ESL 91
SPRING, 2002
FOCUS DISCIPLINE ESSAYS
BIOLOGY

Anna 1
Anna 2
Victor

Anna Levina
ESL 91
Spring, 2002

Essay Topic: Explain why the mitochondria are so important to the function of the cell and what their role is in metabolism and energy production.

There are cells in every living thing on earth. One of the main goals of the cells is to keep living things organized. Living things have bone cells, stomach cells, brain cells and hundreds of other cell types. Each one is different from the other. Each organism has different types of cells that perform different responsibilities.

The most important parts of the cell are the mitochondria, which are known as the "powerhouses of the cells". What the mitochondria do is provide the energy a cell needs to move, divide and a lot of other duties that let cells survive. Mitochondria are very tiny parts of the cell. One cell can consist of thousands of mitochondria. Their quantity in a cell is dependent on what the cell's job is. The more energy a cell needs the more mitochondria it will contain.

The mitochondria's purpose is to break down food molecules so that the cell has the energy to live. When living things eat, they break down the food into little pieces, and the same with the mitochondria. The cell gets nutrients and the mitochondria break down the molecules for the cell to use. When living organisms eat, food goes down into their stomach. The meal is digested and broken down into millions of small molecules; cells absorb these molecules. The mitochondria's job is to break down the molecules in the cells and take out the energy stored inside high-energy phosphate bonds or ATP (Adenosine Triphosphate). After energy is taken from ATP, it becomes ADP (Adenozine diphosphate).

A mitochondrion contains two membranes: the outer membrane and the inner membrane (the latter folds many times (cristae)). There is a surface area inside the mitochondria. It looks like a tabletop where chemical reactions of breaking down food into molecules can take place. The more surface area a mitochondrion has, the more energy it can create.

Inside the mitochondria is a fluid called Matrix. Matrix is very important in the functions of mitochondria. Matrix is a fluid that has water and proteins mixed together. Proteins are those elements that take food molecules and combine them with oxygen. The only places where oxygen can be combined with food molecules in order to release the energy inside are the mitochondria. Mitochondria uses a cycle called Krebs to serve as the sites for the production of cellular energy. The Kreb's cycle results in 24-28 ATP molecules out of one molecule of glucose converted to pyruvate (plus the 4 molecules we get out of glucose). If our mitochondria are working we can get a lot more energy out of one molecule of glucose.

The mitochondria are the only part of the cells apart from the nucleus to have DNA. Even though mitochondrial DNA is much shorter than nuclear DNA, it is also very important. The number of proteins necessary to produce energy comes from mitochondrial DNA, and if this DNA were to be damaged it would stop mitochondria from producing energy. One side effect of damage to mitochondrial DNA is human disease.

A lot of genetic human diseases are caused by mutation in human mitochondria. The most common diseases are disorders of the brain and muscles; although many different organs may be affected. "Such disease may present at any time from childhood to adulthood" (Ross). The seriousness of the sickness depends on the number of mitochondria affected. "People may suffer from a condition known as mosaicism where some of the mitochondria are normal and some are abnormal; the higher the proportion of abnormal mitochondria the worse the symptoms of the disease" (Ross).

The field of mitochondria is one of the fastest growing disciplines in biomedicine. In the past decade more than 26,000 articles on mitochondria were published in over 1000 scientific journals. The goal of these articles is to provide new scientific research on mitochondria, learn how to deal with new diseases and also to provide understanding in a basic science of mitochondria.

 Works Cited

Biology4kids.com: Mitochondria. http://biology4kids.com/files/cell_mito.html

Ross, John. http://www.jdaross.mcmail.com/mitochon.htm

Studios, Andrew Rader. http://kapili.com/m/mitochondria.html

What are Mitochondria? http://wawa.essortment.com/whataremitocho_rkke.htm

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Anna Levina
ESL 91
Spring, 2002

Essay Topic: Research the neurotransmitter, dopamine. Explain how this neurotransmitter works and what its function is in the body and the brain. Be sure to concentrate on how dopamine affects behavior. What happens when something goes wrong in the system; for example, when there is too much or too little dopamine? What treatments are there?

Neurotransmitters are brain chemicals that carry information from one neuron to another. Dopamine is one of the most important neurotransmitters and it performs amajor role in our mental and physical health. The amount of dopamine in our system has an effect on our mind and our life. It affects brain processes that control movement, emotions, and our capacity to experience pleasure and pain. Abnormalities in the production of dopamine bring a number of dangerous diseases.

Neurons containing the neurotransmitter dopamine are grouped in the midbrain in an area called the substantia nigra. Cells within this area produce dopamine normally. When the neural cells which are responsible for the amount of dopamine get weaker, the regular amount of dopamine production goes down. Parkinsonís Disease (PD) begins to appear when the quantity of dopamine is extremely low.

This disorder is very difficult to diagnose. The first stage of PD is not too clear. The person starts to feel weak and tired. Some of the typical symptoms are muscular rigidity, difficulty with balance, slowness of movement, and changes in speech and handwriting. There are some dopamine agonist drugs which attach to dopamine receptors and stimulate them. Some of these drugs are used to treat Parkinsonís Disease.

Sometimes the amount of dopamine in the system is higher than it needs to be. In this case people suffer from mental disorders such as schizophrenia. Drugs which prevent the actions of dopamine are called dopamine antagonists. Drugs such as methylphenidate can help to reduce dopamine activity and help people with schizophrenia and related mental disorders to live a much more normal life. It is very important to recognize the symptoms and seek professional help.

Special research in the past 20 years has proved that brain disorder and some symptoms of severe psychopathology is the result of the effect of drug abuse and addiction on the neurotransmitter dopamine. Drugs such as cocaine change the function and amount of dopamine in the brain and provide a very harmful physiological effect on it. Constant use of cocaine affects human behavior. People who take cocaine become very active. They talk a lot more than they usually do; they have paranoia and depression. People experience hallucinations and delusions. Their moods change very fast from normal to strange.

Since the drug cocaine increases the amount of dopamine, the behavior of people who abuse this drug turns out to be very similar to the behavior of people with symptoms of schizophrenia. It is difficult to distinguish a schizophrenic from a cocaine addict unless mental health professionals know the background of the patient.

Recent research indicates that cigarette smoke might raise the level of dopamine. For a long time scientists have known that nicotine has something to do with the release of dopamine. The researchers are trying to prove, but have not proved yet, the mechanism for cigarette addiction. The research points toward the idea that cigarette smoke slows down the breakdown of dopamine.

Dopamine deficiency may be caused by a mixture of such factors as nutritional shortage, food allergies, environmental pollutants, stress and genetics. A combination of some of these aspects is the reason for changes in brain chemistry which create behavioral problems. It could be a dietary lack of the necessary vitamins or a food allergy which affects the amount of dopamine. It is important to eliminate these wrong foods or add necessary kinds of vitamins to the diet of a person with dopamine deficiency.

President George Bush in 1990 announced that the next 10 years will be the "Decade of the Brain." Since that time scientists have been looking for treatments and cures for the most destructive diseases connected to the brain. It is a fact that 500,000 Americans per year are affected by diseases which develop from weakness of the brain cells that produce dopamine.

One of the main goals of scientists is to completely understand the function of the neurotransmitter dopamine. Detailed study of dopamine will help to distinguish the genes that have harmful effects on the level of the neural cells which are responsible for the amount of dopamine in the human brain.

Bibliography

Berger, Kathleen Stassen. The Developing Person Through the Life Span. New York: Worth, 2001

Gant, Charles M.D. http://www.concentric.net/~skiplac/addnadc.html

News Briefs http://ndsn.org/mayjun97/nature.html

Oxford http://www.oup-usa.org/isbn/0199637660.html

The University of Texas at Austin http://www.utexas.edu/research/dopamine.html

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Victor Brizin
ESL 91
Spring, 2002

Essay Topic: Explain why the mitochondria are so important to the function of the cell and what their role is in metabolism and energy production.

The human body is made from millions of cells, and each cell does job in the body. Inside the cell are thousands of little structures called Mitochondria. The Mitochondria are the powerhouses of the cell; they let the cells survive. The Chief function of Mitochondria is to created energy for cellular activity by the aerobic respiration.

Mitochondria are very tiny organelles. One cell can contain thousand of Mitochondria inside itself, depending on what the cells job is. When the cell needs a lot of energy, it will have more Mitochondria.

Mitochondria have outer and inner membranes. The fluid inside Mitochondria is called Matrix and that has water and proteins all mixed. Those proteins take food molecules and combined them with oxygen. Mitochondria are the only places in the cell were oxygen can be combined with food to release the energy inside. The energy is stored into high energy phosphate or ATP.

Various reactions in the cell can use energy or produce it. Mitochondria can produce hundreds of thousands of ATP molecules every minute in the typical cells. The ATP is transported to the cytoplasm in cells, where it is used for energy reaction. As ATP is used it is converted into ADP, which is returned by the cells to the Mitochondria and used to build more ATP.

The DNA in Mitochondria may track several genetic diseases. While the DNA manages syntheses of enzymes for aerobic respiration, it also codes for proteins important in the nervous system, circulatory system and other body functions. Many of genetic diseases, including diabetes mellitus, deafness, heart disease, Alzheimer's disease, Parkinson's, disease, are associated with mutations in Mitochondrial DNA. A relatively new medical specialty, mitochondrial medicine, tries to understand role of the Mitochondrial DNA mutations in genetic diseases. For example, the identity of the skeleton alleges of Tsar Nicolas II, and his family was recently established using mitochondrial DNA.

The human body depends ON the work of thousandS OF different cells, such as red and white blood cells, neurons and immune cells. They have extremely important functionS, and we couldn't live without the work they do every second . All body cells depend ON energy, which only Mitochondria can produce. Without Mitochondria it would be imposible for humans and animals to exist on Earth.

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