Mutation & Inherited Disease Flashcards
(50 cards)
What are base substitutions?
Replacement of a single base
What are deletions?
When one or more nucleotides are eliminated
What are insertions?
When one or more nucleotides are inserted into a sequence
What are endogenous mutations?
Mutations that occur as errors of replication or DNA repair
DNA is vulnerable to spontaneous damage from what?
Exposure to reactive metabolites or ionizing radiation.
Mutations occur in our somatic cells and gremlins. Which of these two give it the potential of being passed on to offspring?
Mutations in germline.
What are polymorphisms?
Existence of two or more variants (alleles sequence variants) at significant frequencies in the population
Any sequent variant present at a frequency greater than 1% in a population is called?
Polymorphism
Any non pathogenic sequent variant, regardless of frequency is a
polymorphism
What does the term heterozygosity describe?
Percentage difference between allelic sequences. (different versions of a gene)
What is the mean heterozygosity of the human genome?
0.08%
What type of polymorphism classifies a change in a single nucleotide?
Single nucleotide polymorphism.
Most SNPs are substitutions be a different
nucleotide
Where do most SNPs occur?
In non-coding DNA like introns nd intergenic sequences
What are synonymous/silent substitutions?
This is when base change results in a a new codon but specifies the same amino acid
Silent substitutions usually occur at?
the wobble position (3rd base)
Base substitutions that result in a different amino acid are called?
Missense mutations
What is the difference between conservative and non-conservative missense mutations?
Conservative shows replacement with a chemically similar amino acid while non-conservative shows replacement with a dissimilar amino acid.
A base substitution that results into a stop codon is called
nonsense mutation
What is the result of a nonsense mutation?
A truncated protein which is either dysfunctional or nonfunctional
What mutations are a result of an insertion or deletion in coding DNA that is not a multiple of three?
Frame shift mutations
What is the result of frame shift mutations?
They change the translational reading frame, causing a rearrangement of the codons that are read during translation, different amino acid, premature stop codon introduced.
What is penetrance?
This is the frequency of expression of disease phenotype in individuals with a gene mutation
What is the difference between completed and incomplete penetrance?
In complete penetrance, the disease phenotype is expressed in every individual with the mutated gene, while in incomplete penetrance, individuals may have mutated gene bu do not express disease traits.
