Regina's Biology Blog

Muscle Cell Mitochondria © Dennis Kunkel

Mitochondria are the cell's power producers. They convert energy into forms that are usable by the cell. They are the sites of cellular respiration which ultimately generates fuel for the cell's activities. The number of mitochondria in a cell can range from a few to several thousand, depending on the type of cell.

Mitochondria are tubular or oblong shaped and are bounded by double membranes. The double membranes divide the mitochondrion into two distinct parts: the intermembrane space and the mitochondrial matrix. Mitochondria are semiautonomous in that they can divide and grow to make more of themselves. They also have their own DNA and ribosomes. To learn more about mitochondria and other cellular components, visit Journey into the Cell.

Researchers have discovered how Strep bacteria are able to survive and spread throughout the body. The bacteria produce a substance, SpyCEP, that inhibits the ability of immune system cells to respond to an infection. SpyCEP (Strep. pyogenes cell envelope protease) interferes with the production of a certain molecule in the body that sends signals to white blood cells when there is an infection. As a result, the bacteria go undetected until it is too late and the infection spreads.

In the study, the researchers isolated the Strep bacteria and removed the gene responsible for producing SpyCEP. They discovered that without the ability to produce SpyCEP, white blood cells were able to detect and destroy the bacteria. The study was conducted with group A Streptococcus bacteria. This pathogen strain is responsible for several types of diseases including strep throat and "flesh-eating disease."

Learn more about this study, see:

• How Flesh-eating Bacteria Attack The Body's Immune System (Science Daily)

If you are taking a biology course, at some point you will have to do lab experiments. This means that you will also have to complete biology lab reports. You may be thinking, how do I write a good lab report or why do I need to write a lab report at all?

The purpose of writing a lab report is to determine how well you performed your experiment, how much you understood what happened during the experimentation process, and how well you can convey that information in an organized fashion. A good lab report has a format that includes five main sections. They are the introduction, methods and materials, results, discussion and conclusion, and citation.

Keep in mind that an individual instructor may have a specific format that he or she requires you to follow. Please be sure to consult your teacher about the specifics of what to include in your lab report. Also remember that lab reports are individual assignments. You may have a lab partner, but the work that you do and report on should be your own.

Photo courtesy PDPhoto.org

Many people realize the importance of staying fit and eating healthy. Organic foods have long been touted as being more nutritious than foods that are treated with chemicals or pesticides. If you have ever compared the prices of the two types of food at the grocery store, you know that organic foods are certainly more expensive. The question becomes, are organic foods really better for you?

Studies conducted by researchers from the Department of Human Nutrition, University of Copenhagen, suggest that organic foods are no more nutritious than foods grown with pesticides. Three different types of cultivation methods were used in the study. One method involved growing vegetables and fruits with low nutrient inputs and no pesticides. The second method involved treating the food with pesticides and adding low nutrient inputs in the soil. The third method involved using high nutrient inputs along with pesticides.

After harvesting and analyzing of the food, the researchers found no difference in nutritional content between the organically grown and traditionally grown foods. In fact, the only major difference between the crops was that the organically grown crops yielded much less produce.

Learn more about this study, see:

• Organic Food Has No More Nutritional Value Than Food Grown With Pesticides, Study Shows (Science Daily)

Photo courtesy PDPhoto.org

Whether fair or unfair, most people make judgments about others based on appearance. Scientists believe that people determine the intentions of others by looking at their face and facial expressions. In fact, one quick glance at a person's face is all it takes to influence how you feel about them.

With the help of a computer program, scientists from Princeton University have determined the types of faces people consider to be trustworthy or untrustworthy. Characteristics of a trustworthy face include a U-shaped mouth and upturned eyebrows. Characteristics of an untrustworthy face include lips that are curled at the edges and eyebrows that are turned down.

It was also determined that people make evaluations about dominance based on facial observations. If you have a squared, broad chin, you have a characteristic of a dominant person. People with baby face characteristics are considered to be least dominant.

Scientists believe that face-seeking is a hard-wired phenomena in humans. There is also speculation that the brain contains a special mechanism that is used for evaluating faces.

Learn more about this study, see:

• Whom Do We Fear Or Trust? (Science Daily)

Image courtesy of Carolina Biological Supply/Access Excellence

Blood vessels are intricate networks of hollow tubes that transport blood throughout the entire body. There are several types of blood vessels:

• Arteries - elastic vessels that transport blood away from the heart.
  
• Veins - elastic vessels that transport blood to the heart.
  
• Capillaries - extremely small vessels located within the tissues of the body that transport blood from the arteries to the veins.
  
• Sinusoids - extremely small vessels located within the liver, spleen and bone marrow.

Blood travels from the heart via arteries to smaller arterioles, then to capillaries or sinusoids, to venules, to veins and back to the heart. This continuous cycle of blood flow is known as the cardiac cycle.

Migratory Wildebeest in the Serengeti Photograph: Nathan Gregory

Scientists have discovered a disturbing trend among migratory animals. It appears that animal migration is in severe decline all over the world. In some cases, animal migration has ceased altogether.

What are the causes for the decline in migration? They can be narrowed down to four main threats. They are the destruction of habitat, the erection of obstructions, over exploitation, and change in climate.

Scientists believe that the decline in migration is a significant issue due to the impact that migrating animals have on other animals and the environment.

Let's consider wildebeest for example. They play an important ecological role in the Serengeti. They are herbivores that consume large quantities of vegetation and redistribute nutrients through the expulsion of waste. They also provide food for the many predators of the Serengeti. If these migrating animals were to decline in great numbers, there would be severe consequences for the animals and vegetation of the Serengeti.

Learn more about this study, see:

• Going, Going, Gone: Is Animal Migration Disappearing (PLoS Biology)
  Wilcove DS, Wikelski M (2008) PLoS Biol 6(7): e188

Using a newly developed technique, researchers have been able to change skin cells into neurons. The study, involving patients with Lou Gehrig's disease, revealed that a patient's own cells could be used to treat his/her disease.

Nerve Cell © Dennis Kunkel

The researchers accomplished this transformation using a technique called induced pluripotent stem cells (iPS). This technique genetically programs human adult skin cells so that they resemble embryonic stem cells. The cells are then nurtured and prompted into becoming motor neurons.

The success of the iPS technique has led researchers to believe that it will one day replace other human cloning techniques. Much more research must be done before the newly programmed cells can be used for therapeutic treatments.

Learn more about this study, see:

• Stem Cell Technology: First Neurons Created From ALS Patient's Skin Cells (Science Daily)

Most people think of lipids negatively because they associate them with fats. Although some lipids are classified as fats, lipids are not "bad." On the contrary, they provide very important functions in the body.

Lipids are diverse compounds that are grouped together because they are insoluble in water, but soluble in nonpolar solvents such as ether. Common lipid types include fats, phospholipids, and steroids. These lipids have various functions in the body.

Fats are composed of fatty acids and glycerol. They store energy, help to insulate the body, and cushion and protect organs. Phospholipids contain two fatty acids and are a major component of cell membranes. Steroids are cholesterol derived hormones that regulate various physiological functions in the body.

Bacteriophage Structure © Gary E. Kaiser

Bacteria infested produce has caused much concern for consumers. In an attempt to combat this problem, researchers are now looking to other microbes for help.

Yes, that's right. Studies have been conducted with bacteriophages in an attempt to kill bacteria on produce. Bacteriophages are viruses that infect and kill bacteria. They do not cause harm to humans or animals.

In the study, the researchers treated fresh-cut cantaloupe and lettuce with a group of bacteriophages. The results were good in that the treatment drastically reduced the amount of E. coli on the produce.

Learn more about this study, see:

• Antimicrobials Target Pathogens On Fruits (Science Daily)