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Explore Genomic Resources
Our free resource library is packed full of lesson plans, videos, interactive games and other educational content from the National Human Genome Research Institute and our partners.
Read Genomics: Insights
Read articles written by promising researchers about the science they're doing in the lab to inform, educate, and raise awareness about genetics and genomics.
#1
A Brief Guide to Genomics
An organism's complete set of DNA is called its genome. Virtually every single cell in the body contains a complete copy of the approximately 3 billion DNA base pairs, or letters, that make up the human genome.
With its four-letter language, DNA contains the information needed to build the entire human body. A gene traditionally refers to the unit of DNA that carries the instructions for making a specific protein or set of proteins. Each of the estimated 20,000 to 25,000 genes in the human genome codes for an average of three proteins.
This fact sheet reviews:
- DNA, Genes and Genomes
- DNA Sequencing
- The Human Genome Project
- Implications of Genomics for Medical Science
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#2
Chromosomes
Chromosomes are thread-like structures located inside the nucleus of animal and plant cells. Each chromosome is made of protein and a single molecule of deoxyribonucleic acid (DNA). Passed from parents to offspring, DNA contains the specific instructions that make each type of living creature unique.
The term chromosome comes from the Greek words for color (chroma) and body (soma). Scientists gave this name to chromosomes because they are cell structures, or bodies, that are strongly stained by some colorful dyes used in research.
This fact sheet reviews:
- What is a chromosome?
- What do chromosomes do?
- Do all living things have the same types of chromosomes?
- What are centromeres?
- What are telomeres?
- How many chromosomes do humans have?
- How are chromosomes inherited?
- Do males have different chromosomes than females?
- How were chromosomes discovered?
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#3
Chromosome Abnormalities
There are many types of chromosome abnormalities. However, they can be organized into two basic groups: numerical abnormalities and structural abnormalities.
Most chromosome abnormalities occur as an accident in the egg or sperm. In these cases, the abnormality is present in every cell of the body. Some abnormalities, however, happen after conception; then some cells have the abnormality and some do not.
This fact sheet reviews:
- What are chromosomes?
- Where are chromosomes found in the body?
- How many chromosomes do humans have?
- How do scientists study chromosomes?
- What are chromosome abnormalities?
- How do chromosome abnormalities happen?
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#4
Deoxyribonucleic Acid (DNA)
We all know that elephants only give birth to little elephants, giraffes to giraffes, dogs to dogs and so on for every type of living creature. But why is this so?
The answer lies in a molecule called deoxyribonucleic acid (DNA), which contains the biological instructions that make each species unique. DNA, along with the instructions it contains, is passed from adult organisms to their offspring during reproduction.
This fact sheet reviews:
What is DNA?
Where is DNA found?
What is DNA made of?
What does DNA do?
How are DNA sequences used to make proteins?
Who discovered DNA?
What is the DNA "double helix?"
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#5
DNA Sequencing
DNA sequencing means determining the order of the four chemical building blocks - called "bases" - that make up the DNA molecule. The sequence tells scientists the kind of genetic information that is carried in a particular DNA segment.
For example, scientists can use sequence information to determine which stretches of DNA contain genes and which stretches carry regulatory instructions, turning genes on or off. In addition, and importantly, sequence data can highlight changes in a gene that may cause disease.
This fact sheet reviews:
- What is DNA sequencing?
- How new is DNA sequencing?
- What new sequencing methods have been developed?
- Are newer sequencing technologies under development?
- What do improvements in DNA sequencing mean for human health?
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#6
Genome-Wide Association Studies
A genome-wide association study is an approach that involves rapidly scanning markers across the complete sets of DNA, or genomes, of many people to find genetic variations associated with a particular disease. Once new genetic associations are identified, researchers can use the information to develop better strategies to detect, treat and prevent the disease.
Such studies are particularly useful in finding genetic variations that contribute to common, complex diseases, such as asthma, cancer, diabetes, heart disease and mental illnesses.
This fact sheet reviews:
- What is a genome-wide association study?
- Why are such studies possible now?
- How will genome-wide association studies benefit human health?
- What have genome-wide association studies found?
- How are genome-wide association studies conducted?
- How can researchers access data from genome-wide association studies?
- What is NIH doing to support genome-wide association studies?
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#7
Comparative Genomics
Comparative genomics is an exciting field of biological research in which researchers use a variety of tools, including computer-based analysis, to compare the complete genome sequences of different species.
By carefully comparing characteristics that define various organisms - including the genomes of organisms ranging from humans to chimpanzees to yeast - researchers can pinpoint regions of similarity and difference. This information can help scientists better understand the structure and function of human genes, and develop new strategies to combat human disease.
This fact sheet reviews:
- What is comparative genomics?
- What are the benefits of comparative genomics?
- What is a genome made of?
- What results has the field of comparative genomics produced?
- What other genomes have been sequenced?
- How is NHGRI involved in the growth of this new field of research?
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#8
Genetic Mapping
Genetic mapping - also called linkage mapping - can offer firm evidence that a disease transmitted from parent to child is linked to one or more genes. Mapping also provides clues about which chromosome contains the gene and precisely where the gene lies on that chromosome.
Genetic maps have been used successfully to find the gene responsible for relatively rare, single-gene inherited disorders such as cystic fibrosis and Duchenne muscular dystrophy.
Genetic maps are also useful in guiding scientists to the many genes that are believed to play a role in the development of more common disorders such as asthma, heart disease, diabetes, cancer, and psychiatric conditions.
This fact sheet reviews:
- What is genetic mapping?
- How do researchers create a genetic map?
- What are genetic markers?
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#9
Newborn Screening
Newborn screening in the United States is a major public health success that has saved countless lives. Each state runs its own newborn screening program, where almost all newborns are tested for at least 30 serious-but-treatable conditions that occur during childhood.
Almost all of the current newborn screening tests use a dried blood sample collected during the first week after birth to measure the presence of disease biomarkers (a measurable substance or characteristic that is indicative of a disease). Currently, the tests used by state newborn screening programs are fast, low cost and accurate in identifying disease before symptoms appear.
This fact sheet reviews:
- What is newborn screening?
- How does genomics come into it?
- Is the government planning to replace newborn screening with newborn genome sequencing?
- What about the emotional toll on families who receive information about mutations with health consequences?
- What protections are in place for families who do not wish to receive this information?
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#10
Polymerase Chain Reaction (PCR)
Polymerase Chain Reaction (PCR) is a relatively simple and inexpensive technology used to focus in on a segment of DNA and make billions of copies of it. One of the most important scientific advances in molecular biology, PCR amplification is used every day to diagnose diseases, and to identify bacteria and viruses. PCR revolutionized the study of DNA to such an extent that its inventor, Dr. Kary Mullis was awarded the Nobel Prize in Chemistry in 1993.
This fact sheet reviews:
- What is PCR?
- What is PCR used for?
- How does PCR work?
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#11
Cloning
The term cloning describes a number of different processes that can be used to produce genetically identical copies of a biological entity. The copied material, which has the same genetic makeup as the original, is referred to as a clone.
Researchers have cloned a wide range of biological materials, including genes, cells, tissues and even entire organisms, such as a sheep.
This fact sheet reviews:
- What is cloning?
- Do clones ever occur naturally?
- What are the types of artificial cloning?
- What sort of cloning research is going on at NHGRI?
- How are genes cloned?
- How are animals cloned?
- What animals have been cloned?
- Have humans been cloned?
- Do cloned animals always look identical?
- What are the potential applications of cloning animals?
- What are the potential drawbacks of cloning animals?
- What is therapeutic cloning?
- What are the potential applications of therapeutic cloning?
- What are the potential drawbacks of therapeutic cloning? • What are some of the ethical issues related to cloning?
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#12
Knockout Mice
A knockout mouse is a laboratory mouse in which researchers have inactivated, or "knocked out," an existing gene by replacing it or disrupting it with an artificial piece of DNA. The loss of gene activity often causes changes in a mouse's phenotype, which includes appearance, behavior and other observable physical and biochemical characteristics.
This fact sheet reviews:
- What is a knockout mouse?
- What are knockout mice used for?
- What are the drawbacks of knockout mice?
- How are knockout mice made?
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#13
Fluorescence In Situ Hybridization (FISH)
Fluorescence in situ hybridization (FISH) provides researchers with a way to visualize and map the genetic material in an individual's cells, including specific genes or portions of genes. This may be used for understanding a variety of chromosomal abnormalities and other genetic mutations.
This fact sheet reviews:
- What is FISH?
- How does FISH work?
- What is FISH used for?
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#14
DNA Microarray Technology
The DNA microarray is a tool used to determine whether the DNA from a particular individual contains a mutation in genes like BRCA1 and BRCA2. The chip consists of a small glass plate encased in plastic. Some companies manufacture microarrays using methods similar to those used to make computer microchips.
On the surface, each chip contains thousands of short, synthetic, single-stranded DNA sequences, which together add up to the normal gene in question, and to variants (mutations) of that gene that have been found in the human population.
This fact sheet reviews:
- What is a DNA microarray?
- What is a DNA microarray used for?
- How does a DNA microarray work?
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#15
Epigenomics
The epigenome is a multitude of chemical compounds that can tell the genome what to do. The human genome is the complete assembly of DNA -about 3 billion base pairs - that makes each individual unique. DNA holds the instructions for building the proteins that carry out a variety of functions in a cell.
The epigenome is made up of chemical compounds and proteins that can attach to DNA and direct such actions as turning genes on or off, controlling the production of proteins in particular cells.
This fact sheet reviews:
- What is the epigenome?
- What does the epigenome do?
- What makes up the epigenome?
- Is the epigenome inherited?
- What is imprinting?
- Can the epigenome change?
- What makes the epigenome change?
- How do changes in the epigenome contribute to cancer?
- How are researchers exploring the epigenome?
Visit Epigenomics Now.
#16
Biological Pathways
A biological pathway is a series of actions among molecules in a cell that leads to a certain product or a change in the cell. Such a pathway can trigger the assembly of new molecules, such as a fat or protein. Pathways can also turn genes on and off, or spur a cell to move.
This fact sheet reviews:
- What is a biological pathway?
- How do biological pathways work?
- What are some types of biological pathways?
- What is a biological network?
- How do researchers find biological pathways?
- What can biological pathways tell us about disease?
- How can biological pathway information improve health?
- Why are cancer researchers excited about biological pathways?
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#17
Transcriptome
The human genome is made up of DNA (deoxyribonucleic acid), a long, winding molecule that contains the instructions needed to build and maintain cells. These instructions are spelled out in the form of "base pairs" of four different chemicals, organized into 20,000 to 25,000 genes.
For the instructions to be carried out, DNA must be "read" and transcribed - in other words, copied - into RNA (ribonucleic acid). These gene readouts are called transcripts, and a transcriptome is a collection of all the gene readouts present in a cell.
This fact sheet reviews:
- What is a transcriptome?
- What can a transcriptome tell us?
- How can transcriptome data be used to explore gene function?
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#18
Genetic Information Nondiscrimination Act of 2008
The Genetic Information Nondiscrimination Act of 2008, also referred to as GINA, is a federal law that protects Americans from being treated unfairly because of differences in their DNA that may affect their health. The law prevents discrimination from health insurers and employers. The act was signed into federal law on May 21, 2008.
This fact sheet reviews:
- What is genetic discrimination?
- Who needs protection from genetic discrimination?
- What's the Genetic Information Nondiscrimination Act (GINA)?
- Why was the law needed?
- What's included in the law?
- What's not included?
- How does the federal law affect state laws?
- Where can I find more information?
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