Question: How do cells duplicate?
About the article "Biology", section "Cell theory".

Candidate passages:
"Chlamydomonas" is used as a model organism for research on fundamental questions in cell and molecular biology such as:  How do cells move?
How do cells respond to light?
How do cells recognize one another?
How do cells generate regular, repeatable flagellar waveforms?
How do cells regulate their proteome to control flagellar length?
How do cells respond to changes in mineral nutrition?
(nitrogen, sulfur, etc.)
There are many known mutants of "C. reinhardtii".
These mutants are useful tools for studying a variety of biological processes, including flagellar motility, photosynthesis, and protein synthesis.
Since "Chlamydomonas" species are normally haploid, the effects of mutations are seen immediately without further crosses.
In 2007, the complete nuclear genome sequence of "C. reinhardtii" was published.
Channelrhodopsin-1 and Channelrhodopsin-2, proteins that function as light-gated cation channels, were originally isolated from "C. reinhardtii".
These proteins and others like them are increasingly widely used in the field of optogenetics. 
Natural killer cells, or NK cells, are a component of the innate immune system which does not directly attack invading microbes.
Rather, NK cells destroy compromised host cells, such as tumor cells or virus-infected cells, recognizing such cells by a condition known as "missing self."
This term describes cells with low levels of a cell-surface marker called MHC I (major histocompatibility complex) - a situation that can arise in viral infections of host cells.
They were named "natural killer" because of the initial notion that they do not require activation in order to kill cells that are "missing self."
For many years it was unclear how NK cells recognize tumor cells and infected cells.
It is now known that the MHC makeup on the surface of those cells is altered and the NK cells become activated through recognition of "missing self".
Normal body cells are not recognized and attacked by NK cells because they express intact self MHC antigens.
Those MHC antigens are recognized by killer cell immunoglobulin receptors (KIR) which essentially put the brakes on NK cells. 
Natural killer cells, or NK cells, are a component of the innate immune system that does not directly attack invading microbes.
Rather, NK cells destroy compromised host cells, such as tumor cells or virus-infected cells, recognizing such cells by a condition known as "missing self."
This term describes cells with low levels of a cell-surface marker called MHC I (major histocompatibility complex) - a situation that can arise in viral infections of host cells.
They were named "natural killer" because of the initial notion that they do not require activation in order to kill cells that are "missing self."
For many years, it was unclear how NK cell recognize tumor cells and infected cells.
It is now known that the MHC makeup on the surface of those cells is altered and the NK cells become activated through recognition of "missing self".
Normal body cells are not recognized and attacked by NK cells because they express intact self MHC antigens.
Those MHC antigens are recognized by killer cell immunoglobulin receptors (KIR) that, in essence, put the brakes on NK cells.
The NK-92 cell line does not express KIR and is developed for tumor therapy. 
As the cell containing the cilium goes through the cell cycle, ciliogenesis must be regulated.
Cilia usually form during the G1 of the cell cycle and disassemble during mitosis.
It is not known why the cilia assemble and then disassemble, but it is believed that the presence of cilia may interfere with mitosis and, therefore, are removed before mitosis occurs.
Cells that have recently divided and are in the G0 stage of the cell cycle do not have cilia.
During G1, the mother centriole attaches at the cell cortex and forms the cilium.
During S-phase, the mother centrioles and daughter centrioles (new centrioles) duplicate and new daughter centrioles are formed.
Before mitosis can occur in most cells, the cilium is resorbed back into the cell.
After the original cell divides into its two new cells, the cilia reform within the cells after the new cells enter G1. 
The activities of the council aim to enable scientists to answer what it believes are the 'big' questions such as:  Why is there a Universe?
How did galaxies form?
Was there ever life on Mars?
How do planetary systems evolve?
How are the chemical elements created?
How does our climate work?
How can we create new materials to store energy?
How can we meet mankind’s need for abundant clean energy?
How can we design smart materials?
How do cells work?
How do degenerative diseases develop?
How can we design better treatments for cancer?