The first 2000-word biological paper is urgent! ! !

-Examine whether biological genes will change due to the environment.

Genes are DNA fragments on chromosomes in the nucleus of organisms, which control the characteristics of organisms. Genes are also the genetic material left by the previous generation to future generations.

Transgenic technology is to change the gene of an organism through artificial scientific and technological methods, so that its gene changes and its characteristics change accordingly, so as to achieve the purpose of improving varieties.

It can be said that all states of any living thing are related to genes. Therefore, to understand biology, we must first understand genes. Genes can be changed by artificial techniques. In addition, will biological genes change because of environmental changes?

Let's start with the simplest.

One,

Dig out the soil in the same place, and choose 30 plump and roughly the same mung beans and two identical flowerpots. Then plant mung beans, irrigate the same amount of water every day, put basin A in the sun and basin B in the shade;

Second,

Dig out the soil in the same place, and choose 30 plump and roughly the same mung beans and two identical flowerpots. Next, plant mung beans, put both pots C and D in sunny places, water pot C with a lot of water every day, and water pot D with a little water;

Third,

Dig out the soil in different places and choose 30 plump and roughly the same mung beans and two identical flowerpots. Then plant mung beans, irrigate the same amount of water every day, and put E and F in sunny places;

Fourth,

Choose 30 plump and almost identical mung beans and two identical flowerpots. Then plant the mung bean pot H with soil, plant the mung bean pot I with water, and pour the same amount of water every day, all in sunny places;

When I grew up, I found that the situation in each basin was different. So we initially think that biological genes will change due to the environment.

Later, we found some examples.

Take human as an example, the genes in the human body will change because of the environment. In our daily life and work, there are many known or unknown factors that affect the metabolism of trillions of cells in our body. These harmful factors may act on the DNA of somatic cells, leading to the destruction of DNA, abnormal changes in the functions of corresponding genes, and affecting the safety and health of life. Of course, there are quite perfect mechanisms in cells to repair these injuries. However, when the damage degree of DNA exceeds the repair ability of the repair mechanism, problems will occur at the cellular level, and it may take a long time to develop from a small number of cells to a stage where they may show diseases and be detected clinically. In this process, some diseases can be found at an early stage with the help of genetic testing technology, which will greatly reduce the medical expenses and the pain of patients.

Are other creatures like this?

Many experiments show that this is true.

Genetic studies on many Arabidopsis species show that environmental factors have great influence on species genetic diversity and genome. In addition to the "favorite" of scientists in the laboratory, there are many wild Arabidopsis thaliana distributed around the world. Their growth speed, leaf color and branching mode are different. In the latest research, an international team of scientists led by Detlef Weigel of Max Planck Institute for Developmental Biology in Germany collected 19 species of Arabidopsis thaliana from America, Africa, Asia and other polar and subtropical regions, and compared their gene sequences (about10.20 billion base pairs) with those used in the laboratory, thus determining the related genetic differences.

The result is surprising: the breadth of their genetic differences far exceeds the so-called "improved genome". The researchers found that one base pair per 180 is variable. At the same time, the research shows that about 4% of Arabidopsis genome used in the laboratory is either very different from wild species or does not exist in wild species at all. In addition, about one tenth of wild Arabidopsis genes are defective and cannot perform normal functions.

The new research conclusions have raised many new basic questions for scientists. Weigel said, "Maybe there is no so-called genome of a species. So far, the understanding of a single DNA sequence has not allowed scientists to fully understand the genetic potential of a species. " In addition, the plasticity of Arabidopsis genome is also surprising. Although the number of genes in Arabidopsis genome is equivalent to that of humans and some crops, the size of its whole genome is less than one twelfth of that of the latter two. At the same time, there are almost no repetitive sequences and irrelevant "junk" sequences in Arabidopsis genome.

Further research shows that the genes related to the interaction between Arabidopsis thaliana and the external environment (such as resistance to pathogens and infections) are more variable than other functional genes. Weigel believes that this genetic feature reflects the adaptability of Arabidopsis thaliana to the local living environment, and it is these changeable genes that enable Arabidopsis thaliana to tolerate dryness and humidity, heat and cold, and adjust its growing season.

There is another example about animal genes and environment.

The National Academy of Sciences attaches great importance to the impact of genetically modified animals on the surrounding environment.

The US Food and Drug Administration (FDA) asked the expert group of the Committee to list the hot scientific issues related to animal biotechnology. In the report published on August 12, 2002, the Committee put the impact of genetically modified animals on the natural ecosystem environment at the top of all hot issues.

An American company (ABFW, Massachusetts) produced a genetically modified salmon. This kind of fish grows very fast, which is three times as fast as ordinary salmon. Some scientists and environmental organizations have expressed strong concern about this fish. They believe that genetically modified fish will have an advantage in the survival competition with wild salmon, and may bring some harmful genes to other animals in the environment. However, the company claims to have collected a series of information about the hot issues concerned in the report. "What we are going to put on the market is only infertile female salmon, and there is no such environmental problem."

Although this case does not directly explain the changes of genes caused by the environment, the view that genetically modified genes will do harm to the environment indirectly tells the exact answer.

In other words, biological genes will change due to the environment.

The interaction between genes and environmental factors, the expression of gene action can not be separated from the influence of internal and external environment, in a group of individuals with a specific gene, the percentage of individuals who show the characteristics of the gene is called penetrance; In an individual who has a specific gene and expresses the trait, the expression degree of the trait is called the expression degree. Both penetrance and expressive force are influenced by internal and external environment.

Internal environment refers to the sex, age and background genotype of an organism.

External environment:

① temperature. Temperature-sensitive mutants can only show mutant characteristics at certain temperatures, and for general mutants, temperature has different effects on genes. For example, in the first experiment, the characters of two pots of mung beans in ab are different, and most of us have temperature influence;

2 nutrition. The yellow color of rabbit fat depends on the homozygous state of gene Y and the presence of lutein in food. If the food does not contain lutein, then the fat of yy homozygote is not yellow. The function of Y gene is obviously related to the assimilation of lutein. Evolution as far as the content of DNA in cells is concerned, the lower the biological content, the higher the biological content. In terms of the number and types of genes, generally speaking, the lower the organisms, the fewer the higher the organisms. The increase of DNA content and gene number is closely related to the gradual improvement of physiological functions.

Wait a minute.

Gene was originally an abstract symbol, and later proved to be a genetic functional unit occupying a certain position on the chromosome. This investigation and exploration can show that biological genes will change with the environment.

In addition, I will give you a reference, hoping to help you.

Biofuels are promising _ Biological Papers

Do you think the United States is too dependent on imported oil? Some people think that the time is ripe for using biofuels:

● As early as May this year, bus passengers in St. Louis can take buses powered by diesel and soybean oil.

Due to the high yield of corn last year, the ethanol production industry with corn as raw material intends to make ethanol production reach a record level this year.

And the method created by Edgar Lightley. The repeated rise in oil prices made the Pennsylvania farmer very uneasy, and he began to heat his house with a very popular new stove fuel corn.

Although using grain as fuel is nothing new-Rudolf Dissel used peanut oil as fuel to drive cars a century ago-the idea suddenly became very practical. The price of oil is getting higher and higher, but the price of food is so low that politicians and many managers are rethinking this problem. Biofuels that can be completely fueled and renewable have been widely used in Europe. It can ease the oil supply in the United States and help maintain the stability of the American agricultural economy.

Bright prospects

Biofuels don't smell bad. Users report that the waste gas from burning biodiesel with soybeans tastes a bit like French fries. Experts say that even if food prices rise, if the United States gives priority to developing biofuels in order to curb global warming, Shenwu fuel may have a bright future.

Since people began to use gasoline blended fuel in 1970s, corn growers have been urging people to use more ethanol as gasoline fuel. Besides being used as livestock feed and export, the production of biofuel has now become the third largest use of corn.

Last year, the ethanol production industry produced 654.38+0.6 billion gallons of ethanol from corn, and the production scale is still expanding. Archer-Daniels-Midland, Illinois, which produces about half of the total ethanol in the United States, intends to expand its ethanol production capacity by another 20%.

The most surprising thing this year is the advent of biodiesel. The experimental results show that the mixed fuel of soybean oil and diesel oil is as good as ordinary diesel oil (except in particularly cold weather) and much cleaner than ordinary diesel oil. But the standard blended fuel-80% diesel and 20% soybean oil-is too expensive. According to the National Biodiesel Committee, partly due to the low price of soybeans, the price of biodiesel has dropped from $4 to $65,438+$0.25 to $2.25 per gallon. This price is similar to that of ordinary diesel, which is enough for many people to consider using biodiesel.

government subsidy

Government subsidies have also promoted the development of biofuels. In June last year, 165438+ 10, the USDA decided to spend10.50 billion dollars annually to subsidize ethanol producers in the next two years to increase the use of biofuels such as ethanol and biodiesel. At least five states are considering tax incentives to further encourage the use of biodiesel.

Encouraged by the above policies, the output of biodiesel increased sharply, from 500,000 gallons in 1999 to 5 million gallons in 2000. It is estimated that the USDA's policy of encouraging accidents alone can increase biodiesel production by another 36.5 million gallons.

These figures still fall short of the annual output of 56 billion gallons of diesel. However, advocates of biofuel production say that if the oil industry is forced to switch to low-sulfur diesel by 2006, as announced by the Bush administration a few days ago, soybean oil may become the main lubricant for biofuels. In fact, lubricants provide another promising market for cereals. Researchers have developed an equally cheap and environmentally friendly substitute from grain to replace petroleum products as lubricants for semi-trailer hooks, tracks and chain saws.

Such projects will help to inject funds into the long-term depressed agriculture in the United States. According to the Renewable Fuel Association, ethanol production alone can increase farmers' income by $4.5 billion a year.

2,

Advantages and disadvantages of genetically modified food

Key words: food: at present, the United States organizes genetic crops, crop transgenic technology.

(1) The concept and principle of genetically modified food.

Anyone with a little scientific knowledge knows that genes are the most basic unit to control biological traits and record genetic information of biological reproduction. Some or all of the characteristics of an organism can be changed by changing genes.

Genetically modified food is to move and change the genes of animals and plants to create food types with new characteristics. For example, the genes of some animals are transferred to other species by biotechnology, and the genetic tissue of organisms is transformed to make them have characteristics that the original species does not have. These changes can be accomplished according to the goals of human needs. Take this example to illustrate: people can use the genes of fresh fish to help ordinary plants such as tomatoes and strawberries resist the cold; By inserting some bacterial genes into corn and soybean plants, they can better resist pests. The food processed and produced by these genetically modified organisms is genetically modified food.

② Development of genetically modified food.

According to FAO data, the global planting area of genetically modified crops was about 1 1 10,000 hectares in 1997, and it rose to nearly 30 million hectares in 1998, and it is expected to reach 40 million hectares by the end of 1999, with an average increase of more than/kloc-0.

The United States is the country with the most transgenic technology. Since the gene transformation technology was actually put into agricultural production in the early 1990s, 55% of soybeans, 45% of cotton and 40% of corn in the annual output of agricultural products in the United States have been gradually transformed into gene transformation. At present, about 20 kinds of seeds of genetically modified crops are allowed to be planted in the United States, including corn, soybeans, rapeseed, potatoes and cotton. It is estimated that from 1999 to 2004, the market scale of genetically modified agricultural products and food in the United States will expand from $4 billion to $20 billion, and will reach $75 billion in 20 19. Some experts predict that at the beginning of 2 1 century, it is likely that every food in the United States will contain a certain amount of genetically modified ingredients. Other countries, such as Argentina and Canada, are also developing genetically modified agriculture rapidly.

Great progress has also been made in transgenic research in China, which has comparative advantages in gene drugs, transgenic crops, crop gene maps and new varieties. However, few crops actually enter commercial production. As far as crops are concerned, there are only insect-resistant cotton, Petunia, virus-resistant sweet pepper, virus-resistant tomato and delayed ripening tomato. ③ The advantages and disadvantages of genetically modified food to human body and the safety of genetically modified food;

Up to now, genetically modified foods have not undergone long-term safety assessment before they are put on the market, and it is still doubtful whether they are safe for human beings to eat for a long time, and the scientific community knows nothing about whether these foods are safe.

-Positive statement:

Since the first batch of transgenic tomatoes in the United States went on the market, more than 200 million people around the world have eaten thousands of genetically modified foods, and there has not been a food safety incident for more than five years. There are many imported genetically modified soybeans in China. It is estimated that about half of soybean salad oil contains genetically modified ingredients, and there is no problem at present.

The breakthrough of gene technology enables scientists to improve crops in ways unimaginable to traditional breeding experts, and its advantages are obvious. First, the production cost can be reduced. Adding another gene to a variety will change the characteristics of the variety and make it have factors that the original variety does not have, thus enhancing the ability to resist diseases, weeds or pests, thereby reducing the dosage of pesticides and herbicides and reducing the planting cost. Second, it can increase the yield per unit area of crops. After genetic improvement, a crop can adapt to the environment more easily, resist various disasters more effectively, and make its yield higher. Third, transgenic technology can greatly shorten the time for developing crops. Using traditional breeding methods, it takes seven or eight years to cultivate a new variety, while genetic engineering technology can cultivate a brand-new crop variety, and the time can be shortened by half. Therefore, some experts believe that in a few years, transgenic technology will change the world.

Transgenic technology can endow crops with new characteristics according to people's needs. For example, crops can release pesticides by themselves, crops can grow on dry land or saline-alkali land, or they can produce more nutritious food. Scientists also use transgenic technology to develop crops that can produce disease-resistant vaccines and foods. Agricultural map.

-Negative statements:

In the 1999 genetically modified potato incident, an experimental result published by a British researcher said that feeding mice with genetically modified potatoes would lead to abnormal organ growth, weight loss and immune system damage. This experimental result immediately caused a sensation, which led to the worldwide questioning of the safety of genetically modified food.

1999 In May, the authoritative British science magazine (Nature) published John, an associate professor at Cornell University. A paper by Rosie shocked the world. According to the paper, the researchers spread the pollen of insect-resistant transgenic corn-Bt gene corn on the leaves of chicory, and then let butterfly larvae eat these leaves. Four days later, 44% of the larvae died, and the surviving larvae were small and listless. The other group of larvae ate vegetable leaves sprinkled with ordinary corn pollen, and the mortality rate was not high, and there was no growth retardation. Based on this, the paper draws the conclusion that BT transgenic corn pollen contains toxins.

People doubt whether genetically modified crops and genetically modified foods made from them are also harmful to human body. For example, what is the difference between transgenic crops with insect resistance and automatic weeding function and traditional pesticides? Will they "transfer" toxic substances to consumers' organic systems? Also, a genetically modified food can resist bacterial invasion, so will it mutate bacteria inside and outside our bodies and make them immune to all antibiotics? At present, these problems cannot be explained clearly. Moreover, British researchers recently confirmed in the laboratory that after eating transgenic potatoes 10, the kidneys, spleens and digestive tracts of mice were damaged. This deepened people's fears. An article published in Science Journal of China Academy of Sciences recently summarized the "possible" harm of genetically modified food to human health as three points: some toxins can cause acute and chronic poisoning, some genetically modified crops can cause allergic reactions, and the nutritional composition of genetically modified products changes, which makes people's nutritional structure unbalanced.

-Status:

International authoritative organizations such as the World Food and Agriculture Organization, the World Health Organization and the Economic Cooperation Organization all said that artificial transplantation of foreign genes may have "unexpected consequences" for organisms. In other words, we don't have enough scientific means to assess the risks of genetically modified organisms and food.

The International Consumers Federation (whose members include 250 consumer organizations in 1 15 countries) said, "At present, no government or United Nations organization will claim that genetically modified foods are completely safe."