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- Genes affect hundreds of internal and external factors, such as whether a person will get a particular eye color or what diseases they may develop. Changes in genes can also lead to incorrectly formed proteins that cannot perform their functions. These are called gene mutations and may lead to genetic disorders.
www.medicalnewstoday.com/articles/120574
May 15, 2024 · This page provides information about basic genetic concepts such as DNA, genes, chromosomes, and gene expression. Genes play a role in almost every human trait and disease. Advances in our understanding of how genes work have led to improvements in health care and public health.
Sep 7, 2018 · Genetics and genomics both play roles in health and disease. Genetics refers to the study of genes and the way that certain traits or conditions are passed down from one generation to another. Genomics describes the study of all of a person's genes (the genome).
- Overview
- Ancient theories of pangenesis and blood in heredity
- Preformation and natural selection
Genetics is the study of heredity in general and of genes in particular. Genetics forms one of the central pillars of biology and overlaps with many other areas, such as agriculture, medicine, and biotechnology.
Is intelligence genetic?
Intelligence is a very complex human trait, the genetics of which has been a subject of controversy for some time. Even roughly measured via diverse cognitive tests, intelligence shows a strong contribution from the environment.
How is genetic testing done?
Genetic testing typically is issued only after a medical history, a physical examination, and the construction of a family pedigree documenting familial genetic diseases have been considered. The genetic tests themselves are carried out using chemical, radiological, histopathologic, and electrodiagnostic procedures. Genetic testing may involve cytogenetic analyses to investigate chromosomes, molecular assays to investigate genes and DNA, or biochemical assays to investigate enzymes, hormones, or amino acids.
genetics, study of heredity in general and of genes in particular. Genetics forms one of the central pillars of biology and overlaps with many other areas, such as agriculture, medicine, and biotechnology.
Although scientific evidence for patterns of genetic inheritance did not appear until Mendel’s work, history shows that humankind must have been interested in heredity long before the dawn of civilization. Curiosity must first have been based on human family resemblances, such as similarity in body structure, voice, gait, and gestures. Such notions were instrumental in the establishment of family and royal dynasties. Early nomadic tribes were interested in the qualities of the animals that they herded and domesticated and, undoubtedly, bred selectively. The first human settlements that practiced farming appear to have selected crop plants with favourable qualities. Ancient tomb paintings show racehorse breeding pedigrees containing clear depictions of the inheritance of several distinct physical traits in the horses. Despite this interest, the first recorded speculations on heredity did not exist until the time of the ancient Greeks; some aspects of their ideas are still considered relevant today.
Hippocrates (c. 460–c. 375 bce), known as the father of medicine, believed in the inheritance of acquired characteristics, and, to account for this, he devised the hypothesis known as pangenesis. He postulated that all organs of the body of a parent gave off invisible “seeds,” which were like miniaturized building components and were transmitted during sexual intercourse, reassembling themselves in the mother’s womb to form a baby.
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Aristotle (384–322 bce) emphasized the importance of blood in heredity. He thought that the blood supplied generative material for building all parts of the adult body, and he reasoned that blood was the basis for passing on this generative power to the next generation. In fact, he believed that the male’s semen was purified blood and that a woman’s menstrual blood was her equivalent of semen. These male and female contributions united in the womb to produce a baby. The blood contained some type of hereditary essences, but he believed that the baby would develop under the influence of these essences, rather than being built from the essences themselves.
Aristotle’s ideas about the role of blood in procreation were probably the origin of the still prevalent notion that somehow the blood is involved in heredity. Today people still speak of certain traits as being “in the blood” and of “blood lines” and “blood ties.” The Greek model of inheritance, in which a teeming multitude of substances was invoked, differed from that of the Mendelian model. Mendel’s idea was that distinct differences between individuals are determined by differences in single yet powerful hereditary factors. These single hereditary factors were identified as genes. Copies of genes are transmitted through sperm and egg and guide the development of the offspring. Genes are also responsible for reproducing the distinct features of both parents that are visible in their children.
In the two millennia between the lives of Aristotle and Mendel, few new ideas were recorded on the nature of heredity. In the 17th and 18th centuries the idea of preformation was introduced. Scientists using the newly developed microscopes imagined that they could see miniature replicas of human beings inside sperm heads. French biologist Jean-Baptiste Lamarck invoked the idea of “the inheritance of acquired characters,” not as an explanation for heredity but as a model for evolution. He lived at a time when the fixity of species was taken for granted, yet he maintained that this fixity was only found in a constant environment. He enunciated the law of use and disuse, which states that when certain organs become specially developed as a result of some environmental need, then that state of development is hereditary and can be passed on to progeny. He believed that in this way, over many generations, giraffes could arise from deerlike animals that had to keep stretching their necks to reach high leaves on trees.
British naturalist Alfred Russel Wallace originally postulated the theory of evolution by natural selection. However, Charles Darwin’s observations during his circumnavigation of the globe aboard the HMS Beagle (1831–36) provided evidence for natural selection and his suggestion that humans and animals shared a common ancestry. Many scientists at the time believed in a hereditary mechanism that was a version of the ancient Greek idea of pangenesis, and Darwin’s ideas did not appear to fit with the theory of heredity that sprang from the experiments of Mendel.
May 15, 2006 · This chapter focuses on what is known or theorized about the direct link between genes and health and what still must be explored in order to understand the environmental interactions and relative roles among genes that contribute to health and illness.
- Lyla M Hernandez, Dan G Blazer
- 2006
- 2006
Jul 8, 2009 · This chapter provides fundamental information about basic genetics concepts, including cell structure, the molecular and biochemical basis of disease, major types of genetic disease, laws of inheritance, and the impact of genetic variation.
- 2009/07/08
Jan 11, 2024 · Genes contain instructions for life and survival. New genetic discoveries offer insights into how life works, and hope for preventing and curing diseases.
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What is genetics in biology?
Dec 20, 2023 · 20.12.2023. Genetics is the branch of biology that focuses on the study of DNA, hereditary information, and the mechanisms by which traits are passed down from one generation to another. It explores the mutation and variation in genes that give rise to the diversity of life on Earth.
