4 Mapping Eukaryotic chromos by recombination Flashcards
when does recombination happen
meiosis 1 NOT MEISOSIS 2
what is synteny
genes on the same chromo
what is chaismata
site of crossing over
what is recombination
a new combo of alleles
what is recombination frequency
% chance of crossing over during meiosis
which ones are linked and which are not linked AB/ab A/a;B/b
○ Notation: AB/ab = linked
○ A/a;B/b = unlinked
double crossover at 1 site leads to ________
no information swapped
linked genes lead to ____ crossing over, which means more ______ and less _____
less
parental
recombinant
what is the RF formula
○ RF (recombination frequency) = # offspring w recombinant genotypes/ tot # offspring
what is a test cross
○ Crossing ur hybrid w a homozygous recessive
what is a test cross ratio
1;1;1;1
TF - When asked “how many crossover can we detect” we count silent crossovers in our count
F, we do not count silent crossovers
what is a silent crossover
Crossing over happened but letters are the same
what does it mean if we have an RF of 0%
Genes are too close together on chromo to be split by crossing over
what are syntenic genes
○ Genes can be so far apart on the same chromosome (linked) that they act like they are independently assorted
TF all linked genes are syntenic
T
TF all syntenic genes are linked
F, All Linked genes are syntenic but not all syntenic genes are linked
if theres an RF less that 50% consider the genes _____ therefore, _______
linked
syntenic
TF, If the genes are linked they are not mendelian which means they will not have the mendelian ratios
T
what is our plan of attack is we are wanted to get the RF of a trihybrid cross
○ Identify parental, recombinant and double crossovers
○ Identify gene order
- Find the odd one out, that’s the middle gene
○ Calculate individual RFs
- DCs are always recombinant
- Parentals are never
- Count double crossovers in your RF calculations
