Genetic mutations | types, properties, examples and summary (2023)

introduction

A gene is part of the DNA that encodes the synthesis of a protein. All DNA consists of thousands of genes that directly control all the functions of a cell through protein synthesis. The nucleotide sequence for the synthesis ofNormal proteins.

Any change in the DNA nucleotide sequence is called mutation. Factors that cause mutations are called mutagenic or carcinogenic averages. Examine DNA repair methods that use a cell to correct mutations.

Genetic code

Before responding to the details of the mutations, it is important to understand a genetic code.The genetic code can be called a dictionary that recognizes the correspondence between the nucleotide sequence in a gene and the amino acid sequence in a polypeptide chain.

The genetic code consists of three -letter words, which are calledEncodeThere are in the RNAm.

Encode

A codon is a sequence of three nucleotides that encode an amino acid in the polypeptide chain. It is used to form three -letter combinations. A total of 64 of these fuels or codons were formed.

Of the 64 codons, three codes without amino acids. These are called asTermination codonsIf the protein synthesis process ends. A codon is always available at the beginning of the RNA chainIniciationsCodon.This codon (August) encodes the amino acid for methodin.

If one of the bases is changed in the codon, another amino acid will be installed in the polypeptide chain.

Characteristics

The following properties of the genetic code are important;

• The genetic code is specific because a codon always encodes the same amino acid
• Although a codon always encodes the amino acid, an amino acid of more than one codon can be encoded as 61 encoded only 20 amino acids. This characteristic is called a genetic code.
• It does not overlap and is smaller, it always reads by a certain starting point without interruption.

Types of mutations

As we understand how a gene works and why the position of a nucleotide is important in the sequence, move our discussion to types of mutations.

One thing should be taken into account that the genetic code is available in the MRNA, while mutations always occur in the gene.

The different types of mutations that have been identified so far are listed below.

The punctual mutation

These mutations result from changes in a unique or nucleotide base in the codon.

• Transition: In such mutations, a certain pyrimidine is transformed into another pyrimidine, or a certain purine becomes another purine.
• Transversion: These mutations are generated when a certain pyrimidine is replaced by a purine and vice versa.

The MRNA of said mutated gene will also have a different basis in the specified location. A change in the individual base in the MRNA can cause the following effects.

• Silent mutation: If the new codon, created according to the mutation codes for the same amino acid, does not influence the structure of the protein and normal protein occurs. A mutation is called silent mutation.
• Without sense: If the new codon, which results from the mutation, codifies another amino acid, another amino acid is incorrectly included in the structure of the protein. A mutation is called meaningless mutation. You are not acceptable.
• Disparate: In this case, the mutated codon is a programming codon.

Example

An example of punctual mutation is Sicklella anemia.Half of the red blood cells are quickly destroyed because they cannot squeeze by small capillaries.

Marco Marco Mutations

This type of mutation occurs when one or two nucleotides are excluded or inserted in the DNA.

This leads to a massive change in the structure of the protein according to the excluded nucleotide. The programming codon can be generated, which leads to the start date of protein synthesis.

A change of frame change occurs only if one or two nucleotides are excluded or inserted in the gene.

If three or more than three nucleotides of the gene are excluded, the resulting protein has a lack of amino acid in the specified site. A three nucleotide elimination is inCystic fibrosis.In this case, three nucleotides in the CFTR gene lead to an abnormal protein that is absent from the 508 absent from phenylalanine -aminoid^ºPosition. This abnormal protein is rapidly destroyed by the effect of proteasomes.

Similarly, the resulting protein will have an additional amino acid in the specified area if three or often inserted into the gene by three nucleotides.

Mutations on the amendment site

The previously transcribed tactile premrna has several non-coding intermediate sequences that are called introns. These introns are eliminated from pre-arnm to form a functional RNM molecule. Positions called amendment location.

If a mutation occurs in an amendment site, this has an effect on the way introns are eliminated.

Example

An example of the amendment site mutation is a genetic muscle disorder in myotonic dystrophy.

Causes of mutations

Mutations can be spontaneously or induced. They can also occur during the DNA replication process.

Spontaneous mutations

Some mutations can occur spontaneously in any type of cell. Most of these mutations are observed in highly proliferated cells, such as intestinal cells, skin cells, etc., appear at the frequency of 10^-4Bis 10^-7by cell in a generation. The following changes can occur due to spontaneous mutations at the molecular level.

• The tautomization in which the position of a hydrogen atom is changed due to the different standard of the hydrogen bridge.
• Deputy, a Purin base is lost, which leads to an empty point.
• The dismissal, Hydrol7ys of the amino group alters the cytosine base to Uracil and adenine to hypoxantin.

Such mutations can arise in normal healthy cells that are not even affected.

Mutations during DNA replication

Despite the most effective test, some mutations may occur during the DNA replication process. The DNA repair mechanism fails.

Induced mutations

Most mutations are caused by external environmental factors. Solche factors that damage DNA and cause mutations are called carcinogens.

Carcinogenic has two main types; chemical carcinogenic and radiation.

Cancer chemist

This includes five main classes of chemical compounds.

• Policy aromatic hydrocarbons such as benzopyrene in cigarettes
• Aromatic amine as 4-acethylaminofluores
• Nitrosamines such as dietitosamine and dimethylnitrosamine
• Medications such as cyclophosphamide and dietitian
• Natural occurrence connections, such as aflatoxin, which were made by some fungi

These chemical compounds can cause mutations in different mechanisms.

Radiation

The exposure of cells compared to the different types of radiation also causes genetic mutations. The most harmful radiation is UV light and ionized radiation, such as X -rays.

It can cause the following types of DNA damage.

• Pyrimidimer formation inside the DNA tape
• Distance from the bases of the gene, which leads to right -wing or apirimidine places
• Simple or double tape breaks inside DNA
• DNA wire network

ADN -Reparatmecanismen

Cells have extensive repair mechanisms that can effectively repair any mutation in genes. The harmful effects of mutations are observed only if DNA repair mechanisms do not correct these mutations.

The following mechanisms are used by cells to face mutations.

No repair

The mutations in which the bases do not adapt to the DNA tape are corrected by this mechanism.

If the incorporation occurs on a daughter tape, the tape, the creation is recognized by the mut protein. The enzyme of the league is used to join the DNA of the new synthesized piece.

Nucleotide split repair

This mechanism is used to repair the diameters formed by UV rays. Dímeros are recognized by a specific UV endonuclease and a exonuclease (a single enzyme with two activities). It continues this segment and then eliminated from the chain.

Basic repair repair

This process eliminates abnormal basic concepts in the gene. The abnormal base is recognized by a specific glucosyllase enzyme that divides the hydrolytic chain and leaves an empty area.

The empty position is filled by the effect of DNA polymerase and DNA alloy.

Final Union Repair

This mechanism is used to remove tape breaks in DNA. This repair can be made in two ways;

• Non -human DNA threads; DNA non -counterparts are connected and connected
• Final counterpart: Enter the connection of homologous DNA cables

Summary

Gen mutations are DNA damage, which leads to an altered nucleotide sequence in generation.

If a mutation occurs in a gene, the transcribed mRNA of this gene also has an altered nucleotide sequence.

If a single base is changed, it is called specific mutations. Punkt mutation can create three types of affected codon.

• Silent mutation when mutated coding encodes the same amino acid
• Meaningless mutation when mutated coding encodes another amino acid
• Meaningless mutation when the mutated codon is a stop codon

There is a change of frame change due to the introduction or exclusion of one or two nucleotides in the gene, the entire structure of the Arnm reader is postponed and a protein is performed with an aberrant structure.

If a mutation occurs in the amendment, it can cause a gene of genes, which can be seen in myotonic dystrophy.

Several factors can cause genetic mutations.

• You can create spontaneously in any cell
• It can occur during DNA replication
• They can be caused by external factors called carcinogens, that is, chemicals or radiation

Cells have effective DNA repair mechanisms to remove mutations.

• No repair
• Nucleotide split repair
• Basic repair repair
• Final Union Repair

A mutation is only harmful if it cannot be corrected by DNA repair mechanisms.

frequent questions

What are genetic mutations and their boys?

The DNA nucleotide sequence controls the sequence of protein amino acids.

What are the causes of genetic mutations?

Mutations can occur spontaneously in partition cells quickly or are induced by environmental factors.

What happens when a genetic mutation occurs?

When a genetic mutation occurs, the normal sequence of amino acids is altered in the protein.

How can you prevent genetic mutations?

Our body has an efficient system to repair genetic mutations. The disease arises when the repair system fails. However, the best approach it can follow is to avoid exposure to radiation and chemical cancer to reduce the risk of induced mutations.

References

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6. https://commons.wikimedia.org/wiki/File:Codon_usage_bias_in_P._patens.png
7. https://en.wikipedia.org/wiki/DNA_repair#/media/File:Dnarepair1.png
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