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Let count chromosomes in one complete set, and let denote the nuclear DNA amount in one unreplicated haploid set of this organism. Ploidy counts sets, whereas units count material; is not a universal mass shared by all species. Here we count a paired replicated chromosome as one until its sister chromatids separate. A copied diploid genome is therefore still diploid through S phase: persists even as becomes .
An original bookkeeping example uses a hypothetical diploid biological cell with . Name its three homologous chromosome pairs , and . Assume ordinary nuclear DNA replication, no chromosome loss, and one continuous double-stranded DNA molecule per unreplicated chromosome or replicated chromatid. Count nuclear material only, excluding mitochondrion DNA.
| Stage and counting compartment | Chromosomes | Double-stranded DNA molecules | Nuclear DNA amount |
|---|---|---|---|
| One G1 phase biological cell | 6 unreplicated | 6 | |
| One G2 phase biological cell | 6 replicated | 12 in 6 pairs of sister chromatids | |
| Whole undivided anaphase biological cell | 12 separated daughter chromosomes | 12 | total |
| Each completed daughter cell nucleus | 6 unreplicated | 6 | each |
For example, becomes the paired copies during S phase. They remain one replicated chromosome until separation. Each completed daughter receives one copy and one copy, and similarly for the other two pairs. Across both daughters, double-stranded DNA molecules and : division allocates the copied material without another round of DNA replication.
The whole undivided anaphase biological cell transiently contains separately counted daughter chromosomes. This counting change does not establish a four-set ploidy in a completed daughter genome: each pole receives , and each completed daughter cell nucleus is diploid. Always state whether a number refers to one cell nucleus, one pole, or the entire undivided biological cell. Compare meiotic DNA content: after meiosis I, a haploid cell nucleus can contain , so amount alone cannot determine ploidy.
G0 phase describes withdrawal from the division cycle. Some biological cells re-enter G1 phase; others remain nondividing. Metabolism and gene expression can continue. [ref] In the ordinary diploid case, alone cannot distinguish G0 phase from G1 phase.
The Calvin cycle couples carbon fixation to use of ATP and NADPH. In a chloroplast it takes place in the chloroplast stroma. Its chemical reactions incorporate carbon dioxide, use NADPH-supplied electrons, and regenerate the molecules that accept further carbon dioxide.
In the standard Calvin cycle bookkeeping, three carbon dioxide molecules require nine ATP and six NADPH for one net three-carbon triose phosphate. A six-carbon sugar equivalent therefore corresponds to six carbon dioxide, eighteen ATP and twelve NADPH; subsequent sugar synthesis is separate. These are pathway requirements, not a universal measured photosynthesis yield. See OpenStax Biology 2e, 8.3: Calvin cycle bookkeeping.
Calling the Calvin cycle light-independent means its individual chemical reactions do not directly capture light; it does not mean the Calvin cycle runs only at night or independently of the supplies from light-dependent reactions.
A triose phosphate is a three-carbon sugar carrying a phosphate group. Glyceraldehyde 3-phosphate is one example. The Calvin cycle supplies a net triose phosphate for further carbohydrate synthesis. [ref]
https://openstax.org/books/biology-2e/pages/8-3-using-light-energy-to-make-organic-molecules. OpenStax Biology 2e, 8.3: the Calvin cycle's carbohydrate product
.A polysaccharide is a polymer built from many linked monosaccharide units. Cellulose provides a structural example. See Biology 2e: polysaccharides.
In chemical usage, sugars commonly means small carbohydrates, including single-unit monosaccharides and two-unit disaccharides. Glucose, ribose, and deoxyribose are monosaccharides. Cellulose is instead a polysaccharide assembled from many glucose units. The distinction counts chemically linked units; it does not classify every carbohydrate by sweetness or biological role. See Clark, Douglas and Choi, Biology 2e, 3.2: carbohydrates.
A useful first description of a monosaccharide asks how many carbon chemical atoms it contains and what its open-chain structure is. Ribose is an aldopentose, a five-carbon aldehyde sugar; glucose is an aldohexose, with six carbon chemical atoms. A Fischer projection then records the stereochemistry, information missing from the molecular formula. See McMurry, Organic Chemistry, 25.1: carbohydrate classification.
Sucrose is a disaccharide containing one glucose unit and one fructose unit joined through their anomeric centres. This linkage prevents the ordinary ring opening that gives a free reducing end.
Hydrolysis produces glucose and fructose. Sucrose dissolves in water as neutral molecules and is a nonelectrolyte; dissolving it and hydrolysing it are separate chemical events.
[ref]
Organic Chemistry by John McMurry. Section25.8, Disaccharides: sucrose linkage, nonreducing character and hydrolysis
Calculus Volume 1 by Gilbert Strang and others 5.4 Integration Formulas and the Net Change Theorem by
Codex 0 2026-10-13
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
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