Genetics in Medicine - Part 2
Embryonic Stem Cells
Mammalian embryonic stem (ES) cells have the special property of being able to differentiate into virtually every cell type. Because ES cells can be genetically manipulated in vitro and can be transplanted into embryos and adults, they are a powerful tool in biological experiments and hold promise for future medical therapies. The ability to differentiate into all cell types, a property known as p…
Eugenics - British Origins, Positive And Negative Eugenics, Mendelian Inheritance, Intelligence Testing, And American Eugenics
While the idea of improving humans through selective breeding is at least as old as the ancient Greeks, it gained widespread prominence after 1869. In 1883, Sir Francis Galton coined the word "eugenics," from the Greek word eugenes, meaning "well-born" or "hereditarily endowed with noble qualities," to describe this new science of directed human evolution.…
Molecular Evolution - The Antiquity Of Life, Building The Building Blocks: Rna Nucleotides, Linking Subunits Into Chains - Goals for Future Research
All life on Earth is cellular and uses DNA to store genetic information. However, evidence suggests that, on ancient Earth, much complex chemical activity preceded cellular development, and it was probably not DNA-based at the start. What was the nature of this activity, and how did it lead to life? "Molecular evolution" is a term used to describe the stages that preceded the origin …
Fruit Fly: Drosophila
Drosophila melanogaster, a common fruit fly, was one of the first model organisms used in genetic research, and continues to be one of the most important. Thomas Hunt Morgan (1866-1945) developed Drosophila as a model system in 1909. Morgan, along with his students, Calvin Bridges, Alfred Sturtevant, and Hermann Muller, made some of the most important discoveries in genetics through their work wi…
Gel Electrophoresis - Basic Procedure, Separation Of Proteins, Separation Of Dna And Rna
Gel electrophoresis is a widely used technique for separating electrically charged molecules. It is a central technique in molecular biology and genetics laboratories, because it lets researchers separate and purify the nucleic acids DNA and RNA and proteins, so they can be studied individually. Gel electrophoresis is often followed by staining or blotting procedures used to identify the separated…
Gene Discovery - Positional Cloning, Complex Diseases - Approaches for Identifying Genes
Gene discovery is the process of identifying genes that contribute to the development of a trait or phenotype. Researchers often try to discover the genes that are involved in specific diseases. They also try to find the genes that contribute to many other traits. Polymorphic markers along the chromosomes (here shown as different colored bars) are examined to determine which is coinherited wit…
Gene Expression: Overview of Control - The Flow Of Genetic Information From Genes To Proteins, Gene Control Occurs At Several Levels, How Do Cells Regulate Transcription?
The chromosomes of an organism contain genes that encode all of the RNA and protein molecules required to construct that organism. Gene expression is the process through which information in a gene is used to produce the final gene product: an RNA molecule or a protein. Each cell in a multicellular organism such as a human contains the same genes as every other cell. Nonetheless, there are hundred…
Gene Families
Gene families are groups of DNA segments that have evolved by common descent through duplication and divergence. They are multiple DNA segments that have evolved from one common ancestral DNA segment that has been copied and changed over millions of years. The members of a gene family may include expressed genes as well as nonexpressed sequences. Such nonexpressed sequences include promoters, oper…
Gene Flow
Gene flow is the transfer of genetic material between separate populations. Many organisms are divided into separate populations that have restricted contact with each other, possibly leading to reproductive isolation. Many things can fragment a species into a collection of isolated populations. For example, a treacherous mountain pass may cut off one herd of mountain goats from another. In human …
Gene Therapy - Disease Targets, Gene Delivery, Longevity Of Gene Expression, Examples Of Gene Therapy Applications
Gene therapy is a new and largely experimental branch of medicine that uses genetic material (DNA) to treat patients. Researchers hope one day to use this therapy to treat several different kinds of diseases. While rapid progress has been made in this field in recent years, very few patients have been successfully treated by gene therapy, and a great deal of additional research remains to be done …
Genetic Code - Translation, The "wobble" Hypothesis, The Code Has No Gaps Or Overlaps, Exceptions To The Universal Genetic Code
The sequence of nucleotides in DNA determines the sequence of amino acids found in all proteins. Since there are only four nucleotide "letters" in the DNA alphabet (A, C, G, T, which stand for adenine, cytosine, guanine, and thymine), but there are 20 different amino acids in the protein alphabet, it is clear that more than one nucleotide must be used to specify an amino acid. Even t…
Genetic Counselor
Genetic counselors are health professionals trained in genetics, genetic disorders, genetic testing, molecular biology, psychology and psychosocial issues, and the ethical and legal issues of genetic medicine. Most genetic counselors have a master's degree from a genetic counseling training program. The very first class of genetic counselors was graduated from Sarah Lawrence College in 1971…
Genetic Discrimination - Antidiscrimination Legislation, Present Problems And Potential Solutions
The potentially stigmatizing nature of genetic information and its history of abuse necessitate special provisions for its protection. Although the U.S. Supreme Court has established a basic right to privacy (in the case of Roe v. Wade), the nonspecific nature of this privacy protection fails to adequately guard against the unauthorized disclosure of personal genetic information. There have been r…
Genetic Testing - Prenatal Genetic Testing, Assisted Reproduction, Newborn Screening, Symptomatic Genetic Testing, Carrier Testing, Presymptomatic Testing
Genetic testing involves examining a person's DNA in order to find changes or mutations that might put an individual, or that individual's children, at risk for a genetic disorder. These changes might be at the chromosomal level, involving extra, missing, or rearranged chromosome material. Or the changes might be extremely small, affecting just one or more of the chemical bases that …
Geneticist
Genetics intersects almost every other field of biology. For this reason, professionals with a genetics education have a broad range of career opportunities. The recent success of the Human Genome Project has created a great demand for genetics professionals with a variety of expertise in all areas of genetics, not only those applicable to human disease. Geneticists are involved in identifying gen…
Genetics
Genetics is the scientific study of the structure, function, and transmission of genes in living things. The field of genetics includes many disciplines and uses many different techniques. Historically, genetic scientists (geneticists) investigated patterns of inheritance in whole organisms by observing the distribution and segregation of physical characteristics across several generations of bree…
Genome - Eukaryotes, Chromosome Number, Genome Size Or C Value, Number Of Nuclear Genes, "gene Density," And Intergenic Sequences
A genome is the complete collection of hereditary information for an individual organism. In cellular life forms, the hereditary information exists as DNA. There are two fundamentally distinct types of cells in the living world, prokaryotic and eukaryotic, and the organization of genomes differs in these two types of cells. Prokaryotes comprise the bacteria and archaea. The latter were originally …
Genomic Medicine - The Importance Of Snps, The Future Of Medicine
A quote commonly heard these days is that in the history of medicine, the greatest advancements in the treatment of patients have occurred within the past 50 years. But what if a doctor could prevent a disease from occurring, treating the cause rather than the symptoms? We all agree this would be wonderful, but how could a doctor predict a patient's medical future? This dream is now within …
Genomics Industry - Large-scale Sequencing Companies, Gene Mining Companies, Functional Genomics Companies, Population-based Genomics Companies
Fundamental to the myriad of genomic research efforts in operation around the world is the mapping and sequencing of whole genomes. The entire genomes of more than seventy organisms had been completed by early 2002, including the working drafts of the human genome, first published in 2001. The successful completion of the sequencing of these genomes was made possible in part by companies developin…
Genotype and Phenotype - Alleles, Polymorphisms, And Mutations, Dominant, Codominant, And Recessive Genes, Multiple Alleles And Pleiotropy
An individual's genotype is the composition, in the individual's genome, of a specific region of DNA that varies within a population. (The genome of the individual is the total collection of the DNA in a cell's chromosomes. It includes all of the individual's genes, as well as the DNA sequences that lie between them.) Alleles differ in their DNA sequence, and may le…
Growth Disorders - Endocrine Disorders, Skeletal Dysplasias, Excessive Growth
Growth, which usually refers to skeletal growth since it determines final adult height, is an extremely complex process. As such, it is susceptible to a wide range of genetic and physiologic disturbances. Indeed, growth is adversely affected by many if not most chronic diseases of childhood, through many different mechanisms. Skeletal growth depends on hormonal signals for regulation. It also requ…
Hemophilia - Gene Defects Causing Hemophilia, Detection Of Fviii Or Fix Gene Defect In Family: Carrier Detection
Hemophilia A and hemophilia B are genetic disorders in the blood-clotting system, characterized by bleeding into joints and soft tissues, and by excessive bleeding into any site experiencing trauma or undergoing surgery. Hemophilia A and B are clinically indistinguishable. Both have the same type of bleeding manifestations, and both affect males almost exclusively. The coagulation cascade invo…
Heterozygote Advantage - Agricultural Significance, Hypotheses Of Heterozygote Advantage, Heterozygote Superiority In Humans
Heterozygote advantage is the superior fitness often seen in hybrids, the cross between two dissimilar parents. A heterozygote is an organism with two different alleles, one donated from each parent. Fitness means the ability to survive and have offspring. Heterozygote advantage also refers more narrowly to superior fitness of an organism that is heterozygous for a particular gene, usually one gov…
HIV - Hiv And Aids, Hiv Life Cycle: Entering Cells, Hiv Life Cycle: Reproduction, Hiv's Immune-system Impairment Mechanism
HIV, the human immunodeficiency virus, is the virus that causes AIDS, a debilitating and deadly disease of the human immune system. HIV is one of the world's most serious health problems: at the end of 2001, more than 40 million people worldwide were infected with HIV and living with the virus or AIDS. The World Health Organization estimates that about 20 million people have died from AIDS …
Hormonal Regulation - Hormone Receptors, Nuclear Receptors And Their Hormones, Nuclear Hormone Receptors And Transcriptional Regulation, The Importance Of Hormone Concentration
All types of cells are capable of receiving signals from their environment and mounting an appropriate response to the signal, such as chemotaxis toward a nutrient source or toward other cells emitting a pheromone. The A steroid hormone binds to a two-part receptor within the cell. This links with a coactivator, making a complex that binds to DNA. This triggers transcription of the target gene…
HPLC: High-Performance Liquid Chromatography - Components Of Hplc Analysis, Hplc Applications
High-performance liquid chromatography (HPLC) is an advanced form of liquid chromatography used in separating the complex mixture of molecules encountered in chemical and biological systems, in order to understand better the role of individual molecules. In liquid chromatography, a mixture of molecules dissolved in a solution (mobile phase) is separated into its constituent parts by passing throug…
Identification of Human Disease Genes - The Process of Disease-Gene Discovery
In order to help treat human diseases, it is important to understand what causes them to occur. Understanding what causes a disease is the first step in understanding the entire abnormal course of disease. Sometimes it is fairly easy to determine what causes a disease. For example, pneumonia is caused by the Pneumococcus bacterium. However, in other cases it is not nearly as easy to tell what is c…
In Situ Hybridization - Application Of The Probe For Dna Or Rna To Tissues Or Cells, Conditions That Promote Optimal In Situ Hybridization
In situ hybridization is a technique used to detect specific DNA and RNA sequences in a biological sample. Deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) are macromolecules made up of different sequences of four nucleotide bases (adenine, guanine, uracil, cytosine, and thymidine). In situ hybridization takes advantage of the fact that each nucleotide base binds with a complementary nucleot…
Individual Genetic Variation - Variation And Alleles, Scoring Variation In The Lab
"Variety is the spice of life," or so the saying goes. In fact, it is probably more precise to say that variety is the key to life. It is genetic variation that contributes to the diversity in phenotype that provides for richness in human variation, and it is genetic variation that gives evolution the tool that it needs for selection and for trying out different combinations of allel…
Information Systems Manager
An information systems manager (ISM) is a professional whose skills are needed to handle the large amounts of information generated by and analyzed in the modern genetics laboratory. A successful information systems manager needs to be experienced with the technical aspects of computer hardware and networking systems. The daily work may involve managing a team of information technology workers, so…
Internet
Biologists often use two terms to describe alternative approaches for conducting experiments. "In vitro" (Latin for "in glass") refers to experiments typically carried out in test tubes with purified biochemicals. "In vivo" ("in life") experiments are performed directly on living organisms. In recent years, the indispensable use of computers…