Reading Exercise: Gene Mutations

Mutations

What do the squirrel and the tulip have in common?

Both have a mutation in the gene that codes for the protein responsible for their colour. The mutation causes the squirrel to be white and have red eyes. This condition is also called “albinism”. The tulip has a mutation in only one petal giving half of it a yellow colour.

A mutation is a change in a gene that creates a new version of the gene or allele. Mutations happen when there is a mistake in copying DNA during cell division.

For example, one base in a DNA sequence might be replaced with another, a bit like typing the wrong letter in a word. This can happen naturally, but is more likely to happen if DNA has been damaged by radiation or certain chemicals.

The change in the body caused by a mutation can be either positive, negative or have no effect at all. Most of the time mutations only have a small or no effect on the proteins that are produced and do not change how the body works.

The Human Genome Project

In 2003, the first complete human genome was decoded by the Human Genome Project. This project involved many scientists from different countries and produced the map of 3.3 billion base pairs in one set of 46 chromosomes. Your genome contains all the DNA that is found inside your cells.

Further work showed that 99 % of DNA is the same for very human. Mapping a person’s genome can show their risk for developing certain diseases like cancer. It can also help to identify which medicine might be best to treat that person. In addition, mapping the genome can provide information about which genetic disorders someone could pass on to their children.

Questions

  1. What is a mutation and how does it occur?
  2. Mutations happen naturally, but what makes them more likely to occur?
  3. Are mutations positive, negative or none of the two?
  4. Looking at the squirrel, is the mutation affecting its colour positive or negative? Why? (Tip: Think about predators.)
  5. Looking at the tulip, is the mutation affecting its colour positive or negative? Why? (Remember, that the tulip needs to attract butterflies and bees.)
  6. What was the Human Genome Project?
  7. What is a genome?
  8. How much percent of DNA is the same for every human?
  9. Give three advantages of mapping a person’s genome.

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