WEEK 13: Genetic Variability and Disease Flashcards
(45 cards)
What is genetic variation?
differences in DNA sequences between individuals within a population
What are 2 types of genetic variation?
germline
somatic
Explain germline genetic variation
sperm & egg causes inheritance from 1 individual to another, and affects population dynamics + impacts evolution
Explain somatic genetic variation
all other cells causes alteration in DNA that occurs after conception -> not present in the germline & not inherited by children
Define variant
specific regions of genome which differs between 2 indiviuals
Define allele
different versions of the same variant
define polymorphism
one or two (or more) variants of a particular DNA sequence
define single nucleotide polymorphism (SNP)
single base pair variation in the DNA of an individual
What is a mutation?
a change in DNA sequence away from normal
Define haplotype
a set of DNA variants (polymorphisms) close together on the same chromosome tend to be inherited (from a single parent) together more often than expected by chance
what are the 2 mechanisms that alter DNA sequence of a genome?
mutation: alteration in a nucleotide sequence of a short region of a genome which introduces new variants
recombination: alters a large region of the genome (restructuring of part of a genome)
Define recombination
the mixing of regions of parental genetic material during meiosis
what is homologous recombination?
the cross-over and exchange of DNA segments on homologous chromosomes during meiosis in eukaryotic cells
What is translocation?
part of a chromosome breaks and a portion reattaches to a different chromosome (non-homologous)
What does mutation occur as a result of?
it can arise due to errors in DNA replication
it can arise from damage from mutagens
it can arise from deficiency in DNA repair
What are 2 types of mutation, briefly describe them
single nucleotide polymorphism - single base pair diff in the DNA of an individual
structural variants - variation of a region of DNA - larger in size
What do DNA and RNA codons translate to?
amino acids
What impact does the positioning of codons have on translation?
the 3rd position of the codon is often redundant n which amino acid it translates to
the 1st and 2nd position of the codon are more sensitive
what are the 4 different types of SNPs, briefly explain them and their impact?
- synonymous mutation
- change in DNA sequence (3rd position of codon)
- result in no change of amino acid - nonsense mutation
- change in DNA sequence (A -> U)
- STOP codon - non-synonymous mutation
- change in DNA sequence
- change in amino acid - read through mutation
- change in DNA sequence at a STOP codon is changed, so gene is extended beyond the end of sequence
what is a conservative vs non-conservative non-synonymous mutation
cons: change to amino acid with similar physiochemical properties
non-cons: change to amino acid with different physiochemical properties
what are 5 different types of structural variation?
insertion
duplication
copy number variation
deletion
inversion
translocation (part of a chromosome breaks and a portion reattaches to a different chromosome)
what are similarities between mutation and recombination?
- produces rearrangements in the genome
- can produce alterations in the regular functioning and characteristics of an organism
- produces genetic variability in a population
-causes evolution
what are differences between mutation and recombination?
- mutations can be caused by errors and can be induced by external mutagens
- recombination occurs naturally mostly
- mutations are permanent, small-scale changes in the nucleotide sequences
- recombination brings large-scale rearrangements to the genome of organisms, leading to evolution
what is a phenotype a product of
the interactions of gene + environment
