Biology 9 Lesson 21: Genetic mutations
1. Theoretical Summary
1.1. What is gene mutation?
Gene mutations are changes in the structure of a gene that involve one or more pairs of nucleotides.
Types of gene mutations: loss, addition, replacement, inversion of one or several nucleotide pairs.
1.2. Causes of genetic mutations
Due to the complex influence of the internal and external environment, it disrupts the self-replication process of the DNA molecule (mistaken copy), occurring under natural conditions or caused by humans.
1.3. The role of gene mutations
Mutations in genes that produce phenotypes are often harmful to the organism because they disrupt the harmonious unity of genotypes that have been subjected to natural selection and persisted under natural conditions for a long time, causing disturbances in the genetic makeup of the organism. protein synthesis.
Gene mutations are sometimes beneficial to organisms and humans, which are very meaningful in animal husbandry, farming, breeding, and evolution.
2. Illustrated exercise
What is gene mutation? What are some structural changes in genes?
– Genetic mutations are changes in the structure of genes due to the complex influence of the internal and external environment on the DNA molecule that occurs under natural conditions or caused by humans.
Some types of genetic mutations are:
- Loss of a nucleotide pair
- Add a nucleotide pair
- Nucleotide pair substitution
3.1. Essay exercises
Question 1: What causes genetic mutations?
Verse 2: Why are genetic mutations often harmful to the organism itself? State the role and significance of genetic mutations in production practice.
Question 3: Gene B has 3000 nucleotides. Gene B mutates into gene b. When these two genes were duplicated once, they were taken from the cell environment 5998 nucleotides.
1. Determine the length of the gene b.
2. Determine the type of mutation from gene B to gene b.
3.2. Multiple choice exercises
Question 1: Gene mutations are changes in the structure of a gene that are usually associated with
A. a pair of nucleotides.
B. several nucleotide pairs.
C. many nucleotide pairs.
D. whole nucleotide pairs.
Verse 2: What is the phenotypic expression of a gene mutation during an individual’s lifetime?
A. The dominant gene mutation is expressed only in the homozygous form.
B. The dominant gene mutation is expressed in both homozygous and heterozygous forms.
C. The recessive gene mutation is expressed only in the heterozygous form.
D. The recessive gene mutation is not expressed.
Question 3: Expression characteristics of gene mutations are mainly
A. beneficial to the individual.
B. no benefit and no harm to the individual.
C. harmful to individuals.
D. has an advantage over father and mother.
Question 4: The mutant is
A. individuals carrying the gene mutation expressed only in the dominant phenotype.
B. individuals carrying the gene mutation expressed only in the intermediate phenotype.
C. individuals carrying the gene mutation expressed only in the recessive phenotype.
D. individual carrying a gene mutation that is expressed in the phenotype.
After completing this lesson, you should:
- State the concept of gene mutation and list the types of gene mutations.
- Describe the role of genetic mutations in practice.