Sunday, May 1, 2011
There are two major players when it comes to blood typing: antigens and antibodies. Antigens reside on the surface of the blood cell and are of three possible types: antigen A, antigen B, and Rh antigen. Antibodies are present in the blood plasma and appear in the first part of a persons life in response to environmental factors. There are two types of these immunoglobins: Anti-A and Anti-B antibodies.
Friday, April 29, 2011
Cyanobacteria. These are the tiny toxic man killers I am talking about.
Thursday, April 28, 2011
Sunday, April 24, 2011
So why are angiosperms and their life cycle important? Angiosperms make up 90% of living plant species. The two major characteristics of an angiosperm are the flower and the fruit, which play a critical role in the life cycle of the plant. The flower is necessary for sexual reproduction. The angiosperms rely on pollinators, such as insects, to transfer the pollen from flower to flower. The organs within the flower are the sepals, petals, stamens, and carpels. The bright color of the flower petals are an adaption necessary for attracting pollinators. The fruit is used to protect the seeds and help in dispersing the mature seeds. Some angiosperm fruits are not conventionally recognized as a fruit. In maples and dandelions, the fruits have adapted with propellers or parachutes to enhance the movement of the seeds by wind dispersion.
The angiosperm life cycle appears complex and has many characteristic attributes. The haploid part of the cycle begins with the production of the male and female gametophytes. The male gametophyte has two haploid cells that form the tube cell and two sperm. The female gametophyte consists of an embryo sac that holds the egg. After pollution, the sperm are discharged into the ovule. The fertilization signals that transition from a haploid to a diploid stage of the cycle. Angiosperms have double fertilization, which means that one sperm from the male gametophyte fertilizes the egg and the other sperm fertilization a central cell in the ovary and forms an endosperm, which is the food supply for the seed, while it is dormant within the fruit. The seed develops into the sporophyte, which is diploid. Then the life cycle begins again. The adaptive nature of the angiosperms provides the beauty of spring and the nutrition fruits.
Tuesday, April 5, 2011
Before I was even finished taking the assessment test I realized that I knew very little about ecology and the behavior of animals in general. Yeah, I got a taste of it in the early Biology classes but I never needed to take the specialized classes of Ecology or Zoology to get where I am now. So, while looking at various sites and blogs on ecology and animal behavior, I came across a really interesting article on the differing brain sizes in migratory birds versus residential birds and I just had to read more.
There are two major questions scientists asked about the brain size of these birds: is the smaller brain a result of migration or does a smaller brain predestine a bird to migrate? Along with their colleagues, Daniel Sol and Núria Garcia who are CREAF researchers studied 600 passerine species with varying habitats. Within these 600 species, Sol and Garcia found that migratory birds do indeed have smaller brains than residential birds who tough out the sometimes harsh seasonal changes. They also concluded that the decreased brain size is a direct result of migration--contrary to the previously accepted 'protective brain theory'.
As earlier studies have shown, having a larger brain is more desirable than having a smaller brain due to it's large cognitive holding capacity. This theory holds true for residential birds who remain in their habitat from birth until death and who need to constantly learn how to stay alive, search for food, and fend off predators. However, with migratory birds, familiarity and knowledge of their surroundings is not as important since their stay in that area is only temporary. The cost-benefit idea is also a valid explanation of the smaller brains in these birds. The amount of energy they would spend learning the only transitory habitat could be put to better use during their travels. Sol and Garcia stated that "for these species, their innate behavior can be more useful than learned behavior".
As a follow up to their research, the researchers added that an analysis of the pallium and telencephalon in the bird brains would be beneficial to their conclusions since these areas are "involved in learning and behavior innovation processes".
Monday, April 4, 2011
Tuesday, March 29, 2011
An intruder enters, and suddenly it is met by a force that begins the fight. After time, backups arrive to fight until the end. This may sound like the plot of an action or war movie, but really I am talking about the body’s immune system. The initial troops are known as the innate immunity and the ones that come in later are the adaptive immunity. The innate immunity can consist of the physical barriers, such as the skin and mucous membranes. It also involves the secretion of chemical signal, fever, and inflammatory response. The innate immunity is supposes to prevent entry and spread of invaders throughout the body.
The more complex system of immunity is the adaptive immunity. We can call the adaptive immunity, the special force for fighting infection. Once the body is exposed, it reacts by activating B and T cells. The T-cells are a part of the cell-mediated immunity and the B cells are a part of humoral immunity. The humoral immune response is mediated by the release of antibodies. Antibodies are also known as immunoglobulins and have a Y shape that consists of two large heavy chains and two smaller light chains. The antibody has a specific binding site for the antigen or intruder. Once the intruder is bound to the antibody, it is destroyed on-site or is marked for later destruction.
The antibody is specific to its target and since new mutations of bacteria and viruses come around every day, how is the body able to adapt to making so many different antibodies when the genome is so small? A person can produce a million different antibodies and the way we can do this is through DNA rearrangement followed by alternative splicing of the RNA transcript. Let us first discover the marvels of DNA rearrangement. DNA rearrangement is gene reorganization. Gene segments containing information about the formation of antibodies come together and are assembled during the formation of B cells. DNA rearrangement brings together and assembles the antibody coding segments. The different arrangements of the segments allow for many forms of a protein from a small group of genes. The diversity of the B cell formation lies in the formation of the heavy and light chains of the antibody by using variable combinations of genes. In the light chain, DNA rearrangement combines three separated genes to code for one polypeptide. In the heavy chain, four genes are shuffled around by DNA rearrangement to produce the polypeptide. Another factor that affects the variability in antibodies is alternative splicing. Once DNA is transcribed into RNA, there are modifications that must be made. One of the changes is cutting out the introns and exons. This can occur by not cutting out an intron that normally would have been removed or by changing the arrangement, in which the exons are joined after the introns are removed. This allows for variation is coding during translation, leading to new forms of a protein. The process of producing antibodies is complex, but it allows our immune system to hone its skills for fighting intruders.