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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.