The Teaching Goal of the Teaching Design of "Genetic Control of Biological Traits"
1, understand the phenomenon of heredity and variation, and understand and distinguish what is heredity and what is variation.
2. Observe the biological characteristics and tell the biological characteristics and relative characteristics.
3. Understand that biological traits are controlled by genes.
4. Pay attention to transgenic technology.
Key points, difficulties and puzzles
1, with emphasis on traits and relative traits; Genes control biological traits.
2. Difficulties: Genes control biological characters.
3. Confusion points: traits and relative traits.
teaching process
First, import
Teacher: Let's look at a photo first. This is a picture of movie star Jackie Chan and his son. Please look for it. How does a child resemble his father?
Student: Discuss with each other and answer questions.
Teacher: As the students can see, children are like their father in some places and not in others. Guide students to summarize the concepts of heredity and variation.
Teacher: Another example? As you sow, so you reap? . ? A mother gives birth to nine children, and nine children are different? . What biological phenomena can you sum up from these two sentences?
Student: In biology, this similarity between parents and children is called heredity, and the difference between parents and children is called variation.
Second, biological characteristics
Teacher: Give sugar oranges and oranges, and guide students to observe the characteristics of sugar oranges and oranges and find out the differences.
Student: Different sizes, different colors and different tastes?
Teacher: We have given these characteristics of biology a biological name: idiosyncrasy. You can know all your personality just by naked eye observation or simple measurement? Is there a shape on the human body?
Student: Observe yourself or your classmates and discuss in groups.
Do you have an earlobe?
Is it single eyelid or double eyelid?
Can you roll your tongue from both sides to the middle?
Can you bend your thumb back?
Student: Investigate these characteristics in a group and show the results of this group.
The team leader summarizes the survey results.
Teacher: Students know many biological characteristics, so who can define the characteristics? What exactly is a trait? What aspects does the character include? What is relative trait?
Teacher: The teacher guides the students to summarize by themselves, and can be supplemented by multiple students.
Students: Discuss in groups, and summarize related concepts by combining surveys and textbooks:
Any organism has many traits, and its morphological and structural characteristics, physiological characteristics or behavior patterns are all biological traits.
Teacher: Like the students just said, double eyelids, skin color and face shape are biologically called traits. What other biological features do you know?
Teacher: Question: Which of the characters just examined are morphological and structural features? What are the behavioral characteristics?
Student: Answer the teacher's question.
Teacher: The same trait of the same species often has different forms of expression. Have you ever noticed that the same trait varies from individual to individual?
Student: Look carefully and find out the difference between these creatures.
Teacher: Different manifestations of the same trait like this are called relative traits.
Geneticists call the different manifestations of the same trait relative traits. For example, human single and double eyelids, black and white rabbit hair.
Teacher: Ask the students: How are the characteristics of parents passed on to their children?
Where there is enough water and fertilizer in the wheat field, the wheat seedlings are thicker than normal. Is this difference caused by changes in genetic material? Are all the characteristics of an organism heritable? Genes control the characteristics of organisms. Are there any other factors that affect the traits?
Student: Discuss and summarize in groups? Genes control biological characteristics, and the environment also affects biological characteristics? .
Three. Genetic Control Characteristics —— Unveiling the Mystery of Transgenic Mice
Teacher: Show relevant questions: Teacher: Students have a deeper understanding of idiosyncrasy and relative idiosyncrasy. Now, please think: Why do many characteristics of parents appear in us? We know that neither * * nor egg cells carry any traits, so what can parents pass on to their offspring to make their children look like their parents? Did parents pass on certain characteristics such as eyes and nose to their children, or did they pass on something else?
Student: Students make all kinds of guesses.
Teacher: Teachers can guide people to watch slides without evaluating students' guesses. The experimental process of transgenic mice? This is a kind of mouse that has been small for generations. People will see what changes have taken place in its descendants after doing some special treatments. After mating of male and female mice, the fertilized eggs with unfused nuclei were taken out from the fallopian tubes of female mice; Sucking the rat growth hormone gene prepared in advance into a micro syringe, injecting the rat growth hormone gene into the nucleus of a mouse nucleus which is not fused or the nucleus of a fertilized egg under a microscope, and carrying the transferred gene into the fused nucleus of the fertilized egg after injection; The fertilized egg into which the rat growth hormone gene was introduced was injected into the fallopian tubes of mice. In this way, there are two kinds of fertilized eggs in mouse oviduct, one is the fertilized egg with rat growth hormone gene introduced, and the other is the original fertilized egg without transgene in oviduct. As a result, transgenic mice became rats, and transgenic super mice grew 2-3 times faster and doubled in size than mice that gave birth to the same fetus.
Student: Reading textbooks with questions? Enlightenment from transgenic mice? .
Teacher: What are the characteristics of this study?
Student: The weight (or size) of the mouse.
Teacher: Only transgenic mice have become bigger in future generations. What does this mean? What genes control this trait?
Student: Mouse growth hormone gene. It shows that traits are controlled by genes.
Teacher: Good. It can be inferred that in the process of biological seed transmission, is the trait or the gene controlling the trait being transmitted?
Student: It's genes.
Four. Popularization and application of transgenic technology
Teacher: By transferring the gene of one organism into the genome of another organism through biotechnology, the cultivated transgenic organism may show the characteristics controlled by the transferred gene. At present, there are genetically modified crops, genetically modified animals, genetically modified foods and genetically modified drugs.
Display: pictures of genetically modified items.
Student: Look at the picture and ask questions.
Teacher: Think about it. What other genetically modified organisms do you know? What genetically modified foods have you eaten? Is genetically modified food safe? Have you ever doubted it?
Student: Group discussion.
Teachers and students: Teachers can guide students to discuss and analyze the social disputes caused by genetic modification, so that students can fully express their opinions and opinions, so as to have a deep understanding of genetic modification.
Teacher: Extracurricular reading guidance: browse related books and web pages.
Five, the classroom harvest:
Teacher: Show the required questions, ask the students and evaluate them.
Sixth, the class summary:
Teacher's summary: In this lesson, we learned about traits, relative traits and traits of genetically controlled organisms. Do you have any questions about these questions?
Seven, extracurricular development:
Reflections on the influence of transgenic technology on human society. The continuous development of new technologies requires continuous learning.
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