Question

Q) define peiliotrophy nd explain it with example​

Answer 1

Answer:

What Is Pleiotropy?

Occasionally, we see genetic mutations in human beings. A mutation is any sort of genetic alteration that causes a change in the phenotype or expression of that gene. Sometimes we see genetic changes and phenotype changes not from a mutation, but from a gene controlling multiple traits. This is called pleiotropy. As stated, pleiotropy is where one gene winds up controlling multiple phenotypic traits in the organism.

An example of pleiotropy is phenylketonuria, an inherited disorder that affects the level of phenylalanine in the human body. Phenylalanine is an amino acid that can be obtained from food

Explanation:

Answer 2

★ Pleiotropy

Gene pleiotropy refers to a gene that determines or influences the formation of multiple traits. During the development of organisms, many biochemical reactions are interrelated and interdependent. The role of genes is to determine the formation of traits through a series of biochemical reactions that control and affect metabolism.

Since various traits of organisms and various physiological and biochemical processes are interrelated and restrictive, the role of genes must also be interrelated and restrictive. A gene affects this trait and indirectly affects other traits.

Example → Schizophrenia , Sickle cell anemia.

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★ Concept

Gene pluripotency refers to multiple secondary effects produced by one or a pair of mutant genes. Pluripotency is only for the symptoms. It is said that the multi-effect of the gene with multiple effects of the single effect of the gene is very common. Many genetic syndromes caused by mutant genes indicate the existence of gene pleiotropy.

★ Features

In early genetics research, genes were recognized through traits. In this case, the original concept that a gene determines a trait is produced. But when we further study and recognize that genes control the metabolism through their products or enzyme proteins to control the development of traits, this gradually realizes that genes not only directly control the performance of a trait through the action of enzymes , but also change through a trait. Further affected many traits. This is the versatility of genes.

Gene pleiotropy is that a gene can have multiple biological effects. In humans, many single genes can cause an individual to exhibit multiple traits. The lack of gene products caused by a genetic abnormality will often cause a series of abnormalities in biochemical metabolism or tissue structure in different tissues and at different development stages of the individual, that is, the individual will show a variety of traits. The versatility of genes is expressed as the interaction between genes. Since most traits of an organism are the result of the joint action of many enzymes, and these enzymes are synthesized under the control of genes, that is, they are controlled by multiple genes, so they are fundamentally It is the result of the interaction of these genes. For example, genes related to the trait of the color of maize kernels are A, C, R and P, which are located on maize chromosomes III, IX, I and V, respectively. Experiments have shown that at least when there are A and C genes (regardless of homozygosity or heterozygosity), the color of the corn flour paste layer may appear, with A and C supplemented with R (also regardless of heterozygosity or homozygosity), Can make the aleurone layer produce red pigment. If there are A, C, R plus P, purple pigment can be synthesized, otherwise the aleurone layer is colorless.

★ Typical Case

• ①The safflower and white flower genes of pea. In addition to controlling the pea flower color inheritance, the safflower gene can also cause purple spots on the leaf axils and the seed coat is brown; the white flower gene cannot. Rice dwarf gene in addition to the short length outside the control rice plants, but also to promote tillering ability strong, dark green leaves.
• ②The feathering gene of the feathering chicken not only affects the rewinding of the chicken feathers, but also affects the decrease of body temperature, the increase of the heartbeat, the enlargement of the heart and spleen, and the decrease of fertility.
• ③ Another example is phenylketonuria . The primary defect of classic PKU is hereditary deficiency of phenylalanine hydroxylase, and the patient's blood and urine levels of phenylalanine and phenyl-pyruvate are increased. The secondary symptoms are: severe intellectual developmental disorder; phenylalanine cannot be converted to tyrosine , melanin decreases accordingly, and hair color becomes lighter; agitated behavior, hyperactivity; hyperreflexia, excessive muscle tension; the patient has mildew or Rat smell.
• ④For sickle cell anemia , the primary effect is that glutamic acid at the 6th position of the hemoglobin β chain is replaced by valine to form variant hemoglobin HbS. Hemoglobin solubility of homozygous patients decreases and erythrocyte sickle changes. The secondary symptoms are: anemia can cause splenomegaly, weakness, and burnout; increased red blood cell viscosity can cause thrombosis and infarction. Depending on the location of the thrombosis, various symptoms appear, such as heart failure, hematuria, renal failure, cerebrovascular accident, pain in the limbs and leg ulcers, abdominal pain, splenic infarction, etc. This is a very typical example of gene pluripotency.