Module 1 - Unit 2

  • Created by: S.L.S_10
  • Created on: 12-04-15 16:38

Mutations - neutral, harmful or beneficial?

Alterations to the base sequence affect the gene, causing an alternate version. Alternate versions of a gene are called alleles. They are still positioned at the same locus on the chromosome and they code for the same polypeptide but it may alter the proteins structure. Examples of different alleles are found in eye colour, skin colour and hair colour. 

Neutral effects: 
- The mutation is in a non-coding region of the DNA
- Silent mutation, whereby there is no change to the protein even though a base triplet has changed
- The mutation does not lead to any particular advantage or disadvantage.
Example: The ability to smell honeysuckle flowers offers no advantage or disadvantage to an organism. However, the ability for an organism to smell something that could make it ill or kill it will be advantageous. 

Harmful and beneficial effects:
- Having skin with the pigment melanin (produces dark skin) is beneficial to people that live in areas which are exposed to high amount of UV light because it protects them from skin cancer. However, this characteristic is not advantageous in milder climates because not enough vitamin D is synthesised, causing a mutation which led to lighter skin, to allow more vitamin D production
- Inuit people have a diet that is high in vitamin D, from seal blubber and fish. They haven't lost all of their skin pigments but they live in climates with less intense UV light. 

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