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Find out the information about "cell differentiation, canceration and aging" in biology teaching plan of senior two.
Teaching objectives
Knowledge target
1. Understand the relationship between cell differentiation and organism development.
2. Understand the totipotency of cells and its application in scientific research.
3. Understand the causes and incentives of cell canceration and how to prevent cancer.
4. Understand the manifestations and causes of cell aging.
capability goal
1, cultivate students' analytical and comparative ability.
2. Combine practice to cultivate students' ability to use knowledge flexibly.
Affective goal
1. Through learning, students can understand the movement of life and the influence of internal and external factors on the process of life.
2. Guide students to pay attention to the major social problems and human health problems facing the world today. Stimulate social responsibility and mission. Stimulate students' good feelings of caring for life.
Teaching suggestion
Textbook analysis
A cell cycle may be short or relatively long, and the different future of these cells is basically determined when they are produced. During the embryonic development of higher organisms, the proliferation behavior of cells will be different. After the cell with the ability of continuous division is produced, its mission is to produce a new generation of cells-to ensure the growth or reproduction of organisms through cell division and proliferation. Some cells have lost their irreversible ability to divide-they form functional bodies with certain shapes and structures through cell differentiation, and show their life value through metabolism. There are also some cells that temporarily lose their ability to divide and no longer proliferate, but they can restore their proliferation ability under appropriate stimulation.
The knowledge about cell differentiation has been preliminarily understood in junior high school, and it is known that the formation of tissues and organs is the result of cell differentiation. Here we need to briefly introduce the principle of cell differentiation. The main purpose is to make students have a more complete understanding of cell life, and also to lay a foundation for learning the knowledge of biological reproductive development, gene control of protein synthesis, and understanding the principles of the latest biotechnology such as cloning and cell engineering. This part of knowledge should be properly explained, and it should not be excessively expanded or infinitely deepened.
Because of the serious environmental pollution in today's world, cancer has become the number one killer threatening human health. Therefore, understanding the causes of cancer and the main factors inducing cancer will reduce our chances of getting sick and is of great significance to improving the health level of the whole people and the quality of the population. Therefore, it is very meaningful to discover all kinds of dangers and wrong lifestyles around us with a scientific eye.
The knowledge in this section is closely related to many hot issues of new scientific and technological progress, so it is very important to understand or solve some practical problems with practice. It will also stimulate students' enthusiasm for understanding science, and it is also a good opportunity to stimulate students' sense of social responsibility.
Teaching design scheme
Teaching topic: Cell differentiation, canceration and aging in the third section (suggested to be completed in 1 class)
Teaching emphasis: 1, cell differentiation and its results.
2. Relationship between cell differentiation and cell division
Teaching difficulty: 1, the mechanism of cell differentiation, canceration and aging.
2. Characteristics of cell differentiation
Teaching process:
Review: the concept of cell cycle.
Introduce a new lesson: some of the daughter cells produced by cell division will enter the next cell cycle and continue to produce new daughter cells through cell division; However, quite a few cells no longer copy DNA, but enter the stage of cell growth and development. Cell growth is formed by the accumulation of a large number of compounds that make up cells. At this stage, the assimilation of cells is much stronger than the alienation. With the growth of organisms, the morphological structure of cells gradually began to change, and various tissues and organs gradually formed during the embryonic period. This is the process of cell differentiation and the direct cause of organism development. Abnormal cell division and differentiation will lead to cell canceration. Like cell division and cell differentiation, cell aging and death are also normal links in the process of life.
Section III Cell Differentiation, Canceration and Aging
I. Cell differentiation
1, the concept of cell differentiation (page 4 1)
Cell differentiation is a universal life phenomenon. The process from fertilized egg to mature individuals is actually the process from totipotency to specific stability. The division of labor between cells has been strengthened, and the efficiency of life activities has been improved. At the same time, the developmental potential of differentiated cells was gradually inhibited. Cells began to show specificity in morphology, structure and function, and this change was obviously regional. Cells with the same morphology and structure stick together through cell recognition polymerization, and finally form a cell group with obvious differences. The development process of cells from homotype to heterotype is the process of cell differentiation. The result of cell differentiation is the formation of tissue.
Discussion: With the mitosis of early embryonic cells, the number of cells in multicellular organisms increases rapidly. Are the genetic materials of these cells the same? In theory, somatic cells with the same heredity should show the same morphological, structural and functional characteristics. Is that really the case? Why?
The teacher suggested (it is best to guide the students to answer): "All life activities are inseparable from protein." "Nucleic acid plays an extremely important role in biological genetic variation and protein biosynthesis."
2. Causes of cell differentiation
The fundamental reason that determines the direction of cell differentiation is that although the genetic materials in cells of different parts of multicellular organisms are the same, their relative positions are different, and their control over protein synthesis is not exactly the same, which leads to differences in the composition of important life substances such as protein and enzymes in cells of different specific parts, and finally leads to differences in the morphology, structure and function of cells. From the appearance, it is cell differentiation, forming different tissues and organs. As can be seen from the above, in the process of cell differentiation, cytoplasm has an influence on the activity of nucleus. The development direction and final result of life activities are the result of internal and external interaction. Cell differentiation reaches the maximum in embryonic stage, and the post-embryonic development after birth only increases the original tissue volume without adding new tissue types.
3. Characteristics of cell differentiation and cell totipotency:
The stability of cell differentiation is related to the degree of cell differentiation, and cells with significant differentiation will be more stable. Generally speaking, differentiated cells will lose the ability to continue to divide, especially animal cells. In some cases, plant cells can be reversed and regain their ability to divide. Cells that have recovered their ability to divide can still differentiate again under certain environmental conditions. After leaving the original specific environment, the nuclei of animal cells may still recover their ability to divide if the new environmental conditions are suitable. This is because the genetic material is not destroyed during cell differentiation. Cells still retain a complete set of genetic material that species should have. This is the totipotency of cells.
4, knowledge application:
Students discuss and communicate: the application of the above scientific principles in production practice and scientific research.
(page 105) Cloning technology can be applied to the protection of rare animals; 42-page tissue culture technology is widely used in the rapid propagation of rare flowers, rare medicinal materials and fine varieties. In vitro culture and amplification of transplanted medical tissues and organs; In vitro culture and directional differentiation of bone marrow hematopoietic stem cells can save the lives of many patients with hematological diseases.
What are the consequences of abnormal cell division and differentiation?
Second, the canceration of cells: (can be summarized by students after reading or explained by teachers)
1, the cause of cancer cells:
There are genetic information DNA fragments (genes) in cells, which specifically control cell division, differentiation, aging and death. When these genes are disturbed, the program is disordered or the physiological function is unbalanced, the cell division and differentiation will be abnormal. Under normal circumstances, the cell division will not exceed 50 ~ 60 times, and if it is out of control, it will form tumors and cancers. Cancer cells are a group of malignant proliferative cells that have lost their normal physiological functions.
2. Characteristics of cancer cells: (Students communicate after reading)
(1) Infinite malignant hyperplasia
(2) Abnormal morphological structure
(3) The cell membrane is abnormal, and the cells are easy to separate and spread.
There are many kinds of cancers, such as liver cancer, hematologic cancer's (leukemia), bone cancer, intestinal cancer and bladder cancer. With the pollution of the environment, the incidence of cancer is increasing rapidly, and it tends to be younger. Therefore, cancer is the number one killer threatening human health in the world today. Cancer mercilessly claimed many lives, seriously affected the quality of human life and shortened human life. Why does the human body become cancer? What are the factors that induce cancer? What are the characteristics of cancer? How to take appropriate measures for prevention and treatment? ……
3, carcinogenic factors and cancer prevention:
On the basis of students' communication, summarize and sort out (pay attention to the philosophical education of the relationship between internal and external causes)
(1) Internal cause: There are oncogenes and tumor suppressor genes in human body.
Through the research of scientists, many genes related to cancer have been found. These genes can be roughly divided into two categories, which are ubiquitous in human chromosomes. Whether you have cancer or not depends on whether these two genes are activated and whether they can function normally in the appropriate time and space. This belongs to the problem of dynamic regulation in organisms.
(2) External causes:
① Physical factors: all kinds of harmful radiation (such as X-rays, ultraviolet rays and nuclear radiation).
② Chemical factors: harmful chemical drugs and preparations (such as arsenic, benzene and coal tar).
③ Biological factors: the introduction of virus.
Students exchange and discuss: How far are the carcinogenic factors from us? In our daily life, to what extent are we exposed to the above harmful environment?
Smoking and passive smoking, kitchen smoke, automobile exhaust, harmful gases overflowing from decoration coatings, excessive preservatives, additives in cosmetics, pigment essence, aflatoxin, various sprays, refrigerants, etc. Containing carcinogens? Whether it is directly or indirectly related to cancer.
How to grasp the degree of sunbathing? Are there any factors that can induce cancer in the hospital? How to prevent it?
What are the main methods of cancer treatment at present? What is the principle?
Third, cell aging and death.
First of all, it should be clear that this is a normal physiological process. Students cite examples of natural aging and death of cells.
Tip: human red blood cells, skin epidermal cells, bone marrow cavity wall cells, root cap cells and so on.
1, function:
Analyze five characteristics and understand the causal relationship. * * * The same point is that it hinders the exchange and transformation of substances in cell metabolism, which leads to the slowdown and weakening of metabolism. The end result is cell death.
2. Reason:
Briefly introduce the relevant assumptions (there are relevant contents in the teaching reference)
3. Cell death:
There are two types of cell death: normal apoptosis and abnormal death. Normal cell death is an active process under the control of cell genetic material, and there is a set of strict procedures.
It has an important influence on the normal development of organisms. For example, during embryonic development, if there is no apoptosis, there will be no slender fingers; If there is no normal apoptosis, the tadpole's tail will not disappear and will never become a frog. Normal cell death skeleton shoulders the function of maintaining the inherent volume and shape of various tissues and organs; It can also remove abnormal cells in the body in time and eliminate potential hidden dangers; For example, cancer is the result of abnormal cells not dying in time. Therefore, the normal death of cells is a very important regulatory mechanism of organisms, a way for the body to balance cell proliferation and regulate the stability of cells and trees, and an essential life process.
Summarize the life phenomenon of cells.
Investigation activities
Look for information about the latest biological hotspots on the Internet.
Go online to find information about cloning, tissue culture, cell engineering, embryo amplification culture and so on, and get a deeper understanding of the relevant principles.
Form: communicate according to the information compiled by everyone.
Objective: To link the knowledge in class with the practice of production and life after class. Contact with scientific research in related fields. Cultivate students' knowledge transfer ability and knowledge application ability; Cultivate students' self-study ability to find and analyze information with what they have learned.
(1) hold a special issue to show the information compiled by individuals or groups for everyone to exchange and use.
(2) Prepare one or several seminars for communication.
Other investigation activities
1. Check the information about cancer, understand the factors that may induce cancer in daily life, the treatment methods and principles of cancer, and publicize the knowledge of environmental protection and cancer prevention to family members and their communities. (Can exercise social work ability)
(1) You can publicize it in schools or communities by running columns or publicity windows.
(2) Arranged into the form of literary programs, such as sketches, campus plays, etc. For publicity.
(3) Investigate the family environment with your parents when you are ready. Find out the adverse environmental factors that cause pollution and cancer, and formulate rectification measures.
(4) Talk with family members who have smoking habits and pass on the relevant knowledge they have learned to their families. Be a little teacher once, so that scientific knowledge, scientific and healthy lifestyle and related health care knowledge can be popularized in the family.
2. Consult the knowledge about leukemia and understand the common sense of bone marrow donors.
(1) You can check the information online; You can also find information about books.
(2) You can go to a medical college or the Red Cross and other relevant institutions for an interview.
(3) Teachers, scholars or experts from relevant departments may be invited to give lectures on popular science.
3. Investigate whether there are pollution sources that can induce cancer in your home environment and daily life.