"Meiosis and Fertilization" PPT courseware on the relationship between genes and chromosomes (Fertilization in Lesson 2)

Description

"Meiosis and Fertilization" PPT courseware on the relationship between genes and chromosomes (Fertilization in Lesson 2)

Part One: Course Standard Requirements

Explain that organisms that undergo sexual reproduction pass their genetic information to their offspring through gametes.

Core competency docking

1. Scientific thinking - by establishing a model of chromosome changes during meiosis, understanding that exchange and the free combination of non-homologous chromosomes lead to the diversity of gamete chromosome composition, and linking it to fertilization, thereby understanding the chromosomes of sexual reproduction offspring Reasons for compositional diversity.

2. Concept of life - understand the role of meiosis and fertilization in maintaining the genetic stability of sexual reproduction offspring.

3. Scientific inquiry - By observing the meiosis loading of locust spermatocytes, master experimental skills and achieve a perceptual understanding of meiosis.

Meiosis and fertilization PPT, Part 2: Observing meiosis mounting of locust spermatocytes

Autonomous sorting

1. Purpose requirements

Identify the shape, position and number of chromosomes at different stages of meiosis.

Generally, testicles of higher animals or stamens of plants are selected instead of ovaries of higher animals and pistils of plants, mainly because the number of primordial germ cells undergoing meiosis at the same time in testicles and stamens is greater than that in ovaries and pistils, making observation easier.

2. Method steps

[Typical Example 1] (2019·Guangzhou Experimental Middle School Midterm) The number of chromosomes in the somatic cells of a male animal is 2N=20. Observation of sections of a certain tissue under a microscope revealed that the number of chromosomes in some cells is 40 , some cells have 20 chromosomes, and some cells have 10 chromosomes. Then the tissue section is most likely taken from ()

A.Ovary B.Testicle C.Liver D.Brain

[Practice 1] (2019·Chengdu mid-term) Among the following statements about observing cell meiosis experiments, the incorrect one is ()

A. A mount made from onion root tips can be used to observe the synapsis of homologous chromosomes.

B. It is easier to observe the phenomenon of meiosis in mounts made from peach blossom stamens than from peach blossom pistils.

C. In mounts where meiosis can be observed, synapsis of homologous chromosomes may be observed

D. Meiosis can be observed using fixed mounts of locust spermatocytes and broad bean pollen mother cells.

Meiosis and fertilization PPT, Part 3: Diversity of chromosome combinations in gametes and establishing a model of chromosome changes during meiosis

Autonomous sorting

1. Causes of diversity of chromosome combinations in gametes

2. Establish a model of chromosome changes during meiosis

(1) Simulate changes in chromosome number and main behaviors during meiosis

①The pairing of two chromosomes of the same length and different colors represents the _______________ of homologous chromosomes in meiosis I_______________ stage.

②The separation of two chromosomes of the same length and different colors represents the _______________ of homologous chromosomes in meiosis I_______________ stage.

③At the end of meiosis, the number of chromosomes in each cell is _______________ at the beginning, and the number of chromosomes is halved at _______________.

(2) Simulate the free combination of non-homologous chromosomes during meiosis

① To simulate the free combination of non-homologous chromosomes during meiosis, there must be at least _______________ pairs of homologous chromosomes in the cell.

② Assume that there are 2 pairs of homologous chromosomes in the cell. During meiosis I, there are ________ combinations of non-homologous chromosomes; each primordial germ cell divides according to one of the combinations and can produce 2 different chromosome composition types. Gametes; two such primordial germ cells divide according to different combinations, and theoretically can produce _______ gametes with different chromosome composition types.

(3) Simulate the exchange of non-sister chromatids during the tetrad stage of meiosis

① Assuming that there are two pairs of homologous chromosomes in the cell, and only two non-sister chromatids exchange once during the tetrad stage, one such primordial germ cell can theoretically produce ___________ different types of chromosome composition. of gametes.

② The _________ between non-sister chromatids during the tetrad stage of meiosis I and the _________ between non-homologous chromosomes in the later stage, leading to the diversity of gamete chromosome combinations.

Meiosis and fertilization PPT, Part 4: Fertilization

Autonomous sorting

1. Define the process by which ______________ and ______________ recognize each other and merge into ______________.

2. Process

3. Result: The number of chromosomes in the fertilized egg has returned to the number in the somatic cells, ensuring the ____________ number of chromosomes in the species. Half of the chromosomes come from ____________ (father) and the other half come from ____________ (mother).

4. Meaning

(1) The diversity of offspring is conducive to the evolution of organisms in ____________, which reflects the superiority of ____________.

(2) It ensures the constant number of chromosomes in the offspring of each organism and maintains the stability of biological inheritance, which is very important for the __________________ of organisms.

think

A certain eukaryotic organism is dioecious and can undergo sexual reproduction. Its wild type and mutant types are controlled by the R gene and L gene in the mitochondria respectively.

(1) Does the inheritance of this pair of relative traits follow Mendel's laws? Why?

Tips Do not follow. Because the relevant genes are located in mitochondria rather than chromosomes in the nucleus, they do not meet the conditions for the use of Mendel's laws.

(2) Do the mitochondria in fertilized eggs come from sperm or egg cells?

Hint: egg cell.

(3) If the mutant type is used as the female parent and the wild type is used as the male parent, how will the offspring behave when they are crossed? Why?

Tip: All are mutant types. Because all the mitochondria in the fertilized egg come from the mother, and the maternal mitochondria contain the L gene.

(4) If the wild type is used as the female parent and the mutant type is used as the male parent, how will the offspring behave when they are crossed? Why?

Tip: All are wild type. Because all the mitochondria in the fertilized egg come from the mother, and the maternal mitochondria contain the R gene.

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For more information about "The Relationship between Genes and Chromosomes, Meiosis and Fertilization, Fertilization" PPT courseware, please click on the Relationship between Genes and Chromosomes, PPT Meiosis and Fertilization, PPT Fertilization, PPT tag.

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Update Time: 2024-09-26

This template belongs to biology courseware People's Education Press High School Biology Compulsory Course 2 industry PPT template

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