Question

In: Biology

Try-Sachs is a disease characterized by progressive neurologic degeneration, and is caused by a recessive mutation....

Try-Sachs is a disease characterized by progressive neurologic degeneration, and is caused by a recessive mutation. In a certain population, the rate of Try-Sachs is 1 in 4000 births. What is the chance of being a carrier in the population?

Name three common features of plasmid vectors and what can be accomplished by each. Indicate the features that are absolutely required and why (one clear sentence about why).   

           

  

  

Solutions

Expert Solution

Q1)

Given that:

Rate of Tay Sachs = 1 in 4000 births.

Since Tay-Sachs disease is an autosomal recessive disease, the disease is only present in homozygous recessive individuals.
Therefore, the frequency of the homozygous recessive phenotype = q2 = 1/4000 = 0.00025

Therefore, q = =

Thus, p = 1 - q = 1 - 0.0158 = 0.9842

The frequency of carriers can be calculated by Freq(carrier) = 2pq = 2 * 0.9842 * 0.0158 = 0.0311

Thus, the probability of being a carrier for Tay Sachs in this populaiton is 0.0311.

Q2)

Three features that are common for all plasmid vectors are:

  1. Origin of replication: This is a sequence that is recognized by the DNA replication machinery for the replication of the plasmid DNA molecule. This sequence is required to maintain the plasmid in successive generations.
  2. Selectable Marker (Usually antibiotic resistance): A selectable marker is required as it allows users to select for cells that carry the plasmid and not for cells that do not carry the plasmid. This is usually achieved by incorporating an antibiotic resistance gene in the plasmid and then growing the cells in antibiotic-containing media. Only cells that have the plasmid with the resistance gene are able to grow in these conditions.
  3. Multiple Cloning Site: Almost all plasmid vectors also have a Multiple Cloning Site (MCS) that allows users to clone desired DNA fragments into the vector eitehr for expression or for preparing a library.

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