What is a recessive gene
The dominant and recessive gene allows the transmission of hereditary information from parents to children. Each of them has its own location (locus), a specific chromosome.
There are genes that have different forms, but are responsible for one hereditary information. Their biologists are called alleles. For example, the gene that determines the color of the eyes, has several avenues that determine the brown or blue color of the iris.
Recessive and dominant genes
In some cases, the information that is enclosed in the allele will overlap with another type. The overlapping is called dominant, and the overlapping recessive gene. What are their features? To begin with, we note that not all of them must necessarily show a dominant and recessive gene in one chromosome. Enough that they were in the same chromosome. The recessive gene exhibits its typical properties only in those situations when there are analogues with similar characteristics in the homologous pair of both chromosomes.For example, the allele, which is responsible for creating the brown color of the iris, exists in the dominant variant, its properties appear when it is present only in one chromosome, and the recessive gene carries information about the blue membrane, it will appear only if there is a similar set in both chromosomes. That is, the more likely option would be the transfer to the offspring of the brown color of the iris. In the alleles there is information that is required for the synthesis of protein molecules, without which the combination of amino acid residues is impossible. Thousands of changeable components are formed on the basis of twenty essential amino acids, the dominant and recessive gene is needed to encode the hereditary information. The mechanism for creating an individual genetic code is based on the sequential combination of the nitrogenous bases that make up the DNA.
Types of nitrogen-containing heterocyclic compounds
Genetics distinguish four types of nitrogenous bases, which are used in coding the sequence of a compound of polypeptide bonds. A codon consisting of three nitrogenous bases is used to write the protein molecule.The resulting record is the genetic code of a living organism.
Genes are functional units of chromosomes that are responsible for transmitting important information related to development and existence in specific natural conditions to future offspring. Each individual has its own unique characteristics, which are given to him by a combination of amino acids.
In all cells of the human body is 46 chromosomes. Excluding gametes: sperm and eggs, they all include 23 chromosomes. We are talking about 23 pairs of chromosomes - homologues, called equivalent sets. 22 pairs of such homologous variants are considered autosomes, since they are similar in women and men. The last pair, which organisms differ, is called the sex chromosomes. For women, they are represented by two similar X chromosomes, and for men in the combination of X and Y chromosomes. The transfer of physiological and anatomical parameters to children from parents, including hereditary pathologies, is carried out according to strict laws of the location of genes.
Options autosomal heredity
In the case of the dominant variant of heredity, a certain disease or trait is manifested, characterized by being in the chromosome of the dominant gene.For its manifestation, it is sufficient that the autosomal recessive gene overlaps with the dominant species.
Inheritance for the Y chromosome
This situation is characterized by the manifestation of a disease or a specific trait only in men, since this sex chromosome is not in the female set. For example, the inherited hemophilia recessive gene progresses in boys. The disease is associated with disorders of complete blood clotting. The patient constantly has serious bleeding, even with insignificant damage to the blood vessels. There are two types of hemophilia, A and B, associated specifically with recessive alleles that are located on the X chromosome. In women, this problem almost never occurs. Among the historical figures who are carriers of hemophilia, the most famous is considered to be Queen Victoria. The disease was transmitted to her son Leopold, Duke of Albany, as well as to his grandchildren and great-grandchildren, including Russian Tsarevich Alexei Nikolayevich. In the royal families were allowed kinship marriages, which contributed to the transfer of the genetic code, including hemophilia in the male line.
What is color blindness? The recessive gene in such cases also plays an important role. Hereditary transmission of this disease is associated with the X chromosome. His transfer from the mother, who is the carrier, to the son is known. That is why color blindness is detected more often in men with a set of sex chromosomes XY. Approximately 2-8 percent of men suffer from this disease, but among women this indicator does not exceed 0.4 percent.
Dominant and recessive traits allow us to explain many theoretical points related to the encoding and transmission of hereditary information from an adult to offspring. With this knowledge, you can look for ways to prevent problems associated with genetic diseases, look for ways to cure.