Genetic variation Flashcards
only … and … are genetically identical
clones and monzygotic twins
what could be different about the DNA of monozygotic twins
epigenetic inheritance e.g. chromatin and histone modifactions, methylation
types of genetic variation
- single nucleotide polymorphisms (SNPs) 2. Indels 3. copy number variation 4.strucutral rearrangements 5.
polymorphisms
two or more alleles of a gene, common in a population
types of DNA sequencing
sanger next generation
single molecule
what are copy- number generations caused by ?
large insertion/deletions in one chromosome
copy number variation (CNV)
is defined as a phenomenon in which sections of the genome are repeated and the number of repeats in the genome varies between individuals in the human population.
structural rearrangements of chromosomes
translocations
inversion
SNPs
single nucleotide polymorphisms- single base pair changes -occurs at a specific position in the genre, where each variation is present to some appreciable degree within a population
Indels
Insertion and deletions
most genetic variation has…
no phenotypic effect
how can SNPs be detected
DNA hybridisation technique
how deletions differ to SNP
more than one pair is deleted
example of an SNP which causes diseasw
eg. a single base pair change can cause sickle cell anaemia
Indels with phenotypic effect -deletions -insertions
deletion: CF- 3 base pairs
insertion: one base pair can cause albinism
how many indwells have been identified in human genomics
4 x10^5
percentage of indwells which are tandem repeat expansion polymorphisms
30%
what are Short Tandem repeats (STRs)
multi-allelic and used in genetic profiling accordion-like stretches of DNA containing core repeat units of between two and seven nucleotides in length that are tandemly repeated from approximately a half dozen to several dozen times
STRs
short tandem repeats
STRs are also known as
minisateellites
STRs are ..
unique in everyone humans
how can indwells cause a new protein
by coding for a stop codon, by changing the amino acid sequence, by causing a frameshift
why do indwells normally disrupt protein structure
if in coding region it may cause a frame shift due to the non-overlapping nature of dna
effects of base substitutions (4)
silent neutral mis-sense nonsense
effect of genetic variation on INTERGENIC REGIONS
Often no phenotypic effect- silent
effect of genetic variation on non coding regions of genes (introns, promotor, UTRs):
may be silent, however may effect gene expression
effect of genetic variation on protein coding regions
various effects
Sanger method
Method: in vitro DNA synthesis with base specific chain- termination inhibitors. Detection: gel electrophoresis Typical length of sequence: 800 bases -accurate, low throughput
Next generation sequencing
Method: massive parallel in vitro DNA synthesis Detection: fluorescence detection of incorporated nucleotides Typical length of sequence: 100 bases -extremely high throughput
