AP Biology class blog for discussing current research in Biology

Month: April 2012

Eat Your Breakfast!!!

Credit: meglet127 Flickr

I was always told that Breakfast was the most important meal of the day, and I thought that was because breakfast gave me the brain food I needed to be able to function in school. While this is a big reason to eat breakfast, The New York Times has just posted an article describing another reason to eat breakfast. Lowering your risk for Type 2 Diabetes !

Diabetes is a disorder concerning metabolism. More specifically, Diabetes refers to a “malfunction” in the way that our cells react to insulin produced by the pancreas. Type 2 Diabetes is the most common form of diabetes, and occurs when the pancreas is either not producing enough insulin, or our cells aren’t reacting correctly to the insulin our pancreas is producing.

The American Journal of Clinical Nutrition conducted a study in which 29,000 men were followed for 16 years, with their eating habits being closely watched. Over the course of this study, about 2,000 of these men developed type 2 diabetes. The researchers concluded that those who skipped breakfast had a 21% higher risk of developing type 2 diabetes than the others.

There are two theories as to why this may be. First, some scientists believe that a morning meal helps stabilize blood sugar levels throughout the day. Another theory claims that by skipping breakfast, people partake in increased snacking throughout the day, and their intake of sugary snack food dramatically increases.

So think about it! How many of you have skipped breakfast, only to run to the college office scourging for any food you can find? Rather than eat tons of junk throughout the day to compensate for all the real meals you’ve been skipping, try starting your day just a little earlier to fit in a healthy breakfast. You’ll notice the benefits immediately!

For More information on Healthy Breakfasts, Check out this link:

How Old Are You, Polar Bear?


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Do you remember where mammals have DNA? (hint- it isn’t just in the nucleus)

Mammal cells have DNA in both their cell nuclei and their mitochondria. While DNA in the nucleus is a combination of both parents, mitochondrial DNA is inherited directly from the mother. (For more information about nuclear DNA and mitochondrial DNA download:…/dna-definitions.doc)

And what does this have to do with the age of Polar Bears?

Well, according to a recent article in the New York Times, scientists have been surprised to find that polar bears are not so closely related to brown bears as previously thought. For years, scientists thought that the polar bear specie evolved about 150,000 years ago. Adaptations, probably due to natural selection, include white fur and webbed paws – both of which are very helpful in the icy Arctic.

Researchers Axel Jenkle and Frank Haler, of the Biodiversity and Climate Research Center in Frankfurt studied 19 polar bears, 18 brown bears and 7 black bears. After analyzing the nuclear DNA of polar bears, they believe that brown bears and polar bears began taking different evolutionary paths as much as 600,000 years ago.

The old, incorrect, theory was based on mitochondrial DNA. The mitochondrial DNA of polar bears and brown bears are very similar.  Because polar bears live on ice, and there aren’t many fossils saved in the icy arctic, it has been difficult to trace the evolution of these famous white bears.

Now scientists are trying to figure out why the mitochondrial DNA of brown and polar bears is so similar. One hypothesis is that polar bears mated with brown bears during time of global warming or climate changes. There is some evidence of the bottleneck effect, which helps support this theory.


Link to main article:



New Stem Cell Discovered in Brain

Credit Isaac Mao,

At Lund University, researchers have discovered a brand new type of stem cell in the adult human brain, which is thought to be responsible for the regeneration of muscle, bone, cartilage, and adipose tissue.

Stem cells are known for their ability to proliferate into several different cell types, providing a plethora of research opportunities for medical researchers.  These specific stem cells, found near small blood vessels in the brain through the analysis of brain tissue from biopsies, have also been identified in other locations of the body.  In other organs, the stem cell appears to have a similar structure, and is responsible for repair and wound healing, leading scientists to suggest that the curative properties may also apply to the brain.

The next step is to better understand this new type of stem cell, and to learn how to better control and enhance its self-healing properties.  “Our findings show that the cell capacity is much larger than we originally thought, and that these cells are very versatile,” said Gesine Paul-Visse, Ph.D., Associate Professor of Neuroscience at Lund University.

With a more thorough understanding of how this stem cell operates, researchers hope to use it to better treat neurodegenerative diseases and stroke.

As Paul-Visse puts it, “Ultimately the goal is to strengthen these mechanisms and develop new treatments that can repair the diseased brain.”

For more information, read the article “New stem cell found in the brain”

Or look for the original study published in the journal PLos ONE.

So, what do you think?  Will this new stem cell found in the brain make an important impact in neurobiological research?

Birds are gardeners, too.

Christmas Island warbler nest; Richard D. Chandler


Bowerbirds build large and elaborate nests to attract mates. In this process, they decorate the nest with colorful fruit; once the fruit dries up, and the bird no longer needs it, the plant is thrown away, causing the growth of this plant near the nest. These birds accidentally garden plants, this adds to their role in spreading seeds and fertilizing plants. Birds spread seeds by digesting the fruit and then disposing of its seed in a different place. They also pollinate plants while feeding from a flower. Brightly colored flowers attract birds to feed from their nectar; the bird is then covered with pollen from the anthur of the flower’s stamen. When the bird goes to the next plant, the pollen covering their bodies is
placed in the stigma of the flower.

The coloration of plants represents their role in the environmental community. Brightly colored flowers are attractive to birds and
insects. Brightly colored fruit are attractive to animals, including humans, because it makes the consumer think the fruit is ripe. The Bowerbird picks the greenest potato plant to decorate its nest with, because it is the most visually pleasing. This selection causes potato plants that are greener in color to grow around the birds nest, causing the bird to decide what plants grow in certain areas.

Bowerbirds are the only animals, other than humans, to use fruit for a use other then eating. This selection and use makes the birds “accidental genetic engineers” and cultivators of potato bushes near their nest.

It is the natural instinct of certain birds to eat fruit and drink nectar. It is also the natural instinct of Bowerbirds to create decorative
nests to mate and pass on their genes. The natural instincts of birds in general cause certain plants to be fertilized and reproduce. The relationship
between birds and flowers revolves in a cycle that is the foundation of nature.

Photo: Christmas Island warbler nest, Christmas Island, March 1967.

Richard D. Chandler, The Smithsonian Institution

Puberty Before She’s Ready





Precocious puberty, puberty that occurs earlier than usual, is affecting many little girls all over the country. In the article Puberty before age 10- a new ‘normal’, a 6 year old girl, Ainsley, is developing breasts, pubic hair, armpit hair and a few pimples. All of these aspects of puberty are commonly found in girls ages 12-14 but it is occuring in girls at age 6.

Precocious puberty is not only a physical issue but a big emotional problem. AInsley does not feel “normal” compared to the kids at schools. Her precoious puberty is very embarrassing for her. The western doctors don’t have an answer for Ainsley’s precocious puberty and simply accept that precocious puberty has become more rampant in America.

However, there are some answers. Precocious puberty is due to high hormone levels of estrogen. However, a lot of the time these estrogens are not from the ovaries. In fact they come from the environment. These estrogens are called xeno-estrogens. These are chemicals, insulin and sugar, that mimic estrogen; they cause minor health problems but it is a relatively knew chemical in science. The xenoestrogens are causing precocious puberty.

So has the age of puberty increased within these past years? No It has not. Puberty includes three things breast development, pubic hair growth and menstruation. Although the average age of breast development has increased in recent years the average age of menstruation has not.

There are some girls that do not have precocious puberty but start puberty earlier than other girls. However this group is beginning to get blurred together with the girls that actually have precocious puberty. The difference between these two girls is that the girls with precocious puberty will have advanced bone age. They will be shorter than a girl who starts her period later.

Although precocious puberty doesn’t seem that bad, it has negative effects for these girls socially. These girls tend to lose their virginity faster, get depression and have low self-esteem. What do you think, is precocious puberty something we should worry about?


other links:–year-old-girls/


link to article:

Are the teens on teen mom the only ones?

Many people talk about the teens on 16 and Pregnant and how we as a nation have increased our teen pregnancy rates, but according to News Day teen pregnancies are at an all time low. “There has been a phenomenal drop [of 9 percent] in the last two years,” said Brady Hamilton. Many people frown upon the the fact that now more than ever we have been hearing about teen pregnancies but according to this article there has been a 44% drop in teenage pregnancies since 1991.

copyright: Gabrielle A.copyright: Gabrielle Aaron

“The U.S. teen birthrate is still among the highest for industrialized countries, however.” This makes me wonder because we may have the most teenage mothers recorded but what about all of the other industrialized countries that don’t always record every teenage birth. Also in the US we consider 19 year olds teenagers but in many other countries any age above 18 is considered an adult.

The largest concern that I have with this article is that many teenage pregnancies are not considered pregnancies if they are aborted. While I do think that the rates have dropped due to education in schools I still believe that our rates of pregnancies are very high but we just have ways to invalidate it, thus causing less teenage moms. What do you think? Do you think this article is wrong or right?

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