Genes and proteins in health and disease Flashcards
What are proteins made up from?
Chains of amino acids called polypeptides
What are mutations?
Are changes in the DNA that can result in no protein or an altered protein being synthesised
What can mutations do?
Alter genes or chromosomes
What does a single gene mutation affect?
It affects the DNA nucleotide sequences and include deletion, insertion and substitution of nucleotides
What does a nucleotide insertion or deletion result in?
A frameshift mutation or expansion of a nucleotide sequence repeat
What are mutations important for
Evolution
What can a regulatory sequence mutation alter?
Gene expression
What can a chromosome mutation be described as?
Lethal
What are the single gene mutations?
Substitution- minor missense major, nonsense
Insertion- major, frameshift
Deletion- major, frameshift
What is a substitution single gene mutation?
A Dna nucleotide base is removed and another is added to the DNA sequence
What is an insertion single gene mutation?
Additional nucleotide added into a DNA sequence
What is a deletion single gene mutation?
Nucleotide removed from a DNA sequence but not replaced with another
What is the effect of a gene mutation?
It changes the base order within a gene and so alters the amino acid sequence of the protein coded for
What is the effect of a chromosome mutation?
Affects the structure or number of chromosome present in cells
An example of a splice site mutation
An intron being left in the mature RNA and so contributing to protein structure,
it would result in an altered protein that would not function normally
What is a missense?
One amino acid being changed for another.
This may result in a non-functional protein
What is a nonsense?
Results in a premature stop codon being produced which results in a shorter protein
What does a frameshift mutation do?
Cause all of the codons and all of the amino acids after the mutation to be changed
Major effect on the structure
What are the chromosome mutations?
Duplication,deletion, Inversion,translocation
What are deletion chromosome mutations?
Where a section of a chromosome is removed, make them lethal
What are Inversion chromosome mutations?
Where a section of chromosome is reversed. make them lethal
What are translocation chromosome mutations?
A section of a chromosome is added to a chromosome, no its homologous partner,make them lethal
What is the result of a splice site mutation?
some intorns being retained or some exons not being included in the mRNA transcript
Describe the effects of deletion mutations on the structure of the polypeptide coded for by the original gene
Gives a frameshift mutation effects with major changes to amino acid sequence or all amino acid changed after mutation
Describe the effects of substitution mutations on the structure of the polypeptide coded for by the original gene
Results in missense and gives minor changes to polypeptide or only one amino acid changed or result in nonsense if stop codon affected
