uniprot-P83755
Captured UniProt JSON: primaryAccession, organism, sequence and FUNCTION comments

From organelle structure you can explore photosystem II and a PsbA protein record. This connects concepts; it does not establish that the molecular record came from the pictured specimen.

[1] [2] [3]
Evidence for this statement

Source-based explanation

Where to check this statement

go-chloroplast
Captured GO ontology JSON: results[].id and definition.text
uniprot-P83755
Captured UniProt JSON: primaryAccession, organism, sequence and FUNCTION comments

Structure and function

Evidence for this statement

EcoGenesis

    Original teaching diagram of structures and roles described in this article. It is schematic: no specimen geometry, dimensions or measured activity are represented.
    1. Envelope

      Outer and inner membranes

    2. Thylakoid membrane

      Light-driven electron transfer and ATP synthesis

    3. Stroma

      Carbon-fixation reactions

    Envelope, stroma and thylakoids

    The envelope has outer and inner membranes. Inside lies the stroma, with metabolic enzymes and the chloroplast genetic system. Thylakoid membranes form a separate internal system enclosing the lumen; stacks are called grana. The envelope and the thylakoid system are different membranes with different roles.

    [6] [8] [9]
    Evidence for this statement

    EcoGenesis

    Where to check this statement

    biology59-plastids
    Chloroplast envelope, stroma, thylakoid membrane and proton gradient paragraphs
    biology59-overview
    Basic Photosynthetic Structures: envelope, thylakoid membranes, grana, lumen and stroma
    biology59-light
    How Light-Dependent Reactions Work; Figure8.17 explanatory text: PSII/PSI, ATP, NADPH and proton gradient; no figure reused

    How a membrane helps make ATP

    Electron transport builds an electrochemical proton gradient across the thylakoid membrane. Protons returning through ATP synthase drive ATP production on the stromal side. ATP and NADPH support carbon fixation. Separating compartments enables the gradient to do chemical work.

    [6] [7] [8] [9] [10]
    Evidence for this statement

    EcoGenesis

    Where to check this statement

    biology59-plastids
    Chloroplast envelope, stroma, thylakoid membrane and proton gradient paragraphs
    biology59-carbon
    Chloroplasts Capture Energy from Sunlight and Use It to Fix Carbon; carbon-fixation cycle paragraphs
    biology59-overview
    Basic Photosynthetic Structures: envelope, thylakoid membranes, grana, lumen and stroma
    biology59-light
    How Light-Dependent Reactions Work; Figure8.17 explanatory text: PSII/PSI, ATP, NADPH and proton gradient; no figure reused
    biology59-fixation
    The Calvin Cycle; Stages1–3: fixation, reduction and regeneration; no quantitative ATP/NADPH lifetime or evolutionary dating claim used

    Membranes and internal space

    The Gene Ontology definition describes chloroplast organisation through thylakoids and stroma. Some thylakoids form grana; connecting regions are also named in the definition. This organisation helps interpret a micrograph but does not replace its scale or supply dimensions for every chloroplast.

    [1]
    Evidence for this statement

    Explanation of retained sources

    Where to check this statement

    go-chloroplast
    Captured GO ontology JSON: results[].id and definition.text

    Keeping the image caption

    The illustrated material belongs to a control Arabidopsis seedling in a particular study. The 1 μm scale belongs to the original figure. Before comparing another image, check organism, material, conditions and scale: following a link does not turn an Arabidopsis chloroplast image into a spruce chloroplast image.

    [2]
    Evidence for this statement

    Explanation of retained sources

    Structure, process and protein

    Chloroplast is a cellular component, photosynthesis a biological process and photosystem II a molecular complex. These categories explain different aspects of a question. UniProt P83755 identifies another object: the Arabidopsis D1 protein. Conceptual links do not establish a shared specimen across these materials.

    [1] [4] [5] [3]
    Evidence for this statement

    Explanation of retained sources

    Where to check this statement

    go-chloroplast
    Captured GO ontology JSON: results[].id and definition.text
    go-photosynthesis
    Captured GO ontology JSON: results[].id and definition.text
    go-photosystem2
    Captured GO ontology JSON: results[].id and definition.text
    uniprot-P83755
    Captured provider JSON; named selected record and native source versions

    Connected concepts

    Photosynthesis

    Photosynthesis synthesises organic compounds, including carbohydrates, from carbon dioxide using light energy. Gene Ontology identifies it as the biological process GO:0015979.

    [4] [5]
    Evidence for this statement

    Source-based explanation

    Where to check this statement

    go-photosynthesis
    Captured GO ontology JSON: results[].id and definition.text
    go-photosystem2
    Captured GO ontology JSON: results[].id and definition.text
    Photosystem II

    Photosystem II is a molecular complex associated with pigments and electron carriers. In chloroplasts and cyanobacteria it uses light to transfer electrons from water to plastoquinone.

    [5] [3]
    Evidence for this statement

    Source-based explanation

    Where to check this statement

    go-photosystem2
    Captured GO ontology JSON: results[].id and definition.text
    uniprot-P83755
    Captured provider JSON; named selected record and native source versions

    Continue with an organism

    The photographs and molecular record come from separate source materials.

    Norway spruce →Arabidopsis thaliana →

    Your research question

    Save the article to return to your question and this source version.

    Plan a test

    This is your research plan. Completing these fields does not confirm a hypothesis.

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    Sources and versions

    Editorial draft · human review pending

    1. GO:0009507 · chloroplast

      2026-09-09T01:17:34.931415+00:00 · CC-BY-4.0

      Provenance and original
      Original SHA-256
      13082607c7dcc9e92cd281f1fc6a8fdf2878bceba74e9d7b6ad50d43b0ce33ba
      Processing
      Unmodified provider response; article text is an attributed educational summary.
      Version details
      QuickGO response did not supply a native ontology release; retrieval time and exact response hash retained.

      View original JSON · Download original

    2. Arabidopsis thaliana, first leaf of control seedling grown without added NaCl; Figure 3A

      Retrieval date unknown · CC BY 4.0

      Provenance and original
      Original SHA-256
      fe305c7d3a3327a06dda04c186989b5b8b6dec101bfe13aa851a3bc47dc07b14
      Processing
      Panel A extracted; original g/t annotations and 1 µm scale retained; encoded as WebP.
    3. UniProt P83755 · entry 161 / sequence 2

      2026-09-09T01:17:34.554931+00:00 · CC-BY-4.0

      Provenance and original
      Source version
      entry 161; sequence 2
      Original SHA-256
      f16a5f33fbf85a12aa5c91ab31f6092f0bbe3be874040c84c4954e87b20ae3a9
      Processing
      Unmodified provider response; article text is an attributed educational summary.
      Version details
      Provider entry/sequence versions retained.

      View original JSON · Download original

    4. GO:0015979 · photosynthesis

      2026-09-09T01:17:01.233038+00:00 · CC-BY-4.0

      Provenance and original
      Original SHA-256
      8649763135938e40bdb112c62e870749510eea1b750ff5d230a3061be5a3e017
      Processing
      Unmodified provider response; article text is an attributed educational summary.
      Version details
      QuickGO response did not supply a native ontology release; retrieval time and exact response hash retained.

      View original JSON · Download original

    5. GO:0009523 · photosystem II

      2026-09-09T01:17:35.068503+00:00 · CC-BY-4.0

      Provenance and original
      Original SHA-256
      56537702684f4e6949eb9b16430a8830740bc9fd3369b21e7b5a9b711a341b4f
      Processing
      Unmodified provider response; article text is an attributed educational summary.
      Version details
      QuickGO response did not supply a native ontology release; retrieval time and exact response hash retained.

      View original JSON · Download original

    6. Cooper (2000) · Chloroplasts and Other Plastids

      2026-10-01 · Terms of use on source site

      Provenance and original
      Source version
      Selected web passages checked 2026-10-01; no immutable response edition asserted
      Source reading scope
      Named background passages only; not new experimental evidence.
      Location in the original source
      Chloroplast envelope, stroma, thylakoid membrane and proton gradient paragraphs
    7. Alberts et al. (2002) · Chloroplasts and Photosynthesis

      2026-10-01 · Terms of use on source site

      Provenance and original
      Source version
      Selected web passages checked 2026-10-01; no immutable response edition asserted
      Source reading scope
      Named background passages only; not new experimental evidence.
      Location in the original source
      Chloroplasts Capture Energy from Sunlight and Use It to Fix Carbon; carbon-fixation cycle paragraphs
    8. Clark, Douglas & Choi · Biology 2e · 8.1 Overview of Photosynthesis

      2026-10-01 · Terms of use on source site

      Provenance and original
      Source version
      Selected publisher HTML passages checked 2026-10-01
      Source reading scope
      Named foundational biology paragraphs only; background facts checked against classical textbooks and captured GO/UniProt records; not an experimental result.
      Location in the original source
      Basic Photosynthetic Structures: envelope, thylakoid membranes, grana, lumen and stroma
    9. Clark, Douglas & Choi · Biology 2e · 8.2 Light-Dependent Reactions

      2026-10-01 · Terms of use on source site

      Provenance and original
      Source version
      Selected publisher HTML passages checked 2026-10-01
      Source reading scope
      Named foundational biology paragraphs only; background facts checked against classical textbooks and captured GO/UniProt records; not an experimental result.
      Location in the original source
      How Light-Dependent Reactions Work; Figure8.17 explanatory text: PSII/PSI, ATP, NADPH and proton gradient; no figure reused
    10. Clark, Douglas & Choi · Biology 2e · 8.3 Carbon Fixation

      2026-10-01 · Terms of use on source site

      Provenance and original
      Source version
      Selected publisher HTML passages checked 2026-10-01
      Source reading scope
      Named foundational biology paragraphs only; background facts checked against classical textbooks and captured GO/UniProt records; not an experimental result.
      Location in the original source
      The Calvin Cycle; Stages1–3: fixation, reduction and regeneration; no quantitative ATP/NADPH lifetime or evolutionary dating claim used
    Inspect structured data
    Content version
    05e63a6f913c0ae6f9666641cb3ac98455b4b0bf24409c2d92db9819955a2e0a
    Source version
    knowledge-20260909.1
    Updated
    2026-10-01