"Dominant and Recessive Genes" Biological Inheritance and Variation PPT Courseware 3

Description

"Dominant and Recessive Genes" Biological Inheritance and Variation PPT Courseware 3

Review before class

1. Genes: DNA segments on chromosomes that control biological traits

2. Genes are transmitted through sperm or egg cells. Sperm and egg cells are the "bridges" for genes to be transmitted between parents and children.

3. During the cell division process that forms sperm or egg cells, the chromosomes are reduced by half, and one chromosome from each pair enters the sperm or egg cell.

4. Chromosomes exist in pairs in somatic cells of organisms, and genes also exist in pairs; chromosomes and genes in reproductive cells (i.e., sperm and egg cells) are halved, chromosomes exist in singles, and genes exist in singles.

learning target

1. Give examples of the relationship between relative traits and genes.

2. Know what consanguineous marriage is and explain the dangers of consanguineous marriage.

3. Enhance the scientific attitude of seeking truth from facts and the ability to use scientific methods to explain relevant issues in life sciences.

Independent learning (10min)

1. According to the learning objectives, carefully read P32-34 of the textbook, and pay attention to the summary in Figure P33. The black pen outlines the key knowledge, and the red pen marks the doubtful and difficult points.

2. Independently complete the self-study of the tutorial, and independently think about the collaborative inquiry part, further clarify and mark doubtful points, and be prepared to discuss and resolve doubts.

3. Learn to learn independently and you will succeed

Discussion content:

1. Collaborative exploration 1

2. Difficulties in independent learning

Discussion requirements:

1. The executive team leader will arrange a main spokesperson for each question, and other students will ask questions and make supplements.

2. After the discussion, you can display it on the blackboard

Read the first natural paragraph on pages P32 to 33 and answer the following questions

1. What problem did Mendel want to study?

Inheritance of relative traits

2. How did Mendel implement his plan?

Cross purebred tall-stemmed peas and dwarf-stemmed peas to observe the characteristics of the first and second generations of the hybrids.

Why is it forbidden to marry close relatives?

This is because couples who are closely related by blood are more likely to acquire the same disease-causing genes from their common ancestors. Among them, some genetic disease genes are recessive genes. When close relatives marry, the recessive disease-causing genes carried by both couples may be passed on at the same time. Giving it to children greatly increases the incidence of recessive genetic diseases.

For example, the chance of albinism developing in the natural population is 1/10,000. If cousins ​​get married, the chance of developing albinism in their children is 1/1,600, which is more than 6 times higher than if cousins ​​marry.

Class summary:

1. The tall stem of peas is a dominant trait, represented by D. Then the genotype of short-stem peas is _____, and the genotype of tall-stem peas is _____ or _____.

2. If double eyelids are controlled by A and single eyelids are controlled by a, then the Aa individual behaves as _____.

3. A man rolls his tongue, his wife does not roll his tongue, and his son does not roll his tongue. Please write down their genetic types:

Man ( ) × Wife ( )

son( )

4. my country’s Marriage Law stipulates that marriage is prohibited between collateral blood relatives of __________ and __________.

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For more information about the PPT courseware "Inheritance of Biology and Dominant and Recessive Gene Variation", please click the Dominant and Recessive ppt tab of Biological Inheritance and Variation ppt Genes.

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Update Time: 2024-10-06

This template belongs to biology courseware People's Education Edition Biology for Grade 8, Volume 2 industry PPT template

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