"Chromosome Variations" Gene Mutation and Other Variations PPT Courseware

"Chromosome Variations" Gene Mutation and Other Variations PPT Courseware

Part One: Course Standard Requirements

Give examples to illustrate that variations in chromosome structure and quantity may lead to changes in biological traits or even death.

Core competency docking

1. Concept of life - using the structure and function perspective, understand that chromosome deletions, duplications, inversions and translocations can cause changes in the number or arrangement of genes on chromosomes, which in turn can lead to changes in biological traits and even death.

2. Scientific thinking - accurately understand the concept of chromosomes, and be able to use the concept of chromosomes combined with the starting point of development to distinguish haploidy and diploidy (polyploidy).

3. Social Responsibility - Understand that haploid breeding and polyploid breeding utilize the principle of chromosome number variation, and through comparison with hybrid breeding, agree that haploid breeding can significantly shorten the breeding life.

Chromosome variation PPT, part 2: variation in chromosome number

Autonomous sorting

[Typical Example 1] Use potato pollen to directly cultivate potato plants under certain conditions. When certain cells of the potato plant underwent meiosis, normal synapsis of chromosomes was observed. At this time, there were a total of 15 tetrads in the cells. Based on this, it is inferred that the total number of chromosome sets contained in the somatic cells of a normal potato individual is ()

A.2 B.3 C.4 D.5

Analysis: During meiosis to form pollen, homologous chromosomes separate. Then the number of chromosomes in the potato plant formed by direct cultivation of pollen is halved, and the number of chromosome sets is also halved. When the potato plant cells directly cultured with pollen underwent meiosis, normal synapsis of chromosomes was observed and 15 tetrads were formed, indicating that they contained 2 chromosome groups, so the somatic cells of normal potato individuals contained a total of 15 chromosomes. The number of groups is 4.

Answer C

[Practice 1] The figure below shows the chromosomes contained in cells. The genotypes of ①②③④ can be expressed as ()

A.①：AABb　②：AAABBb　③：ABCD　④：A

B.①：Aabb　②：AaBbCc　③：AAAaBBbb　④：AB

C.①：AaBb　②：AaaBbb　③：AAaaBBbb　④：Ab

D.①：AABB　②：AaBbCc　③：AaBbCcDd　④：ABCD

Literacy improvement

Comparison between haploid and polyploid breeding

[Typical Example 2] The figure shows the cultivation process of seedless watermelon:

According to the diagram and combined with the biological knowledge you have learned, decide which of the following statements is wrong ()

A. Colchicine treats the shoot tips of diploid watermelon seedlings, mainly inhibiting the formation of spindles in the early stages of mitosis.

B. Watermelons grown from tetraploid plants contain 4 sets of chromosomes in the peel cells.

C. Seedless watermelon has neither seed coat nor embryo.

D. The root cells of tetraploid watermelon contain 2 sets of chromosomes

Chromosome variation PPT, Part 3: Changes in the number of chromosomes in plant cells induced by low temperature (optional)

Autonomous sorting

1. Experimental principle

Treating _______________ cells of plants with low temperature can inhibit the formation of _______________, causing the chromosomes to be pulled to the poles during cell mitosis, causing the cells to be unable to divide into two daughter cells. As a result, the number of chromosomes in plant cells changes.

2. Method steps

(1) Culture and induction: Place the whole onion with adventitious roots about 1 cm long into the cold room of the refrigerator (_______________ ℃), and induce and culture it for 48 to 72 hours.

(2) Fixing and rinsing: Cut off 0.5 to 1 cm of the induced root tip, soak it in ___________ for 0.5 to 1 hour, ____________________________, and then rinse twice with _______________.

(3) Preparation and observation: including 4 steps of dissociation, _______________, _______________ and preparation; first use a magnifying glass to look for division images with good chromosome morphology. After confirming that the number of chromosomes in a certain cell has changed, observe it with a _______________ magnification microscope.

[Typical Example 3] The following description about the experimental operation of low temperature-induced changes in chromosome number is incorrect ()

A. The purpose of treating the cut root tips with Carnoy's solution is to fix the cell morphology.

B. After treatment with Carnoy's solution, rinse twice with clean water.

C. When making films, dissociate and rinse first, then dye and film.

D. When observing, you should first use a low-power microscope to find division images with better chromosome shapes.

Analysis: After fixation with Carnoy's solution, rinse twice with 95% alcohol, so choose B.

Answer B

[Practice 3] The following statement about the preparation operation in the experiment of low temperature-induced changes in chromosome number is incorrect ()

A. The purpose of dissociation is to separate tissue cells from each other

B. Rinse the dissociated root tips with clean water.

C. The modified phenol fuchsin dye used for dyeing is an alkaline dye

D. The order of operations during production is dissociation → dyeing → rinsing → production

Analysis: The order of operations during film production is dissociation → rinsing → dyeing → film production, so D is selected.

Answer D

Lenovo questions

【In conclusion】

(1) The principle behind the doubling of chromosome number induced by low temperature and colchicine: In the prophase of mitosis, both low temperature and colchicine can inhibit the formation of spindles; in the late phase of mitosis, the number of chromosomes doubles after centromere division; in the late phase of mitosis, because there is no spindle, the number of chromosomes It cannot be pulled to the poles of the cell, and the cell cannot be divided into two, thus doubling the number of chromosomes in the cell. When the temperature returns to normal or the colchicine is completely consumed by cell metabolism, the cells with doubled chromosome number will produce more daughter cells with doubled chromosome number through normal mitosis.

(2) Comparison of two rinses: ① The time is different: the first rinse is after fixation and before dissociation, the second rinse is after dissociation and before staining; ② The reagents are different: the first rinse is with 95% alcohol, the second rinse is Rinse with clean water for the second time; ③The purpose is different: the first time is to wash away the excess Carnoy's solution, and the second time is to wash away the excess dissociation solution.

Chromosome variation PPT, part 4: variation in chromosome structure

Autonomous sorting

1. Type (connection)

Observation of chromosome morphology and size under an optical microscope can be detected

2. Results

The genes ____________________________ arranged on the chromosomes are altered, causing ____________________________.

3. Impact on living organisms

Most are _______________ to living organisms, and some even cause organisms to _______________.

[Typical Example 4] (2018·Hainan Volume, 14) When the heterozygous female fruit fly forms gametes, the corresponding segments between the non-sister chromatids of the homologous chromosomes undergo peer-to-peer exchange, resulting in new gametes type occurs because () occurs during gamete formation

A. Genetic recombination B. Chromosome duplication

C. Chromosome translocation D. Chromosome inversion

Analysis: During meiosis, reciprocal exchange of corresponding segments between non-sister chromatids on homologous chromosomes leads to genetic recombination; in the late stages of meiosis I, the free combination of non-homologous chromosomes can also lead to genetic recombination. Chromosomal duplications, chromosomal translocations, and chromosomal inversions are chromosomal variations.

Answer A

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For more information about the "Gene Mutation and Other Variations Chromosome Variations" PPT courseware, please click the Gene Mutation and Other Variations PPT Chromosome Variations PPT tab.

"Human Genetic Diseases" Gene Mutation and Other Variations PPT download:

"Human Genetic Diseases" Gene Mutation and Other Variations PPT Download

The first part: [Task Driven]

1. Pay attention to the detection and prevention of genetic diseases, and care for patients with genetic diseases.

2. Compare single-gene genetic diseases, polygenic genetic diseases and chromosomal abnormality genetic diseases.

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