DNA
An introduction to DNA.
Short simple articles which explain the role of DNA, what it is and how it’s structure allows it to provide the blueprint for all life.
How does DNA work?
DNA affects the body by controlling what proteins are made. The DNA acts as a recipe book for proteins; each recipe or gene corresponding to a particular protein.
What do proteins do?
Proteins are incredibly important and have two main roles.
A) Structural – that is they make up physical parts of an organism. These proteins are obvious in animal life forms such as muscles, hair and nails, which are all made of proteins. Though slightly less obvious in plants they are just as important, for example proteins both contribute to the strength of plant walls and act as glue to hold plant cells together.
The particular properties of these structural proteins i.e. whether they are strong, weak, brittle, bendy, hard soft, brown, yellow etc… all depends on their shape.
Fingernails are made out of protein. This is one of the many structural roles protein plays in your body.
Photographer: Unknown. Copyright: GFDL
B) Chemical – they control what chemical reactions occur in the organism Proteins that do this are called enzymes. They work by catalysing chemical reactions, ‘encouraging’ a particular reaction to happen while remaining unchanged themselves.
This is really important as an organism is a constantly changing mass of chemicals. The construction of a scab and then a scar when you cut yourself, the growth of a leaf in spring, the digestion of your food, the ripening of a fruit, these processes all rely on chemical reactions. Without enzymes these reactions would not occur.
Other things proteins do, include: Recognising germs (e.g. bacteria and viruses) in plants and animals, and signaling between cells in both animals and plants.
What are proteins?
A protein actually consists of hundreds or thousands of individual units called amino acids. These are linked together in a long chain a bit like a bead necklace.
Proteins are made of lots of sub units joined up in long chains, a bit like a bead necklace.
Photographer: Pschemp. Copyright: GFDL
This chain folds up into a complicated 3D shape. It is the type of amino acids in the chain that determine how the chain folds up and the shape it makes. The 3D shape of each protein is what gives it its individual qualities (see above).
Twenty different types of amino acid are used in the chains that make proteins.
