Lecture 5 Flashcards
(18 cards)
principle of segregation
each individual diploid organism possesses two alleles at a locus that separates in Meiosis, with one allele going into each gamete.
principle of independent assortment
in the process of separation, the alleles at a locus act independently of the alleles at other loci
Recombination
the sorting of alleles into new combinations
recombination frequency
the frequency of recombinant gametes is half of the frequency of crossing over
(total of recombinant progeny)/total number of progeny
recombinant gametes - calculate
1/2r
nonrecombinant gametes - calculate
1/2 (1-r)
linked
- genes located on the same chromosome are linked; belong to the same linkage groups
test cross
cross between individual with unknown genotype and an individual with homozygous recessive phenotype
The frequency of recombination is always
half the frequency of crossing over.
Max proportion of frequency of recombination
50%
calculate recombination frequency
(# recombinant progeny)/(total # progeny) * 100
cis configuration
wild types on the same side with mutant on the other side
p+b+/pb
trans configuration
each chromosome has one wild type and one mutant type
p+b/pb+
the phenotypes of the offspring are the same but
their numbers differ depending on whether alleles are in coupling (cis) or repulsion (trans)
reverse mapping
going back from recombination frequency to figure out # of progeny
genetic maps
chromosome maps constructed using recombination data
map units
- distance on genetic maps measured in cM
- equals 1% recombination
- genetic distances are approximately additive
two-point test cross
a test cross between two genes
