Genetics Final

Question 1

Explain what incomplete penetrance is and why it can cause problems for medicine

Answer 1

Incomplete penetrance is when the genotype does not always produce the expected phenotype. Example is that some people have the allele for polydactyly (usually a dominant allele) but nevertheless have a normal number of fingers and toes). This can be a problem for medicine, specifically genetic counseling because when looking at the genetics of an individual they may have an allele for a genetic disease but never express the phenotype of the other way around where they do not have the allele for that disease but in fact do express the phenotype of that disease.

Question 2

Please explain how duplicate recessive epistasis determines how a phenotype is expressed. In your answer, give an example of a phenotype determined by duplicate recessive epistasis

Answer 2

recessive alleles at either of the two loci are capable of suppressing phenotype. Albinism in snails is aa good example which has two enzymes each controlled by their own locus that both need to be expressed for there to be pigmentation. If there is either an aa or a bb then the snail will be white

Question 3

When constructing a statistical test for investigating if two loci are linked it is a good idea to do a chi squared test of independence. Please tell me why this version of a chi squared is more appropriate than a goodness of fit test

Answer 3

For the chi squared goodness of fit test, the expected value is based on a theoretical relation. For the chi square test of independence, the value is based on the observed values, along with the assumption that they are independent

Question 4

Explain why this statement is incorrect

Completely linked genes are ALWAYS next to each other along a chromosome

Answer 4

In certain areas, where crossing over and recombination cant happen (like the areas of the centromeres) completely linked genes do not need to be right next to each other along the chromosome

Question 5

explain why this statement is incorrect

Unlinked genes are on different chromosomes

Answer 5

If two genes have a recombination rate over 50 percent (or are further than 50 centimorgans apart) and they are on the same gene then they would be considered unlinked while being on the same gene

Question 6

Two genetic varieties of corn, A and B, are field tested in both indiana and virginia. Variety A is more vigorus and produced a higher yeild than B in indiana, but variety B is more productive than A in virginia. What phenomenon in quantitative genetics does this observation illustrate

Answer 6

This variance in phenotype is due to genetic variance and environmental variance or Vge