BIO.6.A

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The student is expected to explain the importance of the cell cycle to the growth of organisms, including an overview of the stages of the cell cycle and deoxyribonucleic acid (DNA) replication models;
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Knowledge and Skills Statement

Science concepts--biological structures, functions, and processes. The student knows how an organism grows and the importance of cell differentiation.

series of events (including interphase, S-phase, M-phase, and cytokinesis) that take place in a cell, resulting in the duplication of DNA (during S Phase), and division of cytoplasm and organelles to produce two identical daughter cells

a biological process wherein cells gain specialized roles and switch from one cell type to another to perform various specific tasks

a highly regulated molecular process where a single molecule of DNA is duplicated to result in two identical DNA molecules

a polynucleotide (nucleic acid) found in most organisms as the genetic material; composed of a specific combination of monomers of nucleic acid, the combination of which determines the genetic sequence of organisms; made up of a sugar (deoxyribose), a phosphate, and a nucleic acid (one of Adenosine, Thiamine, Guanine, and Cytosine)

an individual form of life; a body made up of organs, organelles, or other parts that work together to carry on the various processes of life

Research

Bell, Stephen D. "Molecular Biology: Prime-time Progress." Nature 439, no. 7076 (February 2006): 542-543. https://doi.org/10.1038/439542a.
https://www.nature.com/articles/439542a.

Summary:  DNA is duplicated within a complex macromolecular machine. DNA is replicated by unzipping the double helix to expose the bases that act as a template for copying the genetic material. Both strands of DNA serve as templates, and thus one double helix becomes two. Conceptually, this is a simple reaction, but the devil -- as so often -- is in the detail: the process is mediated by a multitude of proteins and turns out to be mechanically complex. A trio of papers in this issue have made considerable headway in understanding the intricacies of replication.

Research

Ji, Xiangrui, and Jie Lin. "Implications of Differential Size-Scaling of Cell-Cycle Regulators on Cell Size Homeostasis." PLoS Computational Biology 19, no. 7 (July 2023):e1011336. https://doi.org/10.1371/journal.pcbi.1011336

Summary:  Accurate timing of division and size homeostasis is crucial for cells. A potential mechanism for cells to decide the timing of division is the differential scaling of regulatory protein copy numbers with cell size. Here we study a mathematical model combining gene expression and cell growth, in which the cell-cycle activators scale superlinearly with cell size while the inhibitors scale sublinearly. Our work reveals that the differential scaling of cell-cycle regulators provides a robust mechanism of cell size control.