Biology 9 Lesson 33: Artificial mutation in breeding
1. Theoretical Summary
1.1. Inducing artificial mutations by physical agents
a. Radioactive rays
– Types of radiation commonly used to cause mutations are: alpha, beta, and gamma rays.
+ How to proceed:
- Transmembrane, tissue (deep penetration).
- Impact on DNA.
- Genotyping mutations.
- Trauma causes NST mutations.
- Irradiation on germinated seeds, growth apex.
- Plant tissue culture.
b. Ultraviolet rays
- Procedure: The rays penetrate the tissue (shallow penetration).
- Result: Genotypic mutation.
- Application: Microbiological treatment of spores and pollen grains.
c. Thermal shock
– Heat shock is a sudden increase or decrease in the ambient temperature, causing the body’s self-protection mechanism to fail to adjust, causing damage to the mitotic spindle, leading to mitotic disorders and mutations in the number of chromosomes. .
Procedure: Sudden increase or decrease in ambient temperature.
- Loss of self-protection on balance.
- Injury to the mitotic spindle, disorders of cell division.
- Mutations in the number of chromosomes.
+ Application: Causes polyploidy in some plants (especially nightshades).
1.2. Inducing artificial mutations by chemical agents
– For plants:
- Soak dried or germinated seeds in a chemical solution.
- Inject the chemical solution into the ovary.
- Wrap cotton soaked in chemical solution to the growing tip of the stem or shoot.
– For pets: For chemicals to affect testicles or ovaries.
Chemicals commonly used:
- Ethyl Methane Sulphonate (EMS)
- Nitrozo methyl urea (NMU)
- Nitrozo ethyl urea (NEU)
– When chemicals enter cells, chemical solutions act on DNA molecules to replace nucleotide pairs, lose or add nucleotide pairs.
– We can actively cause mutations because there are chemicals that only act on a certain type of nucleotide, so they can actively cause mutations at will.
1.3. Using artificial mutations in breeding
– Select VSV varieties:
- Select mutants that produce highly active substances.
- Select strong growth mutants to increase biomass in yeast and bacteria.
- Select mutants with reduced vitality, no longer capable of causing disease to produce vaccines.
– Select plant varieties: Select mutations that shorten growth time, increase yield and quality, resist pests and diseases, and withstand adverse environmental conditions for multiplication or use in hybrid combinations with plants. selection to create new varieties.
– Select livestock breeds: Only used with some lower animals, difficult to apply to higher animals because higher animals’ reproductive organs are located deep in the body, easy to cause death when handled. by chemical agents.
- Treatment of penicillin fungal spores with radiation produces a penicillin strain that is 200 times more active than the original form.
- Pink cheeks apple variety has been treated with NMU chemical from Gia Loc apple variety (Hai Duong) for 2 crops a year, the fruit is round, sweet, crispy, fragrant, the left cheek when ripe has a pinkish purple color.
- Using polyploids in mulberry, willow, watermelon, grape, orange, tomato… to create polyploid plant varieties with high yield and good quality.
2. Illustrated exercise
Why does one need to choose specific agents when it comes to mutagenesis?
Each agent has a different mutagenic effect, such as radiation having the power to penetrate deep into tissues that are easy to cause gene mutations and chromosomal mutations. ….That’s why one has to choose a specific agent when mutating.
3.1. Essay exercises
Question 1: When mutating by physical and chemical agents, what methods are usually used?
Verse 2: List some of the achievements of using artificial mutations in the breeding of animals, plants and microorganisms.
Question 3: The penicillin strain has been created with 200 times higher activity than the original form by selecting mutants in what direction?
3.2. Multiple choice exercises
Question 1: Which of the following rays is capable of penetrating deep tissues?
A. Infrared rays, X-rays, ultraviolet rays
B. X-rays, gamma rays, alpha rays, beta rays
C. X-rays, ultraviolet rays, gamma rays
D. Ultraviolet rays, alpha rays, beta rays
Verse 2: In microbial breeding, to create vaccines against human and animal diseases, people choose:
A. Mutants produce highly active substances
B. Strong growth mutants
C. Mutants with reduced vitality (weak compared to the original form)
D. Mutants shorten growth time
Question 3: To cause chemical mutations in plants, people usually do not use the following methods:
A. Soak the dried seeds in a chemical solution.
B. inject a chemical solution into the ovary.
C. injection of chemical solution into the body.
D. Wrap cotton impregnated with chemical solution on top of growth in stem or shoot.
Question 4: Which of the following agents is commonly used to produce polyploids?
A. Ethylmethane sulphonate (EMS)
C. Nitrozo methyl urea (NMU)
D. Nitrozo ethyl urea (NEU)
After completing this lesson, you should:
- Describe the need to select specific agents when causing mutations.
- Method of using physical and chemical agents to induce mutations.
- Explain the similarities and differences in the use of mutants.