Genetic Mutations (5.1.1)

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What is a genetic mutation?
A random, unpredictable change in a DNA molecule which changes the usual nucleotide sequence.
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What are mutagens?
Substances that can cause mutations, like cigarette tar and UV light.
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What happens if DNA mutations occur in mitosis?
This is a somatic mutation. It cannot be passed onto offspring, but may contribute to ageing or cancer.
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What happens if DNA mutations occur in meiosis?
These are inheritable mutations. Can be passed onto offspring.
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What are point mutations?
Where one base pair replaces another- also known as substitutions.
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What are insertion/deletion mutations?
Where one or more base pairs are either inserted into or removed from the DNA.
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What genetic diseases are caused by DNA mutations?
Cystic fibrosis- more than 70% of cases a deletion is responsible- 1 triplet code is deleted. Sickle cell anaemia- due to point mutation in gene coding for B-chains in haemoglobin. Some cancers- due to mutations where cell division genes won't stop.
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What is a neutral mutation?
Either mutation occurs on non-coding section of DNA, or it's a silent mutation, meaning that although the base sequence has changed, it still codes for the same amino acid and the final protein is unchanged. Or new characteristic gives no advantage.
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GIve 2 examples of neutral mutations.
Some people can roll their tongues. Some people have attached earlobes and others have detached earlobes.
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Why was the mutation where early humans in Africa had dark skin beneficial?
The pigment melanin protected them from the harmful effects of UV light. But they could still synthesise vitamin D from the action of the intense sunlight on their skin.
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Why might a substitution mutation have less significant consequences than an insertion or deletion?
With a substitution, 1 base changed for another, but since DNA code is degenerate, it may code for same a.a. Even if different a.a is coded for, may not be crucial to shape & function of protein. With insertions/deletions- big changes, frameshifts.
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Other cards in this set

Card 2

Front

What are mutagens?

Back

Substances that can cause mutations, like cigarette tar and UV light.

Card 3

Front

What happens if DNA mutations occur in mitosis?

Back

Preview of the front of card 3

Card 4

Front

What happens if DNA mutations occur in meiosis?

Back

Preview of the front of card 4

Card 5

Front

What are point mutations?

Back

Preview of the front of card 5
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