AQA · GCSE · Biology
Course version: 8461 · Version from Sept 2018
(HT only) A few mutations code for an altered protein with a different…
Full specification wording
DNA structure (biology only): (HT only) A few mutations code for an altered protein with a different shape.
A mutation changes the base sequence of DNA, which can change the sequence of amino acids in the protein made during translation.
Checked against the AQA 8461 specification (opens in a new tab) on .
- Point 16 of 19
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
A mutation changes the base sequence of DNA, which can change the sequence of amino acids in the protein made during translation. Because a protein's shape is determined by the sequence and interactions of its amino acids, a change in amino acid sequence can alter the way the polypeptide folds. A few mutations therefore code for an altered protein with a different shape. For example, a substitution that changes an amino acid in the active site of an enzyme can change the shape of the active site so that the substrate no longer fits. The effect may be harmful, neutral or occasionally beneficial, but the key idea is that a changed amino acid sequence can produce a changed three-dimensional shape and therefore a changed function.
What earns the marks
- A mutation changes the base sequence of DNA, which can change the amino acid sequence of the protein.
- The amino acid sequence determines how a polypeptide folds into its three-dimensional shape.
- A few mutations produce an altered protein with a different shape.
- A change in shape can change the protein's function, for example an enzyme's active site may no longer fit its substrate.
- The effect of a mutation depends on whether the changed amino acids affect the protein's folding or functional regions.
Common mistakes and how to put them right
Saying that a mutation changes the protein's shape directly without mentioning the amino acid sequence.
Put it right by linking DNA base sequence to amino acid sequence to protein folding.
Confusing 'different shape' with 'different function' as if they are the same thing.
Put it right by explaining that shape affects function, but the function may still be similar if the change is small.
Assuming all mutations that change shape are harmful.
Put it right by stating that effects can be harmful, neutral or beneficial.
Exam tips
- Use the chain: base sequence → amino acid sequence → protein folding → shape → function.
- When asked about enzymes, refer to the active site and substrate binding rather than just saying 'the enzyme is denatured'.
- Use the term 'altered protein' to make clear that the protein is different from the one coded for by the original allele.
Try the lesson
The start of the DNA structure (biology only): (HT only) A few mutations code for an altered protein with a different shape. lesson, made from checked teaching notes for this specification point.
Have a go first
While most mutations have little effect, a small number of mutations significantly affect the protein produced. What is the direct consequence of these significant mutations?
Listen
A mutation changes the base sequence of DNA, which can change the sequence of amino acids in the protein made during translation. Because a protein's shape is determined by the sequence and interactions of its amino acids, a change in amino acid sequence can alter the way the polypeptide folds. A few mutations therefore code for an altered protein with a different shape. For example, a substitution that changes an amino acid in the active site of an enzyme can change the shape of the active site so that the substrate no longer fits. The effect may be harmful, neutral or occasionally beneficial, but the key idea is that a changed amino acid sequence can produce a changed three-dimensional shape and therefore a changed function. A strong answer earns marks for these points. A mutation changes the base sequence of DNA, which can change the amino acid sequence of the protein. The amino acid sequence determines how a polypeptide folds into its three-dimensional shape. A few mutations produce an altered protein with a different shape. A change in shape can change the protein's function, for example an enzyme's active site may no longer fit its substrate. A common slip: Saying that a mutation changes the protein's shape directly without mentioning the amino acid sequence. Instead, linking DNA base sequence to amino acid sequence to protein folding. Exam tip: Use the chain: base sequence → amino acid sequence → protein folding → shape → function.
See it
Put it in order
Put these steps in the order they happen.
- 1. Amino acid sequence determines how the polypeptide folds
- 2. Amino acid sequence of the protein can change
- 3. Mutation changes the base sequence of DNA
- 4. For example, an enzyme's active site may no longer fit its substrate
- 5. A change in shape can change the protein's function
- 6. A few mutations code for an altered protein with a different shape
Key words
Say what each word means before you turn the card.
Mutation and protein shape
Try answering aloud or in your head before turning the card.
Protein synthesis and folding
Try answering aloud or in your head before turning the card.
Enzyme action
Try answering aloud or in your head before turning the card.
Structure and function of proteins
Try answering aloud or in your head before turning the card.
See every definition
- Mutation and protein shape
- A few mutations code for an altered protein with a different shape, because a change in amino acid sequence can alter the way the polypeptide folds.
- Protein synthesis and folding
- The sequence of amino acids determines how a polypeptide folds into its three-dimensional shape.
- Enzyme action
- A change in shape can change the protein's function, for example an enzyme's active site may no longer fit its substrate.
- Structure and function of proteins
- A changed amino acid sequence can produce a changed three-dimensional shape and therefore a changed function.
Label the diagram
Some boxes have lost their names. Pick the right name for each number.
1Box 1
2Box 2
3Box 3
There is more to this lesson
The full lesson goes on to check your understanding and help you earn the marks. Create a free account to carry on, with your progress saved.
A week of Premium from your first lesson · Then the free plan continues · No card, no charge
Test your understanding of DNA structure (biology only): (HT only) A few mutations code for an altered protein with a different shape.
Active recall beats re-reading. Take an instant quiz now to test what you’ve learned and lock it into long-term memory.
A week of Premium from your first lesson · Then the free plan continues · No card, no charge