Text 3.1. DNA Structure
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Essential targets:
By the end of this text you should be able to:
● distinguish between a nucleoside, a nucleotide, and a polynucleotide;
● explain how a phosphodiester bond forms;
● discuss the significance of complementary base pairing in DNA.
Pre-reading
Working in pairs, try and answer the following questions before you read the text. Don`t be afraid of guessing the answers! When you have finished, check your answers by reading the text.
1. Who discovered the structure of DNA?
2. What do you know about a nucleoside and a nucleotide?
3. What shape does a molecule of DNA have?
4. What kind of information does a molecule of DNA contain?
Exercise A. Match the words with their definitions:
| to join | A | only one or considered to its own | |
| base | B | serious study of a subject that is intended to discover new facts or test new ideas | |
| ring | C | to connect or fasten things together | |
| support | D | the most important part of something from which new ideas develop | |
| bond | E | a circular line or mark | |
| single | F | sympathetic encouragement and help that you give to someone | |
| research | G | the chemical force that holds atoms together | |
| to discover | H | a single thin piece of thread, wire, hair etc. | |
| double | I | something that is twice the size, quantity, value, or strength of something else | |
| strand | J | to find something that was hidden or that people did not know about before |
■ Read the given text and make your essential assignments:
The description of the double helical structure of DNA (deoxyribonucleic acid) by Watson and Crick in 1953 (see Fact of life) was a landmark in science history. Their discovery sparked off a new era in scientific research which has had, and will continue to have, far-reaching consequences.
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