Chromosomal basis of inheritance chap15 Flashcards
Relationship between genes and chromosomes
Genes are located on chromosomes in diploid cells, chromosomes are present in genes in pairs.
Chromosomal habits
They duplicate before cell division, each duplicated chromosomes contain two copies of each allele, one on each sister chromatid.
Homologous pairs
Separate in meiosis, so each sperm or egg receives just one member. This process mirrors segregation of alleles into gametes in Mendel’s law of segregation.
Chromosomal sorting
The members of different chromosome pairs are sorted into gametes independently of one another in meiosis, just like the alleles of different genes in Mendel’s law of independent assortment.
Key points of chromosomal inheritance
When genes are found on different chromosomes or far apart on the same chromosome, they assort independently and are said to be unlinked.
Key points of chromosomal inheritance (p2)
When genes are close together on the same chromosome, they are said to be linked. That means the alleles, or gene versions, already together on one chromosome will be inherited as a unit more frequently than not.
Key points of chromosomal inheritance (p3)
We can see if two genes are linked, and how tightly, by using data from genetic crosses to calculate the recombination frequency.
Key points of chromosomal inheritance (p4)
By finding recombination frequencies for many gene pairs, we can make linkage maps that show the order and relative distances of the genes on the chromosome.
Recombination frequencies
Comparison of recombination frequencies can also be used to figure out the order of genes on a chromosome. By figuring out which genes have the furthest distance from each other, then finding out the distance between each set of genes in relation to the two with the farthest difference in length.
Gene linkage maps
Using the crossover frequencies, you can construct a map to represent the distances between genes.
