Deoxyribonucleic acid is a molecule composed of two polynucleotide chains that coil around each other to form a double helix carrying genetic instructions for the development, functioning, growth and reproduction of all known organisms and many viruses. DNA and ribonucleic acid (RNA) are nucleic acids. Alongside proteins, lipids and complex carbohydrates (polysaccharides), nucleic acids are one of the four major types of macromolecules that are essential for all known forms of life.
The two DNA strands are known as polynucleotides as they are composed of simpler monomeric units called nucleotides.Each nucleotide is composed of one of four nitrogen-containing nucleobases (cytosine [C], guanine [G], adenine [A] or thymine [T]), a sugar called deoxyribose, and a phosphate group. The nucleotides are joined to one another in a chain by covalent bonds (known as the phospho-diester linkage) between the sugar of one nucleotide and the phosphate of the next, resulting in an alternating sugar-phosphate backbone. The nitrogenous bases of the two separate polynucleotide strands are bound together, according to base pairing rules (A with T and C with G), with hydrogen bonds to make double-stranded DNA. The complementary nitrogenous bases are divided into two groups, pyrimidines and purines. In DNA, the pyrimidines are thymine and cytosine; the purines are adenine and guanine.
Why is DNA so important? Put simply, DNA contains the instructions necessary for life.
The code within our DNA provides directions on how to make proteins that are vital for our growth, development, and overall health.
About DNA
DNA stands for deoxyribonucleic acid. It’s made up of units of biological building blocks called nucleotides. DNA is a vitally important molecule for not only humans, but for most other organisms as well. DNA contains our hereditary material and our genes — it’s what makes us uniqu. But what does DNA actually do? Keep reading to discover more about the structure of DNA, what it does, and why it’s so important.
DNA in health, disease, and aging
Your expansive genome
The complete set of your DNA is called your genome. It contains 3 billion bases, 20,000 genes, and 23 pairs of chromosomes!
You inherit half of your DNA from your father and half from your mother. This DNA comes from the sperm and egg, respectively.
Genes actually make up very little of your genome — only 1 percent. The other 99 percent helps to regulate things like when, how, and in what quantity proteins are produced.
Scientists are still learning more and more about this “non-coding” DNA.
DNA damage and mutations
The DNA code is prone to damage. In fact, it’s estimated that tens of thousands of DNA damage events occur every day in each of our cells. Damage can occur due to things like errors in DNA replication, free radicals, and exposure to UV radiation.
But never fear! Your cells have specialized proteins that are able to detect and repair many cases of DNA damage. In fact, there are at least fiveTrusted Source major DNA repair pathways.
Mutations are changes in the DNA sequence. They can sometimes be bad. This is because a change in the DNA code can have a downstream impact on the way a protein is made.
If the protein doesn’t work properly, disease can result. Some examples of diseases that occur due to mutations in a single gene include cystic fibrosis and sickle cell anemia.
Mutations can also lead to the development of cancer. For example, if genes coding for proteins involved in cellular growth are mutated, cells may grow and divide out of control. Some cancer-causing mutations can be inherited while others can be acquired through exposure to carcinogens like UV radiation, chemicals, or cigarette smoke.
But not all mutations are bad. We’re acquiring them all of the time. Some are harmless while others contribute to our diversity as a species.
Changes that occur in more than 1 percent of the population are called polymorphisms. Examples of some polymorphisms are hair and eye color.
DNA and aging
It’s believed that unrepaired DNA damage can accumulate as we age, helping to drive the aging process. What factors can influence this?
Something that may play a large role in the DNA damage associated with aging is damage due to free radicals. However, this one mechanism of damage may not be sufficient to explain the aging process. Several factors may also be involved.
One theory as to why DNA damage accumulates as we age is based in evolution. It’s thought that DNA damage is repaired more faithfully when we’re of reproductive age and having children. After we’ve passed our peak reproductive years, the repair process naturally declines.
Another part of DNA that may be involved in aging are telomeres. Telomeres are stretches of repetitive DNA sequences that are found at the ends of your chromosomes. They help to protect DNA from damage, but they also shorten with each round of DNA replication.
Telomere shortening has been associated with the aging process. It’s also been found that some lifestyle factors such as obesity, exposure to cigarette smoke, and psychological stress can contributeto telomere shortening.
Perhaps making healthy lifestyle choices like maintaining a healthy weight, managing stress, and not smoking can slow telomere shortening? This question continues to be of great interest to researchers.
What is DNA made of?
The DNA molecule is made up of nucleotides. Each nucleotide contains three different components — a sugar, a phosphate group, and a nitrogen base.
The sugar in DNA is called 2’-deoxyribose. These sugar molecules alternate with the phosphate groups, making up the “backbone” of the DNA strand.
Each sugar in a nucleotide has a nitrogen base attached to it. There are four different types of nitrogen bases found in DNA. They include:
- adenine (A)
- cytosine (C)
- guanine (G)
- thymine (T)
What does DNA do?
DNA helps your body grow
DNA contains the instructions that are necessary for an organism — you, a bird, or a plant for example — to grow, develop, and reproduce. These instructions are stored within the sequence of nucleotide base pairs.
Your cells read this code three bases at a time in order to generate proteins that are essential for growth and survival. The DNA sequence that houses the information to make a protein is called a gene.
Each group of three bases corresponds to specific amino acids, which are the building blocks of proteins. For example, the base pairs T-G-G specify the amino acid tryptophan while the base pairs G-G-C specify the amino acid glycine.
Some combinations, like T-A-A, T-A-G, and T-G-A, also indicate the end of a protein sequence. This tells the cell not to add any more amino acids to the protein.
Proteins are made up of different combinations of amino acids. When placed together in the correct order, each protein has a unique structure and function within your body.
How do you get from the DNA code to a protein?
So far, we’ve learned that DNA contains a code that gives the cell information on how to make proteins. But what happens in between? Simply put, this occurs via a two-step process:
First, the two DNA strands split apart. Then, special proteins within the nucleus read the base pairs on a DNA strand to create an intermediate messenger molecule.
This process is called transcription and the molecule created is called messenger RNA (mRNA). mRNA is another type of nucleic acid and it does exactly what its name implies. It travels outside of the nucleus, serving as a message to the cellular machinery that builds proteins.
In the second step, specialized components of the cell read the mRNA’s message three base pairs at a time and work to assemble a protein, amino acid by amino acid. This process is called translation.
Where is DNA found?
The answer to this question can depend on the type of organism that you’re talking about. There are two types of cell — eukaryotic and prokaryotic.
For people, there’s DNA in each of our cells.
Eukaryotic cells
Humans and many other organisms have eukaryotic cells. This means that their cells have a membrane-bound nucleus and several other membrane-bound structures called organelles.
In a eukaryotic cell, DNA is within the nucleus. A small amount of DNA is also found in organelles called mitochondria, which are the powerhouses of the cell.
Because there’s a limited amount of space within the nucleus, the DNA must be tightly packaged. There are several different stages of packaging, however the final products are the structures that we call chromosomes.
Prokaryotic cells
Organisms like bacteria are prokaryotic cells. These cells don’t have a nucleus or organelles. In prokaryotic cells, DNA is found tightly coiled in the middle of the cell.
What happens when your cells divide?
The cells of your body divide as a normal part of growth and development. When this happens, each new cell must have a complete copy of DNA.
In order to achieve this, your DNA must undergo a process called replication. When this occurs, the two DNA strands split apart. Then, specialized cellular proteins use each strand as a template to make a new DNA strand.
When replication is completed, there are two double-stranded DNA molecules. One set will go into each new cell when division is complete.
Takeaway
DNA is pivotal to our growth, reproduction, and health. It contains the instructions necessary for your cells to produce proteins that affect many different processes and functions in your body.
Because DNA is so important, damage or mutations can sometimes contribute to the development of disease. However, it’s also important to remember that mutations can be beneficial and contribute to our diversity as well.
DNA Test Kits: Find the Right One for You
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According to MIT Technology Review, the number of customers who purchased DNA testing kits exceeded 12 million in 2017. In fact, market research has estimated that the market for genetic health testing could nearly triple — from $99 million in 2017 to $310 million in 2022.
Considering that most DNA kits require a saliva sample to perform an analysis, that’s a whole lot of drool.
Though these kits offer fun facts like whether or not you originate from Neanderthals, they can also include information that offers emotional solace or impacts future choices. Adopted individuals may locate long lost biological relatives, while others might discover if they’re lactose intolerant.
Some might even find they have a genetic variant associated with an increased risk of developing certain health conditions, which can initiate a diet or lifestyle change, or a visit to a doctor.
Yet with all the potential benefits of DNA testing, many consumers are wary of issues surrounding privacy and the security of their personal information. It begs the question: What are these companies doing with personal data that’s arguably more intimate than your social security number?
Genetic information may get shared with or sold to third parties — like drug or insurance companies — for research or business purposes. In this case, it’s easy to see how your genes — the very building blocks of who you are — can suddenly no longer belong to just you.
If you’re considering investing in a DNA test kit, we’ve provided you with the lowdown on six different tests, from price points to privacy policies.
After you purchase a 23andMe kit, the company will mail it to you with instructions for collecting a saliva sample at home. Once the sample is received by a lab, you’ll get your online results in six to eight weeks.
The ancestry kit gives you a breakdown of your global heritage across 150+ regions by percentages (for example, you may be 28.2 percent Eastern European). It also shows your maternal and paternal lineage. You then have the option to connect with others who have your DNA, in order to share and compare genetic similarities and differences.
Meanwhile, the health + ancestry kit includes the aforementioned features, plus information on what your DNA says about your health, traits, and physical features. For example, you can find out how your genetics influence your:
- risk for certain diseases
- sleep
- muscle type
- eye color
23andMe analyzes DNA in the saliva sample using a process called “genotyping.” The lab processes the DNA on a chip that reads hundreds of thousands of variants in your genome. Your personalized report is based on these variants.
QUICK GENETIC REFRESHHuman DNA is about 99.9 percent identical from person to person, but small variants make each person unique. Variants can be associated with heritage, health, and physical traits.
In terms of privacy, 23andMe collects and stores your genetic information. However, the company says it’s only identifiable through a barcode — not your name, credit card info, or email address. This reduces the chance of it being connected to you.
While genetic information isn’t shared or sold on an individual-level unless you consent — by completing an online form or checking a box — 23andme does do this on an aggregate-level for business, marketing, and research purposes. (Pfizer and Genentech are two of 23andMe’s business partners, for example.) In these cases, the data is stripped of all personal details.
For those who are particularly concerned about their genetic information being stored and shared, users can request that 23andMe delete their account and discard their genetic sample at any time. But things may get tricky if your information has already been used for research purposes or shared with a third party. In these cases, it may be too late or your request becomes dependent on the third party’s privacy policy. No matter what DNA test kit you choose, keep this in mind.
Carefully reading privacy policies and terms and conditions is always a good idea.
Helix
- Cost: $80 for initial DNA test kit; $19.99 and up for accompanying products
- Where to buy: Amazon
While Helixoffers a DNA test kit, it’s more of a marketplace to discover how DNA can influence purchases related to everything from health to fashion. Here’s an example: Did you know you can apparently find the perfect wine based on your genetic taste profile?
Customers can purchase the Wine Explorer product in the Helix marketplace along with the Helix DNA test kit. First, you receive the DNA test kit in the mail and provide a saliva sample for analysis — this is a one-time process. Helix then shares only the relevant genetic data with Vinome, the partner who sells Wine Explorer on Helix’s website. Vinome creates and emails you a customized report with your genetic taste results and wine recommendations.
You can continue shopping for a wide variety of products from other Helix partners, like a food sensitivity test or even socks with your DNA sequence printed on them, using your Helix DNA test kit findings.
It takes Helix between four to eight weeks to analyze 22,000 genes using a process known as sequencing. While genotyping looks at single genetic variants, sequencing views the entire genetic sequence. If genotyping is only reading the headlines, sequencing is reading the whole article. Thus, sequencing can give you more information.
Once Helix sequences and analyzes your DNA, it sends only the necessary data to the partner whose product you ordered. Your results are ready two to five days after this.
Helix stores all users’ DNA from the test kit. When you purchase a partner product, you allow Helix to share some of your genetic information with the partner (like your taste profile for Wine Explorer). Each partner has different privacy policies regarding how they then use your genetic information. You can request that Helix destroys your stored saliva sample and DNA by contacting their team. If this information has been shared with a partner company, however, this request is dependent upon their individual privacy policy.
EverlyWell
Everly Well offers three different Genomics tests. The first is the Food Sensitivity+ kit, which helps you discover your body’s food sensitivities and the impact your DNA has on your ability to digest certain foods — from coffee and coconut, to scallops and peanuts. The Metabolism+ test, helps you discover the relationship between your DNA, hormone levels, and weight. The DHA+ kit reveals how DNA influences the amount of DHA — a key nutrient for infant development — in breast milk.
Gaining access to the information offered through these tests can ultimately help you make more informed choices about everything from diet and exercise to breastfeeding decisions.
Each EverlyWell test kit is sold through Helix. In other words, EverlyWell is a Helix partner company. In order to get your results, a Helix DNA test kit must be purchased and taken along with an EverlyWell test kit.
Each EverlyWell test kit contains a biomarker test: Food Sensitivity+ requires a blood test to measure inflammation, Breast Milk DHA+ asks for a breast milk sample to examine DHA levels, and Metabolism+ examines cortisol, testosterone, and TSH levels via a blood sample. Like the Helix DNA test kit, all can be done from home.
Once the saliva sample from the Helix DNA test kit and the biomarker sample from the EverlyWell kits are analyzed (this takes between four to eight weeks), Helix sends relevant DNA information to EverlyWell. After a few days, EverlyWell notifies you via email that your personalized report — rooted in both the genetic and biomarker data — is ready.
Like we mentioned earlier, each company Helix partners with has unique privacy policies. EverlyWell’s privacy policy explains that they collect and store personal information, including name, gender, and email address, as well as your health information, like genetic and biomarker data. EverlyWell can disclose this information to third parties, like their affiliates and business partners, only if it’s de-identified and on an aggregate-level.
AncestryDNA
The AncestryDNA kit combines DNA testing with online family history resources to determine your genetic ethnicity across 350 regions. It also helps you locate biological relatives by matching your DNA to theirs, assuming they’ve also used the product.
The test answers questions like: What part of Asia are my ancestors from? Do I have Native American heritage? Am I related to a famous historical figure?
Like the process used by other DNA test kits, AncestryDNA does this by analyzing a sample of your saliva. It takes six to eight weeks to generate your results.
AncestryDNA uses a process called microarray-based autosomal DNA testing, which examines your entire genome at over 700,000 locations. Armed with this intel, you can then search for family connections using AncestryDNA’s database of over 10 million users and their results. Customers also have access to Ancestry, the company’s online family history resource that includes genealogy resources like a historical person search, millions of family trees, and over 20 billion historical records — census reports, obituaries, and more — to facilitate research.
You can choose whether or not you’d like your genetic ancestry information to be public for other users to find — it’s up to you if you want unknown relatives to be able to locate and contact you.
Ancestry does collect and store your DNA results, though your DNA sample isn’t stored with any identifying information attached to it, and AncestryDNA doesn’t share any individual genetic information with third parties, like insurance or pharmaceutical companies — without your explicit consent. The same goes for research purposes, though they do disclose user information in an aggregated form for research.
While you can request that AncestryDNA destroy your biological samples, if you have agreed to participate in research, they can’t remove your information from active research projects. That said, they won’t use it for future ones.
MyHeritage DNA is a test kit that reveals the ethnic groups and geographic areas you originate from, based on 42 regions. The test kit requires a cheek swab — no spit or blood — to analyze your DNA, which can be collected from home.
Once received by a certified lab, scientists first extract your DNA from the cheek swab sample. Then, they transform this biological information into digital data. Similar to 23andMe, MyHeritage DNA uses a chip to analyze your genome and identify variants. This enables the company to determine what they call your “ethnicity estimate,” which breaks down your geographic heritage by percentage.
It takes three to four weeks to view your results online. In addition to discovering your ethnic origins, this test also compares your DNA to others to help you find relatives and ancestors — but only if they’ve used the product and have requested their information be discoverable. You have this option with your data, too, and can make your information as private or as public as you wish.
MyHeritage has tools to help you build family trees and conduct additional research using birth, marriage, and death records, as well as newspapers. You can even hire a researcher.
MyHeritage DNA stores users’ genetic data, but says these details are secured and protected through multiple layers of encryption. This means there’s no personal information attached to the data. If you consent to allowing MyHeritage to use your genetic information, the data is only used for research purposes and shared on an aggregate — not individual — level.
Living DNA
Living DNA uses a cheek swab sample to uncover your heritage and ethnicity. It takes 10 to 12 weeks to process and customize your results using the DNA sequencing process. With your results, you can see a breakdown of your ancestry across 80 regions (if you have British or Irish heritage, you can see where you originated from within each country), as well as your maternal and paternal lineages.
In addition to being available online, Living DNA gives users the option to have their results printed into a personalized coffee table book and sent to them.
Let’s talk security and privacy: Living DNA says it securely stores and encrypts users’ genetic information using barcodes rather than personal information to identify samples. Living DNA doesn’t use genetic data for any purpose without your consent (other than what’s needed for the test).
Living DNA does not sell your personal information. The company does, however, share your information with genetic experts who work to improve the product. But each of these third parties are required to protect your information and only use it when providing services to Living DNA. If you wish to close your account and discard your DNA sample, Living DNA will comply.
DNA Methylation: Can Your Diet Reduce Your Risk of Disease?
What is DNA methylation?
DNA methylation is an example of one of the many mechanisms of epigenetics. Epigenetics refers to inheritable changes in your DNA that don’t change the actual DNA sequence. That means these changes are potentially reversible.
Your DNA consists of four bases, called cytosine, guanine, adenine, and thymine. A chemical unit called a methyl group, which contains one carbon and three hydrogen atoms, can be added to cytosine. When this happens, that area of the DNA is methylated. When you lose that methyl group, the area becomes demethylated.
DNA methylation often inhibits the expression of certain genes. For example, the methylation process might stop a tumor-causing gene from “turning on,” preventing cancer.
Experts are currently working to better understand the factors that affect DNA methylation. Based on their early findings, there’s some evidence that diet plays a role. This opens up the potential to reduce genetic risk of developing certain conditions, such as breast cancer or heart disease, through simple lifestyle changes.
Read on to learn more about DNA methylation, including how to support you own methylation cycle through your diet.
What does the research say?
Research looking at the extent to which DNA methylation affects gene expression is ongoing. Most of these studies have involved animal models or cell samples. However, a few initial studies involving humans have promising results.
DNA methylation status throughout life
The patterns of DNA methylation change throughout your life. The process occurs the most during the stages of early development and later life.
A 2015 found that DNA methylation patterns are constantly changing during fetal development. This allows all of the body’s organs and tissue to form properly.
A 2012 further broke down the relationship between DNA methylation and age. People over the age of 100 had less methylated DNA than newborns. People around the age of 26 had methylated DNA levels between those of newborns and centenarians, suggesting that DNA methylation slows down as you age. As a result, genes that were once repressed by methylated DNA start to become active, possible resulting in a variety of diseases.
DNA methylation and diet
The process DNA methylation partly relies on several nutrients.
For example, a 2014 study looked at DNA methylation of tumor cells in women with breast cancer. The study’s investigators found that participants who consumed more alcohol were more likely to have decreased DNA methylation. In contrast, those who consumed a lot of folate were more likely to have increased methylation. These results support the idea that consuming certain nutrients affects DNA methylation.
Some other nutrients that may influence DNA methylation include:
- folate
- vitamin B-12
- vitamin B-6
- choline
- methionine
- polyphenols
- genistein, which is found in soy
How can I learn about my own methylation cycle?
Experts use several methods to analyze DNA methylation, depending on the type of information they’re looking for. However, a 2016 reviewTof all the potential methods suggests that next-generation sequencing will likely become the standard method in the future. This method is generally more affordable and requires less complex equipment.
Some clinics do offer DNA methylation profile testing. The results of these tests are difficult to interpret, especially in a way that would be meaningful to you. In addition, several online retailers offer kits you can use to collect a sample of your own DNA to send off for analysis. However, they still won’t be able to tell you much about your own methylation cycle.
In the future, analyzing your own DNA methylation profile might be a routine method for preventing certain diseases. But experts still need to figure out how to effectively interpret the results of these tests in a way that’s useful to the general public.
Is there anything I can do to support my methylation cycle?
While the relationship between diet and DNA methylation needs more exploration, nutrition does seem to play a role. Most of the existing research suggests that DNA methylation relies at least in part on folate, vitamin B-12, vitamin B-6, and choline, in addition to other vitamins and minerals.
Increasing your intake of these nutrients may help to support DNA methylation, preventing certain genes from being expressed. While all of these are available as dietary supplements, it’s best to get as much of them from food as possible.
In some, the gene that codes for methylation of folate, known as the MTHFR gene, may be compromised or have a mutation that prevents the vitamin from being properly used by the body. This is referred to as a “polymorphism” and can result in a variety of symptoms and diseases. An example is elevated levels of homocysteine (a type of amino acid), which can cause damage to arteries. Those who have this polymorphism may find it beneficial to take a supplement of L-methyfolate, the pre-methylated form of folate.
Folate
The National Institutes of Health (NIH)recommends that adults consume 400 micrograms (mcg) of folate per day. Women who are pregnant or nursing should consume closer to 600 mcg.
Good sources of folate include:
- dark, leafy vegetables, such as spinach or mustard greens
- asparagus
- Brussels sprouts
- nuts and beans, such as peanuts and kidney beans
- whole grains
- citrus fruit, such as oranges or grapefruit
Vitamin B-12
The recommendeddaily intake of vitamin B-12 for adults is 2.4 mcg. Food sources containing vitamin B-12 tend to be animal products, so if you follow a vegetarian or vegan diet, make sure to pay attention to your vitamin B-12 intake.
Food sources of vitamin B-12 include:
- meat, particularly beef liver
- fish or shellfish, particularly clams
- chicken
- eggs
- dairy products, such as milk
- fortified cereals
- nutritional yeast
Vitamin B-6
The NIH recommends that adults between the ages of 19 and 50 consume 1.3 milligrams (mg) of vitamin B-6 per day, while older adults should get slightly more.
Food sources of vitamin B-6 include:
- fish
- poultry, such as chicken, turkey, or duck
- organ meats, such as liver, kidney, or tongue
- starchy vegetables, such as potatoes
- non-citrus fruits, such as bananas
Choline
The recommended daily dose of choline differs between adult men and women. Women should aim for 425 mg, while men should get 550 mg.
Foods that contain choline include:
- meat, especially beef and beef liver
- fish, such as salmon, scallops, and cod
- dairy products, including milk and cottage cheese
- wheat germ
- eggs
- cruciferous vegetables, such as broccoli and cauliflower
DNA methylation is a complex process that could hold major clues to health and aging, but many more large-scale human studies are needed to fully understand its effects.
To improve DNA methylation, you can start by adding a few key nutrients, such as folate, B vitamins, and choline, to your diet. Across several studies, these vitamins and nutrients appear to play a role in DNA methylation. As well, they’ll also improve your overall health.