What are the types of gene mutations?

Gene mutation is an irreversible behavior and has more harm than good, so once it happens, the harm it brings to the body is enormous. According to clinical research results, there are four types of gene mutations: nutritional deficiency type, resistance mutation type, fermentation negative mutation type, and conditional lethal mutation type. Therefore, before treatment, the cause must be determined first and then symptomatic treatment can be given.

1. Nutritional deficiency type: After mutation, due to the lack of certain enzymes, additional nutrients are needed to grow and reproduce. Generally, "+" represents the ability to utilize a naturally occurring component or to synthesize an intermediate of a component, while "-" represents a strain that cannot synthesize the component. For example, his- represents a histidine-deficient strain, which requires the addition of histidine to the culture medium.

2. Resistance mutation type : Generally, S represents sensitivity to chemicals or antibiotics, and r represents resistance. For example, str8 means that the strain is sensitive to streptomycin and cannot grow in the presence of streptomycin. This type of mutation is the easiest to obtain and is widely used. Medical | Education Network collected and compiled.

3. Fermentation-negative mutant: after mutation, it loses the ability to ferment certain sugars but can still use other sugars as carbon source. This is due to the loss of the enzyme that breaks down the sugar after the mutation. Since lactose fermentation can be displayed by an indicator based on pH changes, Lac- (lactose fermentation negative) mutants can be used as research tools.

4. Conditional lethal mutant: It has a lethal effect under certain conditions and the mutant strain cannot grow, but it can still grow under other conditions that do not have a lethal effect. The most commonly used is the temperature-sensitive mutation. They cannot grow within the temperature range in which their parents can grow, especially at higher humidity (42°C), but can grow at lower temperatures (25°C). This strain is called ts strain. The reason for this is that the peptide chain structure of some enzymes changes, which reduces the enzyme's heat resistance. Therefore, it cannot survive at higher temperatures. This method of using temperature to screen mutant strains is relatively simple and has been widely used.