Amazing DNA facts
1. On February 28, 1953, Francis Crick and James Watson figured out the structure of deoxyribonucleic acid (DNA). That structure, a 'double helix', can "unzip" (separate into two long strands) to make copies of itself. This discovery confirmed suspicions that DNA carried an organism's hereditary information.
2. DNA molecules are linked, one after another, like pearls on a very long string.
3. DNA molecules are the "software" that direct cellular activity and determine everything about an organism - from what it looks like to how long it is likely to live. Genes are pieces of this DNA, and are the fundamental units of heredity.
4. The complete human genome consists of approximately 3 billion DNA molecules.
5. On average, each chromosome has about 65 million DNA molecules.
6. A gene is a stretch of DNA molecules (ranging in length from thousands to tens of thousands of DNA molecules, in some cases they may be even larger).
7. Between genes, along the length of a chromosome, there may be long stretches of DNA, which have no known function.
8. A chromosome contains about 1000 genes.
9. Humans have approximately 30,000 different genes spread out over the 46 chromosomes.
10. Humans get one complete set of genes from each parent.
11. In April 2003, the National Human Genome Research Institute (NHGRI) celebrates the completion of the human genome sequence and the 50th anniversary of the description of the DNA double helix.
12. The nucleus, or control centre, of a cell, is where the DNA is coiled up into chromosomes. With the exception of reproductive cells, every cell has 46 chromosomes. Twenty-two pairs of the chromosomes are similar in terms of size, shape and genetic content. The twenty-third pair determines the sex of the individual, and is composed of either two x chromosomes (female) or an x and a y chromosome (male).
13. DNA molecules are incredibly long. If all of the DNA from all of your cells was stretched out into a single thread, it would extend to the moon and back about one million times!
14. DNA is found inside every cell in our body (apart from red blood cells).
15. Each cell contains roughly 2 metres of DNA.
16. Humans have roughly 100,000,000,000,000 (100 trillion cells).
17. If you unravelled all of your DNA from all of your cells and laid out the DNA end to end, the strand would stretch from the Earth to the Sun hundreds of times (the sun is approximately 98 million miles away from Earth).
18. You could fit 25,000 strands of DNA side by side in the width of a single adult hair.
19. The DNA is tightly coiled up and structured into 46 chromosomes.
20. Our chromosomes are arranged in pairs. We inherit one copy of the pair from our Mum and one from our Dad.
21. When chromosomes are stained they can be quite easily recognised by their distinctive stripy patterns. This is used to check whether people have the right number of chromosomes and check for any rearrangements.
22. There are approximately 3 billion (3,000,000,000) chemical letters (otherwise known as bases) in the DNA code in every cell in your body.
23. This is a massive amount of information. It would fill 200 yellow pages in small type font.
24. If you tried typing the whole genetic code out (typing at 200 letters per minute) it would take 29 years (without taking any breaks!).
25. The DNA is made up of 4 building blocks (an alphabet of 4 letters spelling out the instructions to help us grow, develop and function).
26. The four letters in the DNA alphabet- A, C, G and T -are used to carry the instructions for making all organisms. The sequence of these letters holds the code - just like the order of letters that makes words mean something. Each set of three letters corresponds to a single amino acid.
27. Sections of DNA that code for proteins are called genes. The complete set of genetic information for an organism is called the genome. The latest estimate is that there are between 20,000 and 25,000 genes in the human genome.
28. We share a lot of DNA with other animals, plants and microorganisms.
29. Every cell in your body has 46 chromosomes except for egg and sperm cells.
30. Women’s chromosomes are described as 46,XX; men’s as 46,XY.
Women have
46 chromosomes (44 autosomes plus two copies of the X chromosome) in their body cells and are described as 46,XX. 23 chromosomes (22 autosomes plus an X chromosome) in their egg cells.
Men have
46 chromosomes (44 autosomes plus an X and a Y chromosome) in their body cells and are described as 46,XY. 23 chromosomes (22 autosomes plus an X or Y chromosome) in their sperm cells.
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