ANT203H5 Lecture Notes - Lecture 17: Polymerase Chain Reaction, Human Genome Project, Alu Element
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Searching for Answers in our Genome
- Molecular anthropology is a discipline of physical anthropology focused in the study of
the genetic variation in human populations
- Information on genetic polymorphisms, at the protein or DNA level, is fundamental in
order to understand the origin, demographic histories and genetic relationships between
contemporary human populations.
A Wonderful Research Tool: the PCR Technique
- The discovery of the Polymerase Chain Reaction (PCR) technique (Mullis, 1983) opened
a wide range of possibilities for the study of the genetic variation directly at the DNA
o PCR – polymerase chain reaction: technique to amplify the DNA multiple times
o This technique revolutionized the way we study the DNA; so he got the nobel
prize for this
Types of DNA Markers
- There are many types of DNA markers in the human genome that can provide
information about our evolution.
- A brief description of some of these markers follows.
DNA Markers: Single Nucleotide Polymorphisms (SNPs)
- SNPs are single nucleotide base substitutions.
o They are just changes in one letter
o This is frequent in our genome
- SNPs are the most abundant markers in the human genome. More than 37 million SNPs
have been reported in the most recent 1,000 genomes data release.
DNA Markers: Alu Insertions
- Alu retroelements are part of the family of jumping genes known as short interspersed
elements or SINEs. Alu sequences are roughly 300 nucleotides in length, and they are
dispersed along the human genome.
o They are polymorphic; and are present in some chromosomes (can be used to
study evolutionary events)
- Some Alu sequences are polymorphic in human populations (presence/absence of the Alu
insertion). The insertion of an Alu sequence only happens once in a particular genome
o You can see whales and hippos share some of these insertions (they are closest
Detection of Alu Polymorphisms
- Electrophoresis: technique separating fragments by size (depending on what substrate
o A way to identify them, as DNA is negatively charged (and it will go towards the
DNA Markers: Microsatellite Polymorphsms (aka STRs)
- Microsatellites are tandemly repeated short nucleotide sequences (2-13 nucleotides)
dispersed all over the genome. In many cases, they show polymorphism in the number of
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