Sunday, May 1, 2011

Blood Typing

After taking the assessment test, I realized I needed to brush up on blood typing. It is a fairly easy subject but everyone needs a refresher, right?

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.

There are two systems of blood-grouping: The ABO system and the Rh system. The ABO system is better recognized and understood, but the Rh system is quite different. When a person's blood is tested they are given one of the following designations: A, B, AB, or O which signifies which (if any) antigens are present on the surface of their RBCs. A (-) or (+) is then placed after the letter(s) to indicate the absence (-) or presence (+) of the Rh antigen on their cells. These designations are important when it comes to blood transfusions and pregnancy.

For instance, if a patient receives a blood transfusion from someone whose blood type differs from their own, agglutination of the cells may occur. Agglutination of the red blood cells is a state where the cells literally clump together resulting in an adverse effect in the individual. This agglutination is in response to the Anti-A antibodies binding with the A antigens and Anti-B antibodies binding with the B antigens on the cells. However, with type-O blood, there are no antigens present on the cells, thus, when Anti-AB serum is added to the blood no agglutination occurs. Traditionally, it is understood that type O- individuals are universal donors because their RBCs contain no antigens and type AB+ individuals are universal recipients because they have all possible antigens on the surface of their cells.

As mentioned earlier, the Rh factor of blood is exceedingly important during pregnancy. A pregnant, Rh- woman carrying a Rh+ fetus can begin to develop Rh antibodies if some of the fetus's blood crosses the placental barrier and enters the mothers bloodstream (in the case of a fetomaternal hemorrhage during childbirth). This switching from Rh- to Rh+ may cause the mother to develop Rh disease. Additionally, if a Rh- mother becomes Rh+ after her first pregnancy and later carries a fetus with Rh- blood and the mothers blood crosses the barrier, hemolytic disease of the newborn may occur.

Friday, April 29, 2011

Tiny Toxic Man Killers

Cyanobacteria. These are the tiny toxic man killers I am talking about.
This title page gives a short overview of what I'm going to be talking about and the different forms cyanobacteria can have.

The next slide I would explain that cyanobacteria is blue green algae that is actually bacteria.
This bacteria is photosynthetic and of course gives off oxygen as a waste product. This
cyanobacteria is found worldwide and in any conditions from the hypersaline conditions to the
extreme hot, extreme cold, and any type and time of exposure to UV light.

My next slide with just pictures I would talk about how cyanobacteria is usually found in
freshwater but can also be found on rock soil and sand and that the blooms in the upper right
hand corner are the toxic part of the algae.

When you think of toxins you think of the pictures on my next slide. Black widow, puffer fish, snakes, poison dart frogs and the list goes on. This bacteria however is a pretty mean 'predator'. The cocktail of toxins that are given off
by the blooms range from a potent neurotoxin (most poisonous natural neurotoxin) which shuts down signaling in the brain, hepatotoxin which damages the liver, endotoxin which is just a term for a broad range of bacterial toxins (on the outer membrane of the gram negative bacteria), and cytotoxin again a general term that is a toxin that has toxic effects on certain cells.

Lastly, you need to give credit where credit is due with a reference page.

Thursday, April 28, 2011


I see that I'm not alone in not knowing a lot about Angiosperms as Daphne has done her slides on this topic as well! Angiosperms are the flowering plants and they are the most diverse group of land plants. Like the gymnosperms, angiosperms are seed-producing plants, but the angiosperms have derived characteristics that set them apart from the gymnosperms.

One of the most significant derived characteristics that distinguishes the angiosperms from other seed plants is the flowers. The flowers are the reproductive organs and can aid angiosperms by enabling adaptability and broadening the ecological niches open to them. Due to this fact, the angiosperms dominate terrestrial ecosystems. The seeds that were mentioned are enclosed and contain an endosperm and endosperm formation generally begins after fertilization and the endosperm is a highly nutritive tissue that can provide food for the seedling when it first appears.Some other derived characteristics include stamens with two pairs of pollen sacs causing adaptations to specialized
pollination and well as to prevent self fertilization, as well as a closed carpel that encloses the ovules. The carpel and accessory parts may become the fruit. This enclosed carpel is another way to prevent self-fertilization and therefore increase diversity. Angiosperms also have reduced male and female gametophytes which decrease the time from pollination to fertilization of the ovary. This more rapid seed set has led to such flowering plant adaptations as annual herbaceous life cycles.

Even with all this information that distinguishes angiosperms from other plants, it is still hard to picture what exactly we are looking at here. When looking at the agricultural significance of angiosperms, we can see many different foods that are used in our everyday life.
Products of angiosperms include members of the rose family which include apples, pears, cherries, apricots, plums and other fruits as well as members of the legume family which include plants that have pods with their seeds inside such as various types of beans and peas. The gourd family is also included in the angiosperms and pumpkins and melons are found in this category. Tomatoes and peppers which are found in the nightshade family as well as wheat, oat, rice, and barley which are found in the grass family are all produced by angiosperms. The grass family is most significant when it comes to feedstock for animals. With all of these different families all found within the angiosperms, it is not surprising that angiosperms make up 90% of today's plant species. Next time you look at the meal you're about to consume, I bet you think of angiosperms!

Sunday, April 24, 2011


When I say angiosperms, the average person would not assume I am discussing flowering plants. An angiosperm is one of three clades of vascular plants. The seed plants are broken down into two groups, gymnosperms and angiosperms. Gymnosperms are characterized by the lack of encasement around their seeds. The angiosperms differ from the gymnosperms because their seeds develop in chambers. The ovary that contains the seed is found within the flower and the flower, ultimately becomes a fruit.

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

Smaller Brains in Migratory Birds

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 NĂºria 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

So, On the assessment test I got a question wrong, I know big surprise. The one I am going to focus on for my blog was the following question:

Genomic imprinting, DNA methylation, and histone acetylation are all examples of which one of the following (choose one):

The answer to this question was E) epigenetic inheritance. I don't know much about epigenetics so I thought I would research it a little more. Epigenetics is actually a study about the 'heritable changes in phenotype or gene expression' this actually does not happen because of a change in DNA sequence but rather non-genetic factors that allow the gene to express itself differently.

Tuesday, March 29, 2011

Intruders Beware

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.