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Mitosis allocates copied chromosomes to daughter cell nuclei. The spindle apparatus aligns sister chromatids before separation in anaphase.

The copying has already occurred during S phase, before mitosis. Nuclear chromosome segregation and cytokinesis, the partition of the cytoplasm, are distinct processes: two daughter cell nuclei can form inside one undivided biological cell.^[ref]

The original cartoon follows a hypothetical diploid animal biological cell with $2n=4$. Its two homologous chromosome pairs are $A,a$ and $B,b$; upper- and lower-case letters identify homologues, not dominant and recessive alleles. In prophase and metaphase, each replicated chromosome contains two sister chromatids: four replicated chromosomes contain eight chromatids, rather than eight replicated chromosomes. The X shape depicts two associated copies, not the shape of every chromosome throughout the cell cycle.

This open mitosis cartoon shows nuclear envelope breakdown and reassembly. Closed mitosis in some yeasts retains the nuclear envelope while daughter chromosomes separate inside it; the cartoon is therefore not a universal cellular architecture.^[ref]

A nuclear localization sequence is an ordered stretch of amino acid residues that can direct protein import into a cell nucleus. In the classical pathway, importin α recognizes the nuclear localization sequence, and importin β mediates passage through the nuclear pore complex. Other recognition pathways exist. An exposed nuclear localization sequence is a targeting feature, not a guarantee of import under every condition.^[ref]

RNA export is a different cargo pathway: RNA travels associated with proteins, as a ribonucleoprotein, rather than being imported by its own nuclear localization sequence. Export of messenger RNA connects nuclear transcription to cytoplasmic biological translation.^[ref]

Section of The Cell: A Molecular Approach, 2nd edition by Geoffrey M. Cooper. The 2000 publication date and author credits belong to the whole book; no separate chapter byline is established. Sinauer Associates publishes the book; NCBI Bookshelf at the National Library of Medicine hosts the text.

Online text: www.ncbi.nlm.nih.gov/books/NBK9928/

Cited passages: Opening paragraph; Membrane Proteins, integral, peripheral and transmembrane proteins, single and multiple membrane-spanning regions and covalently attached lipid anchors.

Section of The Cell: A Molecular Approach, 2nd edition by Geoffrey M. Cooper. Whole-book author: Geoffrey M. Cooper; no separate chapter byline is established. Sinauer Associates publishes the book; NCBI Bookshelf at the National Library of Medicine hosts the text. The publication year 2000 belongs to the second edition; no separate section revision date is established.

Online text: www.ncbi.nlm.nih.gov/books/NBK9953/

Cited passages: Lysosomal Acid Hydrolases; Phagocytosis and Autophagy; Figures 9.35–9.37. The inspected content was available through indexed section text; the host restricts direct browsing.

Section of The Cell: A Molecular Approach, 2nd edition by Geoffrey M. Cooper. Whole-book author: Geoffrey M. Cooper; no separate chapter byline is established. Sinauer Associates publishes the book; NCBI Bookshelf at the National Library of Medicine hosts the text. The year 2000 belongs to the second edition; no separate section revision date is established.

Online text: www.ncbi.nlm.nih.gov/books/NBK9957/

Cited passages: The Ubiquitin-Proteasome Pathway, Figure 7.39; Lysosomal Proteolysis, Figure 7.41. Indexed section text was inspected; direct Bookshelf browsing was restricted.

Section of The Cell: A Molecular Approach, 2nd edition by Geoffrey M. Cooper. The 2000 publication date and author credits belong to the whole book; no separate chapter byline is established. Sinauer Associates publishes the book; NCBI Bookshelf at the National Library of Medicine hosts the text.

Online text: www.ncbi.nlm.nih.gov/books/NBK9898/

Cited passages: Mobility of Membrane Proteins, lateral movement, cytoskeletal restriction and junction barriers.

Online text: www.ncbi.nlm.nih.gov/books/NBK9889/

Section of The Cell: A Molecular Approach, 2nd edition by Geoffrey M. Cooper. The 2000 date and personal author credits belong to the whole book; no separately credited chapter author is established. Sinauer Associates publishes the book; NCBI Bookshelf at the National Library of Medicine hosts the text.

Cited passages: Opening paragraph and Figure 9.1, retrieved in search result for the exact Bookshelf section; Targeting Proteins to the Endoplasmic Reticulum; Insertion of Proteins into the ER Membrane, Figure 9.10; Protein Folding and Processing in the ER, Figure 9.14; Export of Proteins and Lipids from the ER, Figures 9.20 and 9.21; full section text retrieved through search.

Section of The Cell: A Molecular Approach, 2nd edition by Geoffrey M. Cooper by whole-book author Geoffrey M. Cooper. Sinauer Associates published the second edition in 2000. NCBI Bookshelf at the National Library of Medicine hosts the text; it is not the author. No separate chapter byline or revision date is established.

Online text: www.ncbi.nlm.nih.gov/books/NBK9958/

Cited passages: Cytokinesis, Figure 14.30 and Figure 14.31 captions. Complete subsection and captions were inspected in indexed authored text; direct access returned a browser challenge.

Section of The Cell: A Molecular Approach, 2nd edition by Geoffrey M. Cooper. Whole-book authors: Geoffrey M. Cooper. No separate chapter author is credited. The 2000 publication date belongs to the whole-book edition. Sinauer Associates publishes the book; NCBI Bookshelf at the National Library of Medicine hosts the online text. No separate section publication or revision date is established.

Online text: www.ncbi.nlm.nih.gov/books/NBK9838/

Cited passages: The Cell: A Molecular Approach, 2nd edition by Geoffrey M. Cooper, The Golgi Apparatus: Indexed official section text: opening paragraphs and Organization of the Golgi, Figures 9.22–9.23; Indexed official section text: Protein Sorting and Export from the Golgi Apparatus, Figure 9.27 and targeting discussion; Official indexed citation header: Cooper GM, second edition, Sinauer Associates, 2000.

Section of The Cell: A Molecular Approach, 2nd edition by Geoffrey M. Cooper, by Geoffrey M. Cooper; Sinauer Associates, 2000. NCBI Bookshelf hosts the text; no independent chapter author or revision date is established.

Cited passages: Transport of Metabolites across the Inner Membrane; Figure 10.12.