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Chapter 5

BIOLOGY 1A03 Chapter Notes - Chapter 5: Noncoding Dna, Oligonucleotide, Genetic Linkage

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Rosa Da Silva

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Bio 1A03 March 16th, 2017
Genetic Variation
Key Points
-different types of DNA sequences can lead to genetic variation
-detection of genetic variation
-harmless vs harmful changes in DNA sequences
-different DNA sequences and variations are prevalent within and across various populations
Tandem Repeats: can be several thousand nucleotides in length and be present next to each
other in multiple identical or near identical copies
.directly adjacent to each other
Simple Sequence Repeats: repeats as short as 2 nucleotides
-not all variations in the genome have an observed affect
-the outcome of a variation depends on the exact nature of the change and where in the
genome the change occurs
Polymorphisms and Genetic Variation
-a DNA polymorphism is one of two or more alternative forms (alleles) at a chromosomal
region (locus) that differs in either a single nucleotide base, or have variable numbers of
tandem repeats
-a large number of polymorphisms reside in non-coding DNA, they can be used to assemble a
high-density genetic map, referred to as DNA markers
-DNA markers are detectable using microarray analysis PCR and souther blot, and can be used
to identify individuals and show relatedness
Detecting SNP’s
—SNP’s are the most common type of genetic variation
—brought about by a single nucleotide base substitution
-occurs every 1 in 350 base pairs
-if a SNP is located close to a gene, it can be used as a marker, and can be passed on from
parent to child
-Microarray: oligonucleotides that match the common allele and all possible variant SNO
alleles are attached to the glass
.to detect SNP’s, millions of short, single stranded oligonucleotides of known sequence (and
contain a base complimentary to SNP) are attached to the chip
.fragments of the single-stranded fluorescently-labeled DNA are hybridized to the chip
.it is possible to match the emergent fluorescent pattern based on which SNP each individual
has (including homo, and heterozygous information)
Detecting VNTRs with PCR
-“DNA fingerprinting”
-uses variable number of tandem repeats because while VNTR loci are very similar between
close relatives, they are variable enough that unrelated people will not have the same VNTRs
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