L5 Linkage Mapping

Question 1

Law of independent assortment

Answer 1

The law of independent assortment states that the alleles of one gene sort into gametes independently of the alleles of another gene.

Question 2

Chromosomal Theory of Heredity

Answer 2

fundamental unifying theory of genetics which identifies chromosomes as the carriers of genetic material.

Question 3

Recombination

Answer 3

DNA recombination involves the exchange of genetic material either between multiple chromosomes or between different regions of the same chromosome.

Question 4

Poisson Distribution

Answer 4

It measures the probability that a certain number of events occur within a certain period of time

Question 5

Huntington’s disease

Answer 5

Huntington’s disease (HD) is a genetic neurodegenerative disease. This means that it is a disease of the brain that is passed down from parent to child.

Question 6

Positional cloning

Answer 6

Positional cloning is a laboratory technique used to locate the position of a disease-associated gene along the chromosome. This approach works even when little or no information is available about the biochemical basis of the disease. Positional cloning is used in conjunction with linkage analysis.

Positional cloning typically involves the isolation of partially overlapping DNA segments from genomic libraries to progress along the chromosome toward a specific gene. During the course of positional cloning, one needs to determine whether the DNA segment currently under consideration is part of the gene.

Question 7

Genetic mapping

Answer 7

to identify chromosomal location of genetic variants

Genetic mapping is the process of determining the order of and relative distance between genetic markers (specific sequences or heritable elements that generate a phenotype) on a chromosome based on their pattern of inheritance.

Question 8

Chi square test

Answer 8

The chi-squared test is used to determine whether there is a significant difference between the expected frequencies and the observed frequencies in one or more categories.

measures how well data fits to a known distribution

Question 9

Maximum likelihood methods

Answer 9

In statistics, maximum likelihood estimation (MLE) is a method of estimating the parameters of a statistical model, given observations. MLE attempts to find the parameter values that maximize the likelihood function, given the observations.

Likelihood of the odds

• probability of supporting the parameter given the data
• LOD is the log-ratio of two likelihoods

Question 10

Isozymes

Answer 10

enzymes that differ in amino acid sequence but catalyze the same chemical reaction

Question 11

Recombinant Inbred Lines

Answer 11

RILs are useful for preliminary mapping of any trait that differs between the parental strains used to generate the population. The great thing about RILs is that the same mapping population can be maintained and used over and over again to map all kinds of different traits. They can also reveal multiple loci contributing to any trait of interest. The downside is that they are less statistically powerful for analyzing effects of any one particular locus, because each RIL also harbors potentially confounding background genetic variation.

Question 12

Near Isogenic Lines

Answer 12

Near-isogenic lines (NILs) are strains which genetic makeups are identical except for few specific locations or genetic loci

NILs are most useful when you have a candidate gene or one particular locus of interest. They will allow you to measure the effect of allelic variation at that locus only, while eliminating background genetic variation. NILs are more powerful than RILs but can only be used to study one locus at a time. Furthermore, you can’t generate useful NILs until you have a candidate locus to “zoom in on,” which typically comes from previous RIL studies.

Question 13

Advanced intercross RILS

Answer 13

Advanced intercross populations, in which multiple inbred strains are mated at random for many generations, have the advantage of greater precision of genetic mapping because of the accumulation of recombination events across the multiple generations.

Question 14

Multiparent Advanced Intercross Lines

Answer 14

• testing multiple alleles in multiple genetic backgrounds

1. diallele cross
2. generations of intermating
3. 5-6 selfing generations

Question 15

covariance

Answer 15

covariance is a measure of the joint variability of two random variables.

Question 16

Physical maps

Answer 16

physical map is based on the actual number of nucleotide pairs between loci.

Question 17

Genetic map

Answer 17

The relative distances between positions on a genetic map are calculated using recombination frequencies

Question 18

Synteny

Answer 18

Physical co-localisation of genetic loci on the same chromosome within an individual or species
- conservation of order of loci across taxa

Question 19

Association Mapping

Answer 19

Association mapping (genetics), also known as “linkage disequilibrium mapping”, is a method of mapping quantitative trait loci (QTLs) that takes advantage of historic linkage disequilibrium to link phenotypes (observable characteristics) to genotypes (the genetic constitution of organisms), uncovering genetic associations.