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Plants are eukaryotes. A typical photosynthetic leaf cell has a cell nucleus, mitochondria, chloroplasts, and a cell wall outside its cell membrane. A root cell need not have chloroplasts; the plant's parts specialize for different functions. Plants perform cellular respiration as well as photosynthesis. See OpenStax Biology 2e, 4.3: plant cell organization.

A plant cell is a eukaryotic biological cell belonging to a plant. A cell wall outside the cell membrane provides mechanical support, while a large vacuole often occupies much of the interior. Photosynthetic plant cells contain chloroplasts; root cells and other nonphotosynthetic plant cells need not. Water entry can generate turgor pressure against the cell wall, explaining why cellular water balance contributes to the firmness of a leaf. ^[ref]

A plastid is an organelle of the lineage that includes chloroplasts. A chloroplast is a photosynthetic plastid; the terms are not interchangeable because some plastids are nonphotosynthetic. Endosymbiotic theory connects plastid origins to cyanobacteria, while endosymbiotic gene transfer and organelle protein import explain genetic and functional integration with the host.

Researcher in chloroplast gene regulation. With Alice Barkan, Chotewutmontri investigated damage-triggered psbA messenger RNA translation, connecting protein synthesis with an assembly-linked autoregulatory circuit in photosystem repair.^[ref]

A prokaryote is an organism whose biological cells lack a membrane-bounded cell nucleus. The DNA of its chromosomes occupies a nucleoid within the cytoplasm. Bacteria and archaea have this cellular organization. Both contain ribosomes that perform biological translation and a selective cell membrane; neither is a bag of unorganized chemicals. See OpenStax Biology 2e, 4.2: prokaryotic organization.

The word prokaryotic describes organization, not a single exclusive clade. Grouping bacteria and archaea by the absence of a cell nucleus is useful for comparing biological cells, but does not establish that they share a more recent ancestor with one another than either does with eukaryotes. See three-domain system and two-domain system for the different ancestry models.

Prokaryotic does not mean membrane-free. Cyanobacteria contain internal thylakoid membranes for oxygenic photosynthesis, despite lacking chloroplasts and a cell nucleus. Many prokaryotes have circular chromosomes, but circular shape and a single chromosome are not defining requirements. See OpenStax Biology 2e, 22.2: bacterial and archaeal structures.

Coauthor of experiments reconstructing functional transfer of a chloroplast gene to the cell nucleus. The study connected movement of DNA between compartments with the regulatory changes required for the transferred gene to operate.^[ref]

Robin Hill reported oxygen evolution by isolated chloroplasts. Studying the organelle separately from the whole plant connects a component of photosynthesis with a defined subcellular preparation.

The experiment asks whether the light-driven oxygen-producing machinery can remain functional after isolation. It helped make photosynthesis accessible to direct biochemical analysis.^[ref]

Biochemist.

Institutional biographical record: specialcollections-blog.lib.cam.ac.uk/?p=27166

Sabeeha S. Merchant studies photosynthesis, metabolism and how organisms manage essential metals. Her laboratory uses Chlamydomonas reinhardtii, a single-celled green alga, to investigate responses to limitations of iron and copper. Such limitations raise a concrete biochemical question: which essential tasks can a biological cell maintain when several proteins compete for a scarce chemical element? ^[ref]

Merchant is the first author of the 2007 report of the approximately 120-million-base-pair nuclear genome of Chlamydomonas reinhardtii. The team used comparative genomics to identify candidate genes associated with chloroplasts and flagella. The organism is revealing because it combines photosynthesis with motile flagella: comparisons with photosynthetic and nonphotosynthetic organisms can help distinguish these functional groups. Shared occurrence across species suggests candidate functions; experimental tests are still needed to establish what an individual protein does.^[ref]

Coauthor of experiments reconstructing functional transfer of a chloroplast gene to the cell nucleus. The study connected movement of DNA between compartments with the regulatory changes required for the transferred gene to operate.^[ref]

Researcher in photosynthesis. Bellafiore and collaborators showed that STN7 kinase is required for state transitions and light adaptation, connecting a chloroplast kinase with redistribution of excitation between photosystems.^[ref]

A botanist who investigated the phototropin-dependent movement of chloroplasts away from strong illumination, using mutants to connect a receptor to the avoidance response.^[ref]

Separates thylakoid lumen from chloroplast stroma in a chloroplast.

Waldan K. Kwong coauthored research on chlorophyll.^[ref]

Chlorophyll is a family of molecules that absorb light for photosynthesis. In chloroplasts, chlorophyll works with proteins in thylakoid membranes; absorbing light initiates energy capture rather than directly constructing a sugar. See OpenStax Biology 2e, 8.2: photosynthetic pigments.