Extreme Biology

by Melody

Regulation is a very important theme in biology.  It is present in everything around us, and without it the world would be in chaos.  The world and things around us are constantly changing.  It is regulation that keeps things in balance through positive and negative feedback.  Homeostasis is the process in which things are regulated so they are kept in balance. Like I said, regulation is a part of everything from the cell to a population.

Molecular
On the molecular level (think carbohydrates and proteins etc.) an important example of regulation is the lac-operon.  It may have a funny name but the lac-operon serves a very vital purpose in regulating your digestive system every time you eat or drink a dairy product (which contain lactose).  The lac-operon is a gene that codes for the making of lactase (an enzyme that breaks down lactose).  Whenever you drink milk your digestive system is filled with lactose. The presence of the lactose “turns on” the lac-operon and causes it to make lactase. However, it is energy expensive. Therefore, the lac-operon only makes the lactase when it is needed (when you eat a dairy product).  This is an example of gene regulation. This website goes into more detail about the lac-operon.

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Cellular
The cell also needs to be regulated.  A prime example of this is the cell membrane, which is a barrier between the cytoplasm and the extracellular space.  The cell membrane is semi-permeable (meaning it only lets certain things in, and keeps other things out). It is made up of a lipid bi-layer and proteins are imbedded within it that can transport certain things in and out of the cell and are important in cell communication. It is important because it takes waste out of the cell and stops bad invaders from coming in.

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Organismal
Regulation is also important on an organismal level. An example would be osmoregulation (or the regulation of water).  Water and solute concentrations need to be maintained in an organism. The regulation is dependent on the environment the organism lives in. So, a fish, and other marine animals, are hypoosmotic to their environment.  This means that they have a lower water concentration than where they live.  Therefore, they regulate by drinking constantly, rarely urinating and secreting a lot of salt.  The opposite is true for land animals.  Land dwellers are hyperosmotic to their environment so they need to be constantly drinking. A message is sent to your brain that tells you that you are thirsty when you start to lose too much water.  Another way land animals osmoregulate is by using metabolic water.

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Another organismal example is the way the pancreas regulates blood sugar levels.  The pancreas releases two hormones that are important to blood sugar regulation; they are insulin and glucagon.  When the amount of glucose in your blood rises (which would happen when you eat a lot of candy or carbohydrates) insulin is released.  Insulin stimulates cells in your body to start absorbing and using glucose. Glucagon has the opposite effect.  It is released when blood sugar levels are too low.  It causes cells to release glucose into the blood stream. However glucagon also acts as a control for when your body releases too much insulin.  So the blood sugar concentration is regulated and kept at levels that are healthy for the organism.

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Population
In an environment, different species fall into different niches (or level of an ecosystem).  However, there is only room for one species in each niche.  This is because of a limited amount of resources such as food.  Each environment has a carrying capacity (or a limit on how many organisms can survive in it).  This carrying capacity serves as a regulator because it stops the population from growing too big.  The organisms often compete for the resources and whoever wins gets them. If there are no resources left the organisms cannot survive to reproduce and they will die out.

(Campbell, Neil A., and Jane B. Reece. AP Edition Biology. 7th ed. San Francisco: Pearson Education Inc., 2005. 1145.)

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Community
Regulation also occurs between different species in a community.  This is shown in the predator-prey relationship.  When there is a large amount of prey it is regulated when the predators feed on the prey.  This stops many organisms from overpopulating and using too many resources in the environment.

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Biosphere
Lastly, humans, on a biosphere level, also often control Regulation. An example of this would be hunting.  When a deer population gets too big the government controls the amount of deer that can be hunted so that the populations do not get too big.  This affects humans, the deer and the plants (among many other organisms) that in turn effects our biosphere. Regulation is key in the way our world works as a whole, because without it there would not be a normal level of harmony.

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This entry was posted on Tuesday, May 6th, 2008 at 10:23 am and is filed under AP Biology, Themes in Biology. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.