Paramecium bursaria

Paramecium bursaria is a species of ciliate protozoan that has a mutualistic symbiotic relationship with green alga called Zoochlorella.

Taxonomy:

Domain: Eukarya
Kingdom: Protista
Phylum: Ciliophora
Class: Oligohymenophorea
Order: Peniculida
Family: Parameciidae
Genus: Paramecium
Species: bursaria

Habitat:

Paramecia are widespread in freshwater environments, and are especially common in scums.

Predators:

In the 1930's a Russian biologist named Gause used Paramecium and Didinium to examine the predator-prey relationship. Both are microscopic organisms. Paramecium is the prey and Didinium is the predator.

Prey:

Paramecium feed on micro-organisms like bacteria, algae, and yeasts. To gather its food, the paramecium uses its cilia to sweep the food along with some water into the cell mouth after it falls into the oral groove. The food goes through the cell mouth into the gullet, which is like the stomach. When there is enough food in it so that it has reached a certain size it breaks away and forms a food vacuole. The food vacuole travels through the cell, through the back end first. As it moves along enzymes from the cytoplasm enter the vacuole and digest it. The digested food then goes into the cytoplasm and the vacuole gets smaller and smaller. When the vacuole reaches the anal pore the remaining undigested waste is removed.

Anatomy:

P. bursaria is 80-150 μm long, with a wide oral groove, two contractile vacuoles, and a single micronucleus as well as a single macronucleus.

Historical information:

The first eukaryotic kingdom was the kingdom Protista. 1 billion year ago, the diverse protists appeared.


Interesting information:

The algae live inside the Paramecium in its cytoplasm and provide it with food, while the Paramecium provides the alga with movement and protection.

P. bursaria is the only species of Paramecium that forms symbiotic relationships with algae, and are often used in biology classrooms as examples of protozoans, and as examples of symbiosis.

More information on Paramecium bursaria:

http://microbewiki.kenyon.edu/index.php/Paramecium#Description_and_Significance

http://www.101science.com/paramecium.htm

http://www.microscopy-uk.org.uk/mag/indexmag.html?http://www.microscopy-uk.org.uk/mag/articles/param1.html

Guest Lecturer: Louise Mead

On Thursday, Louise Mead of the National Center for Science Education came to our school and gave us a lecture. Although we could not move around the classrom as we always do when we have a lab, this lecture certainly gives us a lot of information about evolution. In her lecture, she mainly focused on the evidence for evolution. To explain, she provided many pictures and described them in details. Also, she talked about how different people look at evolution differently.

"What is evolution and do you accept it?" -- this was how she started her lecture. This is what I wrote: evolution is a change in species over time. I accept evolution because it is the way of life.

She related these questions to the day's lecture. The first thing she talked about was the evidence for evolution. They include biogeography, comparative anatomy, molecular biology, fossil record, and developmental biology.


Biogeography
It is the districution of plants and aminals over space and time.

Comparative anatomy
The bone structure for humans, bats, and birds are very similar, but they are not exactly identical. Why? Because of different environments and ways of living.

Comparative biochemistry and molecular biology
Humans have 2 chromosomes less than chimpanzees, gorillas, and orangutans. The reason for this is that one of the 2 centromeres became inactivated during the formation of human chromosome 2.

Fossil record
By using fossils, scientists can find out more of the evolution of species. For example, scientists found out that fins could become limbs.

Developmental biology
It is possible: genes of humans and mice have something in common.


Besides the evidence for evolution, Louise Mead also talked about creation. A report showed that most people believed God created human beings while fewer people believed God had no part in the process. As for me, I think evolution exists because many evidence shows that evolution is occuring over generations. However, it is indeed hard for some religious people to accept evolution.

This lecture is very meaningful since it provides a lot of information and pictures where we cannot find in the book. The lecture makes me have a better concept of what evolution is and to understand how scientists discovered evolution.

To conclude, evolution is a really interesting topic since it makes people hard to believe and wonder how humans are actually evolved from earlier species.

Meat raises lung cancer risk

Summary:

According to the article, people who eat a lot of red meat and processed meats have a higher risk of several types of cancer, including lung cancer and colorectal cancer.

A big study shows that people who eat a lot of meat have a higher risk of liver and esophageal cancer and that men who eat red meat get pancreatic cancer more easily. "The people in the top 20 percent of eating processed meat had a 20 percent higher risk of colorectal cancer -- mostly rectal cancer -- and a 16 percent higher risk for lung cancer."

Meats can cause cancer by several routes. They are both sources of saturated fat and iron, which have independently been associated with carcinogenesis. Meat is also a source of several chemicals known to cause DNA mutations, including N-nitroso compounds (NOCs), heterocyclic amines (HCAs) and polycyclic aromatic hydrocarbons (PAHs).


Reflection:

Have you ever thought of the meat you eat daily may lead to cancer? Yes, cancer! All kinds of red and processed meat may be a cause of cancer. Red meat included all types of beef, pork and lamb. Processed meat included bacon, red meat sausage, poultry sausage, luncheon meats, cold cuts, ham and most types of hot dogs including turkey dogs. All these meats should be familiar to you because you eat them every day.

I was totally shocked when I first looked at this article. It is unbelievable that the meats in the hamburgers and sandwiches give people a higher risk of getting cancer. The thing that makes me less worried is that I don't eat a lot of meats. I prefer vegetables to meats.

I think statistics do show that meat really increases the chances of getting cancer. Meat is also a cause of DNA mutations. However, meat is a part of our lives. Every day, you need vegetables and meats to meet a balanced diet. Is it possible to make everyone stop eating meat?

In my opinion, the best way now is to limit the amount of meat we eat each day. I think everything is good if you use it in an adequate amount. But I really hope that meat is not an essential cause of cancer because it will affect a lot of people if so.

Visit the following websites to get more detailed information:

• http://news.yahoo.com/s/nm/20071211/hl_nm/cancer_meat_dc_1
• http://medicine.plosjournals.org/perlserv/?request=get-document&%20doi=10.1371/journal.pmed.0040325

Genetic Face Lab

I was really curious at first. What does it mean by 'genetic face lab'? Does it have anything to do with my face?

Hehe.. actually, it has nothing to do with my face. Instead, the whole class had the opportunity to create a face by tossing a coin. Yes, a coin! There are two sides of a coin: head and tail, and we used these two sides of the coin to determine the characteristics of the face. It's kind of fun.

Want to see my work? It's up above. I know it's a bit... um... weird, but I think it's partly because I cannot draw well using the computer. Anyways, this lab helps me relax a lot and I enjoy the process of creating this strange face. By the way, do you have any idea if this is a boy or a girl?

Answer: Boy

Cooking with DNA: A Protein Synthesis Simulation

I love Rice Krispy Treat! It's great that the whole class could make Rice Krispy Treat in class and EAT it! Since the process of making Rice Krispy treats is analogous to the process of protein synthesis in cells, so making Rice Krispy can help all of us understand better about the protein synthesis process.

I was so happy that I was picked to be the group leader, which was actually the rRNA. I was supposed to direct and keep track of the whole thing. I also had to manage my group members(tRNAs), record the order in which they deliver their ingredients and instructions (amino acids), and coordinate the manufacturing of the protein.

My group was very effecient and cooperative. We were the fastest group to finish making the Rice Krispy treat and I don't think we made any mistake in the process of making it. It's really fun! I only ate a little piece of it and it tasted really good. Hope I will have a chance to COOK WITH DNA in the future!

News Article: Pollution-Busting Plants

Summary:

"A French hybrid of an aspen tree may one day rid water supplies of the industrial degreaser—and human carcinogen—trichloroethylene (TCE), one of the most common contaminants at toxic waste sites in the U.S. And the tiny, but tractable, plant Arabidopsis may mop up the residue of RDX, a military explosive blasted into the soils at firing ranges." said the article.

As we all know, plants are the Earth's good friends. They help to absorb carbon dioxide and, at the same time, give out oxygen by the process called photosynthesis. They improve the air quality and give people the impression of freshness.

Researchers are trying their best to make good use of plants. They tried to put a cytochrome (an enzyme) known as P450 2E1 into plants. They used a bacteria to insert the genetic code for this cytochrome isolated from rabbits into the genetic instructions of the hybrid aspen tree, which belongs to the poplar family.

The result turned out to be really amazing. The aspen sucked the contaminant out of the water much faster than unaltered aspen and removed a lot of it by the time they were done drinking the poison. It also boosted the tree's ability to absorb the chloroform left over after cleaning drinking water, the industrial solvent carbon tetrachloride and even vinyl chloride. They could also remove benzene, a known human carcinogen, 10 times faster than control plants.

Biologists working with the Arabidopsis plant, a flowering weed, successfully demonstrated that inserting a variant of cytochrome P450 isolated from battlefield bacteria allowed it to break down the RDX left behind in the soil of firing ranges. Such altered Arabidopsis, when drinking RDX-laced water, removed 90 to 97 percent of it.

The goal right now is to create trees that provide a low-cost option for cleaning contaminated groundwater and sites that might not otherwise be purified due to the expense of chemical and microbial treatments.

Reflections:

Right now, we are studying the topic of gene technology. We are learning about gene engineering. This article is somehow also related to transgene. Researchers inserted genetic code for cytochrome into the genetic instructions of the hybrid aspen tree. From this, we can see that gene engineering is really useful in our lives.

Gene technology benefits the environment, which in turn benefits us. According to the article, the genetically modified aspen proved capable of removing benzene, a human carcinogen, from air or trichloroethylene, the most common contaminant at U.S. toxic waste sites, from water while the Arabidopsis plant could break down the RDX left behind in the soil of firing ranges and removed 90 to 97 percent of RDX when drinking RDX-laced water. All these transgenic trees provide us with a cleaner and more comfortable environment.

The technology nowadays does make our lives much easier and more convenient. I really hope that more discoveries of gene technology can further improve our daily lives. The thing we can do is to treasure the plants and try to discover more wonderful things from them.

Want to know more about this article? Visit the following website:

http://www.sciam.com/article.cfm?articleID=A5B6ED51-E7F2-99DF-30AEE27247438296&chanID=sa022

DNA

On Monday, when the bell was about to ring, the whole class went out of the classroom to make DNA. What did we use to make DNA? Ourselves!!

We arranged ourselves in a straight line and tried to figure out the 5' and 3' ends. We used a bit of time to review what we have learned about DNA. DNA is made up of purines and pyrimidines. It starts from the 5' end and we always extend the 3' end. They are basic things. Since we have boys and girls in the class, it was easy to demonstrate the structure of DNA. Boys could act as purines while girls acted as pyrimidines. In this way, boys and girls always pair up with each other because purines and pyrimidines pair up with each other.

Later in this week, we went deeper into the structure and discovery of DNA. It was pretty difficult to imagine that the little DNA is the genetic material and thus so essential in our lives. On Friday, we also had the chance to construct a paper model of DNA, but I did not make one because I did not have time.

The next topic is gene technology. What other things will I discover in this chapter?