Curiosity Challenge: How do Cells Work?

Hi Jollie, thanks for the question. This is a hard question to answer because cells are so different from each other. Cells are specialized to do the job they perform. Nerve cells look completely different than liver cells and perform a different function within the body. Also animal, plant, and bacterial cells all differ from one another. To answer your question I’m going to focus on the general principles that enable animal cells to function.

Cells were initially discovered (observed) following the invention of microscopes in the 17^th century.  Cell theory, stating that cells form the fundamental unit of life, was put forward over 150 years later. In the 20^th and 21^st centuries a major goal of biological research has been to understand how cells work, so that we can recognize what goes wrong in disease and how best to intervene to cure the condition. The working of individual cells can be summarized basically as follows:

1.     Proteins do the work of the cell. They perform the function of the cell whether that’s to send an electrical signal along a nerve fiber, or to detect invading pathogens as part of the immune system. These functions occur via enzymatic reactions that require energy.

The central dogma of biology,
which describes how DNA encodes protein assembly.
From NCBI Molecular Biology Reviews.

2.     Cells get their energy by converting sugars (glucose) into ATP (adenosine triphosphate) in specialized structures called mitochondria. ATP is a carrier of energy and it’s used in lots of different enzymatic reactions where its breakdown releases the stored energy and enables the reaction to occur.

3.     Where do proteins come from? Simply from DNA. DNA contains small units called genes, which provide the information or code required to tell the cell how to make proteins out of individual building blocks (amino acids). By turning on one set of genes and turning off another set of genes, cells acquire specialized functions so that a liver cell looks and functions differently from a nerve cell.

So we know a lot about how a cell works. But would it surprise you if I told you that only last month (March 2016) scientists reported the design of the first cell to contain the minimal number of genes that support cell growth and replication. Of the 473 genes required to generate the simplest cell, scientists know the function of only 324 of those genes. This synthetic cell was a bacterial cell and far less complex than human cells, which have approximately 20,000-25,000 genes. The Human Genome Project provided the full sequence of human DNA in 2003 (the first draft was released in 2001).  Since then, scientists all over the world have been trying to translate that information to identify all the genes in the human genome, the function of the proteins they encode, and how these genes are controlled, such as in the ENCODE project. This information will help scientists discover how cellular function becomes disrupted in disease and will hopefully provide the means to design targeted therapies to combat those conditions.

Find out more about the biology of cells and organisms at the Cambridge Science Festival!

• Build Your Own Living Organism: Bioengineering for Everyone (two-day workshop) at the EMW Community Space, 934 Massachusetts Ave., Cambridge. Saturday, April 16, from 1-5pm, and Sunday, April 17, from 1-3pm.  Bioengineering allows us to speed up the evolution process!  Build your own living organism during this introductory two-day workshop for ages 10+.  Pre-register at http://bit.ly/1OPVVdR.

• CELL @ Novartis Open House - Check It Out! at CELL@Novartis, 22 Windsor St., Cambridge, April 21st 1-4pm and April 23rd 10am-2pm. Through hands-on experimentation and minds-on problem solving, our programs aim to develop technical skills, build confidence, and open a world of possibilities for students to explore biomedical research and STEM.

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Karen Featherstone is a research scientist specializing in molecular and cell biology. Karen’s Ph.D and post-doctoral research investigated how DNA is regulated and how this determines cell function.