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Root: Information Storage and Flow (ISF)
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Overview of root Information Storage and Flow



What Do Information & Data Have to Do With Biology?

First we need to define our terms. Information is factual knowledge or details about a particular subject, object, or activity [1]. Data (singular, datum) are facts or information used usually to calculate, analyze, or plan something [2].

Usually we think of information and data sharing as unique traits of human culture and technology. Humans certainly spend more time sharing information than any other species. We also are the only species that uses symbolic information. That means we:

  • Records information and data in symbols (letters, numbers, etc.),
  • Stores the symbols (and so the information) in a stable form outside of our brain, and
  • Refers back to the externally stored information later [3].


We have been recording and storing information for over 40,000 years [4]. We have painted or carved symbols in stone, printed them on paper or parchment, and recorded them on clay, wax, or other soft materials. In the 19th century we added metal and plastic disks, and in the 20th century, magnetic tape. In the 21st century, as computers grow to be more and more a part of our daily lives, optical and digital media are becoming the most common forms of information storage for many of us.

Cave painting from the cave of Altamira.

Cave painting from the cave of Altamira in The Anthropos Pavilion of The Moravian Museum, Brno, Czech Republic. Similar paintings are the oldest form of human symbolic expression known.

Tidbit: Our use of symbols is unique, but sharing information about the world around us to others is not unique to humans. Biologists have identified many species of apes, other mammals, and birds in which individuals teach others what they have learned about local environment. This information can include where to find water, migration routes, foods to seek out or avoid, and local hazards. Some species even teach offspring how to make and use tools.


There are MANY forms of information

Information/data we are consciously aware of is just a tiny piece of the whole picture. Organisms continuously produce, store, and transmit many kinds of information, in many different forms, and have been doing so since life began nearly 4 billion years ago. Most of this information storage and flow goes on without our ever knowing it.


Essential information is stored in DNA

The most obvious forms of biological information is coded and stored in DNA and RNA molecules. As you will learn later, a genome is the complete, organized set of DNA instructions required to produce an organism of a particular species. Genomes are subdivided into genes, which are the regions of DNA that code for proteins and RNAs. Located between the genes are regulatory regions, which cells and organisms use to control which genes in their genome are expressed, and when.

Knowing the complete genome sequence for a species does not mean we fully understand how the individual genes work together to create that organism. For example, when the first complete human genome sequence was announced in 2003, news outlets widely reported that we now had the "blueprint" for a human being. Since then we have made great progress in understanding how genes work together, and discovered whole new levels of gene regulation. Still, we have a lot to learn about:

  • How our genes are controlled,
  • How they work together to produce individual people,
  • How they have changed during the evolution of our species, and
  • How and when our genes contribute to disease.



Chemical signals carry information within and between cells and organs

A cell's genome does not act in isolation. Every cell has dozens of chemical signaling pathways that form a complex communication system. Molecules at the start of the pathways sense the current internal state of the cell, and external local conditions outside the cell. The signaling pathways transmit that information to several locations:

  • Signals reaching the nucleus activate or inhibit transcription factors (proteins that control gene transcription). Transcription factors regulate gene expression in response to local conditions.
  • Signals to the cytoskeleton can change cell shape, or move the cell towards or away from a stimulus.
  • Signals can trigger cytoplasmic responses like secretion of molecules, or changes in enzyme functions.
  • Signals can activate or block ion flow through membrane channels, or affect transmembrane transport.
  • Signals can stimulate cell division.
  • Signals can even cause a damaged or unneeded cell to self-destruct, a process called apoptosis.


Organs and systems exchange information through hormones and nerves

Unicellular organisms rely on cell signaling pathways to sense and respond to the world around them. Multicellular organisms must regulate and control many different interacting processes happening in separate cells. Direct cell-to-cell communication is essential for multicellular organisms, but it is one of three ways of sharing and managing information. Nearly all multicellular plants and animals transmit information over longer distances via hormones. These are chemical messages that travel in body fluids from a source to target cells where they trigger a response.

Besides direct cell-to-cell signaling and hormones, animals communicate information over long distances through their nervous system. Nerves are unique to animals; plants do not have an equivalent system. This might seem to put plants at a disadvantage, but there is a trade-off: nervous systems demand a lot of resources.

About This Root

The Branches and Leaves of this Root focus on molecular biology and cell signaling. Molecular biology is the study of how cells use DNA and RNA to store and transmit information, and to make proteins. The Branches and Leaves explain how DNA is organized into genes and genomes within cells. They describe how DNA, RNA, and proteins store and transmit information within a single cell, and how that information is passed along to daughter cells. Other pages introduce the different processes of mutation that change DNA over time.

The Branches and Leaves for cell signaling describe essential pathways by which cells sense their LOCAL internal and external environments, convert the stimulus into a recognizable signal (signal transduction), and respond to the stimulus. As you will see, one of the responses cell signaling controls is gene expression. The two topics will connect together again in the Branches and Leaves that explore the cell cycle and cell division.


How Is This Root Connected to the Others?

This Root centers on the molecular processes of information storage and flow. That does not mean information storage and flow is not important at higher levels of scale. Other Roots examine the related processes and pathways.

Root: FME-Flow of Matter and Energy: The energy balance of a cell and whether it needs to prepare to divide are two internal processes that are monitored closely by the cell signaling system. When a cell does not have sufficient energy and mass to reproduce, the cell signaling system will block cell division. Instead, the cell will divert resources towards building up energy stores and collecting needed molecules. Among the molecules needed are nucleotides, which are the chemical building blocks of DNA and RNA.

Root: SGH-Structure, Growth, Homeostasis, & Reproduction: In multicellular organisms, the endocrine and nervous systems are responsible for sensing and responding to the environment. The information exchanged between cells, tissues, and organs via these systems maintains normal function (homeostasis), and regulates growth and reproduction. The endocrine and nervous systems are highly specialized, but they operate on the same basic principles as cell-cell signaling. Both systems stimulate cell and tissue responses via cell signaling systems. Much of what you learn in this Root will help you later to understand how hormonal and neural signaling work.

Root: EDU-Evolution, Diversity, & Unity of Life: To understand evolutionary processes we have to look at DNA. Variation between members of a species is the result of small differences in DNA sequences between individuals. Selection acts on that variation so that some individuals produce more offspring than others. The information stored in a favored organism's genome "flows" to the next generation more frequently than the information from the genome of a less favored organism. Put another way, evolution is the end result of how well information that promotes survival flows from one generation to the next.

Root: IEP-Interactions and Emergent Properties: Many diseases are caused by specific viruses, bacteria, fungi, parasites, or other pathogens. Other diseases can be traced to single gene mutations. Still others occur when cell signaling systems break down. Much of what we know about how cell signaling works in normal cells was discovered by scientists trying to understand disease.

Other diseases are caused by complex interactions between many systems. Cancer for example is caused by toxic agents in our environment that damage DNA and affect gene regulation. This disrupts normal signaling, metabolism, and cell and organ structure. Most damaged cells die, but a few survive and grow to form the cancer. Cancer is one of the topics explored in Root: IEP.

What Specific Branches & Leaves are Connected to This Root?


Sources

[1] http://www.merriam-webster.com/dictionary/information
[2] http://www.merriam-webster.com/dictionary/data
[3] Deacon, T. 1997. The Symbolic Species: Co-evolution of Language and the Brain. Norton & Co., 527pp. Go to summary.
[4] http://www.livescience.com/48199-worlds-oldest-cave-art-photos.html



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Page last modified on Monday 22 of June, 2015 06:40:34 EDT

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