thylakoid

Examples of thylakoid in the following topics:

• Main Structures and Summary of Photosynthesis

  • In multicellular autotrophs, the main cellular structures that allow photosynthesis to take place include chloroplasts, thylakoids, and chlorophyll.
  • Within the double membrane are stacked, disc-shaped structures called thylakoids.
  • The thylakoid membrane encloses an internal space called the thylakoid lumen.
  • A stack of thylakoids is called a granum, and the liquid-filled space surrounding the granum is the stroma or "bed."
  • Stacks of thylakoids called grana form a third membrane layer.

• The Two Parts of Photosynthesis

  • The light-dependent reactions take place in the thylakoid membranes in the granum (stack of thylakoids), within the chloroplast.
  • Two types of photosystems are embedded in the thylakoid membrane: photosystem II ( PSII) and photosystem I (PSI).
  • Light-dependent reactions, which take place in the thylakoid membrane, use light energy to make ATP and NADPH.

• Comparing Plant and Animal Cells

  • Like mitochondria, chloroplasts have outer and inner membranes, but within the space enclosed by a chloroplast's inner membrane is a set of interconnected and stacked fluid-filled membrane sacs called thylakoids .
  • Each stack of thylakoids is called a granum (plural = grana).
  • The chloroplast has an outer membrane, an inner membrane, and membrane structures called thylakoids that are stacked into grana.
  • The space inside the thylakoid membranes is called the thylakoid space.
  • The light harvesting reactions take place in the thylakoid membranes, and the synthesis of sugar takes place in the fluid inside the inner membrane, which is called the stroma.

• Processes of the Light-Dependent Reactions

  • Two types of photosystems, photosystem I (PSI) and photosystem II (PSII), are found in the thylakoid membrane inside the chloroplast .
  • Cytochrome b6f complex and ATP synthase are also major protein complexes in the thylakoid membrane that work with the photosystems to create ATP and NADPH.
  • The electron transport chain moves protons across the thylakoid membrane into the lumen.
  • The net result is a low pH in the thylakoid lumen and a high pH in the stroma.

• The Evolution of Plastids

  • Unlike most prokaryotes, however, they have extensive, internal membrane-bound compartments called thylakoids, which contain chlorophyll and are the site of the light-dependent reactions of photosynthesis .
  • In addition to thylakoids, chloroplasts found in eukaryotes have a circular DNA chromosome and ribosomes similar to those of cyanobacteria.
  • Stacks of thylakoid membranes compartmentalize photosynthetic enzymes and provide scaffolding for chloroplast DNA.

• Prochlorophytes

  • These organisms lack red and blue Phycobilin pigments and have staked thylakoids, both of which make them different from Cyanophyta (Cyanobacteria).

• Cyanobacteria

  • In most forms the photosynthetic machinery is embedded into folds of the cell membrane, called thylakoids.
  • Their plasma membrane contains only components of the respiratory chain, while the thylakoid membrane hosts both respiratory and photosynthetic electron transport.

• Absorption of Light

  • Therefore, many carotenoids are stored in the thylakoid membrane to absorb excess energy and safely release that energy as heat.
  • (a) Chlorophyll a, (b) chlorophyll b, and (c) β-carotene are hydrophobic organic pigments found in the thylakoid membrane.