Linkage and linkage maps Flashcards
what is a Model organism and why are they important?
A model organism is an organism that we use to study mainly genetic concepts that apply to us as humans. Research using model organisms can help us understand plants, animals, and microbes and lead to discoveries that impact our everyday lives through life-saving medicine and a stable food supply. There are many historical and recent discoveries that have been made using model organisms.
why linkage between two genes on a single chromosome does not allow the two genes to assort independently.
This is because they are on the same chromosome meaning that they will move together. The only way for them to be split up would be through crossing over events
Predict parental and recombinant type frequencies, assuming two genes are independently assorting
In this case, we can assume that It would be a 50-50 ratio if the genes are linked, if the genes are NOT linked then the ratio can be anywhere between 0-50 %
how to set up test crosses to test for independent assortment
Test crosses can be used to determine whether a dominant phenotype is homozygous or heterozygous
If the unknown parent is homozygous dominant, all offspring will express the dominant phenotype
If the unknown parent is heterozygous, half the offspring should be dominant and half recessive
Test crosses can also be used to determine if two genes are linked or unlinked by mating with a known heterozygote
If there is an equal ratio of the four potential phenotypes, the two genes are likely unlinked (independent assortment)
If there are two phenotypes in high amounts and two phenotypes in low amounts (recombinants), the two genes are likely linked
A chi-squared test for association can be used to determine the statistical likelihood of each scenario
sex linkage vs linkage
Genetic linkage is caused when two genes are located on the same chromosome. A chromosome is a long string of many, many genes attached together. The two genes will travel together during meiosis, which is important for separating chromosome pairs. And sex linkage is when a gene is located on a sex chromosome (X or Y)
