As a dedicated educator, it is often necessary to write a lecture draft, which helps students understand and master systematic knowledge. Then the question is coming, how to write the lecture draft? The following is the lecture draft of "DNA is the main genetic material" that I have compiled for you. You are welcome to learn from it, and I hope it will help you. Content and position of lecture draft 1

1 teaching material analysis

1.1

In the section "DNA is the main genetic material", firstly, the related cytological basis (mitosis, meiosis and fertilization) learned before was linked, and the linkage role of chromosomes in the inheritance of the previous generation was clarified. Then, through the analysis of the chemical components of chromosomes, it was found that its main components were DNA and protein. So, is the genetic material DNA or protein? The textbook lays the groundwork here, then proves that DNA is genetic material through two classic experiments, and finally lists the fact that a few organisms only have RNA but no DNA, and draws the conclusion that "DNA is the main genetic material". The content of this section reflects the process and method of people's understanding of scientific concepts in the structural system, and is an excellent material for inquiry teaching. In teaching, by giving full play to the leading role of teachers, optimizing the classroom structure and using examples of the history of science skillfully, the process of imparting knowledge is optimized into a scientific inquiry process, so that students can learn the methods of scientific research in inquiry, thus infiltrating the education of scientific methods.

1.2 teaching emphasis

① the principle and process of pneumococcal transformation experiment.

② the principle and process of phage infecting bacteria test.

1.3 teaching difficulties the principle and process of transformation experiment of pneumococcus.

2 Analysis of academic situation

2.1 Students have mastered the cytological basis of mitosis, meiosis and fertilization, and mastered the reproductive process of organisms, the chemical composition of chromosomes, protein and the elemental composition of nucleic acids, which laid a cognitive foundation for learning new knowledge.

2.2 high school students have a certain cognitive ability, and the purpose, continuity and logic of thinking have been initially established, but they are still far from perfect. Their minds can not effectively control their behavioral impulses, and they are passionate about exploring things, but they often lack rational thinking about the purpose and process of exploration and the formation of conclusions.

3 teaching goal design

3.1 cognitive goal ① Understand the main carrier of genetic material ② Experiment of transformation of pneumococcus and experiment of bacteriophage infecting bacteria, and understand that DNA is the main genetic material

3.2 Intelligent goal ① Cultivate students' ability of scientific inquiry by simulating the process of scientific discovery and infiltrating scientific research methods ② Cultivate students' ability of information processing by learning perceptual graphic materials ③ Further cultivate students' scientific thinking such as analysis, comparison, reasoning and induction.

3.3 Emotional Objectives ① To cultivate students' scientific attitude of seeking truth from facts and spirit of continuous inquiry by simulating the process of scientific discovery ② To further stimulate the establishment of students' materialistic dialectical view

4 Teaching method design

Taking "autonomy (initiative), inquiry and cooperation" as the three basic dimensions of classroom students' learning, with the guidance of cultivating students' scientific quality, In order to focus on the education of scientific methods, this class adopts the "inquiry-discovery" teaching mode, which combines various teaching methods such as enumeration, discussion, comparison and induction, and is accompanied by multimedia-assisted teaching. Teachers guide students to simulate scientific discoveries by enumerating examples, and analyze, discuss, summarize and summarize them. Basic procedures of "inquiry-discovery" teaching mode:

5. An overview of the teaching process

5.1 Creating situations, setting doubts and introducing perceptual materials to gain perceptual confusion

① As you sow, you reap what you sow; "The sons of dragons, phoenixes and mice can dig holes"; "One mother gives birth to nine children, and even ten mothers are alike". Students, in this class, we use textbooks as learning materials to explore and solve this problem by ourselves.

② (Projection): Experiment on Grafting of Larvae of Umbrella (Figure omitted)

The shape of the top of Umbrella is controlled by the genetic material in the nucleus ③ Review the process of mitosis, meiosis and fertilization

Chromosome plays an important role in biological heredity

5.2 One of the inquiry activities: exploring experimental materials

Laying the groundwork: choosing suitable experimental materials is the key to success or failure of scientific research. Whether it is advanced, complex or low-level, simple creatures, their * * * material basis is protein and nucleic acid.

Doubt: Since both of them contain protein and nucleic acid, what kind of organism do you think is suitable for the experimental materials?

student discussion: (omitted)

student exploration: analyze, compare and select the best materials from eukaryotes, prokaryotes, viruses and other biological groups. "DNA is the main genetic material" lecture draft 2

Hello, judges and teachers! I said that the topic of the class is "DNA is the main genetic material". This section proves that DNA is genetic material through three classic experiments, and finally lists the fact that a few organisms only have RNA but no DNA, and draws the conclusion that "DNA is the main genetic material". The textbook not only guides students to think deeply in the form of questions according to the exploration course of scientists, but also tells the specific methods of these two experiments in detail. It embodies the process and method of people's understanding of scientific concepts in the structural system, and is an excellent material for inquiry teaching. Exploring the process and principle of "pneumococcal transformation experiment" and "phage infecting bacteria test" is the key and difficult point in teaching. In teaching, by giving full play to the guiding role of teachers, optimizing the classroom structure, and skillfully using examples of the history of science, the process of imparting knowledge is optimized into a scientific inquiry process, so that students can learn scientific research methods in the process of inquiry and discovery, thus infiltrating scientific method education.

Through the previous study, students have mastered the cytological basis of mitosis, meiosis and fertilization, and mastered the reproductive process of organisms, the chemical composition of chromosomes, the elemental composition of protein and nucleic acids, which laid a cognitive foundation for the study of new knowledge. At the same time, high school students have certain cognitive ability and passion for exploring things, but they often lack rational thinking about the purpose and process of exploration and the formation of conclusions.

According to the new curriculum standards, I have set the following three teaching objectives

1. Knowledge and skills objectives:

① Understand the main carrier of genetic material

② Understand that DNA is the main genetic material through the transformation experiment of pneumococcus and the experiment of bacteriophage infecting bacteria

2. Process and method objectives:

① Simulate the process of scientific discovery, Infiltrate scientific research methods to cultivate students' scientific inquiry ability

② Cultivate students' information processing ability through the study of perceptual graphic materials

③ Further cultivate students' scientific thinking ability such as analysis, comparison, reasoning and induction and their ability to solve practical problems

④ Learn to communicate and cooperate, * * * Accomplish a certain task

3. Emotional attitude and values:

① Cultivate students' scientific attitude of seeking truth from facts and spirit of continuous inquiry through simulating the process of scientific discovery

② Cultivate the consciousness of inquiry learning and cooperative learning through inquiry experiments, realize scientists' scientific spirit, improve students' biological science literacy

③ Recognize that people's understanding of things is a continuous development process < P > Aiming at the above teaching objectives and. Based on the concept of "independent inquiry, comprehensive infiltration, cooperative activities and innovative development", let students "take the road of inquiry again" and guide them to experience the process of scientific inquiry and understand scientific research methods. Cultivate students' ability of autonomous learning and cooperative learning, and use "self-efficacy theory" in the classroom to stimulate students' interest in learning and explore their potential by means of developmental evaluation, and at the same time promote their own sustainable development.

The specific teaching plan and strategies are as follows:

Taking the early speculation of human genetic material as the source of the problem, the students can understand the role of chromosomes in biological inheritance by reviewing the changes of chromosomes during meiosis and fertilization. Compulsory Biology 1 has learned that the main components of chromosomes are DNA and protein, so who plays a decisive role in heredity? Set doubts to stimulate students' thirst for knowledge. At this time, guide students to analyze and summarize the characteristics of genetic material with existing knowledge. Then organize students to recall the composition and function of protein, compare which aspects of protein may have the characteristics of genetic material, and I added background knowledge: at that time, scientists had not figured out the specific structure of DNA. This not only reviews the old knowledge, but also gives students a good understanding of why many scientists speculated that the genetic material was protein in the early days, while students had previously learned that the genetic material was DNA through various media, which once again aroused students' strong thirst for knowledge and pushed them to explore how to know that the genetic material was DNA instead of protein.

The choice of experimental materials is the key to success. First, ask a question: All organisms contain protein and nucleic acid. What kind of organisms do you think are the most suitable for experimental materials? And guide students to analyze, compare and screen from the composition structure of eukaryotes, prokaryotes, viruses and other biological groups to explore the best materials. By comparing the structures of these organisms, students understand that since there are protein and nucleic acids in all organisms, it is easy to analyze simple materials such as viruses with few interference factors. At the same time, through the exploration of experimental materials, students also make a preliminary prediction on the design ideas of the experiment.

The transformation experiment of pneumococcal is the key and difficult point in teaching. Students first learn this experiment while observing the animation courseware of Griffith's transformation experiment of pneumococcal, and then spend about 3 minutes to complete the following charts and realize the design ideas of these experiments. Where is the scientific design? How is the experimental conclusion confirmed step by step? In the fourth step of the experiment, after the S-type bacteria killed by heating were mixed with the nontoxic R-type bacteria, why did the mice die? It is not easy for students to understand, so I add relevant knowledge: in a certain temperature range, after heating denatures and deactivates protein and DNA, lowering the temperature can restore DNA activity, but protein can't. In the process of completing the form, let the students think positively and ask questions boldly. The students mention all kinds of questions.

For example, some students mentioned:

1. Why didn't mice transform the mixture of the two?

2. Why is the "transforming factor" not the whole S-type bacteria but a specific substance?

For these two questions, you may also find them in the process of preparing lessons:

The design of the teaching materials in this place is not perfect. In fact, after Griffith's experiment, some scientists also raised these two questions and made corresponding experiments to rule out these two possibilities. I didn't simply introduce how scientists design experiments to rule out these two possibilities. If you simply tell it, it will lead to students' ambiguous understanding of knowledge, and at the same time lose a good opportunity to inspire students to design their own experiments. I asked students to design their own experiments to explore whether there are these two possibilities. (Briefly introduce these two groups of experiments) Students analyzed the phenomena of different experiments and drew different conclusions. Through these two groups of experiments, students supplemented and improved Griffith's experiments and cultivated students' rigorous scientific attitude. Then I briefly introduce the experimental results of scientists: these two groups of experiments can transform R-type bacteria into S-type bacteria. Students will understand that it is indeed something in S-type bacteria that transforms R-type bacteria. S-type bacteria are composed of many substances, so what is the "transformation factor"? This will arouse students' curiosity, and then I will guide students to think. If you are a scientist, what methods do you use to explore what this "transformation factor" is? Divide the students into groups and let each group spend about 5 minutes designing experiments to explore what is the transformation factor. Then each group sent representatives to show their own experimental designs. Finally, I showed Avery and his colleagues' experiments through multimedia, so that students' thinking process collided and compared with scientists' thinking process. Let them find their own shortcomings by comparing with scientists' thinking. Some students also find that their thinking is so similar to that of scientists, and they can become scientists themselves by building up their self-confidence. Through "process-based teaching", students actively discover the key design idea of the experiment-separating protein from DNA and observing their functions separately.

In the process of designing inquiry experiments, some students in some groups also put forward some questions, such as: 1.DNA is a macromolecular substance, was it transported into bacteria by initiative? 2. We also eat some biological cells, which also contain active DNA, so does it affect our cells like the transformation experiment of pneumococcus, making our cells become other things? 3. Why does the textbook say that Avery's experiment can't convince everyone because the extracted DNA is always mixed with 2% protein, but the third group of experiments proves that protein can't transform the DNA after it is hydrolyzed by enzyme? For these good questions, let the students record them and ask them to consult relevant materials to solve them after class. In the process of learning "Transformation Experiment of Pneumococcus", students actively participated in the exploration, which solved the important and difficult points in teaching. I don't have to force the process of inquiry experiment. Students really take the initiative to participate in the process of inquiry and enjoy the fun of exploration and discovery. Group discussion also improves students' cooperative learning ability.

"The experiment of bacteriophage infecting bacteria" is also the focus of teaching. After explaining the background knowledge about T2 bacteriophage to students, let students learn the experiment by reading the relevant contents of the textbook and observing Figure 3-6. Students are required to ask at least three questions for this experiment, and the more they ask, the better, and discussion is allowed. Students actively use their brains, ask their own questions, select representative questions and write good questions on the blackboard, for example:

1. Isotopes such as C and O are selected as labeling elements when studying photosynthesis. Why do you choose 35S and 32P as labeling elements here? Use isotopes such as c and o, okay?

2. Why are T2 phage particles located in the supernatant after centrifugation, while infected Escherichia coli is located in the sediment?

3. why is the radioactivity of the sediment in the first experiment very low, rather than not?

4. Why is the radioactivity of the supernatant of the second experiment low, not not zero?