Every cell you've ever had carries the same instructions, written in a code with only four letters. Here's how it was found, and how it works.
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Students will describe DNA as a double spiral with bases that pair A with T and G with C, explain how DNA copies itself by unzipping, and explain that a gene is a section of DNA that directs one protein, carried out to the ribosomes by RNA.
The pairing rule does all the work. Because A only fits T and G only fits C, either half of a DNA molecule is enough to rebuild the other half.
A mutation is any permanent change in a gene or chromosome. Many are harmful, some aren't, and one in a sex cell is passed to every cell of the offspring.
Write a strand like AGTAAC and have the student write the matching strand underneath (TCATTG). Then 'unzip' it and rebuild both halves. The book's own review question does exactly this.
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Before You Start
The words this lesson uses. Tap a card to see what it means, then come back to them whenever a question uses one.
Part One
Questions about the story you just read. Pick your answer straight off, or press Find it in the story if you would rather hunt for the sentence first.
Part Two
The word cards are at the top of this page. Look back at them as often as you need, then answer.