Part IV

1. If two events are independent, we can multiply the seperate probabilities of each event to determine the probability of both events occurring. If two loci are located on non-homologous chromosomes, the probability of one chromosome with one type of allele going to a pole during meiosis does not influence which allelemorph at a non-homologous chromosome goes to the same pole during anaphase. These independent events result in the 1:1:1:1 testcross ratio for two alleles at each of two loci.
   
   
2. Whe two events are not independent then Probability(A) x Probability(B) does not equal Probability(A and B). When two events are not independent we must consider the conditional probability to determine the joint probability of both events occuring. In general, Probability(A) x Probability(B/A) = Probability(A and B).
   
   
3. The Probability(B/A) is the conditional probability of B given that event A has occurred. The probability of event B occurring is changed when event A has already occurred. This is because the sample space is reduced for event B when event A has occurred.
   
   
4. For marker assisted selection (MAS), as the recombination between the marker and the QTL increases, the effectiveness of MAS decreases. This is because a smaller proportion of favorable QTL genotypes will be selected when recombination between the marker and QTL is increased.
   
   
5. For single marker-QTL associations, the mean of each QTL genotype cannot be estimated unless the recombination fraction between the QTL and the marker is known. Because the recombination fraction between the QTL and marker is unknown, only the mean of each marker class can be estimated.
   
   
6. The mean of each QTL class cannot be estimated unless interval mapping is conducted. Interval mapping means that the QTL is flanked by a marker on either side.
   
   
7. For single marker-QTL associations, the peak lod score of the QTL cannot be determined. For interval mapping, the peak lod score is the QTL position only when there is a single QTL between the flanking markers.