Chapter 7: Linkage and Chromosome Mapping Flashcards
linked genes are
certain genes segregate as if part of same chromosome-inherited as a single unit
characteristics of genes linked on the same chromosome
- no crossing over occurs
- only two genetically different gametes are produced
- complete linkage produces parental gametes in equal proportions
crossing over between two linked genes involves 2 nonsister chromatids and generates
recombinant gametes
gametes with two new allele combinations
why will the number of recombinant genes never exceed 50%?
outer chromosomes will never recombine
genes that are located closely to one another are
- less likely to have chiasma between them
- less likely crossing over will occur
who created the first chromosomal map?
Alfred Sturtevant
the chromosomal theory states that…
chromosomes contain genes in linear order
the maximum frequency of recombined genes is
50%
single crossovers are used to determine the
distance between two linked genes
double crossovers are used to determine the
order of three genes on a chromosome
chromosome mapping is used to
understand genetic control of disease transmission
the greater the distance between two genes the less
accuracy of gene mapping
equation for interference
I = 1-C
equation for coefficient of coincidence
C= observes DCO/ expected DCO
describe the relationship between observed and expected with positive interference
- low observed
- high expected
