100 Facts About DNA

100 Facts About DNA

by Dr. Hsien-Hsien Lei
Posted August 20, 2007 in DNA Fun, DNA in General

scientist 1I’m on vacation this week but that doesn’t mean Eye on DNA is going to be silent. I’ve prepared posts in advance and figured this list of 100 facts about DNA should keep you busy! It’s not particularly well-organized since I created using stream of consciousness. Ommm.

  1. DNA stands for deoxyribonucleic acid.
  2. DNA is part of our definition of a living organism.
  3. DNA is found in all living things.
  4. DNA was first isolated in 1869 by Friedrich Miescher.
  5. James Watson and Francis Crick figured out the structure of DNA.
  6. DNA is a double helix.
  7. The structure of DNA can be likened to a twisted ladder.
  8. The rungs of the ladder are made up of “bases”
  9. Adenine (A) is a base.
  10. Thymine (T) is a base.
  11. Cytosine (C) is a base
  12. Guanine (G) is a base.
  13. A always pairs with T in DNA.
  14. C also pairs with G in DNA.
  15. The amount of A is equal to the amoun tof T, same for C and G.
  16. A+C = T+G
  17. Hydrogen bonds hold the bases together.
  18. The sides of the DNA ladder is made of sugars and phosphate atoms.
  19. Bases attached to a sugar; this complex is called a nucleoside.
  20. Sugar + phosphate + base = nucleotide.
  21. The DNA ladder usually twists to the right.
  22. There are many conformations of DNA: A-DNA, B-DNA, and Z-DNA are the only ones found in nature.
  23. Almost all the cells in our body have DNA with the exception of red blood cells.
  24. DNA is the “blueprint” of life.
  25. Chromosomal or nuclear DNA is DNA found in the nucleus of cells.
  26. Humans have 46 chromosomes.
  27. Autosomal DNA is part of chromosomal DNA but does not include the two sex chromsomes – X and Y.
  28. One chromosome can have as little as 50 million base pairs or as much as 250 million base pairs.
  29. Mitochondrial DNA (mtDNA) is found in the mitochondria.
  30. mtDNA is only passed from the mother to the child because only eggs have mitochondria, not sperm.
  31. There’s a copy of our entire DNA sequence in every cell of our body with one exception.
  32. Our entire DNA sequence is called a genome.
  33. There’s an estimated 3 billion DNA bases in our genome.
  34. One million bases (called a megabase and abbreviated Mb) of DNA sequence data is roughly equivalent to 1 megabyte of computer data storage space.
  35. Our entire DNA sequence would fill 200 1,000-page New York City telephone directories.
  36. A complete 3 billion base genome would take 3 gigabytes of storage space.
  37. If unwound and tied together, the strands of DNA in one cell would stretch almost six feet but would be only 50 trillionths of an inch wide.
  38. In humans, the DNA molecule in a non-sex cell would have a total length of 1.7 metres.
  39. If you unwrap all the DNA you have in all your cells, you could reach the moon 6000 times!
  40. Our sex cells–eggs and sperm–have only half of our total DNA.
  41. Over 99% of our DNA sequence is the same as other humans’.
  42. DNA can self-replicate using cellular machinery made of proteins.
  43. Genes are made of DNA.
  44. Genes are pieces of DNA passed from parent to offspring that contain hereditary information.
  45. The average gene is 10,000 to 15,000 bases long.
  46. The segment of DNA designated a gene is made up of exons and introns.
  47. Exons have the code for making proteins.
  48. Introns are intervening sequences sometimes called “junk DNA.”
  49. Junk DNA’s function or lack thereof is a source of debate.
  50. Part of “junk DNA” help to regulate the genomic activity.
  51. There are an estimated 20,000 to 25,000 genes in our genome.
  52. In 2000, a rough draft of the human genome (complete DNA sequence) was completed.
  53. In 2003, the final draft of the human genome was completed.
  54. The human genome sequence generated by the private genomics company Celera was based on DNA samples collected from five donors who identified themselves only by race and sex.
  55. If all the DNA in your body was put end to end, it would reach to the sun and back over 600 times (100 trillion times six feet divided by 92 million miles).
  56. It would take a person typing 60 words per minute, eight hours a day, around 50 years to type the human genome.
  57. scientist 09If all three billion letters in the human genome were stacked one millimeter apart, they would reach a height 7,000 times the height of the Empire State Building.
  58. DNA is translated via cellular mechanisms into proteins.
  59. DNA in sets of 3 bases, called a codon, code for amino acids, the building blocks of protein.
  60. Changes in the DNA sequence are called mutations.
  61. Many thing can cause mutations, including UV irradiation from the sun, chemicals like drugs, etc.
  62. Mutations can be changes in just one DNA base.
  63. Mutations can involve more than one DNA base.
  64. Mutations can involve entire segments of chromosomes.
  65. Single nucleotide polymorpshisms (SNPs) are single base changes in DNA.
  66. Short tandem repeats (STRs) are short sequences of DNA repeated consecutively.
  67. Some parts of the DNA sequence do not make proteins.
  68. Genes make up only about 2-3% of our genome.
  69. DNA is affected by the environment; environmental factors can turn genes on and off.
  70. There are many ways you can analyze your DNA using commercially available tests.
  71. Paternity tests compare segments of DNA between the potential father and child.
  72. There are other types of relationship testing that compares DNA between siblings, grandparents and grandchild, etc.
  73. DNA tests can help you understand your risk of disease.
  74. A DNA mutation or variation may be associated with a higher risk of a number of diseases, including breast cancer.
  75. DNA tests can help you understand your family history aka genetic genealogy.
  76. DNA tests can help you understand your ethnic make-up.
  77. DNA can be extracted from many different types of samples: blood, cheek cells, urine.
  78. DNA can be stored either as cells on a cotton swab, buccal brush, or frozen blood or in extracted form.
  79. In forensics, DNA analysis usually looks at 13 specific DNA markers (segments of DNA).
  80. The odds that two individuals will have the same 13-loci DNA profile is about one in one billion.
  81. A DNA fingerprint is a set of DNA markers that is unique for each individual except identical twins.
  82. Identical twins share 100% of their genes.
  83. Siblings share 50% of their genes.
  84. A parent and child share 50% of their genes.
  85. You can extract DNA at home from fruit and even your own cheek cells.
  86. DNA is used to determine the pedigree for livestock or pets.
  87. DNA is used in wildlife forensics to identify endangered species and people who hunt them (poachers).
  88. DNA is used in identify victims of accidents or crime.
  89. DNA is used to exonerate innocent people who’ve been wrongly convicted.
  90. Many countries, including the US and UK, maintain a DNA database of convicted criminals.
  91. The CODIS databank (COmbined DNA Index System) is maintained by the BI and has DNA profiles of convicted criminals.
  92. Polymerase chain reaction (PCR) is used to amplify a sample of DNA so that there are more copies to analyze.
  93. We eat DNA every day.
  94. DNA testing is used to authenticate food like caviar and fine wine.
  95. DNA is used to determine the purity of crops.
  96. Genetically modified crops have DNA from another organism inserted to give the crops properties like pest resistance.
  97. Dolly the cloned sheep had the same nuclear DNA as its donor mom but its mitochondrial DNA came from from the egg mom. (Does that make any sense?)
  98. People like to talk about DNA even if it bears no relation to science or reality.
  99. A group of bloggers who write regularly about DNA and genetics have banded to gether to form The DNA Network.
  100. Lists about DNA can get a little boring.

What do you think I left off the list?

Human Molecular Genetics 2
DNA From The Beginning from Cold Spring Harbor
Human Genome Project
NOVA Cracking the Code of Life
Yahoo! Encyclopedia
Molecular Biology Notebook

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Comment by Berci Meskó

What a list! :)

Just some minor suggestions/questions:

No. 23: Red blood cells do lack DNA. (As mentioned in No. 31)

No. 30: It has been reported that mitochondria can occasionally be inherited from the father… (http://tinyurl.com/22qmoa)

I love this list, especially the last item. :)

Comment by David Bradley

101 – My Dad knows what DNA stands for

Comment by emily boynton

your mom knows what DNA is!!!!!!!!!!!

Comment by Shelby


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Comment by NA

No. 21 is different then what I was taught. Thank you for the correct definition!!!! I was taught wrong (professors can be wrong just like anyone else). I was taught a nucleotide was A,G,C, or T and didn’t include the sugars and phosphate. So I searched the web and it turns out that the sugar and phosphate is included in the definition of a nucleotide.

I agree with the first respondent that mitochondria has been shown to be passed on from the father in some cases. Again, my genetics professor was wrong again (I just love it when a professor brain washes students in the idea that this and that can’t occur and then you read in the news a year or two later that it can occur, lol).


[...] 100 Facts About DNA (Eye on DNA): A great post from Hsien. What would happen if she wouldn’t be on vacation? [...]

Comment by Ruth

yikes, i didn’t know about #16!


[...] list was found on Eye on DNA by Dr. Hsien-Hsien Lei.   Check out the website for more DNA info. No [...]


[...] Maybe there weren’t more microbiology submissions this time around because microbiologists like to take long summer vacations. When I go on vacation, it’s long walks in a place far away from computers, but Eye on DNA goes on vacation by listing 100 Facts About DNA. [...]

Comment by home boy conner Subscribed to comments via email

to many christ who would read all those

Comment by Hsien


To many, Christ who would read all those.

Is that what you meant?

Perhaps Christ would be a DNA enthusiast, I’m not sure….

Comment by SN

Actually, #13 & #14 are wrong. In triplex DNA ‘G’ can pair with ‘G’ and ‘A’ with ‘A’

Thank for the comment, SN. Obviously, the examples above are for the most common form of B-DNA so #13 and 14 are not flat out wrong. If we were to get technical about it, we’d have list characteristics for all the permutations of DNA including Z-DNA, quadruplex DNA, inter- and intramolecular triplex DNA, slipped-strand DNA, etc., etc. Quite beyond the scope of these basic 100 facts.

Comment by TrophyGurl2010 Subscribed to comments via email

If I would of had this list maybe I would have made a higher score than 363 on my Biology I state test. This is very helpful now that I’m in Biology II.

Hi TrophyGurl, Hope you’re having fun in Biology II! I’m sure you know most of these facts already.


[...] Poorly understood science as opposed to what? String theory? Neurophysiology? Paleontology? And did she say “few solid facts”? Clearly, Annalee needs to read my list of 100 Facts About DNA. [...]

Comment by Feed

Just wanted to applaud you on your effort.

Comment by DNA Subscribed to comments via email

You said in 23 that every single cell in our body has DNA although that is not true. Everyone exept red blookd cells have DNA. Just a friendly reminder. ;]

Comment by mee again. Subscribed to comments via email
Comment by rachel

omg! this helped me with my science project soooooo much!

Comment by abhijith atharga Subscribed to comments via email

Though m a biotechnology student, this helped me a lot to know more about DNA. i’ve never studied this much of facts about DNA. thanks a lot for this…..

Comment by imari

are their really cells in ur mouth???????????????????? (–)

Comment by Jessica

5. James Watson and Francis Crick figured out the structure of DNA.
i am truly sorry but that statement is not correct it was actually rosalind franklin, watson’s partener tha dicovered DNA. Watson had hated her, so when he figured out what she dicovered, he left franklin to work with crick n they tried recieving credit.


[...] You have no idea what DNA is and where it is found in your body. (Although you can easily bring yourself up to speed by reading 100 Facts About DNA.) [...]

Comment by carlos

It is really cool. Thanks for all the facts. You can see more on. DNAW.Pbwiki.com Thank you

Comment by AJ Johnson

What kind of diseases can you find through DNA?

Comment by Chimera

i read the odds of you having the same DNA as someone else is 5000 billion billion to 1, and not mentioned is the possibility that a person can two individual sets of DNA in the body resulting in them being a Chimera though very rare it has happened.

Comment by alisha

Can you find all diseases through DNA?

Comment by roger Subscribed to comments via email

I’m pretty sure #16 should be:

A + C = T + G

(since A = T, C = G)

Thanks for catching that typo, Roger!

Comment by roger Subscribed to comments via email

Oh, dear! I think the correction is incorrect! :)

(Comments wont nest below this level)

ARGH. I need more sleep! Thanks. ;)

Comment by m grabow

I have heard that if all of the dna from every living thing today, and from every living thing that ever lived in the history of the earth was gathered together, it could fit into one aspirin tablet. Is there any truth to this? (And, could this be the start of another list?)

Comment by online doctor

Fact 100 is the greatest one of all. Thank you!

Comment by Brian McVicar

Is DNA actually acidic? Forgive me if it is already in the list somewhere. It is a cool list, though.

Comment by michael

What do you think of zecharia sitchin’s theory of evolution? In particular introns?

Comment by Mircea Tirziu Subscribed to comments via email

Great job, but:
1. You said A+C=T+G. I think that you would say
A=T and C=G
2. Sure, a mistake. The nucleotide has a much smaller capacity to store information as a byte.

Comment by Lauren

#30 says sperm don’t have mitochondria.

They do.
They have a LOT.
They need the energy to move the flagellum.

Just thought I’d say. :)

Comment by Gabriel ursabia

i love this fact thank you very much.

Comment by cara

Is the DNA in your mouth the same as the DNA in your blood when you are alcoholic or a smoker?


[...] Maybe there weren’t more microbiology submissions this time around because microbiologists like to take long summer vacations. When I go on vacation, it’s long walks in a place far away from computers, but Eye on DNA goes on vacation by listing 100 Facts About DNA. [...]

Comment by Freddy

I have a dog named Lucy!!!!!!!!!!!!!

Comment by emma

Very very good… I am in 5th grade doing my science project (extracting DNA from spinach) and it helped my report a lot thanks!!

Comment by Mindy Subscribed to comments via email

My parents have passed on, but I always remember my mother telling me her pregnancy with me was a delayed reaction because her and my father hadn’t had relations in a while.
Can my brother and I find out if we have the same father by a blood test(DNA)?
I am suspcting my dad may have been my dads father, but they are all deceased except for my brother and I.

Thanks, Mindy

Comment by nagalakshmi

i understand dis very much it helped me thanks a lot


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