DNA - Structure and Function
Genetics, Cloning, and the Human Genome Project
sugar phosphate backbone
phosphate
sugar
base
cytosine
Nucleotide
(sugar, phosphate and base)
weak
hydrogen
base
pairs
c
g a gc
t
adenine
thymine
guanine
a
t g
c t
A close-up look at
nucleotides linked
together in DNA
Each nitrogenous base pair is held together by weak hydrogen bonds and stacked flat on top of each other like steps.
To each base pair, a two sugar-one phosphate complex is attached. This formed the so-called nucleic acid.
Facts About Your DNA
Inside every cell in your body there is a nucleus that contains your genetic material. That genetic material is
deoxyribonucleic acid – DNA for short. Your DNA controls many of the things about you, but scientists still are
not sure about the exact role of nature (your genes) and nurture (how you were raised) in making you who and
what you are.
Here are some facts:
1. Almost every cell in your body contains about 2.91 billion DNA.
2. The DNA is divided into two sets of 23 chromosomes.
3. You get one set of chromosomes from your mother and one set from your father.
4. Every time your cells divide, the information is copied and divided into the new cells. Every time those
chromosomes are passed on from mother or father, they are recombined to make unique chromosomes —
YOUR chromosomes.
Nucleotides and the Structure of DNA
1. Structurally, DNA is made up of nucleotides.
2. A nucleotide is made up of a sugar, a phosphate and a base.
3. Nucleotides hook together to make the sugar-phosphate backbone of every strand of DNA.
4. Bases pair up with opposite matching bases on the other strand of DNA making up the double-helix structure.
5. The pairs are linked by weak hydrogen bonds.
6. There are four kinds of nucleotides or “base pairs” -- A for adenine, T is for thyamine, G is for guanine and C
is for cytosine. A always pairs with T. G always pairs with C.
7. They are linked together (the two strands of DNA) and stacked like a ladder who’s sides spiral around each
other into their famous double helix shape.
Content Collaboration
Collaborative consultation on website genetics and genomics from Dr. Stephen M. Carleton, Assistant Professor,
Department of Anatomy and Cell Biology, SUNY Health Science Center at Brooklyn.
CITING RESEARCH REFERENCES
Amsel, Sheri. “Digestive System.” The Large Intestine. Exploring Nature Educational Resource. © 2005 - 2009.
November 20, 2009. <http://exploringnature.org/db/detail.php?dbID=20&detID=42>
©Sheri Amsel
www.exploringnature.org