Genetics lecture 1 Flashcards
Where can genetic mutations occur?
Single base pair changes, small deletions or insertions in coding or non-coding regions, and by chromosomal rearrangements
Can occur in the absence of a clinical problem
What are some important things to know about our genome?
- <2% of the genome codes for protein
- Repeated sequences make up approximately 50% of the human genome
- Alternative splicing of mRNA transcripts and chemical modifications of the proteins yield different protein products from the same gene
Can changes in non-coding sequences lead to diseases?
Yes!!
Diseases can be caused by changes in coding sequences or non-coding sequences. They all lead to changes in protein structure, function and/or expression
What is the difference between transition and transversion mutations?
Transition: purine to purine, or pyrimidine to pyrimidine mutation
Transversion: purine to pyrimidine or vice versa
What can missense mutation lead to?
Change in a single amino acid
What can nonsense mutation lead to?
Insertion of a stop codon
What can mutations in RNA splicing lead to?
Exon skipping
What can mutations in regulatory structures lead to?
Changes in protein modifications
What can insertion (1-2 bp) lead to?
Change in reading frame
What can deletion lead to?
Loss of function of a protein
What can repeat expansion lead to?
Altered structure
What are some consequences of non-coding mutation?
- Promoter: transcription altered; increase or decrease in protein level
- RNA splicing: exon skipping/intron retention
- Repeat expansion: altered expression
What is single nucleotide polymorphism (SNP)?
A single base difference in nucleotide sequence at specific loci between 2 individuals. Can be due to substitution, deletion or insertion
Make up majority of human genetic variation. Can be in both coding and non-coding regions. May or may not alter a protein’s function
Each person has a unique SNP pattern
