Mutations,mutagensis And Dna Repari Flashcards
Genetic material
-each cell has 23 pairs of chromosomes (46 in total)
-long sequences of nucleotides bases organised into genes
-most of the dna is the same in all humans
Mutations
• change in the nucleotide sequence of DNA
•Position of mutations within genetic sequence is crucial to function
Synonymous mutations
do not change the encoded amino acid
-redundancy of the genetic code i.e. GGT, GGA, GGC, and GGG all code for glycine
Non-Synonymous mutations
change the encoded amino acid, mutant protein, potential altered biological/function
Splice site mutations
-ie at intron/exon boundaries
-Can exclude exons,include introns in final amino acid,potential altered/mutantproteins.
Promoter mutations
may affect control of gene expression, hence levels of protein production.
Role of mutations in evolution
-Somatic mutations - can occur in any of the cells of the body except the germ cells (sperm and egg) and therefore are not passed on to children.
-Germline mutations – occurs in body’s reproductive cell (egg or sperm) that becomes incorporated into the DNA of every cell in the body. These are inherited from parents to offspring. “survival of the fittest”
-Long-term species survival - enhanced by mutation- allows adaptation to changing environments
BALANCE
Short-term survival - requires accurate maintenance of genetic record
Polymorphism(common mutations )
-DNA change, with at least one variant (allele) found in at least 1% of the population
Most common type of variation involves single base pair changes ie single nucleotide polymorphism, or SNP (pronounced snip),
-can also be much larger in size and involve long stretches of DNA.
-Non-disadvantageous mutation becoming established in a population
HOWEVER:-
DNA fingerprints
scientists are studying how SNPs in the human genome correlate with disease, drug response, and other phenotypes
combinations of multiple SNPS, environmental exposures, = complex genetic diseases ie arthritis, cancer risk stratification
