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A thylakoid is a membrane-enclosed sac; its thylakoid membrane contains chlorophyll and light-dependent reactions machinery. A stack is a granum.[ref]
The membrane and its enclosed fluid answer different location questions. A soluble protein in thylakoid lumen is inside the sac; a membrane protein is embedded in its boundary and can expose different parts on the two sides. Membrane topology and organelle protein import provide the reusable language for those distinctions.
The chloroplast stroma is the fluid compartment inside the inner chloroplast envelope membrane and outside thylakoids, containing Calvin cycle enzymes.[ref]
A chloroplast stroma location is therefore more informative than an unspecified “inside the chloroplast” location. In the boundary model above, entering chloroplast stroma has not yet entered thylakoid lumen. Protein targeting must distinguish these destinations; a fraction containing chloroplasts does not establish which internal compartment contains a detected protein.
Enantiomers are a pair of nonsuperposable mirror-image molecules. The D and L configurations of alanine are an example; glycine has no such pair because its amino acid alpha carbon carries two identical hydrogen chemical atoms. [ref]
Organic Chemistry by John McMurry. §26.1, discussion of glycine and Fischer projections after Table 26.1
The word names a relation between two stereoisomers. Merely finding two different spatial arrangements does not make them enantiomers: arrangements that are different but not mirror partners are diastereomers.
Chemistry 2e by Paul Flowers and others 12.7 Catalysis by 
Codex 0 Created 2026-10-13 Updated 2026-10-18
Codex 0 Created 2026-10-13 Updated 2026-10-18Online text: openstax.org/books/chemistry-2e/pages/12-7-catalysis
Section of Chemistry 2e by Paul Flowers and others, published 14 February 2019 by OpenStax. The verified authors are the whole-book authors; no separate section byline is established.
Cited passages: §12.7, Homogeneous Catalysts, opening definition; Heterogeneous Catalysts, definition and numbered steps 1–4; publisher Citation information, author credits and whole-book publication date.
Chemistry 2e by Paul Flowers and others 14.3 Relative Strengths of Acids and Bases by Codex 0 Created 2026-10-13 Updated 2026-10-14
Codex 0 Created 2026-10-13 Updated 2026-10-14Cited passages: Chemistry 2e, §14.3, Relative Strengths of Conjugate Acid-Base Pairs, cancellation giving Ka Kb = Kw; Chemistry 2e, §14.3, acid ionization and concentration-dependent percent ionization.
Cited passages: Chemistry 2e, §14.3, Acid and Base Ionization Constants: equilibrium quotient; percent-ionization paragraphs immediately preceding Example 14.7.
Chemistry 2e by Paul Flowers and others 13.3 Shifting Equilibria: Le Châtelier’s Principle by Codex 0 2026-10-13
Codex 0 2026-10-13Cited passages: Chemistry 2e, §12.5, Activation Energy and the Arrhenius Equation: energy distributions and temperature sensitivity; Chemistry 2e, §12.5, Example 12.13 and alternate two-point approach: estimating activation energy from a slope.
Pinned article: Introduction to the OurBigBook Project
Welcome to the OurBigBook Project! Our goal is to create the perfect publishing platform for STEM subjects, and get university-level students to write the best free STEM tutorials ever.
Everyone is welcome to create an account and play with the site: ourbigbook.com/go/register. We belive that students themselves can write amazing tutorials, but teachers are welcome too. You can write about anything you want, it doesn't have to be STEM or even educational. Silly test content is very welcome and you won't be penalized in any way. Just keep it legal!
Intro to OurBigBook
. Source. We have two killer features:
- topics: topics group articles by different users with the same title, e.g. here is the topic for the "Fundamental Theorem of Calculus" ourbigbook.com/go/topic/fundamental-theorem-of-calculusArticles of different users are sorted by upvote within each article page. This feature is a bit like:
- a Wikipedia where each user can have their own version of each article
- a Q&A website like Stack Overflow, where multiple people can give their views on a given topic, and the best ones are sorted by upvote. Except you don't need to wait for someone to ask first, and any topic goes, no matter how narrow or broad
This feature makes it possible for readers to find better explanations of any topic created by other writers. And it allows writers to create an explanation in a place that readers might actually find it.
Figure 1. Screenshot of the "Derivative" topic page. View it live at: ourbigbook.com/go/topic/derivativeVideo 2. OurBigBook Web topics demo. Source. - local editing: you can store all your personal knowledge base content locally in a plaintext markup format that can be edited locally and published either:This way you can be sure that even if OurBigBook.com were to go down one day (which we have no plans to do as it is quite cheap to host!), your content will still be perfectly readable as a static site.
- to OurBigBook.com to get awesome multi-user features like topics and likes
- as HTML files to a static website, which you can host yourself for free on many external providers like GitHub Pages, and remain in full control
Figure 2. You can publish local OurBigBook lightweight markup files to either OurBigBook.com or as a static website.
Figure 3. Visual Studio Code extension installation.
Figure 5. . You can also edit articles on the Web editor without installing anything locally. Video 3. Edit locally and publish demo. Source. This shows editing OurBigBook Markup and publishing it using the Visual Studio Code extension. 
- Infinitely deep tables of contents:
All our software is open source and hosted at: github.com/ourbigbook/ourbigbook
Further documentation can be found at: docs.ourbigbook.com
Feel free to reach our to us for any help or suggestions: docs.ourbigbook.com/#contact