Module 8- Module 8 - Alteration of the sequence of bases in DNA can alter the structure of proteins Flashcards
What is a mutation?
This is when there is a change to the base nucleotide sequence of DNA
What is substitution mutation?
This is when one or more bases is swapped for another
What is a deletion mutation?
This is when one or more bases are removed causing a frameshift
What is an addition mutation?
This is when one or more bases are added causing a frameshift
What is a duplication mutation?
One or more bases are repeated
What is an inversion mutation?
The DNA of a single gene is cut in 2 place. The cut portion is inverted 180degrees then rejoined to the same place within the gene
Frequently result in a non- functional protein
What is a translocation mutation?
A sequence of bases which is moved from one location in the genome to another. This can be a movement within the same chromosome or a movement to a different chromosome
Why do some mutations not lead to a change in the amino acid sequence?
Some amino acids are degenerate meaning that it doesn’t always cause a evident change
What mutations will have the least impact on an amino acid sequence?
Substitution and inversion
What are mutagenic agents?
These are factors that increase the likelihood of a mutation happening
What are the 4 main examples of a mutagenic agent?
- Ultraviolet radiation
- Ionising radiation
- Chemicals
- Viruses
What are the 3 ways mutagenic agents can increase the rate of mutations?
- Acting as a base
- Altering bases
- Changing the structure of DNA
How does a mutation of human genes that code for tumour suppressor genes cause cancer?
A mutation in a tumour suppressor proteins could cause a change in the DNA base sequence resulting in a change in the tertiary structure of the tumour suppressor proteins resulting in uncontrolled cell division
3 marks
Explain how a single base substitution causes a change in the structure of this polypeptide.
Do not include details of transcription and translation in your answer.
- Change in sequence of amino acids
- Change in hydrogen/ionic/disulfide bonds
- Alters tertiary structure
2 marks
Integrase inserts the DNA copy anywhere in the DNA of the host cell. It may even insert the DNA copy in one of the host cell’s genes. The insertion of the DNA copy in one of the host cell’s genes may cause the cell to make a non-functional protein. Explain how
- Causes frame shift
- Different sequence of amino acids in polypeptide / primary structure alters the tertiary structure
2 marks
The faulty allele that causes Ellis-van Creveld syndrome is the result of a mutation of a gene called EVC. This mutation leads to the production of a protein that has one amino acid missing. Suggest how a mutation can lead to the production of a protein that has one amino acid missing.
Loss of 3 bases / triplet = 2 marks
2 marks
Suggest how the production of a protein with one amino acid missing may lead to a genetic disorder such as Ellis-van Creveld syndrome.
- Change in tertiary structure / active site
- So non-functional protein
Sickle cell disease (SCD) is a group of inherited disorders. People with SCD have sickle-shaped red blood cells. A single base substitution mutation can cause one type of SCD. This mutation causes a change in the structure of the beta polypeptide chains in haemoglobin.
Explain how a single base substitution causes a change in the structure of this polypeptide. Do not include details of transcription and translation in your answer.
- Change in sequence of amino acids/primary structure
- Change in hydrogen/ionic/disulfide bonds
- Alters tertiary structure
1 mark
What is a substitution mutation?
Replacement of a base by a different base in DNA
