The Human Genetics Education Resource
Human genetics can be defined as the study of trait inheritance as it occurs in humans. While this is a very basic definition, it is also a broad one as genetics is complex. Genetics is comprised of many different fields, including molecular biology, genomics, cytogenetics, gene manipulation, and genetic counseling, to name but a few. Scientists struggle to understand why we look, behave, and populate as we do. Genetics explains who we are. Studying human genetics is leading us to a better understanding of genetic-related disease states and disorders, and aids us in finding ways to manipulate or eradicate these factors.
Interactive sites are great for children who have trouble focusing or who need extra stimulation to be engaged with teaching materials. This listing covers a variety of formats including quizzes, matching games, and guided explorations of human anatomy. Teaching resources also offer do-at-home activities such as crossword puzzles and science experiments as well as fun facts and lesson plans for parents or teachers to present to children. Enjoy the wonder of the human body!
History of Genetics
The history of genetics is usually thought to have begun with the work of a friar, Gregor Mendel and his pea plants in the mid-1800s. However, the early theories of Hippocrates and Aristotle were similar to the ideas of pangenesis presented by Charles Darwin. In 1000 CE, Albucasis, an Arab physician also known as Abu al-Qasim al-Zahrawi presented a case study of a family suffering from hemophilia, a well-known genetic disorder. Gregor Mendel’s work from 1856 to 1865 was the first systematic study of trait inheritance. He used pea plants as they were easy to cross-breed. His discoveries of trait inheritance went largely unnoticed until the beginning of the 20th century when his theories were rediscovered.
- Genetics Timeline This timeline demonstrates the beginning of genetic hypotheses.
- Genetics Terminology Glossary of genetic terms for quick referral.
- Human Genome Project Information Website dedicated to the Human Genome Project spanning 13 years.
- History of deoxyribonucleic acid (DNA) DNA history beginning with Gregor Mendel.
Gregor Mendel performed his cross-breeding experiments on over 29,000 pea plants in a 9-year period. During that time, he devised two laws that are the basis of molecular genetics. The First Law states that when the two members of a gene pair (alleles) separate during the formation of gametes, one half carries one allele and the other half gets the other. The Second Law is the principle of independent assortment that states genes for different traits sort themselves independently of one another during gamete formation. Further study led to his conclusion that one allele is dominant to another with a characteristic pattern of 3:1 or 9:3:3:1. Over time, his theories have grown to incorporate dominance factors, such as sex-linked characteristics and traits that do not automatically sort independently.
- Gregor Mendel The life and times of Gregor Johann Mendel.
- General Information Broad overview of Mendelian inheritance.
- Mendel’s Genetics In-depth look at cross-breeding.
- Interactive TutorialInteractive site to practice the monohybrid cross.
Molecular genetics is a branch of genetics dealing with trait expression as evidenced by the DNA sequences of chromosomes on the molecular level. This field of study tells us what genes are systematically passed on and those that are more random in nature. Determining which chromosomes cause certain disorders is useful in guiding research towards gene therapy to reduce or eliminate the incidence of a genetic disorder. The Human Genome Project, the cumulative effort of 18 countries over 13 years, identified 20,000 to 25,000 genes in the DNA of humans and sequences of chemical-based pairs. Molecular genetics has practical applications in DNA forensics, finding new energy sources, and the environment.
- DNA and Molecular Genetics History of molecular genetics.
- Gene Sequencing Overview of the physical structure of DNA.
- The Omics Definitions of the subtypes of genomic studies.
- Genomics Excellent article outlining the varied uses for the study of the genome.
- Pharmacogenomics Relation between genetic makeup and individualized pharmaceuticals.
- Proteomics Explanation of proteomics along with a guide to identifying proteins.
- Transcriptomics Practical applications for this field of study related to gene expression.
- Metabolomics Gene expression as it relates to stresses placed on the metabolites in the human organism.
The interactions that occur with gene sequencing do not follow a simple formula. Other factors play a role in the determination of trait inheritance. Some disorders are sex-linked, such as hemophilia passing from mother to son. Others still have dominance influences, either complete or incomplete.
- Punnett Squares These are diagrams that show primary and secondary gene inheritance patterns.
- Dominance Describes the various types of gene dominance.
- Gene Interactions Discovery of sex-linked chromosomes in fruit flies.
- Gene and Protein Database Guide Guide to further gene interaction information and alternate databases.
DNA and Chromosomes
DNA was discovered in the 1ate 1800s by Johann Friedrich Miescher when he isolated what he called nuclein from a cell nucleus. Not much attention was given to his findings until the 1940s and 1950s when it was proven that DNA carried genetic material and had the now-famous double-helix shape. (Watson and Crick won the Nobel Prize for their work, but it was largely based on the research of Rosalind Franklin, who was not nominated.) The helical shape explained how base pairs of adenine-thymine and guanine-cytosine were held together. Humans have over 3 billion base pairings on the 23 chromosomes in which DNA is contained.
- Discovery of DNA How the structure of DNA was discovered.
- DNA Glossary Glossary of terms related to the structure of DNA.
- DNA Structure Website with superb graphics showing the structure of DNA, including base pairs and nucleotides.
- Chromosomes National Human Genome Research site that details chromosomes.
Gene Expression and Regulation
Gene expression is the process whereby DNA information coded in the genes is turned into proteins. Gene expression relates to the coiling and uncoiling of DNA and is regulated by transcription activators. These activators transcribe DNA information into messenger RNA (mRNA). The process of translation is the next step with mRNA and transfer RNA (tRNA) working together along with ribosomes to create proteins. Gene regulation can occur anywhere along the pathway and is necessarily a complex process given the multicellular nature of humans.
- Definition of Gene Expression Illustrates the parts of the gene responsible for gene activation and expression.
- How Many Genes Are There? Estimations in the number of possible genomes for the human species.
- Gene Regulation Specifics to understanding why gene regulation is necessary in eukaryotes.
- Transcription and Translation Outlines the two steps necessary for protein synthesis
- Genetic Codes Sequencing of genetic codes, nucleotides and amino acids.
Genetic Evolution and Mutation
Mitosis and meiosis are the two types of cell division that occur within the human body. Meiosis pertains to the sex cells, and mitosis is the reproduction of every other type of cell. How cells evolve and/or mutate is dependent on these processes as the cells have to divide and replicate. Evolution of genetic makeup occurs over time in response to external factors, specifically gene mutation. Mutation is an actual change in the nucleotide sequences of a gene occurring at the chromosomal or molecular level. Basically, DNA fails to duplicate itself correctly, either by substituting one base pair for another, inserting an extra base pair, or deleting a section of DNA.
- Mitosis and Meiosis How cells are formed.
- Gene Mutations Different types of mutations and how to calculate mutation rates.
- Causes of Mutations How mutations occur along with genetic evolution.
- Gene Evolution Begins with a review of mitosis and meiosis and leads into evolution and population genetics.
- Genetic Disorders Classifications of genetic disorders.
- Common Genetic Disorders Examples of single gene disorders.
Research into the specific gene sequences that cause disease has boomed over the last several decades. Gene manipulation by insertion of genetic material into a defective gene involves identifying the gene, cloning it and then reinserting it into cells using the patient’s own cells, is seen as the future of decimating genetic diseases such as cystic fibrosis, sickle-cell disease, and hemophilia. Cancer cells have been injected with new instructions, and so far results have been promising. The implications of such research are huge from ethical, legal, and social standpoints as scientists continue to find new ways of combatting disease at the molecular level.
- Genetics and Medical Research Advances in medical genetic research with respect to vaccines, enzyme replacement, drugs, and gene therapy.
- Issues in Genetic Research The ethical, legal and social issues that accompany gene therapy and manipulation.
- Glossary Up to date genetic research terminology.
- Genetics and Cancer Article touting possible gene manipulation to beat cancer.
- Gene Therapy In-depth gene therapy study for individuals with severe combined immunodeficiency (SCID).