Tour of Basic Genetics
Tour of Basic Genetics
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What is Heredity?
Learn how traits pass from parents to offspring.
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What is a Trait?
Explore traits, the characteristics that make us unique.
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What is DNA?
Get to know DNA, the molecule that holds the universal code of life.
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What is a Gene?
Take a look at genes, the instructions for building a body.
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What is a Protein?
Learn how proteins form the foundation for all living things.
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What is a Chromosome?
These vehicles of inheritance pack a lot of information.
Characteristics of Inheritance
How Inheritance Works
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What is Heredity?
Learn how traits pass from parents to offspring.
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What is a Trait?
Explore traits, the characteristics that make us unique.
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What are dominant and recessive?
The terms dominant and recessive describe the inheritance patterns of certain traits.
But what do they really mean?
Visible Inherited Traits
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Observable Human Characteristics
Take a look at several inherited human characteristics and learn more about them. Which variations do you have?
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Traits Activities
Do these fun activities about inherited traits and disease risk with your family or at public gatherings.
Gene Examples In Depth
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PTC: The Genetics of Bitter Taste
An accidental discovery leads to important clues about human evolution.
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Genes and Blood Type
Take a look at the inheritance of the ABO blood typing system and the genes behind it.
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The Time of Our Lives
Learn about the genetic underpinnings of biological clocks.
Genetically Modified Foods
What would you do in the following situations?
Genetic engineering offers a time-saving method for producing larger, higher-quality crops with less effort and expense. Yet such benefits must be balanced against the risks of changing the genetic makeup of organisms.
What are those risks, and how likely are they to occur? In order to define them, we need to understand the science of plant genetic engineering.
- You are a tomato farmer whose crops are threatened by a persistent species of beetle. Each year, you spend large sums of money for pesticides to protect your crops. A biotechnology company introduces a new strain of tomato plant that produces a natural pesticide, making it resistant to the beetle. By switching to this new strain, you could avoid both the beetle and the chemical pesticides traditionally needed to fight it.
- As a family physician, you often treat children who suffer from infectious diseases that could easily be prevented through vaccination. But the parents of many of your patients cannot afford the cost of vaccinations. You hear of a new approach that would reduce the cost to a fraction of its current price: genetically modified fruits and vegetables that contain various vaccines. By simply eating a banana, a child could be protected against disease—without getting a shot!
- You are the leader of a developing nation. Hunger is a problem among your citizens: the salty coastal wetlands of your country can't support the growth of needed crops, and your slow economy can't support importing enough food for everyone. A biotechnology company has genetically modified a rice plant that can thrive in salt water, providing your nation with the opportunity to feed its citizens while bolstering its economy.
Genetic engineering offers a time-saving method for producing larger, higher-quality crops with less effort and expense. Yet such benefits must be balanced against the risks of changing the genetic makeup of organisms.
What are those risks, and how likely are they to occur? In order to define them, we need to understand the science of plant genetic engineering.
Genetically modified: what exactly are we talking about?
For thousands of years, humans have been genetically enhancing other organisms through the practice
of selective breeding. Look around you: the sweet corn and seedless watermelons at the supermarket,
the purebred dogs at the park, and your neighbor's prize rosebush are all examples of how humans have
selectively enhanced desirable traits in other living things.
The type of genetic enhancement that generates the most concern goes a step beyond selective breeding, however. Technology now allows us to transfer genes between organisms. For example, the tomato plant's beetle resistance relies on a gene from a bacterium (Bacillus thuringiensis), which scientists inserted into the tomato plant's genome. This gene, called cry1Ac, encodes a protein that is poisonous to certain types of insects, including the beetle.
How is this done? Gene transfer technology is simply a sophisticated version of a cut-and-paste operation. Once the desired gene is identified in the native organism's genome, it can be cut out, transferred to the target plant, and pasted into its genome. (The illustration to the right describes the "gene-gun" approach, which is one of several gene transfer methods.) Once the new gene has been introduced, the plant can be bred to create a new strain that passes the gene from generation to generation.
The type of genetic enhancement that generates the most concern goes a step beyond selective breeding, however. Technology now allows us to transfer genes between organisms. For example, the tomato plant's beetle resistance relies on a gene from a bacterium (Bacillus thuringiensis), which scientists inserted into the tomato plant's genome. This gene, called cry1Ac, encodes a protein that is poisonous to certain types of insects, including the beetle.
How is this done? Gene transfer technology is simply a sophisticated version of a cut-and-paste operation. Once the desired gene is identified in the native organism's genome, it can be cut out, transferred to the target plant, and pasted into its genome. (The illustration to the right describes the "gene-gun" approach, which is one of several gene transfer methods.) Once the new gene has been introduced, the plant can be bred to create a new strain that passes the gene from generation to generation.
Benefits versus risks of genetically modified plants
Can you think of some possible risks of growing plants that contain genes from other organisms? Let's
examine our earlier examples: the beetle-resistant tomato, the vaccination banana, and the saltwater rice
plant. We've already covered the potential advantages of these plants, but what are the concerns?
Cross-breeding with wild populations. For all of these examples, a primary concern is preventing genetically modified versions from mixing with the naturally existing populations of plants from which they're derived. Plants rely on the transfer of pollen, via insects or the air, to breed and produce offspring, and it's difficult to control how they cross-breed in the wild.
In most cases, it's not yet clear how introduction of the non-native gene would affect wild populations. Critics of genetically modified plant technology cite the need to learn more about the potential long-term impacts of genetically modified plants on the environment before mass-producing them.
Toxicity or allergic reactions. Many people suffer from allergies to various food items, including nuts, wheat, eggs, or dairy products. There is concern that the protein products of introduced genes may be toxic or allergenic to certain individuals.
When farmers start growing genetically modified crops, they stop growing the old varieties. These old varieties are important sources of diverse genes that give plants other desirable characteristics. For example, a new pest or disease could come along and destroy the genetically modified rice. If one of the old rice varieties has a gene that makes it resistant, it could be cross-bred to make the saltwater rice resistant as well. If we lose the old varieties, we also lose their useful genes.
It has been estimated that 70% of all processed foods in the United States contain at least one genetically modified ingredient—usually a product of soy plants. There are initiatives afoot to require food manufacturers to provide clear labeling on processed food products that contain genetically modified ingredients. This would make it easier for people with allergies to avoid foods that might pose a danger to them, and it would allow those who oppose genetically modified foods to opt out of buying them.
Unlike countries such as Australia and Japan, the United States currently has no laws requiring companies to label products containing genetically modified ingredients.
Despite the controversy surrounding them, genetically modified plants have taken root in our world. As with any new technology, members of society have the responsibility to become informed about genetically modified plants, in order to make decisions about their responsible use and regulation.
Cross-breeding with wild populations. For all of these examples, a primary concern is preventing genetically modified versions from mixing with the naturally existing populations of plants from which they're derived. Plants rely on the transfer of pollen, via insects or the air, to breed and produce offspring, and it's difficult to control how they cross-breed in the wild.
In most cases, it's not yet clear how introduction of the non-native gene would affect wild populations. Critics of genetically modified plant technology cite the need to learn more about the potential long-term impacts of genetically modified plants on the environment before mass-producing them.
Toxicity or allergic reactions. Many people suffer from allergies to various food items, including nuts, wheat, eggs, or dairy products. There is concern that the protein products of introduced genes may be toxic or allergenic to certain individuals.
When farmers start growing genetically modified crops, they stop growing the old varieties. These old varieties are important sources of diverse genes that give plants other desirable characteristics. For example, a new pest or disease could come along and destroy the genetically modified rice. If one of the old rice varieties has a gene that makes it resistant, it could be cross-bred to make the saltwater rice resistant as well. If we lose the old varieties, we also lose their useful genes.
It has been estimated that 70% of all processed foods in the United States contain at least one genetically modified ingredient—usually a product of soy plants. There are initiatives afoot to require food manufacturers to provide clear labeling on processed food products that contain genetically modified ingredients. This would make it easier for people with allergies to avoid foods that might pose a danger to them, and it would allow those who oppose genetically modified foods to opt out of buying them.
Unlike countries such as Australia and Japan, the United States currently has no laws requiring companies to label products containing genetically modified ingredients.
Despite the controversy surrounding them, genetically modified plants have taken root in our world. As with any new technology, members of society have the responsibility to become informed about genetically modified plants, in order to make decisions about their responsible use and regulation.
Partially funded by the Educational Resources Development Council, University of Utah.
Destroying or changing habitats can endanger the animals, plants, and other organisms that live there. By effective managing these ecosystems, we can help preserve threatened and endangered species.
The science of Conservation Biology looks at individuals and populations that have been affected by habitat loss, exploitation, and/or environmental change. Information gained from studying these organisms informs decisions that will ensure their survival into the future.
The science of Genetics looks at inherited characteristics and the genes that underlie them.
Put the two together and you get the science of Conservation Genetics
Conservation Genetics
Conservation Biology + Genetics = Conservation GeneticsDestroying or changing habitats can endanger the animals, plants, and other organisms that live there. By effective managing these ecosystems, we can help preserve threatened and endangered species.
The science of Conservation Biology looks at individuals and populations that have been affected by habitat loss, exploitation, and/or environmental change. Information gained from studying these organisms informs decisions that will ensure their survival into the future.
The science of Genetics looks at inherited characteristics and the genes that underlie them.
Put the two together and you get the science of Conservation Genetics
How is Conservation Genetics Done?
Conservation geneticists use DNA data from an organism to inform management choices.
As in any scientific field, conservation scientists use a defined approach to their work:
ray Analysis
The human genome contains approximately 21,000 genes. At any given moment, each of
our cells has some combination of these genes turned on, and others are turned off.
How do scientists figure out which are on and which are off?
Scientists can answer this question for any cell sample or tissue by gene expression profiling, using a technique called microarray (pronounced MY-crow-ah-ray) analysis.
Microarray analysis involves breaking open a cell, isolating its genetic contents, identifying all the genes that are turned on in that particular cell, and generating a list of those genes.
Scientists can answer this question for any cell sample or tissue by gene expression profiling, using a technique called microarray (pronounced MY-crow-ah-ray) analysis.
Microarray analysis involves breaking open a cell, isolating its genetic contents, identifying all the genes that are turned on in that particular cell, and generating a list of those genes.
DNA microarray analysis is a technique that scientists use to determine whether genes are on or off.
Scientists know a gene is on in a cell if its mRNA is present.
Identification, Inventory, and Analysis
- Define populations and areas of interest. Because there are so many species of organisms, endangered or threatened species usually take priority.
- Observe the population. What are the known forms of the species? What are known or suspected relatives of the species? What are the physical characteristics used to classify the different forms and species?
- Form hypotheses about relationships between populations and/or species and test these hypotheses by examining genetic characteristics of the organisms (DNA or protein data).
- Use mathematical models to analyze the data. Determine how much diversity exists in separate populations of the species, as well as the rate at which genes are exchanged among populations (gene flow).
Interpretation and Management
Scientists and managers work together to identify endangered organisms. To begin to develop a management strategy, they investigate the organism's habitat:- Determine the degree to which the organism is adaptable to various temperatures, soils, and water conditions.
- Examine factors that influence genetic diversity, such as the identity and characteristics of plant pollinators. The health and welfare of pollinating species may be critical to the survival of an endangered plant species.
- Study threats to the integrity of the species' habitat, including human, climatic, and other factors.
DNA Extraction
DNA is extracted from human cells for a variety of reasons. With a pure sample of DNA you can test a newborn for a genetic disease, analyze forensic evidence, or study a gene involved in cancer. Try this virtual laboratory to perform a cheek swab and extract DNA from human cells.Try It Yourself!
HOW TO EXTRACT DNA FROM ANYTHING LIVINGNeurons Transport Messages in the Brain
Neurons are the cells that pass chemical and
electrical signals along the pathways in the brain. They come in many
shapes and sizes. Their shapes and connections help them carry out
specialized functions, such as storing memories or controlling muscles.
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