UMKC GENETICS TEST 2 EXAM
QUESTIONS AND ANSWERS GRADED A+
2026
Which form of human DNA analysis is used by the FBI? - ANS CODIS of 13 loci
(Combined DNA Index System)
Describe CODIS - ANS -Uses 13 separate loci
-Alleles used are short tandem repeats
-The number of alleles and loci mean that the probability of a similar match is as low as 1x10^18
Chiasmata - ANS -Sites of crossing over
-Occurs between non-sister chromatids
T or F, Chiasmata never occur between sister chromatids? - ANS -False
-It happens, but is extremely rare
_________ arise from two crossovers. - ANS Double Recombinants
@COPYRIGHT 2026/2027 ALL RIGHTS RESERVED
1
,In three-point test crosses, double recombinants will give ___________. - ANS Parental
Classes
Double crossovers lead to _________ of recombination frequencies between distant markers. -
ANS Underestimates
How do you calculate m.u.? - ANS (Actual recombinants)/(Total Progeny) x 100
Haldane's Mapping Function - ANS A mathematical formula to "correct" unforeseen
crossover
How does Haldane's Mapping function work? - ANS -Recombination frequencies are
converted to a mean (m) value of crossovers the should have taken place
-This is based on the chance of no cross over events occurring, and the Poisson distribution
Perkin's Formula - ANS Works only on tetrad-producing organisms
Which three people are considered the originators of population genetics? - ANS -R.A.Fischer
-S. Wright
-J.B.S. Haldane
According to Fischer, Mendel should have obtained a _:_ ratio when retesting his F2 progeny. -
ANS 1.7:1 instead of his 2:0 ratio
What are some reasons Mendel was able to obtain a 2:1 ratio? - ANS -May have replanted
seeds when not all ten germinated
@COPYRIGHT 2026/2027 ALL RIGHTS RESERVED
2
, -Lucky he picked a diploid plant and chose seven unlinked loci
How were genes identified before genome sequences? - ANS Complementation and
Positional Cloning
Complementation - ANS Introducing a library of wild type DNA fragments into a mutant
organism and looking for the DNA and Complements
_________ are ideal for fine detail mapping. - ANS Molecular Markers
Steps to Positional/Map Based Cloning - ANS -Cross mutant to wild type
-Score traits of progeny
-Isolate DNA and analyze alleles in parents and progeny
-Generate a genetic map
-Define adjacent markers
-Narrow Region in which gene may lie
-Examine Genome sequence for genes
-Sequence alleles in mutants as first step in confirmation
Recombination frequency and physical distance correlate, but ________ do not. -
ANS Absolute distance
What does m.u. represent? - ANS An average across a region, this value varies across the
chromosome.
@COPYRIGHT 2026/2027 ALL RIGHTS RESERVED
3
QUESTIONS AND ANSWERS GRADED A+
2026
Which form of human DNA analysis is used by the FBI? - ANS CODIS of 13 loci
(Combined DNA Index System)
Describe CODIS - ANS -Uses 13 separate loci
-Alleles used are short tandem repeats
-The number of alleles and loci mean that the probability of a similar match is as low as 1x10^18
Chiasmata - ANS -Sites of crossing over
-Occurs between non-sister chromatids
T or F, Chiasmata never occur between sister chromatids? - ANS -False
-It happens, but is extremely rare
_________ arise from two crossovers. - ANS Double Recombinants
@COPYRIGHT 2026/2027 ALL RIGHTS RESERVED
1
,In three-point test crosses, double recombinants will give ___________. - ANS Parental
Classes
Double crossovers lead to _________ of recombination frequencies between distant markers. -
ANS Underestimates
How do you calculate m.u.? - ANS (Actual recombinants)/(Total Progeny) x 100
Haldane's Mapping Function - ANS A mathematical formula to "correct" unforeseen
crossover
How does Haldane's Mapping function work? - ANS -Recombination frequencies are
converted to a mean (m) value of crossovers the should have taken place
-This is based on the chance of no cross over events occurring, and the Poisson distribution
Perkin's Formula - ANS Works only on tetrad-producing organisms
Which three people are considered the originators of population genetics? - ANS -R.A.Fischer
-S. Wright
-J.B.S. Haldane
According to Fischer, Mendel should have obtained a _:_ ratio when retesting his F2 progeny. -
ANS 1.7:1 instead of his 2:0 ratio
What are some reasons Mendel was able to obtain a 2:1 ratio? - ANS -May have replanted
seeds when not all ten germinated
@COPYRIGHT 2026/2027 ALL RIGHTS RESERVED
2
, -Lucky he picked a diploid plant and chose seven unlinked loci
How were genes identified before genome sequences? - ANS Complementation and
Positional Cloning
Complementation - ANS Introducing a library of wild type DNA fragments into a mutant
organism and looking for the DNA and Complements
_________ are ideal for fine detail mapping. - ANS Molecular Markers
Steps to Positional/Map Based Cloning - ANS -Cross mutant to wild type
-Score traits of progeny
-Isolate DNA and analyze alleles in parents and progeny
-Generate a genetic map
-Define adjacent markers
-Narrow Region in which gene may lie
-Examine Genome sequence for genes
-Sequence alleles in mutants as first step in confirmation
Recombination frequency and physical distance correlate, but ________ do not. -
ANS Absolute distance
What does m.u. represent? - ANS An average across a region, this value varies across the
chromosome.
@COPYRIGHT 2026/2027 ALL RIGHTS RESERVED
3
