Genetic mutations Flashcards
What is an allele?
Alternative form of a gene found at the same locus on homologous chromosome
What is a genetic mutation?
Change in DNA sequence of a genome
What are germline mutation?
Mutation in germ cells
What are somatic mutations?
Mutation during development or adult life
Which type of mutation affects more cells?
a) germline
b) somatic
Germline
How can mutations be classified by affected cell type?
Germline or somatic mutations
What can loss of function cause?
Reduced activity or loss of gene product
What can gain of function cause?
Gene product acquires new function or altered expression levels
What is dominant-negative mutation?
Loss of function due to interference of the mutant gene product with the normal gene product
How can mutations by classified by the effect on function?
Loss of function
Gain of function
Dominant-negative
What is non-dysjunction?
Failure of chromosomes to seperate
What type of chromosomal abnormalities does non-dysjunction cause?
a) numerical changes
b) structural changes
a
What is aneuploidy?
The loss or gain of 1 or more chromosome
What is monosomy?
Loss of one chromosome
What is trisomy?
Gain of one chromosome
What is polyploidy?
Gain or one or more complete sets of chromosomes
Why are numerical changes not common?
Cause embryonic lethality or severe diseases
What causes structural changes
a) chromosome breakage and abnormal reunion
b) non-dysjunction
a
What is translocation?
Transfer from 1 chromosome to another
What is reciprocal?
2 chromosomes exchange segments
What is a robertsonian change?
Breakpoint is near the centromere of acrocentric chromosomes
What is an acrocentric chromosome?
1 arm much shorter than the other
What is inversion?
Chromosome segment reversed in position
What is a pericentric inversion?
Involves the centromere
What is a paracentric inversion?
Involves only 1 arm of the chromosome
Other than translocations and inversion what other structural changes can occur and what causes this?
Insertion and deletion due to unequal crossover during homologous recombination
What is a ring chromosome?
Broken chromosome segment forms a ring
What is an isochromosome?
Loss of 1 arm and duplication of the other
What is a transition substitution?
Same type of nucleotide replaced (purine for purine)
What is a transversion?
Different type of nucleotide replaced (purine for pyrimidine)
