# Presentation: 173849

**Notes:**
National DNA Day commemorates the completion of the Human Genome Project in April 2003 and the description of DNA’s double helix structure in April 1953.

**Notes:**
The stringy stuff in the test tube is DNA that has been extracted from an organism. But you can’t tell which one of these organisms it came from just by looking at it. That’s because DNA looks exactly the same in every organism on Earth.

**Notes:**
DNA contains all of the information necessary to make a complete organism, like the human shown here. DNA is a very useful molecule for storing this information because it is extremely stable - you can’t break it apart easily. It’s also easy to replicate. That is, machinery in the cell can make many copies of it with few mistakes.

**Notes:**
The DNA molecule is organized into segments called genes.

**Notes:**
You may have heard of genes. They contain the information needed to build proteins which do much of the work in our bodies. Each gene codes for a different type of protein. 

Optional: Let’s take a look at how a protein is made. Open the How Proteins Are Made animation on the next slide.

## Click to Play

**Notes:**
This slide contains a hyperlink to a webpage called TranscriptionTranslation.html.  This can be downloaded from the DNA Day resources webpage (www.genome.gov/dnaday)

If this link becomes non-functional:
Click on the above image
Right-click
Select Edit Hyperlink
Navigate to the location of TranscriptionTranslation.html
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**Notes:**
As you just saw in the animation, proteins are responsible for carrying out specific functions. They might be responsible for breaking down the food we eat, making our muscles contract or keeping our skin tight.

**Notes:**
But individual proteins are rarely able to perform their functions by themselves. Proteins work with other proteins to get the job done. Shown here, a protein embedded in the membrane of the cell is interacting with six other proteins.

**Notes:**
Proteins often interact with each other in very complex ways. Proteins may act upon and be acted upon by many other proteins in the cell, or outside the cell. That’s why figuring out the function of a gene’s protein product can be extremely challenging for scientists. They have to figure out where their particular protein fits into these complicated pathways. 

**Notes:**
The genes that code for particular proteins can be turned on and off. When a gene is on, that particular protein is being made in the cell. When a gene is off, the protein it codes for isn’t being produced.

**Notes:**
Every cell in our body contains a copy of the exact same genetic code. This means that each of our cells contain every gene needed to produce every protein. BUT every cell doesn’t produce every protein - they only produce the proteins needed by their particular cell type.

**Notes:**
Our body’s ability to turn genes on and off is what allows us to have many different kinds of cells that do different jobs. For example, a nerve cell has some genes turned on and other genes turned off. And a muscle cell has a different set of active and inactive genes. Point to the different genes that are on and off in each cell type.

## Slide 13

**Notes:**
Optional Slide: Use this slide to describe more details about the structure of DNA, if appropriate for your audience.

**Notes:**
DNA is made up of four building blocks. A, T, C, and G.

Optional: for advanced audiences you may want to explain that these letters stand for adenine, thymine, cytosine and guanine

**Notes:**
The building blocks make up the DNA helix. Let’s take a closer look.

**Notes:**
The building blocks are called nucleotides.

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You might have heard of the “DNA Code” or scientists “sequencing a gene”. This is what they’re talking about. The building blocks that make up DNA are arranged in long strands, called a sequence, that makes up the DNA code. 

**Notes:**
The entire DNA sequence makes up what we call the “human genome”. The genome is the term used for all of the DNA in a cell which includes 3 billion DNA building blocks, or nucleotides. That’s roughly 200 one-thousand page phone books worth of information in each cell!

**Notes:**
Each of us has variations in the DNA sequence of our genome, making us unique individuals. These variations look like this. Point to the nucleotides that vary. This individual has a G in this position of her genome, while this individual has an A in the same place. But you can also see that in most other positions they share the exact same nucleotides. 

Optional: Let’s take a closer look at DNA sequence variations. Open the Making SNPs Make Sense animation on the next slide.

## Click to Play

**Notes:**
This slide contains a hyperlink to a webpage called MakingSNPsMakeSense.html.  This can be downloaded from the DNA Day resources webpage, www.genome.gov/dnaday 

If this link becomes non-functional:
Click on the above image
Right-click
Select Edit Hyperlink
Navigate to the location of MakingSNPsMakeSense.html
Click OK

**Notes:**
Out of our 3 billion nucleotides there is only 1 difference in every one-thousand, making us 99.9% identical to one another. This means that what makes us unique is contained in only 0.1% of our whole genome.

**Notes:**
The nucleotide variations present in genes can result in physical differences in the proteins they produce. Shown here, are two variations of a gene. These variants produce protein products that are folded slightly differently in this region. Point to the circles showing where the proteins differ. This difference in shape could make the protein variants function differently from one another.

**Notes:**
Variations in genes and their protein products can result in differences in physical traits such as the three so-called “single-gene traits” shown here.  It is important to remember that single-gene traits are rare. 

Optional information about these traits: 
Hemophilia - protein clotting factors are shaped improperly and don’t plug holes in blood vessels that are cut. That’s why individuals with hemophilia are unable to stop bleeding.
PKU - caused by a mutation in a gene on chromosome 12. The gene codes for a protein called PAH (phenylalanine hydroxylase), an enzyme in the liver. This enzyme breaks down the amino acid phenylalanine into other products the body needs. When this gene is mutated, the shape of the PAH enzyme changes and it is unable to properly break down phenylalanine. Phenylalanine builds up in the blood and poisons nerve cells (neurons) in the brain.
PTC Gene - It is important to note that not all variations in genes are disease-causing. For example, students in the class may have done the PTC bitter taste test. It is now known that variations in a single gene on chromosome 7 largely determine if you are a taster or non-taster.  Depending on the variant, the person’s receptors will or won’t bind to the PTC molecule.

**Notes:**
Variations in our genes are not the only thing that make us who we are. Environmental effects like how much we exercise, what we eat, who our friends are and exposure to toxins play a big role in shaping our individuality.

**Notes:**
A great way to think about this is to look at identical twins. Identical twins are basically clones. They share exactly the same genetic information. But, if you’ve ever met twins, you know that often they can be very different from each other.
That’s because identical twins experience different environmental conditions that shape who they are and make them unique individuals.

**Notes:**
Complex traits like asthma are influenced by both genes and the environment. For example, there may be genes that make someone more susceptible to asthma or modify the severity of the disease. But environmental factors like smoking and allergens also play a big part in someone’s likelihood of developing asthma.

**Notes:**
Scientists are faced with the daunting challenge of figuring out the roles environment and genetics play in making us who we are. The Human Genome Project has made great advances in giving us the tools to understand the factors that influence complex traits.  Completed in 2003, the Human Genome Project was a 13-year project coordinated by the U.S. Department of Energy and the National Institutes of Health. 

**Notes:**
The goals of the Human Genome Project were to identify all of our genes,  sequence our entire 3 billion nucleotide genome and store all the information in a massive database that is available to the public. 

## Slide 30

**Notes:**
The Human Genome Project was a global effort. Anonymous DNA samples were sent to facilities around the world where researchers mapped, sequenced and analyzed the samples.  The information they collected was sent to a central database, where it serves as an incredible resource for human genetics researchers.

**Notes:**
But work to understand the human genome is only just beginning. For example, the function of over half of our genes is still waiting to be discovered. Genetics research continues in labs around the world.

**Notes:**
With the Human Genome Project complete, researchers are now beginning work to answer larger questions. What makes us similar and what makes us different?  When and how are genes turned on and off? How do genes and the environment interact? 

**Notes:**
Analyzing variation within and between populations and individuals is an important area of research.

Optional information about the HapMap Project: The HapMap is a catalog of common genetic variations that occur in human beings. It describes what these variants are, where they occur in our DNA, and how they are distributed among populations in different parts of the world. Using the information in the HapMap, researchers will be able to find genes that affect health and disease as well as individual responses to medications and environmental factors. 

**Notes:**
Roughly, only 2% of the human genome codes for proteins.Equally important however, are other DNA sequences that control when genes are turned on and off and those that are important in chromosome structure. The ENCODE project (which stands for the ENCyclopedia Of DNA Elements) is working to identify all functional elements like these in the human genome sequence.

**Notes:**
Understanding the timing involved in genes being turned on and off is another hot area of research. Microarray and protein expression technologies have revolutionized our ability to detect when genes are active and inactive in a cell.

**Notes:**
Optional Slide: Taking a more in-depth look at a microarray.

**Notes:**
Optional Slide: Taking a more in-depth look at how microarrays are analyzed.

**Notes:**
Optional Slide: Taking a more in-depth look at how protein expression profiling works.

**Notes:**
Another area of important research is understanding how DNA, proteins and the environment interact. This is a challenge for scientists because the interactions are complex and difficult to quantify. However, major strides are being made in areas such as the genetics of addiction and mental illness.

**Notes:**
Optional Slide: Scientists are busily sequencing the genomes of animals as well. They select which genomes to sequence based on many factors. Take dogs for example. Dogs share many diseases with humans, live in the same environments as people, come in wildly diverse breeds and often have well-documented pedigrees. Different dog breeds are being sequenced such as the poodle and the boxer. If you are a researcher who works with a particular model organism you may wish to talk about what makes your organism unique and interesting to study. If a photo of your organism isn’t shown on this slide, use the blank slide template to add a photo(s).

**Notes:**
Sequencing the DNA of other organisms can help us understand how the genes in humans work because we often share many of the same genes. For example, mice and humans share most of their genes. Only around 300 genes are unique for each species.

The images on this slide depict Piebald Syndrome in which mice and humans have the same white patch on their stomach and forehead resulting from a mutation in the same gene.

**Notes:**
The future looks bright for genetics. Many advances are on the horizon. Personalized medicine, genetic susceptibility to disease, and gene therapy are already areas of research today that will become applications tomorrow.

**Notes:**
People vary in their response to a prescribed medication, both with respect to how well it works and to adverse side effects.

**Notes:**
Scientists, physicians and the pharmaceutical industry are actively developing ways to customize medical treatments to suit our unique genetic signatures. This emerging science is called personalized medicine.

**Notes:**
A similar area of research is understanding how people differ in their susceptibility to certain diseases. Researchers are developing genetic tests that can predict a person’s risk of developing some common diseases such as heart disease or asthma for example. In the future, a doctor might prescribe a drug developed to prevent the onset of a disease and recommend lifestyle changes the at-risk individual should make.

**Notes:**
Gene therapy also holds great promise for fixing genetic defects at the molecular level. Using viruses or other means to carry DNA, researchers are working to develop methods for adding a normally-functioning copy of a gene to cells where an abnormally functioning copy is expressed.

## Slide 48

**Notes:**
Optional Slide: This set of slides contains optional material for those who wish to address ethical issues in genetics research.

## Slide 49

**Notes:**
Optional Slide: Before we start talking about ethical issues, it is important to note that, because environment and genetics work together to make us who we are, we will never be able to create so-called “designer babies”. Read quote.

## Slide 50

**Notes:**
Optional Slide: Consider opening the floor to discussion using the Seeds for Thought on the following slides.  

## Slide 51

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Optional Slide

## Slide 52

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Optional Slide

## Slide 53

**Notes:**
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## Slide 54

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