Dna Sequencing & Profiling 5.5

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 Inquiry Question 5: Can population genetic patterns be predicted with any accuracy?

Content Descriptor: Investigate the use of technologies to determine inheritance patterns in a population using, for example:

DNA sequencing and profiling: (5.5.1)

DNA profiling (fingerprinting):

Involves determining the identity of an individual. It does not determine the genome or sequence of a DNA molecule.

  1. DNAis extracted and 
  2. DNAis cut using a restriction 
  3. DNAreplicated using polymerase chain reaction
  4. Electrophoresisseparates the STR based on length
  5. Stainedwith radioactive 

Used in paternity cases, identifying bodes and diagnosing inherited disorders. Restriction enzymes cut DNA along specific restriction sites. Polymorphisms (SNPs) at these sites can inactivate the restriction site, causing the unique fingerprint of each individual in the species.

DNA sequencing:

Determining the exact order of nucleotides in a DNA molecule.

  1. DNAis purified and 
  2. Genomeis replicated using enzymes
  3. Nucleicbases are stained
  4. Gene sequencing machine analyses date to produce genome sequence (this may involveelectrophoresis)

Used for determining evolution patterns, identifying phenotypic issues with SNPS

Content Descriptor: Investigate the use of data analysis from a large-scale collaborative project to identify trends, patters and relationships, for example:

The use of population genetics data in conservation management: (5.5.2)

Conservation Management:

Population genetics data can be used to identify issues with endangered animals. Sampling of differences across the population can be used to determine the size of the gene pool. One example of this is the endangered mountain Pygmy-possum. Genetics testing showed that they had an extremely small gene pool in each of the isolated populations. This lack of genetic diversity likely means that a small population would be unable to adapt to climate change. Populations from mount Kosciusko were crossbred with those from mount Bulla. This example of genetic flow helped to increase the biodiversity of the population.

Another example is the Tasmanian Devil. Study of SNPS showed that Tasmanian devils have very little genetic diversity. This meant many of them had a predisposition to not fight the fatal DFTD. In 2017 scientists found a way to force the expression of genes which fight the cancer.

Population genetics studies used to determine the inheritance of a disease or disorder: (5.5.3)

In Australia, all babies are screened for phenylketonuria (PKU). Other screening programs test for Fragile X syndrome. Testing can be performed on newborns, mothers or parents to determine if they are a carrier.

An example of a disease which is tested for is Huntingtin’s. This disease causes brain degeneration and loss of cognitive function, with an international prevalence of approximately 0.006%. It is dominant, and can be screened for; however, data analysis shows that 10% of cases involve new mutations and are not related to inheritance. Sequencing for the number of HD alleles can determine if an individual may or may not develop Huntingtins (less than 35 repeats will not develop 40 or more will develop).

Population genetics relating to human evolution: (5.5.4)

Humans are classified as a primate. There are genetic variations between human populations and individuals within a population. The 1000 Genomes Project started in 2008 as an international research to catalogue human genetic variations and changes in human evolution and predisposition to disease.

Study of mtRNA (mitochondrial DNA) has been used to support the ‘Out of Africa’ model of human migration, suggesting that there have been multiple migrations, with all present humans descending from a single group.

Inquiry Question Review: How can the genetic similarities and differences within and between species be compared? (5.5.5)

You should be able to:

  • Describeand compare DNA fingerprinting and sequencing
  • Giveexamples for the use of genetic technologies in a variety of areas