Human genetics is the study of inheritance as it does in humans. Human genetics encompasses various overlapping fields including: classical genetics, cytogenetics, molecular genetics, biochemical genetics, genomics, population genetics, developmental genetics, clinical genetics, and genetic counseling.
Genes can be a common factor of the quality of most human nature traits. The study of human genetics can be useful because it can answer questions about human nature, understand disease and the development of effective disease treatment, and understand the genetics of human life. This article only explains the basic features of human genetics; for genetic disorders, please see: medical genetics.
Video Human genetics
Genetic differences and inheritance patterns
The inheritance of human traits is based on the inheritance model of Gregor Mendel. Mendel concluded that inheritance depends on different inheritance units, called factors or genes.
Autosomal dominant inheritance
The autosomal nature is associated with a single gene on autosomes (non-sex chromosomes) - they are called "dominant" because one copy - inherited from one parent - is enough to cause this property to appear. This often means that one parent must also have the same trait, unless it has arisen because of a new mutation that is unlikely to happen. Examples of autosomal dominant traits and disorders are Huntington's disease and achondroplasia.
Autosomal recessive inheritance
The autosomal recessive nature is one of the inherited patterns for a trait, disease, or disorder that is passed on through the family. For recessive traits or illnesses shown two copies of the nature or disorder should be presented. The characteristics or genes will lie on non-sex chromosomes. Because it takes two copies of a trait to display a trait, many people can unknowingly become carriers of the disease. From an evolutionary perspective, recessive diseases or traits can remain hidden for generations before displaying a phenotype. An example of an autosomal recessive disorder is albinism, cystic fibrosis.
X-linked and Y-linked inheritance
X-linked genes are found on the sex X chromosome. X-linked genes such as the autosomal gene have a dominant and recessive type. Recessive X-linked disorders are rarely seen in women and usually only affect men. This is because men inherit the X chromosome and all X-linked genes will be inherited from the maternal side. Dad just passes their Y chromosome to their sons, so there is no X-linked character that will be inherited from father to son. Males can not be carriers of recessive X recessive properties, because they have only one X chromosome, so all X related properties inherited from the mother will appear.
Women express X-related disorders when they are homozygous for disorders and become carriers when they are heterozygous. X-linked dominant inheritance will show the same phenotype as heterozygotes and homozygous. Just like the X-linked heritage, there will be a lack of male inheritance, which makes it indistinguishable from the autosomal nature. One example of X-linked properties is the Coffin-Lowry syndrome, caused by mutations in the ribosomal protein gene. These mutations produce skeletal, craniofacial, mental retardation, and short stature.
X chromosomes in women undergo a process known as X inactivation. X inactivation is when one of the two X chromosomes in a woman is almost completely inactive. It is important that this process occurs if a woman produces twice the normal amount of X chromosome protein. The mechanism for inactivation of X will occur during the embryonic stage. For people with disorders such as trisomy X, where the genotype has three X chromosomes, X-inactivation will disable all X chromosomes until there is only one active X chromosome. Men with Klinefelter syndrome, which has an extra X chromosome, will also undergo X inactivation to have only one X chromosome that is completely active.
Y-linked inheritance occurs when genes, trait, or disorders are transferred through the Y chromosome. Because the Y chromosome can only be found in men, the Y-related features are only passed from father to son. The determinants of the testes, located on the Y chromosome, determine the individual virility. In addition to maleity inherited on the Y chromosome, no other Y-related characteristics were found.
Genealogy analysis
The pedigree is a diagram showing the ancestral relationship and the transmission of genetic traits over several generations within a family. Square symbols are almost always used to represent men, while circles are used for women. Pedigrees are used to help detect many different genetic diseases. A pedigree can also be used to help determine opportunities for parents to produce offspring with certain traits.
Four different properties can be identified by genealogy chart analysis: autosomal dominant, autosomal recessive, x-linked, or y-linked. Partial penetration can be shown and calculated from the pedigree. Penetration is the percentage of frequencies expressed by which the individual of a particular genotype shows at least some degree of specific mutant phenotype associated with the nature.
Inbreeding, or mating between closely related organisms, can clearly be seen on the genealogy chart. Genealogy charts Royal families often have high inbreeding rates, therefore customary and preferable to royalties to marry other members of the royalty. Genetic counselors generally use genealogy to help couples determine whether parents will be able to produce healthy children.
Karyotype
A karyotype is a very useful tool in cytogenetics. A karyotype is a description of all the chromosomes in the metaphase stage arranged according to the length and position of the centromere. A karyotype can also be useful in clinical genetics, because of its ability to diagnose genetic disorders. In a normal karyotype, aneuploidy can be detected clearly able to observe missing or extra chromosomes.
Giemsa appeal, g-banding, of karyotype can be used to detect deletion, insertion, duplication, inversion, and translocation. G-milkfish will stain the chromosomes with unique bright and dark bands for each chromosome. FISH, in situ fluorescent hybridization, can be used to observe deletion, insertion, and translocation. FISH uses fluorescent probes to bind to a specific sequence of chromosomes that will cause the chromosomes to be unique color fluorescence.
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Genomics
Genomics refers to the field of genetics related to the structural and functional studies of the genome. The genome is all of the DNA contained in an organism or cell including nuclear DNA and mitochondria. The human genome is a collection of genes in humans contained in human chromosomes, consisting of more than three billion nucleotides. In April 2003, the Human Genome Project was able to sequence all the DNA in the human genome, and to discover that the human genome comprises about 20,000 protein-coding genes.
Medical genetics
Medical genetics is a branch of medicine that involves the diagnosis and management of hereditary disorders.The medical genetics is the genetic application for medical care.This overlaps human genetics, for example, research on the causes and inheritance of genetic disorders will be considered in human genetics and medical genetics, while individual diagnosis, management, and counseling with genetic disorders will be considered as part of medical genetics.
Population genetics
The genetic population is a branch of evolutionary biology responsible for investigating processes that cause changes in allele frequencies and genotypes in the population based on Mendel's inheritance. Four different forces can affect frequency: natural selection, mutation, gene flow (migration), and genetic shift. The population can be defined as a group of crossbreeding individuals and their descendants. For human genetics, the population will consist only of the human species. The Hardy-Weinberg principle is a widely used principle for determining the frequency of alleles and genotypes.
Mitochondrial DNA
In addition to core DNA, humans (like almost all eukaryotes) have mitochondrial DNA. Mitochondria, the cell's "powerhouse", have their own DNA. Mitochondria are inherited from one's mother, and their DNA is often used to trace the maternal lineage (see Eve of mitochondria). Mitochondrial DNA only has a length of 16kb and encodes 62 genes.
Gen and gender
The genital determination system XY is the sex-determining system found in humans, mostly other mammals, some insects ( Drosophila ), and some plants ( Ginkgo > i>). In this system, the sex of an individual is determined by a pair of sex chromosomes ( gonosomes ). Women have two types of same sex chromosomes (XX), and are called homogametic sex. Males have two different sex chromosomes (XY), and are called heterogametic sex.
X-linked characters
Sex is the phenotypic expression of the allele associated with the sex of the individual chromosomes. This mode of inheritance differs from the inheritance of traits on the autosomal chromosome, in which both sexes have the same inheritance probability. Since humans have more genes on X than Y, there are many more X-linked features than Y-linked features. However, women carry two or more copies of the X chromosome, resulting in a potential toxic dose of X-linked genes .
To correct this imbalance, mammalian women have developed a unique dose-compensation mechanism. Specifically, by means of a process called X-chromosome inactivation (XCI), female mammals transcriptionally silencing one of their two Xs in a complex and highly coordinated way.
Human nature with possible monogenic or oligogenic inheritance patterns
Handicapping Condition
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Chromosomal
Source of the article : Wikipedia
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