Bio 1A03-Theme 5 Module 1 .docx - Different sequences lead...

Different sequences lead to genetic variation
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Human genome contains instructions for coding
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Exons and regulatory proteins that code for proteins make up a small part of the sections
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Non coding RNA and single copy genes, variety of different repeated nucleotide sequences such
as tandem repeats (several thousand nucleotides in length)
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Simple sequence repeats (two nucleotides)
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Repeated over and over
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Different sequences can result in genomic variation both within and across organisms
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Not all variations in the sequences will have an observed effect
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Variation within non protein coding regions of the genome
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Genetic variations that affect organisms can be serious or beneficial
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Distribution of sequences depends on the change that occurs and where in the genome the
change happens to occur
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Effects of a change occurring in a non-coding region or non-regulatory regions
DNA polymorphisms and genetic variation
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Map out chromosomes
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DNA sequences can be determine and annotated
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Once this is done it can be possible to identity nucleotide sequences of coding and non-
coding DNA regions
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Provides insight into mechanisms of inherited diseases and genetic variability
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DNA polymorphisms are 1 of 2 or more alternate forms (or alleles) at a chromosomal regions
(locus) that differs in in a nucleotide base or have varied nucleotide repeats in a given
population of individuals
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DNA sequencing projects revealed a large number of DNA polymorphism and reside in non
coding regions of DNSA
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Allow for the assembly of high-density genetics maps are often called DNA markers
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DNA markers are detected using DNA array analysis, PCR, southern blot, DNA sequencing
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Used to identity individuals and show relatedness
Detecting SNPs
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99.9% of human DNA sequences are the same, genetic variations account for differences
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Single nucleotide polymorphisms (SNPs) are the most common type of genetic variation
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Brought about by single nucleotide base changes or substitutions in a DNA sequences
that can occur in an entire population
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Found scattered through the genome and found in coding and non coding regions
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1 in every 350 base pairs
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Occur in noncoding regions
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If found close to a specific gene they can be used as DNA markers
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If linked to a specific gene it can be passed on from a parent to a child (the SNP
is also passed on)
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DNA microarray is used to detect SNPs
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Oligonucleotides that match the common allele and all possible variant SNP alleles are
attached to the glass of the microarray chip
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Single oligonucleotides contain a known sequence, contain a nucleotide base in the
middle which is complementary to the SNP allele