The BBC Explainer series is designed to intrigue and inform, encouraging those who discover the documentaries to further explore through links to additional information found on the BBC website.
Self-study activity:
The video below explains in three minutes what DNA is about. Go over the transcript below and complete the blanks with the missing words.
BBC Knowledge Explainer DNA from Territory on Vimeo.
You can find out more on DNA on the BBC Science site.
DNA is the instruction manual for how to build life. From (1) ... to plants to human beings, it defines us all. The complete set of instructions encoded in an organism DNA is called its genome, and it’s passed from parents to (2) ... during reproduction. Information is stored in DNA, using just four types of molecule which occur in pairs. There are billions of these pairs, organized in a double-hill structure which is both strong and compact. These pairs also allow each strand to act as a (3) ... for the other, a remarkably efficient way to safeguard this precious genetic information.
DNA falls into pair-packages called chromosomes that are stored in the nucleus of the (4) ... . Different species have different numbers of chromosomes, human have 23 pairs. Chromosomes contain many (5) ... . A (6) ... is a section of DNA that holds the instructions for a protein. Proteins are essential for life and perform a huge variety of jobs, from controlling the function of a single cell to determining the shape of a whole organism. Within (7) ... each organism has very similar DNA. In human beings, the difference between a human person and another is a fraction of 1%. But it what makes us individuals, giving us different facial (8) ... , hair colour and height. The uniqueness of our DNA can be used like a fingerprint to identify us with an incredibly degree of (9) ... . By reading DNA, scientists have discovered that we share sequences not just with our own species but with other living thing on earth. Chimpanzees, one of our closest living relatives share about 96% of our DNA, but we also we things in common with fish, plants and bacteria, powerful evidence that all life came from a single universal (10) ... billions of years ago.
We haven’t just learnt to read the instruction manual for life, we can rewrite it as well. People have been manipulating DNA since before we knew it existed, selectively (11) ... plants and animals to bring out desirable traits. Now genetic engineering allows us to directly alter DNA in a lab, creating new varieties of life, from plants that can resist (12) ... or drought to bacteria that can mass produce life-saving hormones.
But we don’t yet know what all that DNA does. (13) ... sequences make no proteins at all and have perhaps mistakenly been labelled junk. Some people are worried about these gaps in our knowledge and unforeseen problems they believe genetically modified organisms may cause. What is clear is that the instruction manual for life is more (14) ... , elegant and complex than we could have possibly imagined. DNA has revealed many of its secrets, but we still have much to learn.
H/T to New Technology for Teachers.
Key:
1 microbes 2 offspring 3 back-up 4 cell 5 genes 6 gene7 species8 features 9 accuracy 10 ancestor 11 breeding12 disease13 Lengthy14 subtle
