Mutations
This lesson covers:
- What 'DNA mutations' are
- How mutations can arise
- The possible consequences of mutations
- The three types of mutations: 'substitution', 'insertion', and 'deletion'
What is a mutation?
A change to the structure of an organisms cells
A change in the base sequence of DNA
A change in the way an organism looks
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True of false? Mutations can occur spontaneously in our cells, but certain factors can increase the risk.
True
False
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Which of the following can increase the risk of mutations?
(Select all that apply)
Carcinogens like those found in cigarette smoke
A balanced diet
Ionising radiation such as x-rays and gamma rays
Regular exercise
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Will exposure to ionising radiation always cause a mutation?
Yes
No
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one / two / three / four / five
A triplet, or a codon, is a set of bases which codes for amino acid.
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A mutation to one of the bases in DNA can change the that a triplet (codon) codes for.
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What is the most likely result of a genetic mutation?
A significant advantage to the organism
A significant disadvantage to the organism
No significant change to the organism
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Most mutations occur in _______________ .
Coding DNA
Non-coding DNA
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Non-coding DNA often controls the expression of coding DNA.
What does it mean for a gene to be expressed?
It's turned off, so the proteins it codes for will not be produced
It's turned on, so the proteins it codes for will be produced
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What happens in a substitution mutation?
One base in the sequence is replaced with a different base
A base is deleted from the sequence
An extra base is added into the sequence
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Enzymes are proteins that speed up the rate of chemical reactions.
Describe how a change of one of the bases in the gene for an enzyme could affect the functioning of that enzyme.
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How many triplets (codons), and thus amino acids are affected by a substitution mutation?
1
2
3
4
5
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What happens in an insertion mutation?
An extra base is added into the sequence
A base is deleted from the sequence
One base in the sequence is replaced with a different base
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Which type of mutation usually has a larger impact on the protein: substitution mutations, or deletion mutations?
Substitution mutation
Deletion mutations
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